KNOT Offshore Partners (KNOP) 20-F 17 Mar 22 2021 FY Annual report (foreign) Financial data

Document and Entity Information

Document and Entity Information	12 Months Ended
	Dec. 31, 2021shares
Document Type	20-F
Entity Registrant Name	KNOT Offshore Partners LP
Entity Central Index Key	0001564180
Document Period End Date	Dec. 31, 2021
Document Registration Statement	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Title of 12(b) Security	Common units
Trading Symbol	KNOP
Security Exchange Name	NYSE
Document Annual Report	true
Document Transition Report	false
Document Shell Company Report	false
Entity File Number	001-35866
Entity Incorporation, State or Country Code	1T
Entity Address, Address Line One	2 Queens Cross
Entity Address, Postal Zip Code	AB15 4YB
Entity Address, City or Town	Aberdeen
Entity Address, Country	GB
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding	33,708,541
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Accounting Standard	U.S. GAAP
Entity Shell Company	false
Amendment Flag	false
Auditor Name	Ernst & Young AS
Auditor Firm ID	1572
Auditor Location	Oslo, Norway
Business Contact [Member]
Contact Personnel Name	Gary Chapman
Contact Personnel Email Address	E-mail: gch@knotoffshorepartners.com
City Area Code	44 (0)
Local Phone Number	1224 618420
Entity Address, Address Line One	2 Queens Cross
Entity Address, Postal Zip Code	AB15 4YB
Entity Address, City or Town	Aberdeen
Entity Address, Country	GB

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020	Dec. 31, 2019
Operating revenues: (Notes 2(e), 5 and 17)
Time charter and bareboat revenues		$ 269,306,000		$ 278,581,000	$ 282,502,000
Loss of hire insurance recoveries (Notes 2(t) and 8)		11,450,000
Other income		373,000		641,000	59,000
Total revenues and other income (Notes 2(e), 5, 6, 7 and 17)		281,129,000		279,222,000	282,561,000
Operating expenses:
Vessel operating expenses (Notes 2(e) and 17)		72,114,000		61,005,000	60,129,000
Depreciation (Note 13)		99,559,000	[1]	89,743,000	89,844,000
Impairment (Note 21)	[1]	29,421,000
General and administrative expenses		6,461,000		5,392,000	4,858,000
Total operating expenses		207,555,000		156,140,000	154,831,000
Operating income		73,574,000		123,082,000	127,730,000
Finance income (expense): (Notes 2(f) and 17)
Interest income		2,000		125,000	865,000
Interest expense (Note 9(a))		(28,065,000)		(31,645,000)	(50,735,000)
Other finance expense (Note 9(b))		(1,011,000)		(705,000)	(845,000)
Realized and unrealized gain (loss) on derivative instruments (Note 10)		9,960,000		(25,679,000)	(17,797,000)
Net gain (loss) on foreign currency transactions		(96,000)		57,000	(252,000)
Total finance expense		(19,210,000)		(57,847,000)	(68,764,000)
Income before income taxes		54,364,000		65,235,000	58,966,000
Income tax benefit (expense) (Notes 2(r) and 16)		(488,000)		(10,000)	(9,000)
Net income		53,876,000		65,225,000	58,957,000
Series A Preferred unitholders' interest in net income		6,900,000		7,200,000	7,200,000
General Partner's interest in net income		862,000		1,072,000	956,000
Limited Partners' interest in net income		$ 46,114,000		$ 56,953,000	$ 50,801,000
Earnings per unit (Basic): (Note 19)
General Partner unit (basic & diluted)		$ 1.38		$ 1.74	$ 1.55
Earnings per unit (Diluted): (Note 19)
General Partner unit (basic & diluted)		1.38		1.74	1.55
Common Units [Member]
Earnings per unit (Basic): (Note 19)
Common unit (basic)		1.38		1.74	1.55
Earnings per unit (Diluted): (Note 19)
Common unit (diluted)		1.38		$ 1.74	$ 1.55
Class B Units
Earnings per unit (Basic): (Note 19)
Common unit (basic)		2.62
Earnings per unit (Diluted): (Note 19)
Common unit (diluted)		$ 2.62
[1]	The carrying value of the Windsor Knutsen was written down to its estimated fair value as of June 30, 2021. See Note 21—Impairment of Long-Lived Assets.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Consolidated Statements of Comprehensive Income
Net income	$ 53,876	$ 65,225	$ 58,957
Other comprehensive income, net of tax	0	0	0
Comprehensive income	$ 53,876	$ 65,225	$ 58,957

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents (Notes 2(g) and 11)	$ 62,293	$ 52,583
Amounts due from related parties (Note 17(c))	2,668	5,726
Inventories (Note 2(i))	3,306	2,652
Other current assets (Notes 2(j) and 12(b))	5,626	5,511
Total current assets	73,893	66,472
Long-term assets:
Vessels, net of accumulated depreciation (Notes 2(k), 2(l), 2(m), 2(n), 13 and 17(e))	1,598,106	1,708,786
Right-of-use assets (Note 6)	2,742	1,490
Intangible assets, net (Notes 2(o) and 14(a))	75	681
Derivative assets (Notes 2(q), 10 and 11)	1,015
Accrued income	1,450	2,867
Total long term assets	1,603,388	1,713,824
Total assets	1,677,281	1,780,296
Current liabilities:
Trade accounts payable (Note 17(d))	3,872	3,848
Accrued expenses	6,429	5,380
Current portion of long-term debt (Notes 11 and 15)	88,578	184,188
Current lease liabilities (Note 6)	648	652
Current portion of derivative liabilities (Notes 2(q), 10 and 11)	6,754	10,695
Income taxes payable (Notes 2(r) and 16)	548	86
Current portion of contract liabilities (Notes 2(o) and 14(b))	1,518	1,518
Prepaid charter (Note 2(s))	6,186	5,424
Amount due to related parties (Note 17(c))	1,424	2,140
Total current liabilities	115,957	213,931
Long-term liabilities:
Long-term debt (Notes 2(p), 11 and 15)	878,548	846,157
Lease liabilities (Note 6)	2,093	838
Derivative liabilities (Notes 2(q), 10 and 11)	4,260	19,358
Contract liabilities (Notes 2(o) and 14(b))	651	2,168
Deferred tax liabilities (Notes 2(r) and 16)	228	295
Deferred revenues	2,529
Total long-term liabilities	888,309	868,816
Total liabilities	1,004,266	1,082,747
Commitments and contingencies (Notes 2(t) and 18)
Series A Convertible Preferred Units (Notes 19 and 20)	84,308	89,264
Partners' capital:
General partner interest: 640,278 and 615,117 units issued and outstanding at December 31, 2021 and 2020, respectively.	10,492	10,895
Total partners' capital	588,707	608,285
Total liabilities and equity	1,677,281	1,780,296
Common Units [Member]
Partners' capital:
Common unitholders	568,762	$ 597,390
Class B Units
Partners' capital:
Common unitholders	$ 9,453

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Allowance for doubtful accounts	$ 0	$ 0
General partners' capital account, units issued	640,278	615,117
General partners' capital account, units outstanding	640,278	615,117
Common Units [Member]
Limited partners' capital account, units issued	33,708,541	32,694,094
Limited partners' capital account, units outstanding	33,708,541	32,694,094
Class B Units
Limited partners' capital account, units issued	588,945	0
Limited partners' capital account, units outstanding	588,945	0

Consolidated Statements of Chan

Consolidated Statements of Changes in Partners' Capital - USD ($) $ in Thousands		General Partner Unit [Member]Accumulated Other Comprehensive Income [Member]	General Partner Unit [Member]	Common Units [Member]ATM	Common Units [Member]	Class B Units	Accumulated Other Comprehensive Income [Member]ATM	Accumulated Other Comprehensive Income [Member]	ATM	Total
Beginning balance at Dec. 31, 2018			$ 11,531		$ 631,244			$ 0		$ 642,775
Net income			956		50,801			0		51,757
Other comprehensive income			0		0	$ 0		0		0
Cash distributions			(1,332)		(70,804)			0		(72,136)
Ending balance at Dec. 31, 2019			11,155		611,241			0		622,396
Convertible preferred units, beginning balance at Dec. 31, 2018										89,264
Net income										7,200
Cash distributions										(7,200)
Convertible preferred units, ending balance at Dec. 31, 2019										89,264
Net income			1,072		56,953			0		58,025
Other comprehensive income			0		0	0		0		0
Cash distributions			(1,332)		(70,804)			0		(72,136)
Ending balance at Dec. 31, 2020			10,895		597,390			0		608,285
Net income										7,200
Cash distributions										(7,200)
Convertible preferred units, ending balance at Dec. 31, 2020										89,264
Net income			862		45,466	648		0		46,976
Conversion of preferred units to common units					4,856			0		4,856
Net proceed from issuance of capital		$ 0	451	$ 525			$ 0		$ 525
IDR Exchange	[1]		(384)		(10,079)	10,463		0
Conversion of Class B (one-eight) to common units	[1]				1,308	(1,308)		0
Other comprehensive income			0		0	0		0		0
Cash distributions			(1,332)		(70,704)	(350)		0		(72,386)
Ending balance at Dec. 31, 2021			$ 10,492		$ 568,762	$ 9,453		$ 0		588,707
Net income										6,900
Conversion of preferred units to common units										(4,856)
Cash distributions										(7,000)
Convertible preferred units, ending balance at Dec. 31, 2021										$ 84,308
[1]	On September 7, 2021, the Partnership entered into an exchange agreement with Knutsen NYK and the Partnership’s general partner whereby Knutsen NYK contributed to the Partnership all of Knutsen NYK’s IDRs, in exchange for the issuance by the Partnership to Knutsen NYK of 673,080 common units and 673,080 Class B Units, whereupon the IDRs were cancelled. As of December 31, 2021, 84,135 of the Class B Units had been converted to common units.

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Partners' Capital (Parenthetical) - shares	Dec. 31, 2021	Nov. 10, 2021	Dec. 31, 2021	Sep. 07, 2021
Common Units [Member]
Number of units in exchange of IDRs	673,080		673,080	673,080
Number of units converted			215,292
Class B Units [Member]
Number of units in exchange of IDRs				673,080
Number of units converted	84,135	84,135

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020	Dec. 31, 2019
OPERATING ACTIVITIES
Net income		$ 53,876,000		$ 65,225,000	$ 58,957,000
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation		99,559,000	[1]	89,743,000	89,844,000
Impairment	[1]	29,421,000
Amortization of contract intangibles / liabilities		(912,000)		(912,000)	(912,000)
Amortization of deferred debt issuance cost		3,519,000		2,503,000	2,617,000
Drydocking expenditure		(4,235,000)		(2,724,000)	(252,000)
Income tax expense		488,000		10,000	9,000
Income taxes paid		(83,000)		(87,000)	(132,000)
Interest expense		24,546,000		29,141,000	48,117,000
Interest paid		(25,103,000)		(30,985,000)	(49,037,000)
Unrealized (gain) loss on derivative instruments		(20,054,000)		22,042,000	18,676,000
Unrealized (gain) loss on foreign currency transactions		13,000		(507,000)	44,000
Changes in operating assets and liabilities
Decrease (increase) in amounts due from related parties		3,058,000		(3,039,000)	(1,547,000)
Decrease (increase) in inventories		(653,000)		(225,000)	152,000
Decrease (increase) in other current assets		(117,000)		(1,865,000)	(912,000)
Decrease (increase) in accrued revenue		1,418,000		1,108,000	(168,000)
Increase (decrease) in trade accounts payable		18,000		700,000	(2,100,000)
Increase (decrease) in accrued expenses		1,605,000		(15,000)	1,073,000
Increase (decrease) prepaid revenue		763,000		(1,469,000)	1,121,000
Increase (decrease) in amounts due to related parties		(716,000)		597,000	142,000
Net cash provided by operating activities		166,411,000		169,241,000	165,692,000
INVESTING ACTIVITIES
Additions to vessel and equipment		(11,536,000)		(339,000)
Net cash provided by (used in) investing activities		(11,536,000)		(21,433,000)
FINANCING ACTIVITIES
Proceeds from long-term debt (Note 15)		444,300,000		33,000,000
Repayment of long-term debt (Note 15)		(505,822,000)		(92,834,000)	(84,534,000)
Payment of debt issuance cost		(5,215,000)		(90,000)	21,000
Cash distribution		(79,386,000)		(79,336,000)	(79,336,000)
Net cash used in financing activities		(145,147,000)		(139,260,000)	(163,848,000)
Effect of exchange rate changes on cash		(18,000)		510,000	(30,000)
Net increase (decrease) in cash and cash equivalents		9,710,000		9,058,000	1,813,000
Cash and cash equivalents at the beginning of the period		52,583,000		43,525,000	41,712,000
Cash and cash equivalents at the end of the period		62,293,000		52,583,000	$ 43,525,000
General Partner [Member]
FINANCING ACTIVITIES
Net proceeds from issuance of common stock		451,000
Limited Partner [Member]
FINANCING ACTIVITIES
Net proceeds from issuance of common stock		$ 525,000
Tove Knutsen [Member]
INVESTING ACTIVITIES
Acquisition of Tove Knutsen (net of cash acquired)				$ (21,094,000)
[1]	The carrying value of the Windsor Knutsen was written down to its estimated fair value as of June 30, 2021. See Note 21—Impairment of Long-Lived Assets.

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2021
Description of Business
Description of Business	1) Description of Business KNOT Offshore Partners LP (the “Partnership”) was formed as a limited partnership under the laws of the Republic of the Marshall Islands. The Partnership was formed for the purpose of acquiring 100% ownership interests in four shuttle tankers owned by Knutsen NYK Offshore Tankers AS (“KNOT”) in connection with the Partnership’s initial public offering of its common units (the “IPO”), which was completed on April 15, 2013. As of December 31, 2021, the Partnership had a fleet of seventeen shuttle tankers, the Windsor Knutsen Bodil Knutsen Recife Knutsen Fortaleza Knutsen Carmen Knutsen, Hilda Knutsen, Torill Knutsen Dan Cisne Dan Sabia, Ingrid Knutsen Raquel Knutsen, Tordis Knutsen, Vigdis Knutsen, Lena Knutsen Brasil Knutsen Anna Knutsen Tove Knutsen, The consolidated financial statements have been prepared assuming that the Partnership will continue as a going concern. The Partnership expects that its primary future sources of funds will be available cash, cash from operations, borrowings under any new loan agreements and the proceeds of any equity financings. The Partnership believes that these sources of funds (assuming the current rates earned from existing charters) will be sufficient to cover operational cash outflows and ongoing obligations under the Partnership’s financing commitments to pay loan interest and make scheduled loan repayments and to make distributions on its outstanding units. Accordingly, as of March 17, 2022, the Partnership believes that its current resources, including the undrawn portion of its revolving credit facilities of $55 million, are sufficient to meet working capital requirements for its current business for at least the next twelve months.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2) Summary of Significant Accounting Policies (a) Basis of Preparation The consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). All intercompany balances and transactions are eliminated on consolidation. The consolidated financial statements include the financial statements of the entities listed in Note 4—Subsidiaries. (b) Business Combinations and Asset Acquisitions Business combinations are accounted for under the purchase method of accounting. On acquisition, the identifiable assets, liabilities and contingent liabilities are measured at their fair values at the date of acquisition. Any excess of the cost of acquisition over the fair values of the identifiable net assets acquired is recognized as goodwill. The consideration transferred for an acquisition is measured at fair value of the consideration given. Acquisition related costs are expensed as incurred. The results of operations of the acquired businesses are included in the consolidated results as of the date of the applicable acquisition. Dependent on the facts and circumstances, the assessment of a transaction may be considered the acquisition of an asset, when substantially all of the fair value of assets acquired is concentrated in a single identifiable asset, rather than a business combination. Asset acquisitions are accounted for by allocating the cost of the acquisition to the individual assets acquired and liabilities assumed on a relative fair value basis. Acquisition related costs are capitalized as a component of the assets acquired. See Note 22- Acquisitions. (c) Reporting Currency The consolidated financial statements are prepared in the reporting currency of U.S. Dollars. The functional currency of the vessel-owning Partnership subsidiaries is the U.S. Dollar, because the subsidiaries operate in the international shipping market, in which all revenues are U.S. Dollar-denominated and the majority of expenditures are made in U.S. Dollars. Transactions involving other currencies during the year are converted into U.S. Dollars using the exchange rates in effect at the time of the transactions. As of the balance sheet dates, monetary assets and liabilities that are denominated in currencies other than the U.S. Dollar are translated to reflect the year-end exchange rates. Resulting gains or losses are reflected separately in the accompanying consolidated statements of operations. (d) Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. Significant items subject to such estimates and assumptions include the useful lives and impairment of Vessels, drydocking, purchase price allocation and income taxes. (e) Revenues and Operating Expenses The Partnership’s time charter contracts include both a lease component, consisting of the lease of the vessel, and non-lease component, consisting of operation of the vessel for the customers. The bareboat element is accounted for as an operating lease on a straight-line basis over the term of the charter, while the service element consisting of the operation of the vessel is recognized over time as the services are delivered. Revenue from time charters is recognized net of any commissions and is not recognized during days the Vessel is off-hire. Revenue is recognized from delivery of the Vessel to the charterer, until the end of the contract period. Under bareboat charters, the Partnership provides a specified Vessel for a fixed period of time at a specified day rate and the Partnership recognizes revenues from bareboat charters as operating leases on a straight-line basis over the term of the charter, net of any commissions. Where the term of the contract is based on the duration of a single voyage, the partnership evaluates whether the voyage contain leases and, if so, recognizes lease revenue as described above, and if not, recognizes revenue in accordance with ASC 606 upon the satisfaction of the performance obligations in the contract, i.e, when the underlying transportation service is provided to the customer. Voyage expenses are all expenses unique to a particular voyage, including bunker fuel expenses, port fees, cargo loading and unloading expenses, canal tolls and agency fees. Voyage expenses are paid by the customer under time charter and bareboat charters. Voyage expenses are paid by the Partnership for spot contracts and during periods of off-hire and are recognized when incurred. Vessel operating expenses include crewing, repairs and maintenance, insurance, stores, lube oils and communication expenses. Vessel operating expenses are paid by the Partnership for time charters, spot contracts and during off-hire and are recognized when incurred. The Partnership directly employs one onshore employee and no seagoing employees. Related parties have provided the management services for the Vessels and employ the crews that work on the Vessels. The Partnership is not liable for any pension or post-retirement benefits. See Note 17—Related Party Transactions. (f) Financial Income (Expense) Other finance expense includes external bank fees and commitment fees paid on undrawn revolving credit facility. (g) Cash and Cash Equivalents The Partnership considers all highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents. (h) Trade Accounts Receivable Accounts receivable are recorded at the invoiced amount and do not bear interest. Under terms of the current time charters and bareboat charters, the customers are committed to pay for the full month’s charter the first day of each month. See Note 2(s)—Prepaid Charter. The allowance for expected credit losses is the Partnership’s best estimate of the expected credit losses over the remaining lives of the assets. Expected credit losses are estimated using historical credit loss experience, relevant available information, from internal and external sources, relating to current conditions and reasonable and supportable forecasts of economic conditions impacting the collectability of the assets. There was no allowance for expected credit loss or amounts written off against the allowance as of December 31, 2021 and 2020. The Partnership does not have any off-balance-sheet credit exposure related to its customers. (i) Inventories Inventories, which are comprised of lubricating oils and, for vessels not operating on time charter or bareboat charter, also bunkers, are stated at the lower of cost or net realizable value. For vessels on time charters or bareboat charters, there are no bunkers, as the charterer supplies the bunkers, which principally consist of fuel oil. Cost is determined using the first-in, first-out method for all inventories. (j) Other Current Assets Other current assets principally consist of prepaid expenses and other receivables. (k) Vessels and Equipment Vessels and equipment are stated at the historical acquisition or construction cost, including capitalized interest, supervision and technical and delivery cost, net of accumulated depreciation and impairment loss, if any. Expenditures for subsequent conversions and major improvements are capitalized, provided that such costs increase the earnings capacity or improve the efficiency or safety of the vessels. Generally, the Partnership drydocks each vessel every 60 months until the vessel is 15 years old and every 30 months thereafter, as required for the renewal of certifications issued by classification societies. For vessels operating on time charters, the Partnership capitalizes the costs directly associated with the classification and regulatory requirements for inspection of the vessels and improvements incurred during drydocking. Drydock cost is depreciated on a straight-line basis over the period until the next planned drydocking takes place. The Partnership expenses costs related to routine repairs and maintenance performed during drydocking or as otherwise incurred. For vessels that are newly built or acquired, an element of the cost of the vessel is initially allocated to a drydock component and depreciated on a straight-line basis over the period until the next planned drydocking. When significant dry-docking expenditures occur prior to the expiration of this period, the Partnership expenses the remaining balance of the original drydocking cost in the month of the subsequent drydocking. For vessels operating on bareboat charters, the charter-party bears the cost of any drydocking. Depreciation on vessels and equipment is calculated on a straight-line basis over the asset’s estimated useful life, less an estimated residual value, as follows: ​ ​ ​ ​ ​ Useful Life Hull 23 years Anchor-handling, loading and unloading equipment 23 years Main/auxiliary engine 23 years Thruster, dynamic positioning systems, cranes and other equipment 23 years Drydock costs 2.5 – 5 years ​ A Vessel is depreciated to its estimated residual value, which is calculated based on the weight of the ship and estimated steel price. Any cost related to the disposal is deducted from the residual value. Historically, the useful life of the Partnership’s vessels and equipment was assessed as 25 years commencing from the date the vessel and equipment were delivered from the shipyard. As of June 30, 2021, the Partnership considered factors related to the ongoing use of the vessels and equipment, gradual shifts in market conditions and other long-term factors associated with the global oil and maritime transportation industries and based on this has reassessed the useful life as being 23 years. This change in estimate was applied prospectively from July 1, 2021 and impacted the entire fleet of shuttle tanker vessels. The change in estimate resulted in an increase in depreciation diluted (l) Right-of-use assets and lease liabilities The Partnership assesses whether a contract contains a lease at inception of the contract. The assessment involves the exercise of judgement about whether it depends on a specified asset, whether the Partnership obtains substantially all the economic benefits from the use of that asset, and whether the Partnership has the right to direct the use of the asset. The Partnership does not separate lease components from non-lease components as lessee. The Partnership recognizes a right-of-use asset and a lease liability at the lease commencement date, except for short-term leases of 12 months or less, which are expensed on a straight-line basis over the lease term. (m) Capitalized Interest Interest expense incurred on the Partnership’s debt during the construction of the Vessels exceeding one year is capitalized during the construction period. (n) Impairment of Long-Lived Assets Vessels and equipment, vessels under construction and intangible assets subject to amortization are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require a long-lived asset or asset group to be tested for possible impairment, the Partnership first compares undiscounted cash flows expected to be generated by that asset or asset group to its carrying value. If the carrying value of the long-lived asset or asset group is not recoverable on an undiscounted cash flow basis, impairment is recognized to the extent that the carrying value exceeds its fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. See Note 21—Impairment of Long-Lived Assets (o) Intangibles Intangible assets represent contractual rights for charters obtained in connection with business and asset acquisitions that have favorable contractual terms relative to market as of the acquisition dates. Contract liabilities represent contractual rights obtained in connection with business acquisitions that have unfavorable contractual terms relative to market as of the acquisition dates. The favorable and unfavorable contract rights have definite lives and are amortized to revenues over the period of the related contracts. Intangible assets with a definite life are tested for impairment whenever events or circumstances indicate that their carrying amount may not be recoverable. An impairment loss is recognized if the carrying amount exceeds the estimated fair value of the asset. The contract related intangible assets and liabilities and their amortization periods at acquisition dates are as follows: ​ ​ ​ ​ ​ ​ Amortization Intangible category Period Above market time charter— Tordis Knutsen 4.8 years Above market time charter— Vigdis Knutsen 4.9 years Unfavorable contractual rights— Fortaleza Knutsen 12 years Unfavorable contractual rights— Recife Knutsen 12 years ​ The intangible for the above market value of the time charter contract associated with the Tordis Knutsen Vigdis Knutsen The unfavorable contractual rights for charters associated with Foraleza Knutsen Recife Knutsen Fortaleza Knutsen Recife Knutsen Fortaleza Knutsen Recife Knutsen (p) Debt Issuance Costs Debt issuance costs, including fees, commissions and legal expenses, are deferred and presented net of debt. Debt issuance costs of term loans are amortized over the term of the relevant loan. Amortization of debt issuance costs is included in interest expense. These costs are presented as a deduction from the corresponding liability, consistent with debt discount. (q) Derivative Instruments The Partnership uses derivatives to reduce market risks associated with its operations. The Partnership uses interest rate swaps for the management of interest risk exposure. The interest rate swaps effectively convert a portion of the Partnership’s debt from a floating to a fixed rate over the life of the transactions without an exchange of underlying principal. The Partnership seeks to reduce its exposure to fluctuations in foreign exchange rates through the use of foreign currency forward contracts. All derivative instruments are initially recorded at fair value as either assets or liabilities in the accompanying consolidated balance sheets and subsequently measured to fair value. The Partnership does not apply hedge accounting to its derivative instruments. Changes in the fair value of the derivative instruments are recognized in earnings. Gains and losses from the interest rate swap contracts of the Partnership related to long-term mortgage debt and foreign exchange forward contracts are recorded in realized and unrealized gain (loss) on derivative instruments in the consolidated statements of operations. Cash flows related to interest rate swap contracts are presented as cash flows provided by operating activities. Cash flows related to foreign exchange forward contracts entered into to economically hedge operating expenses in currencies other than U.S. Dollars are presented as cash flows provided by operating activities in the consolidated statements of cash flows, while cash flows related to foreign exchange forward contracts entered into to hedge contractual obligations to pay the shipyard in currencies other than functional currency of U.S. Dollars are presented as cash flows used in investing activities in the consolidated statements of cash flows. (r) Income Taxes Historically, part of the Partnership’s activities were subject to ordinary taxation and taxes were paid on taxable income (including operating income and net financial income and expense), while part of the activities were subject to the Norwegian Tonnage Tax Regime (the “tonnage tax regime”). Under the tonnage tax regime, tax is based on the tonnage of the vessel, and not operating income. Net financial income and expense remain taxable as ordinary income at the regular corporate income tax rate. Income taxes arising from the part of activities subject to ordinary taxation are included in income tax expense in the consolidated statements of operations. For the portion of activities subject to the tonnage tax regime, tonnage taxes are classified as vessel operating expenses, while the current and deferred taxes arising on net financial income and expense are reflected as income tax expense in the consolidated statements of operations. See Note 16—Income Taxes. The Partnership accounts for deferred income taxes using the liability method. Under the liability method, deferred tax assets and liabilities are recognized for the anticipated future tax effects of temporary differences between the financial statement basis and the tax basis of the Partnership’s assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. A valuation allowance for deferred tax assets is recorded when it is more likely than not that some or all of the benefit from the deferred tax asset will not be realized. Recognition of uncertain tax positions is dependent upon whether it is more-likely-than-not that a tax position taken or expected to be taken in a tax return will be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. If a tax position meets the more-likely-than-not recognition threshold, it is measured to determine the amount of benefit to recognize in the financial statements based on U.S. GAAP guidance. The Partnership recognizes interest and penalties related to uncertain tax positions in income tax expense. (s) Prepaid Charter Under terms of the time charters and bareboat charters, the customer pays for the month’s charter the first day of each month that is recorded as prepaid charter revenues. (t) Commitments, Contingencies and Insurance Proceeds Liabilities for loss contingencies arising from claims, assessments, litigation, fines and penalties and other sources are recorded when it is probable that a liability has been incurred and the amount can be reasonably estimated. Legal costs incurred in connection with loss contingencies are expensed as incurred. See Note 18—Commitments and Contingencies. Insurance claims for property damage for recoveries up to the amount of loss recognized are recorded when the claims submitted to insurance carriers are probable of recovery. Claims for property damage in excess of the loss recognized and for loss of hire are considered gain contingencies, which are generally recognized when the proceeds are received. (u) Fair Value Measurements The Partnership utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. The Partnership determines fair value based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels: ● Level 1 Inputs: Unadjusted quoted prices in active markets for identical assets or liabilities accessible to the reporting entity at the measurement date. ● Level 2 Inputs: Other than quoted prices included in Level 1 inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability. ● Level 3 Inputs: Unobservable inputs for the asset or liability used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. (v) Recently Adopted Accounting Standards There are no recent accounting standards whose adoption had a material impact on the consolidated financial statements in the current year. (w) New Accounting Standards Not Yet Adopted In March 2020, the Financial Accounting Standards Board (“FASB”) issued ASU 2020-04 Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Reporting. In August 2020, the FASB issued ASU 2020-06 Debt—Debt with conversion and other options (subtopic 470-20) and Derivatives and Hedging—contracts in entity’s own equity (subtopic 815-40): Accounting for convertible instruments and contracts in an entity’s own equity Other recently issued accounting pronouncements are not expected to materially impact the Partnership.

Formation Transactions and Init

Formation Transactions and Initial Public Offering	12 Months Ended
	Dec. 31, 2021
Formation Transactions and Initial Public Offering
Formation Transactions and Initial Public Offering	3) Formation Transactions and Initial Public Offering During April 2013, the following transactions occurred in connection with KNOT’s transfer of the interests in KNOT Shuttle Tankers AS and the subsequent IPO: Capital Contribution (i) KNOT contributed to the Partnership’s subsidiary KNOT Offshore Partners UK LLC (“KNOT UK”) its 100% interest in KNOT Shuttle Tankers AS, which directly or indirectly owned (1) Knutsen Shuttle Tankers XII KS, the owner of the Recife Knutsen and the Fortaleza Knutsen , (2) Knutsen Shuttle Tankers XII AS, the general partner of Knutsen Shuttle Tankers XII KS, and (3) the Windsor Knutsen and the Bodil Knutsen and all of their related charters, inventory and long-term debt. This was accounted for as a capital contribution by KNOT to the Partnership. Recapitalization of the Partnership (ii) The Partnership issued to KNOT 8,567,500 subordinated units, representing a 49.0% limited partner interest in the Partnership, and 100% of the incentive distribution rights (“IDRs”), which entitled KNOT to increasing percentages of the cash the Partnership distributed in excess of $0.43125 per unit per quarter. (iii) The Partnership issued 349,694 general partner units to the General Partner representing a 2.0% general partner interest in the Partnership. Initial Public Offering (iv) In connection with the IPO, the Partnership issued and sold to the public, through the underwriters, 8,567,500 common units (including 1,117,500 common units sold pursuant to the full exercise of the underwriters’ option to purchase additional units), representing a 49.0% limited partner interest in the Partnership. The price per common unit in the IPO was $21.00 . The Partnership received gross proceeds of approximately $179.9 million in connection with the IPO. Expenses relating to the IPO, including, among other things, incremental costs directly attributable to the IPO, were deferred and charged against the gross proceeds of the IPO, whereas other costs were expensed as incurred. The net proceeds of the IPO (approximately $160.7 million, after deducting underwriting discounts, commissions and structuring fees and offering expenses payable by the Partnership) were used by the Partnership to make a cash distribution to KNOT of approximately $21.95 million (which equals net proceeds from the underwriters’ option exercised in full after deducting the underwriting discounts and commissions), to repay approximately $118.9 million of outstanding debt and pre-fund approximately $3.0 million of the Partnership’s one-time entrance tax into the Norwegian tonnage tax regime. The remainder of the net proceeds was made available for general partnership purposes. Agreements In connection with the IPO, at or prior to the closing of the IPO, the Partnership entered into several agreements, including: ● An Administrative Services Agreement with KNOT UK, pursuant to which: ● KNOT UK agreed to provide to the Partnership administrative services; and ● KNOT UK is permitted to subcontract certain of the administrative services provided under the administrative services agreement to Knutsen OAS (UK) Ltd. (“KOAS UK”) and Knutsen OAS Shipping AS (“KOAS”), both wholly owned subsidiaries of TS Shipping Invest AS (“TSSI”); ● Amended Technical Management Agreements with KNOT Management AS (“KNOT Management”), a wholly owned subsidiary of KNOT, that govern the crew, technical and commercial management of the vessels in the fleet; ● A Contribution and Sale Agreement with KNOT pursuant to which the Partnership acquired the entities that comprised its initial fleet; ● Amendments to certain of the Partnership’s existing vessel financing agreements to permit the transactions pursuant to which the Partnership acquired its initial fleet in connection with the IPO and to include a $20.0 million revolving credit facility; and ● An Omnibus Agreement with KNOT, the General Partner and the other parties thereto governing, among other things: ● To what extent the Partnership and KNOT may compete with each other; ● The Partnership’s option to purchase the Carmen Knutsen, the Hilda Knutsen , the Torill Knutsen , the Ingrid Knutsen and the Raquel Knutsen from KNOT; ● Certain rights of first offer on shuttle tankers operating under charters of five or more years; ● The provision of certain indemnities to the Partnership by KNOT; and ● KNOT’s guarantee of the payment of the hire rate under the original Bodil Knutsen and Windsor Knutsen charters for a period of five years following the closing date of the IPO. ​

Subsidiaries

Subsidiaries	12 Months Ended
	Dec. 31, 2021
Subsidiaries
Subsidiaries	4) Subsidiaries The following table lists the Partnership’s subsidiaries and their purpose as of December 31, 2021. ​ ​ ​ ​ Company Name Jurisdiction of Formation Purpose KNOT Offshore Partners UK LLC ​ Marshall Islands ​ Holding Company ​ KNOT Shuttle Tankers AS ​ Norway ​ Holding Company ​ KNOT Shuttle Tankers 12 AS ​ Norway ​ Majority owner of Knutsen Shuttle Tankers XII KS ​ KNOT Shuttle Tankers 17 AS ​ Norway ​ Owner of the Bodil Knutsen ​ KNOT Shuttle Tankers 18 AS ​ Norway ​ Owner of the Windsor Knutsen ​ Knutsen Shuttle Tankers XII KS ​ Norway ​ Owner of the Fortaleza Knutsen Recife Knutsen ​ Knutsen Shuttle Tankers XII AS ​ Norway ​ General partner of Knutsen Shuttle Tankers XII KS ​ Knutsen Shuttle Tankers 13 AS ​ Norway ​ Owner of the Carmen Knutsen ​ Knutsen Shuttle Tankers 14 AS ​ Norway ​ Owner of the Hilda Knutsen ​ Knutsen Shuttle Tankers 15 AS ​ Norway ​ Owner of the Torill Knutsen ​ KNOT Shuttle Tankers 20 AS ​ Norway ​ Owner of the Dan Cisne ​ KNOT Shuttle Tankers 21 AS ​ Norway ​ Owner of the Dan Sabia ​ Knutsen NYK Shuttle Tankers 16 AS ​ Norway ​ Owner of the Ingrid Knutsen ​ Knutsen Shuttle Tankers 19 AS ​ Norway ​ Owner of the Raquel Knutsen ​ KNOT Shuttle Tankers 24 AS ​ Norway ​ Owner of the Tordis Knutsen ​ KNOT Shuttle Tankers 25 AS ​ Norway ​ Owner of the Vigdis Knutsen ​ KNOT Shuttle Tankers 26 AS ​ Norway ​ Owner of the Lena Knutsen ​ KNOT Shuttle Tankers 32 AS ​ Norway ​ Owner of the Brasil Knutsen ​ KNOT Shuttle Tankers 30 AS ​ Norway ​ Owner of the Anna Knutsen ​ KNOT Shuttle Tankers 34 AS ​ Norway ​ Owner of the Tove Knutsen ​ ​

Significant Risks and Uncertain

Significant Risks and Uncertainties Including Business and Credit Concentrations	12 Months Ended
	Dec. 31, 2021
Significant Risks and Uncertainties Including Business and Credit Concentrations
Significant Risks and Uncertainties Including Business and Credit Concentrations	5) Significant Risks and Uncertainties Including Business and Credit Concentrations Each of the Vessels is currently employed under fixed rate charters, except for Anna Knutsen Vigdis Knutsen As of December 31, 2021, all of the Partnership’s Vessel crews, which are employed through KOAS were represented by collective bargaining agreements that are renegotiated annually, or bi-annually. The Partnership did not incur any loss relating to its trade receivables during the years ended December 31, 2021, 2020 and 2019. The following table presents time charter and bareboat revenues and percentage of revenues for material customers that accounted for more than 10% of the Partnership’s revenues during the years ended December 31, 2021, 2020 and 2019. All of these customers are subsidiaries of major international oil companies. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ (U.S. Dollars in thousands) ​ 2021 ​ 2020 ​ 2019 ​ Eni Trading and Shipping S.p.A. $ 43,823 16 % $ 44,175 16 % $ 44,610 16 % Fronape International Company, a subsidiary of Petrobras Transporte S.A. ​ 45,115 17 % 45,235 16 % 45,116 16 % Repsol Sinopec Brasil, B.V., a subsidiary of Repsol Sinopec Brasil, S.A. ​ 37,030 14 % 33,947 12 % 36,346 13 % Brazil Shipping I Limited, a subsidiary of Royal Dutch Shell ​ 59,825 22 % 76,959 28 % 66,199 23 % Galp Sinopec Brasil Services BV ​ 35,622 13 % 35,684 13 % 35,541 13 % ​ The Partnership has financial assets that expose it to credit risk arising from possible default by a counterparty. The Partnership considers its counterparties to be creditworthy banking and financial institutions and does not expect any significant loss to result from non-performance by such counterparties. The maximum loss due to credit risk that the Partnership would incur if counterparties failed completely to perform would be the carrying value of cash and cash equivalents, and derivative assets. The Partnership, in the normal course of business, does not demand collateral from its counterparties.

Operating Leases

Operating Leases	12 Months Ended
	Dec. 31, 2021
Operating Leases
Operating Leases	6) Operating Leases Revenues The Partnership’s primary source of revenues is chartering its shuttle tankers to its customers. The Partnership uses two types of contracts, time charter contracts and bareboat charter contracts. The Partnership’s time-charter contracts include both a lease component, consisting of the bareboat element of the contract, and non-lease component, consisting of operation of the vessel for the customers, which includes providing the crewing and other services related to the Vessel’s operations, the cost of which is included in the daily hire rate, except when off hire. ​ The following table presents the Partnership’s revenues by time charter and bareboat charters and other revenues for the years ended December 31, 2021, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) ​ 2021 ​ 2020 ​ 2019 Time charter revenues (service element included) ​ $ 224,191 ​ $ 233,346 ​ $ 237,387 Bareboat revenues ​ ​ 45,115 ​ ​ 45,235 ​ ​ 45,115 Other revenues (loss of hire insurance recoveries and other income) ​ ​ 11,823 ​ ​ 641 ​ ​ 59 Total revenues ​ $ 281,129 ​ $ 279,222 ​ $ 282,561 ​ See Note 2(l)—Right-of-use assets and lease liabilities. ​ As of December 31, 2021, the minimum contractual future revenues to be received from time charters and bareboat charters during the next five years and thereafter are as follows (including service element of the time charter, but excluding unexercised customer option periods): ​ ​ ​ ​ ​ (U.S. Dollars in thousands) ​ ​ 2022 ​ $ 198,385 2023 ​ ​ 99,805 2024 ​ ​ 102,560 2025 ​ ​ 94,803 2026 ​ ​ 51,088 2027 and thereafter ​ ​ 13,672 Total $ 560,313 ​ The minimum contractual future revenues should not be construed to reflect total charter hire revenues for any of the years. Minimum contractual future revenues are calculated based on certain assumptions such as operating days per year. In addition, minimum contractual future revenues presented in the table above have not been reduced by estimated off-hire time for periodic maintenance. The amounts may vary given unscheduled future events such as vessel maintenance. The Partnership’s fleet as of December 31, 2021 consisted of: ● the Fortaleza Knutsen , a shuttle tanker built in 2011 that is currently operating under a bareboat charter that expires in March 2023 with Fronape International Company, a subsidiary of Petrobras Transporte S.A. (“Transpetro”); ● the Recife Knutsen , a shuttle tanker built in 2011 that is currently operating under a bareboat charter that expires in August 2023 with Transpetro; ● the Bodil Knutsen , a shuttle tanker built in 2011 that is currently operating under a rolling charter contract with Knutsen Shuttle Tankers Pool AS, a subsidiary of KNOT, which currently expires in April 2022 , with options of the charterer to extend until June 2022 . The vessel will commence on a new time charter contract with Equinor in the fourth quarter of 2023 or the first quarter of 2024. The new charter is for a fixed period, at the charterer’s option, of either one year or two years with options for the charterer to extend the charter, in either case, by two further one-year periods; ● the Windsor Knutsen , a conventional oil tanker built in 2007 and retrofitted to a shuttle tanker in 2011 that is currently operating under a time charter that expires in September 2022 with PetroChina, with options to extend until March 2024 . The vessel will commence on a new time charter contract with Equinor in the fourth quarter of 2024 or the first quarter of 2025. The new charter is for a fixed period, at the charterer’s option, of either one year or two years , with options for the charterer to extend the charter, in either case, by two further one-year periods; ● the Carmen Knutsen , a shuttle tanker built in 2013 that is currently operating under a time charter that expires in January 2023 , with Repsol Sinopec Brasil, B.V. a subsidiary of Repsol Sinopec Brasil, S.A. (“Repsol”), with options to extend until January 2026 ; ● the Hilda Knutsen , a shuttle tanker built in 2013 that is currently operating under a time charter that expires in August 2022 with Eni Trading and Shipping S.p.A. (“ENI”), with options to extend until August 2025 ; ● the Torill Knutsen , a shuttle tanker built in 2013 that is currently operating under a time charter that expires in November 2022 with ENI, with options to extend until November 2024 ; ● the Dan Cisne , a shuttle tanker built in 2011 that is currently operating under a bareboat charter that expires in September 2023 with Transpetro; ● the Dan Sabia , a shuttle tanker built in 2012 that is currently operating under a bareboat charter that expires in January 2024 with Transpetro; ● the Ingrid Knutsen , a shuttle tanker built in 2013 that is currently operating under a time charter that expires in February 2024 with Vår Energi Marine AS, a Norwegian subsidiary of Vår Energi (“Vår”), with options to extend until February 2029 ; ● the Raquel Knutsen , a shuttle tanker built in 2015 that is currently operating under a time charter that expires in June 2025 with Repsol, with options to extend until June 2030 ; ● the Tordis Knutsen , a shuttle tanker built in 2016 that is currently operating under a time charter that expires in July 2022 , with Petrobras with an option for charterer to extend the charter by one month . The vessel will commence on a new 3 -year time charter contract with a major oil company in 2023 ; ● the Vigdis Knutsen , a shuttle tanker built in 2017 and was operating under a time charter that expired in March 2022 with a subsidiary of Shell. The vessel will commence on a new 3 -year time charter contract with a major oil company in 2023 ; ● the Lena Knutsen , a shuttle tanker built in 2017 that is currently operating under a time charter that expires in September 2022 with a subsidiary of Shell. The vessel will commence on a new 3 -year time charter contract with a major oil company in 2023 ; ● the Brasil Knutsen , a shuttle tanker built in 2013 that is currently operating under a time charter that expires in September 2022 with Galp Sinopec Brazil Services B.V. (“Galp”), with options to extend until September 2028 ; ● The Anna Knutsen , a shuttle tanker built in 2017. On February 11, 2022 the Partnership agreed on the commercial terms for a new time charter contract for the Anna Knutsen with a major oil company to commence in the second quarter of 2022 for a fixed period, at the charterer’s option, of either (a) one year , with options for the charterer to extend the time charter by up to four further one-year periods, or (b) two years , with options for the charterer to extend the time charter by up to three further one-year periods; and ● The Tove Knutsen , a shuttle tanker built in 2020 that is currently operating under a time charter that expires in October 2027 with Equinor, with options to extend until October 2040 . Lease obligations The Partnership does not have any material leased assets but has some leased equipment on operational leases on the various ships operating on time charter contracts. As of December 31, 2021, the right-of-use asset and lease liability ​ A maturity analysis of the Partnership’s lease liabilities from leased-in equipment as of December 31, 2021 is as follows: ​ ​ ​ ​ ​ (U.S. Dollars in thousands) ​ 2022 ​ $ 703 2023 ​ 703 2024 ​ ​ 703 2025 ​ ​ 703 2026 ​ ​ 59 2027 and thereafter ​ ​ — Total ​ $ 2,871 Less imputed interest ​ 130 Carrying value of operating lease liabilities ​ $ 2,741 ​

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2021
Segment Information
Segment Information	7) Segment Information The Partnership has not presented segment information as it considers its operations to occur in one reportable segment, the shuttle tanker market. At December 31, 2021, 2020 and 2019, the Partnership’s fleet operated under twelve time charters and four bareboat charters. See Note 5—Significant Risks and Uncertainties Including Business and Credit Concentrations for revenues from customers accounting for over 10% of the Partnership’s consolidated revenue. In both time charters and bareboat charters, the charterer, not the Partnership, controls the choice of which trading areas the Vessels will serve. Accordingly, the Partnership’s management, including the chief operating decision makers, does not evaluate performance according to geographical region.

Insurance Proceeds

Insurance Proceeds	12 Months Ended
	Dec. 31, 2021
Insurance Proceeds
Insurance Proceeds	8) Insurance Proceeds Windsor Knutsen In December 2020, the Windsor Knutsen In addition, as of December 31, 2021, the Partnership had claimed and received payments of $4.1 million (net of deductible amounts) for hull and machinery recoveries. Tove Knutsen In March 2021, the Tove Knutsen In addition, as of December 31, 2021, the Partnership had claimed $0.1 million (net of deductible amounts) for hull and machinery recoveries. As of December 31, 2021, the Partnership had not received payment for this claim, resulting in an open insurance claim of $0.1 million. Bodil Knutsen In April 2021, the Bodil Knutsen Tordis Knutsen In July 2021, the Tordis Knutsen

Other Finance Expenses

Other Finance Expenses	12 Months Ended
	Dec. 31, 2021
Other Finance Expenses
Other Finance Expenses	9) Other Finance Expenses (a) Interest Expense The following table presents the components of interest cost as reported in the consolidated statements of operations for the years ended December 31, 2021, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Interest expense ​ $ 24,546 ​ $ 29,142 ​ $ 48,118 Amortization of debt issuance cost and fair value of debt assumed ​ 3,519 ​ 2,503 ​ 2,617 Total interest cost ​ $ 28,065 ​ $ 31,645 ​ $ 50,735 ​ (b) Other Finance Expense The following table presents the components of other finance expense for the years ended December 31, 2021, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Bank fees, charges ​ $ 463 ​ $ 441 ​ $ 597 Commitment fees ​ 548 264 248 Total other finance expense ​ $ 1,011 $ 705 $ 845 ​

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2021
Derivative Instruments
Derivative Instruments	10) Derivative Instruments Interest Rate Risk Management The consolidated financial statements include the results of interest rate swap contracts to manage the Partnership’s exposure related to changes in interest rates on its variable rate debt instruments and the results of foreign exchange forward contracts to manage its exposure related to changes in currency exchange rates on its operating expenses, mainly crew expenses, in currency other than the U.S. Dollar and on its contract obligations. The Partnership does not apply hedge accounting for derivative instruments. The Partnership does not speculate using derivative instruments. By using derivative financial instruments to economically hedge exposures to changes in interest rates, the Partnership exposes itself to credit risk and market risk. Derivative instruments that economically hedge exposures are used for risk management purposes, but these instruments are not designated as hedges for accounting purposes. Credit risk is the failure of the counterparty to perform under the terms of the derivative instrument. When the fair value of a derivative instrument is positive, the counterparty owes the Partnership, which creates credit risk for the Partnership. When the fair value of a derivative instrument is negative, the Partnership owes the counterparty, and, therefore, the Partnership is not exposed to the counterparty’s credit risk in those circumstances. The Partnership minimizes counterparty credit risk in derivative instruments by entering into transactions with major banking and financial institutions. The derivative instruments entered into by the Partnership do not contain credit risk-related contingent features. The Partnership has not entered into master netting agreements with the counterparties to its derivative financial instrument contracts. Market risk is the adverse effect on the value of a derivative instrument that results from a change in interest rates, currency exchange rates or commodity prices. The market risk associated with interest rate contracts is managed by establishing and monitoring parameters that limit the types and degree of market risk that may be undertaken. The Partnership assesses interest rate risk by monitoring changes in interest rate exposures that may adversely impact expected future cash flows and by evaluating economical hedging opportunities. The Partnership has historically used variable interest rate mortgage debt to finance its vessels. The variable interest rate mortgage debt obligations expose the Partnership to variability in interest payments due to changes in interest rates. The Partnership believes that it is prudent to limit the variability of a portion of its interest payments. To meet this objective, the Partnership has entered into London Interbank Offered Rate (“LIBOR”) based interest rate swap contracts to manage fluctuations in cash flows resulting from changes in the benchmark interest rate of LIBOR. These swaps change the variable rate cash flow exposure on the mortgage debt obligations to fixed cash flows. Under the terms of the interest rate swap contracts, the Partnership receives LIBOR-based variable interest rate payments and makes fixed interest rate payments, thereby creating the equivalent of fixed rate debt for the notional amount of its debt hedged. As of December 31, 2021 and 2020, the total notional amount of the Partnership’s outstanding interest rate swap contracts that were entered into in order to hedge outstanding or forecasted debt obligations were $462.3 million and $516.2 million, respectively. As of December 31, 2021 and 2020 the carrying amount of the interest rate swaps contracts was a net liability of $10.0 million and a net liability of $30.1 million, respectively. See Note 11—Fair Value Measurements. Changes in the fair value of interest rate swap contracts are reported in realized and unrealized gain (loss) on derivative instruments in the same period in which the related interest affects earnings. The Partnership and its subsidiaries utilize the U.S. Dollar as their functional and reporting currency, because all of their revenues and the majority of their expenditures, including the majority of their investments in vessels and their financing transactions, are denominated in U.S. Dollars. Payment obligations in currencies other than the U.S. Dollar, and in particular operating expenses in NOK, expose the Partnership to variability in currency exchange rates. The Partnership believes that it is prudent to limit the variability of a portion of its currency exchange exposure. To meet this objective, the Partnership entered into foreign exchange forward contracts to manage fluctuations in cash flows resulting from changes in the exchange rates towards the U.S. Dollar. The agreements change the variable exchange rate to fixed exchange rates at agreed dates. The following table presents the realized and unrealized gains and losses that are recognized in earnings as net gain (loss) on derivative instruments for the years ended December 31, 2021, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Realized gain (loss): ​ ​ ​ Interest rate swap contracts ​ $ (10,094) ​ $ (3,528) ​ $ 3,812 Foreign exchange forward contracts ​ — ​ (109) ​ (2,933) Total realized gain (loss): ​ (10,094) ​ (3,637) ​ 879 Unrealized gain (loss): ​ ​ ​ ​ ​ Interest rate swap contracts ​ 20,054 ​ (21,795) ​ (20,663) Foreign exchange forward contracts ​ — ​ (247) ​ 1,987 Total unrealized gain (loss): ​ 20,054 ​ (22,042) ​ (18,676) Total realized and unrealized gain (loss) on derivative instruments: ​ $ 9,960 ​ $ (25,679) ​ $ (17,797) ​

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Measurements
Fair Value Measurements	11) Fair Value Measurements (a) Fair Value of Financial Instruments The following table presents the carrying amounts and estimated fair values of the Partnership’s assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2021 and December 31, 2020. Fair value is defined as the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ December 31, 2020 ​ Carrying Fair Carrying Fair (U.S. Dollars in thousands) Amount Value Amount Value Financial assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 62,293 ​ $ 62,293 ​ $ 52,583 ​ $ 52,583 Non-current derivative assets: ​ ​ ​ ​ ​ ​ Interest rate swap contracts ​ 1,015 ​ 1,015 ​ — ​ — Financial liabilities: ​ ​ ​ ​ Current derivative liabilities: ​ ​ ​ ​ ​ ​ Interest rate swap contracts ​ 6,754 ​ 6,754 ​ 10,695 ​ 10,695 Non-current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 4,260 ​ 4,260 ​ 19,358 ​ 19,358 Long-term debt, current and non-current ​ 974,596 ​ 974,596 ​ 1,036,118 ​ 1,036,118 ​ The carrying amounts shown in the table above are included in the consolidated balance sheets under the indicated captions. Carrying amount of long-term debt, current and non-current, above excludes capitalized debt issuance cost of $7.5 million and $5.8 million as of December 31, 2021 and 2020, respectively. The carrying value of trade accounts receivable, trade accounts payable and receivables/payables to owners and affiliates approximate their fair value. The fair values of the financial instruments shown in the above table as of December 31, 2021 and 2020 represent the amounts that would be received to sell those assets or that would be paid to transfer those liabilities in an orderly transaction between market participants at that date. Those fair value measurements maximize the use of observable inputs. However, in situations where there is little, if any, market activity for the asset or liability at the measurement date, the fair value measurement reflects the Partnership’s own judgment about the assumptions that market participants would use in pricing the asset or liability. Those judgments are developed by the Partnership based on the best information available in the circumstances, including expected cash flows, appropriately risk-adjusted discount rates and available observable and unobservable inputs. The following methods and assumptions were used to estimate the fair value of each class of financial instruments: ● Cash and cash equivalents and restricted cash: The fair value of the Partnership’s cash balances approximates the carrying amounts due to the current nature of the amounts. As of December 31, 2021 and 2020 there is no restricted cash. ● Interest rate swap contracts: The fair value of interest rate swap contracts is determined using an income approach using the following significant inputs: (1) the term of the swap contract (weighted average of 3.4 years and 4.3 years, as of December 31, 2021 and 2020, respectively), (2) the notional amount of the swap contract (ranging from $5.2 million to $37.5 million as of December 31, 2021 and ranging from $7.0 million to $40.1 million as of December 31, 2020), discount rates interpolated based on relevant LIBOR swap curves; and (3) the rate on the fixed leg of the swap contract (rates ranging from 0.71% to 2.90% for the contracts as of December 31, 2021 and rates ranging from 0.71% to 2.90% for the contracts as of December 31, 2020). ● Long-term debt: With respect to long-term debt measurements, the Partnership uses market interest rates and adjusts for risks such as its own credit risk. In determining an appropriate spread to reflect its credit standing, the Partnership considered interest rates currently offered to KNOT for similar debt instruments of comparable maturities by KNOT’s and the Partnership’s bankers as well as other banks that regularly compete to provide financing to the Partnership. (b) Fair Value Hierarchy The following table presents the placement in the fair value hierarchy of assets and liabilities that are measured at fair value on a recurring basis (including items that are required to be measured at fair value or for which fair value is required to be disclosed) as of December 31, 2021 and December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements ​ ​ ​ ​ at Reporting Date Using ​ ​ ​ ​ ​ Quoted Price ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ in Active ​ Significant ​ ​ ​ ​ ​ Carrying ​ Markets for ​ Other ​ Significant ​ ​ Value ​ Identical ​ Observable ​ Unobservable ​ ​ December 31, ​ Assets ​ Inputs ​ Inputs (U.S. Dollars in thousands) 2021 (Level 1) (Level 2) (Level 3) Financial assets: ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 62,293 ​ $ 62,293 ​ $ — ​ $ — Non-current derivative assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest rate swap contracts ​ ​ 1,015 ​ ​ — ​ ​ 1,015 ​ ​ — Financial liabilities: ​ ​ ​ ​ Current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 6,754 ​ — ​ 6,754 ​ — Non-current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 4,260 ​ — ​ 4,260 ​ — Long-term debt, current and non-current ​ 974,596 ​ — ​ 974,596 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements ​ ​ ​ ​ at Reporting Date Using ​ ​ ​ ​ ​ Quoted Price ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ in Active ​ Significant ​ ​ ​ ​ ​ Carrying ​ Markets for ​ Other ​ Significant ​ ​ Value ​ Identical ​ Observable ​ Unobservable ​ ​ December 31, ​ Assets ​ Inputs ​ Inputs (U.S. Dollars in thousands) 2020 (Level 1) (Level 2) (Level 3) Financial assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 52,583 ​ $ 52,583 ​ $ — ​ $ — Financial liabilities: ​ ​ ​ ​ Current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 10,695 ​ — ​ 10,695 ​ — Non-current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 19,358 ​ — ​ 19,358 ​ — Long-term debt, current and non-current ​ 1,036,118 ​ — ​ 1,036,118 ​ — ​ The Partnership’s accounting policy is to recognize transfers between levels of the fair value hierarchy on the date of the event or change in circumstances that caused the transfer. There were no transfers into or out of Level 1 and Level 2 as of December 31, 2021 and December 31, 2020.

Trade Accounts Receivable and O

Trade Accounts Receivable and Other Current Assets	12 Months Ended
	Dec. 31, 2021
Trade Accounts Receivable and Other Current Assets
Trade Accounts Receivable and Other Current Assets	12) Trade Accounts Receivable and Other Current Assets (a) Trade Accounts Receivable Trade accounts receivable are presented net of provisions for expected credit loss. As of December 31, 2021 and 2020, there were no trade receivables and no provision for expected credit loss. (b) Other Current Assets Other current assets consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ (U.S. Dollars in thousands) At December 31, 2021 At December 31, 2020 Insurance claims for recoveries ​ $ 124 ​ $ — Refund of value added tax ​ ​ 1,805 ​ ​ 1,429 Prepaid expenses ​ 1,158 ​ 1,050 Other receivables ​ 2,540 ​ 3,032 Total other current assets ​ $ 5,627 ​ $ 5,511 ​

Vessels and Equipment

Vessels and Equipment	12 Months Ended
	Dec. 31, 2021
Vessels and Equipment
Vessels and Equipment	13) Vessels and Equipment As of December 31, 2021 and 2020, Vessels with a book value of $1,598 million and $1,709 million, respectively, are pledged as security for the Partnership’s long-term debt. See Note 15—Long-Term Debt. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ Accumulated ​ ​ ​ (U.S. Dollars in thousands) Vessels & equipment depreciation impairment Net Vessels Vessels, December 31, 2019 ​ $ 2,129,012 ​ $ (451,524) ​ $ — ​ $ 1,677,488 Additions ​ 115,277 ​ — ​ ​ — ​ 115,277 Drydock costs ​ 5,764 ​ — ​ ​ — ​ 5,764 Disposals ​ — ​ — ​ ​ — ​ — Depreciation for the year ​ — ​ (89,743) ​ ​ — ​ (89,743) Vessels, December 31, 2020 ​ $ 2,250,053 ​ $ (541,267) ​ $ — ​ $ 1,708,786 Additions (1) ​ 14,065 ​ — ​ ​ — ​ 14,065 Drydock costs ​ 4,235 ​ — ​ ​ — ​ 4,235 Disposals ​ (2,641) ​ 2,641 ​ ​ — ​ — Depreciation and impairment for the period (2) ​ — ​ (99,559) ​ ​ (29,421) ​ (128,980) Vessels, December 31, 2021 ​ $ 2,265,712 ​ $ (638,185) ​ $ (29,421) ​ $ 1,598,106 (1) During the scheduled second renewal survey drydocking of the Bodil Knutsen a ballast water treatment system was installed on the vessel. A Volatile Organic Compounds (VOC) recovery system was installed on the Bodil Knutsen during the fourth quarter of 2021. ​ (2) The carrying value of the Windsor Knutsen was written down to its estimated fair value as of June 30, 2021. See Note 21—Impairment of Long-Lived Assets. ​ Drydocking activity for the years ended December 31, 2021 and 2020 is summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ (U.S. Dollars in thousands) At December 31, 2021 At December 31, 2020 Balance at the beginning of the year ​ $ 17,106 ​ $ 18,523 Costs incurred for dry docking ​ 4,235 ​ 2,724 Costs allocated to drydocking as part of acquistion of asset ​ — ​ 3,040 Drydock amortization ​ (7,883) ​ (7,181) Balance at the end of the year ​ $ 13,458 ​ $ 17,106 ​

Intangible Assets and Contract

Intangible Assets and Contract Liabilities	12 Months Ended
	Dec. 31, 2021
Intangible Assets and Contract Liabilities
Intangible Assets and Contract Liabilities	14) Intangible Assets and Contract Liabilities (a) Intangible Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Above market ​ Above market time ​ ​ ​ ​ time charter charter Total (U.S. Dollars in thousands) ​ Tordis Knutsen ​ Vigdis Knutsen ​ intangibles Intangibles, December 31, 2019 ​ $ 608 ​ $ 678 ​ $ 1,286 Additions ​ — ​ — ​ — Amortization for the year ​ (303) ​ (302) ​ (605) Intangibles, December 31, 2020 ​ $ 305 ​ $ 376 ​ $ 681 Additions ​ — ​ — ​ — Amortization for the period ​ (305) ​ (301) ​ (606) Intangibles, December 31, 2021 ​ $ — ​ $ 75 ​ $ 75 ​ The intangible for the above market value of time charter contract associated with the Tordis Knutsen Vigdis Knutsen The estimated future amortization of intangible assets at December 31, 2021 is as follows: ​ ​ ​ ​ ​ (U.S. Dollars in thousands) ​ ​ 2022 ​ ​ 75 Total ​ $ 75 ​ (b) Contract Liabilities The unfavorable contractual rights for charters associated with Fortaleza Knutsen Recife Knutsen Fortaleza Knutsen Recife Knutsen Fortaleza Knutsen Recife Knutsen ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance of Amortization for Balance of Amortization for Balance of ​ ​ December 31, ​ the year ended ​ December 31, ​ the year ended ​ December 31, (U.S. Dollars in thousands) ​ 2021 ​ December 31, 2021 ​ 2020 ​ December 31, 2020 ​ 2019 Contract liabilities: ​ ​ ​ ​ ​ Unfavourable contract rights ​ $ (2,169) ​ $ 1,517 ​ $ (3,686) ​ $ 1,517 ​ $ (5,203) Total amortization income ​ ​ $ 1,517 ​ ​ $ 1,517 ​ ​ ​ ​ Accumulated amortization for contract liabilities was $16.0 million and $14.5 million as of December 31, 2021 and 2020, respectively. The amortization of contract liabilities that is classified under time charter and bareboat revenues for the next five years is expected to be as follows: ​ ​ ​ ​ ​ (U.S. Dollars in thousands) ​ 2022 $ 1,517 2023 ​ ​ 652 2024 ​ ​ — 2025 ​ ​ — 2026 ​ ​ — 2027 ​ ​ — Total ​ $ 2,169 ​

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2021
Long-Term Debt
Long-Term Debt	15) Long-Term Debt Long-term debt as of December 31, 2021 and 2020, consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, (U.S. Dollars in thousands) Vessel 2021 2020 $345 million loan facility ​ Anna Knutsen, Tordis Knutsen, Vigdis Knutsen, Brasil Knutsen, Lena Knutsen ​ $ 338,726 ​ $ — $320 million loan facility ​ Windsor Knutsen, Bodil Knutsen, Carmen Knutsen, Fortaleza Knutsen, Recife Knutsen, Ingrid Knutsen ​ ​ 222,133 ​ ​ 252,245 $55 million revolving credit facility ​ ​ ​ — ​ 34,279 Hilda loan facility Hilda Knutsen ​ 72,308 ​ 78,462 Torill loan facility Torill Knutsen ​ 75,000 ​ 81,667 $172.5 million loan facility Dan Cisne, Dan Sabia ​ 45,340 ​ 58,340 Raquel loan facility Raquel Knutsen ​ — ​ 52,725 Tordis loan facility Tordis Knutsen ​ — ​ 75,871 Vigdis loan facility Vigdis Knutsen ​ — ​ 77,136 Lena loan facility Lena Knutsen ​ — ​ 75,950 Brasil loan facility Brasil Knutsen ​ — ​ 50,997 Anna loan facility Anna Knutsen ​ — ​ 62,196 Tove loan facility ​ Tove Knutsen ​ ​ 81,883 ​ ​ 86,250 $25 million revolving credit facility with NTT ​ 25,000 ​ 25,000 $25 million revolving credit facility with Shinsei ​ ​ ​ ​ 25,000 ​ ​ 25,000 Raquel Sale & Leaseback ​ Raquel Knutsen ​ ​ 89,206 ​ ​ — Total long-term debt ​ $ 974,596 ​ $ 1,036,118 Less: current installments ​ 90,956 ​ 186,723 Less: unamortized deferred loan issuance costs ​ 2,378 ​ 2,535 Current portion of long-term debt ​ 88,578 ​ 184,188 Amounts due after one year ​ 883,640 ​ 849,395 Less: unamortized deferred loan issuance costs ​ 5,092 ​ 3,238 Long-term debt, less current installments, and unamortized deferred loan issuance costs ​ $ 878,548 ​ $ 846,157 ​ The Partnership’s outstanding debt of $974.6 million as of December 31, 2021 is repayable as follows : ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (U.S. Dollars in thousands) Sale & Leaseback Period repayment Balloon repayment Total 2022 ​ $ 4,960 $ 85,996 $ — $ 90,956 2023 ​ ​ 5,177 ​ 79,768 ​ 225,906 ​ 310,851 2024 ​ ​ 5,418 ​ 38,107 ​ 123,393 ​ 166,918 2025 ​ ​ 5,640 ​ ​ 28,372 ​ ​ 65,506 ​ ​ 99,518 2026 and thereafter ​ ​ 68,010 ​ ​ 18,822 ​ ​ 219,521 ​ ​ 306,353 Total ​ $ 89,205 ​ $ 251,065 ​ $ 634,326 ​ $ 974,596 ​ As of December 31, 2021, the interest rates on the Partnership’s loan agreements were LIBOR plus a fixed margin ranging from 1.75% to 2.4%. $345 Million Term Loan Facility In September 2021, the Partnership’s subsidiaries which own the Tordis Knutsen Vigdis Knutsen Lena Knutsen Anna Knutsen Brasil Knutsen The $345 Million Loan Facility contains the following financial covenants: ● Positive working capital of the borrowers and the Partnership; ● Minimum liquidity of the Partnership of $15 million plus increments of $1.5 million for each owned vessel with less than 12 months remaining tenor on its employment contract up to 8 vessels and $1 million for each owned vessel with less than 12 months remaining tenor on its employment contract up to 12 additional vessels in excess of 8 vessels; ● Minimum book equity ratio for the Partnership of 30% ; and ● Minimum EBITDA to interest ratio for the Partnership of 2.50 . The $345 Million Loan Facility also identifies various events that may trigger mandatory reduction, prepayment, and cancellation of the facility, including if the aggregate market value of the vessels is less than 125% of the outstanding balance under the facility, upon a total loss or sale of a vessel and customary events of default. As of December 31, 2021, the borrowers and the guarantors were in compliance with all covenants under this facility. $320 Million Term Loan Facility and $55 Million Revolving Credit Facility In September 2018, the Partnership’s subsidiaries which own the Windsor Knutsen Bodil Knutsen Fortaleza Knutsen the Recife Knutsen Carmen Knutsen Ingrid Knutsen The Vessels, assignments of earnings, charterparty contracts and insurance proceeds are pledged as collateral for the Multi-vessel facility. The Partnership and the borrowers (except for the Partnership subsidiary that owns the Recife Knutsen and the Fortaleza Knutsen) are guarantors, and the Multi-vessels Facility is secured by vessel mortgages on the Windsor Knutsen Bodil Knutsen Fortaleza Knutsen Recife Knutsen Carmen Knutsen Ingrid Knutsen. The Multi-vessels Facility contains the following financial covenants: ● Positive working capital of the borrowers and the Partnership; ● Minimum liquidity of the Partnership of $15 million plus increments of $1.5 million for each owned vessel with less than 12 months remaining tenor on its employment contract up to 8 vessels and $1 million for each owned vessel with less than 12 months remaining tenor on its employment contract up to 12 additional vessels in excess of 8 vessels; ● Minimum book equity ratio for the Partnership of 30% ; and ● Minimum EBITDA to interest ratio for the Partnership of 2.50 . The Multi-vessels Facility also identifies various events that may trigger mandatory reduction, prepayment and cancellation of the facility, including if the aggregate market value of the vessels is less than 125% of the outstanding balance under the Multi Vessel Facility, upon a total loss or sale of a vessel and customary events of default. As of December 31, 2021, the borrowers and the guarantors were in compliance with all covenants under this facility. Hilda Loan Facility In May 2017, the Partnership’s subsidiary, Knutsen Shuttle Tankers 14 AS, which owns the vessel Hilda Knutsen The Hilda Facility contains the following primary financial covenants: ● Positive working capital of the borrower and the Partnership; ● Minimum liquidity of the Partnership of $15 million plus increments of $1 million for each additional vessel acquired by the Partnership in excess of eight vessels and $1.5 million for each owned vessel with less than 12 months remaining tenor on its employment contract; ● Minimum book equity ratio for the Partnership of 30% ; and ● Minimum EBITDA to interest ratio for the Partnership of 2.50 . The Hilda Facility also identifies various events that may trigger mandatory reduction, prepayment and cancellation of the facility, including if the market value of the vessels is less than 110% of the outstanding loan under the Hilda Facility for the first two years, Torill Loan Facility In January 2018, the Partnership’s subsidiary, Knutsen Shuttle Tankers 15 AS, which owns the vessel Torill Knutsen ● Positive working capital of the borrower and the Partnership; ● Minimum liquidity of the Partnership of $15 million plus increments of $1.5 million for each owned vessel with less than 12 months remaining tenor on its employment contract up to 8 vessels and $1 million for each owned vessel with less than 12 months remaining tenor on its employment contract in excess of 8 vessels; ● Minimum book equity ratio for the Partnership of 30% ; and ● Minimum EBITDA to interest ratio for the Partnership of 2.50 . The Torill Facility also identifies various events that may trigger mandatory reduction, prepayment and cancellation of the facility, including if the market value of the vessel is less than 110% of the outstanding loan under the Torill Facility for the first two years, 120% for the third and fourth year and 125% thereafter, upon a total loss or sale of a vessel and customary events of default. As of December 31, 2021, the borrower and the guarantor were in compliance with all covenants under this facility. $172.5 Million Secured Loan Facility In April 2014, KNOT Shuttle Tankers 20 AS and KNOT Shuttle Tankers 21 AS, the subsidiaries owning the Dan Cisne Dan Sabia Dan Cisne Dan Cisne Dan Sabia The Dan Cisne Facility and the Dan Sabia Facility are guaranteed by the Partnership and secured by a vessel mortgage on the Dan Cisne Dan Sabia The Dan Cisne Facility and Dan Sabia Facility contain the following financial covenants: ● Minimum liquidity of the Partnership of $15 million plus increments of $1 million for each additional vessel acquired by the Partnership in excess of eight vessels and $1.5 million for each owned vessel with less than 12 months remaining tenor on its employment contract; and ● Minimum book equity ratio for the Partnership of 30% . The facility also identifies various events that may trigger mandatory reduction, prepayment and cancellation of the facility, including if the market value of either of the vessels are less than 125% of the respective loan, upon a total loss or sale of a vessel and customary events of default. As of December 31, 2021, the borrowers and the guarantor were in compliance with all covenants under this facility. Tove Loan Facility In July 2019, KNOT Shuttle Tankers 34 AS, the subsidiary owning the Tove Knutsen Tove Knutsen The Tove Facility contains the following financial covenants: ● Positive working capital of the Partnership; ● Minimum liquidity of the Partnership of $15 million plus increments of $1.5 million for each owned vessel with less than 12 months remaining tenor on its employment contract up to 8 vessels and $1 million for each owned vessel with less than 12 months remaining tenor on its employment contract in excess of 8 vessels; ● Minimum book equity ratio for the Partnership of 30% ; and ● Minimum EBITDA to interest ratio for the Partnership of 2.50 . The Tove Facility also identifies various events that may trigger mandatory reduction, prepayment and cancellation of the facility, including if the market value of vessel falls below 110% of the outstanding loan, upon total loss or sale of the vessel and customary events of default. As of December 31, 2021, the borrower and the guarantors were in compliance with all covenants under this facility. $25 Million Revolving Credit Facility with NTT In June 2021, KNOT Shuttle Tankers AS extended the maturity of its $25 million unsecured revolving credit facility with NTT Finance Corporation. The extended facility will mature in August 2023, bears interest at LIBOR plus a margin of 1.8% and has a commitment fee of 0.5% on the undrawn portion of the facility. The commercial terms of the facility are unchanged from the facility entered into in June 2017 with NTT Finance Corporation. $25 Million Revolving Credit Facility with Shinsei In November 2020, KNOT Shuttle Tankers AS entered into an unsecured revolving credit facility with Shinsei Bank. The facility will mature in November 2023, bears interest at LIBOR plus a margin of 1.75% and has a commitment fee of 0.7% on the undrawn portion of the facility. ​ Raquel Sale and Leaseback On December 30, 2020, the Partnership through its wholly-owned subsidiary, Knutsen Shuttle Tankers 19 AS, which owned the Raquel Knutsen

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Taxes
Income Taxes	16) Income Taxes (a) Components of Current and Deferred Tax Expense All of the income from continuing operations before income taxes was taxable in Norway for the years ended December 31, 2021, 2020 and 2019. Our Norwegian subsidiaries are subject to Norwegian tonnage tax rather than ordinary corporate taxation. Under the tonnage tax regime, tax is payable based on the tonnage of the vessel, not on operating income, and is included within operating expenses. Net financial income and expense remain taxable as ordinary income at the regular corporate income tax rate of 22% and is recorded as an income tax expense. The amount of tonnage tax included in operating expenses for each of the years ended December 31, 2021, 2020 and 2019 was $0.3 million, $0.2 million and $0.2 million respectively. See Note 2(r)—Income Taxes. The activities taxable in the UK relate to KNOT UK and is based on the operating income for the entity. The significant components of current and deferred income tax expense attributable to income from continuing operations for the years ended December 31, 2021, 2020 and 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Current tax benefit (expense) ​ $ (488) ​ $ (10) ​ $ (9) Deferred tax benefit (expense) ​ — ​ — ​ — Income tax benefit (expense) ​ $ (488) ​ $ (10) ​ $ (9) ​ (b) Taxation Income taxes attributable to income from continuing operations was an income tax expense of $488,000 for the year ended December 31, 2021, an income tax expense of $10,000 for the year ended December 31, 2020 and an income tax expense of $9,000 for the year ended December 31, 2019, and differed from the amounts computed by applying the Norwegian and the UK ordinary income tax rate of 22% and 19% in 2021, 22% and 19% in 2020, and 22% and 20% in 2019, to tonnage tax and pretax net income, respectively, as a result of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (U.S. Dollars in thousands) 2021 2020 2019 Income tax benefit (expense) within Norway ​ $ (479) ​ $ — ​ $ — ​ Income tax benefit (expense) within UK ​ (9) ​ (10) ​ (9) ​ Income tax benefit (expense) ​ $ (488) ​ $ (10) ​ $ (9) ​ Effective tax rate ​ (1) % 0 % 0 % ​ (c) Components of Deferred Tax Assets and Liabilities The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities as of December 31, 2021 and 2020 are presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (U.S. Dollars in thousands) 2021 2020 Deferred tax assets: ​ ​ ​ ​ Financial derivatives ​ $ — ​ $ — Financial loss carry forwards for tonnage tax ​ 23,485 ​ 20,863 Total deferred tax asset ​ 23,485 ​ 20,863 Less valuation allowance ​ (23,485) ​ (20,863) Net deferred tax asset ​ — ​ — Deferred tax liabilities: ​ ​ ​ ​ Entrance tax ​ 228 ​ 295 Total deferred tax liabilities ​ ​ 228 ​ ​ 295 ​ ​ $ 228 ​ $ 295 ​ The net deferred tax liability is classified in the consolidated balance sheets as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (U.S. Dollars in thousands) 2021 2020 Current deferred tax asset ​ $ — ​ $ — Non-current deferred tax liabilities ​ 228 ​ 295 Net deferred tax liabilities ​ $ 228 ​ $ 295 ​ Changes in the net deferred tax liabilities at December 31, 2021 and 2020 are presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (U.S. Dollars in thousands) 2021 2020 Net deferred tax liabilities at January 1, ​ $ 295 ​ $ 357 Change in temporary differences ​ (58) ​ (72) Translation differences ​ (9) ​ 10 Net deferred tax liabilities at December 31, ​ $ 228 ​ $ 295 ​ The Partnership records a valuation allowance for deferred tax assets when it is more likely than not that some or all of the benefit from the deferred tax asset will be realized. The valuation allowances were $23.5 million and $20.9 million as of December 31, 2021 and 2020, respectively. The valuation allowances relate to the financial loss carry forwards and other deferred tax assets for tonnage tax that, in the judgment of the Partnership, are more-likely-than not to be realized reflecting the Partnership’s cumulative loss position for tonnage tax. In assessing the realizability of deferred tax assets, the Partnership considers whether it is more-likely-than-not that some portion or all of the deferred tax assets will not be realized taking into account all the positive and negative evidence available. As of December 31, 2021, the Partnership determined that the deferred tax assets are likely to not be realized, and the booked value was, therefore, zero. There is no expiration date for losses carried forward. After the reorganization of the Partnership’s predecessor’s activities into the new group structure in February 2013, all profit from continuing operations in Norway is taxable within the tonnage tax regime. The consequence of the reorganization is a one-time entrance tax into the Norwegian tonnage tax regime due to the Partnership’s acquisition of the shares in the subsidiary that owns the Fortaleza Knutsen Recife Knutsen Lena Knutsen As of December 31, 2021, the total income taxes payable are estimated to be $0.6 million and consist primarily of net financial income and expense taxable in Norway at the normal corporate income tax rate, payable Norwegian entrance tax and ordinary UK corporation tax. As of December 31, 2020, the total income taxes payable were estimated to be $0.1 million and consisted of payable Norwegian entrance tax and ordinary UK corporation tax. As of December 31, 2021, approximately $0.06 million of the estimated entrance tax of $0.29 million is estimated to be payable in the first and second quarter of 2022 and is presented as income taxes payable, while $0.23 million is presented as non-current deferred taxes payable. As of December 31, 2020, approximately $0.08 million of the estimated entrance tax of $0.38 million was estimated to be payable in the first and second quarter of 2021 and was presented as income taxes payable, while $0.30 million was presented as non-current deferred taxes payable. The tax loss carry forward from ordinary taxation and financial loss carry forwards for tonnage tax have no expiration dates. The Partnership’s Norwegian income tax returns are subject to examination by Norwegian tax authorities going back ten years. The Partnership had no unrecognized tax benefits as of December 31, 2021 and 2020. During the years ended December 31, 2021 and 2020, the Partnership did not incur any interest or penalties on its tax returns. On December 14, 2017, the Norwegian government concluded the negotiations with the EFTA Surveillance Authority regarding the Norwegian tonnage tax regime, which has been approved for another ten years, until 2027. Pursuant to the approval, Norway has introduced restrictions that eliminates the ability of companies that own vessels under certain bareboat charters to qualify for the Norwegian tonnage tax regime. Companies that no longer qualify for the Norwegian tonnage tax -regime will instead be subject to Norwegian corporate income tax. However, there are no limitations on intra-group bareboat chartering, as well as bareboat charters where crewing services are carried out by a related party. In order to constitute a related party, a minimum of 25% ownership/control is required, according to the “associated enterprise” definition in the ATAD directive (Council Directive EU 2016/1164.) Due to the fact that KNOT has an ownership interest in the Partnership that exceeds 25% as well as an ownership interest of 100% in KNOT Management and KNOT Management Denmark AS

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2021
Related Party Transactions
Related Party Transactions	17) Related Party Transactions (a) Related Parties Prior to the IPO, the Partnership’s predecessor operated as an integrated part of KNOT. KNOT is owned 50% by TSSI and 50% by Nippon Yusen Kaisha (“NYK”). The Windsor Knutsen Bodil Knutsen Carmen Knutsen Hilda Knutsen Torill Knutsen Ingrid Knutsen Raquel Knutsen Tordis Knutsen Vigdis Knutsen Lena Knutsen Brasil Knutsen Anna Knutsen Tove Knutsen Fortaleza Knutsen Recife Knutsen Dan Cisne Dan Sabia The Partnership is a party to an administrative services agreement with KNOT UK, pursuant to which KNOT UK provides administrative services, and KNOT UK is permitted to subcontract certain of the administrative services provided under the administrative services agreement to KOAS UK and KOAS. On May 7, 2015, the Partnership entered into an amendment to the administrative services agreement, which allows KNOT UK to also subcontract administrative services to KNOT Management. Effective as of February 26, 2018, the Partnership entered into a second amendment to the administrative services agreement extending the term of the agreement indefinitely, subject to termination by any party upon 90 days’ notice for any reason. The amounts of such costs and expenses included in the consolidated statements of operations for the years ended December 31, 2021, 2020 and 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Statements of operations: ​ ​ ​ ​ ​ ​ Time charter and bareboat revenues: ​ ​ ​ ​ ​ ​ ​ ​ ​ Time charter income from KNOT (1) ​ $ 6,427 ​ $ 4,883 ​ $ 15,910 Operating expenses: ​ ​ ​ Vessel operating expenses (2) ​ ​ 16,812 ​ ​ 14,693 ​ ​ 14,489 Technical and operational management fee from KNOT to Vessels (3) ​ 8,429 ​ 7,342 ​ 6,954 Operating expenses from other related parties (4) ​ ​ 866 ​ ​ 515 ​ ​ 487 General and administrative expenses: ​ ​ ​ ​ Administration fee from KNOT Management (5) ​ 1,277 ​ 1,131 ​ 1,280 Administration fee from KOAS (5) ​ 780 ​ 654 ​ 663 Administration fee from KOAS UK (5) ​ 80 ​ 118 ​ 116 Administration and management fee from KNOT (6) ​ 58 ​ 49 ​ 170 Total income (expenses) ​ $ (21,875) ​ $ (19,619) ​ $ (8,249) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, ​ At December 31, ​ At December 31, (U.S. Dollars in thousands) 2021 2020 2019 Balance Sheet: ​ ​ ​ ​ ​ ​ ​ ​ ​ Vessels: ​ ​ ​ ​ ​ ​ ​ ​ ​ Drydocking supervision fee from KNOT (7) ​ $ 134 ​ $ 47 ​ $ — Equipment purchased from KOAS (8) ​ ​ 1,840 ​ ​ — ​ ​ — Total ​ $ 1,974 ​ $ 47 ​ $ — (1) Time charter income from KNOT: On December 17, 2018, the Partnership’s subsidiary that owns the Windsor Knutsen and Royal Dutch Shell (“Shell”) agreed to suspend the vessel’s time charter contract. The suspension period commenced March 4, 2019, and ended April 5, 2020, when the vessel was redelivered to Shell. During the suspension period, the Windsor Knutsen operated under a time charter contract with Knutsen Shuttle Tankers Pool AS, a subsidiary of KNOT, on the same terms as the existing time charter contract with Shell. After completing its drydock in the second quarter of 2021, the Bodil Knutsen has operated under a time charter with Knutsen Shuttle Tankers Pool AS. The charter expires in April 2022, with two one-month extensions at the charterer’s option. (2) Vessel operating expenses: KNOT Management or KNOT Management Denmark provides technical and operational management of the vessels on time charter including crewing and crew training services. (3) Technical and operational management fee, from KNOT Management or KNOT Management Denmark to Vessels : KNOT Management or KNOT Management Denmark provides technical and operational management of the vessels on time charter including crewing, purchasing, maintenance and other operational service. In addition, there is also a charge for 24-hour emergency response services provided by KNOT Management for all vessels managed by KNOT Management. (4) Operating expenses from other related parties : Simsea Real Operations AS, a company jointly owned by the Partnership’s Chairman of the Board, Trygve Seglem, and by other third-party shipping companies in Haugesund, provides simulation, operational training assessment and other certified maritime courses for seafarers. The cost is course fees for seafarers. Knutsen OAS Crewing AS, a subsidiary of TSSI, provides administrative services related to East European crew on vessels operating on time charter contracts. The cost is a fixed fee per month per East European crew onboard the vessel. (5) Administration fee from KNOT Management, Knutsen OAS Shipping AS (“KOAS”) and Knutsen OAS (UK) Ltd. (“KOAS UK”) : Administration costs include compensation and benefits of KNOT Management’s management and administrative staff as well as other general and administration expenses. Some benefits are also provided by KOAS and KOAS UK. Net administration costs are total administration cost plus a 5% margin, reduced for the total fees for services delivered by the administration staffs and the estimated shareholder costs for KNOT that have not been allocated. As such, the level of net administration costs as a basis for the allocation can vary from year to year based on the administration and financing services offered by KNOT to all the vessels in its fleet each year. KNOT Management also charges each subsidiary a fixed annual fee for the preparation of the statutory financial statement. (6) Administration and management fee from KNOT Management and KNOT Management Denmark : For bareboat charters, the shipowner is not responsible for providing crewing or other operational services and the customer is responsible for all vessel operating expenses and voyage expenses. However, each of the vessels under bareboat charters is subject to a management and administration agreement with either KNOT Management or KNOT Management Denmark, pursuant to which these companies provide general monitoring services for the vessels in exchange for an annual fee. (7) Drydocking supervision fee from KNOT and KOAS : KNOT and KOAS provide supervision and hire out service personnel during drydocking of the vessels. The fee is calculated as a daily fixed fee. (8) During the scheduled second renewal survey drydocking of the Bodil Knutsen a ballast water treatment system was installed on the vessel. Parts of the system were purchased from Knutsen Ballast Water AS, a subsidiary of TSSI, for $1.84 million. (b) Transactions with Management and Directors Trygve Seglem, the Chairman of the Partnership’s board of directors and the President and CEO of KNOT, controls Seglem Holding AS, which owns 100% of the equity interest in TSSI, which controls KOAS. TSSI owns 50% of the equity interest in KNOT. NYK, which owns 50% of the equity interest in KNOT, has management and administrative personnel on secondment to KNOT. See the footnotes to Note 17(a)—Related Party Transactions—Related Parties for a discussion of the allocation principles for KNOT’s administrative costs, including management and administrative staff, included in the consolidated statements of operations. (c) Amounts Due from and Due to Related Parties Balances with related parties consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, ​ At December 31, (U.S. Dollars in thousands) 2021 2020 Balance Sheet: ​ ​ Trading balances due from KOAS ​ $ 290 ​ $ 170 Trading balances due from KNOT and affiliates (1) ​ 2,378 ​ 5,556 Amount due from related parties ​ $ 2,668 ​ $ 5,726 Trading balances due to KOAS ​ $ 1,205 ​ $ 1,596 Trading balances due to KNOT and affiliates ​ 219 ​ 544 Amount due to related parties ​ $ 1,424 ​ $ 2,140 (1) On December 31, 2020, the Partnership’s wholly owned subsidiary, KNOT Shuttle Tankers AS, acquired KNOT’s 100% interest in KNOT Shuttle Tankers 34 AS, the company that owns and operates the Tove Knutsen. Trading balances due from KNOT and affiliates as of December 31, 2020 includes the post-closing settlement amount of $3.6 million related to the acquisition of the Tove Knutsen . Amounts due from and due to related parties are unsecured and intended to be settled in the ordinary course of business. The majority of these related party transactions relate to vessel management and other fees due to KNOT, KNOT Management, KOAS UK and KOAS. (d) Trade accounts payables and other currents assets Trade accounts payables to related parties are included in total trade accounts payables in the balance sheet. The balances to related parties consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, ​ At December 31, (U.S. Dollars in thousands) 2021 2020 Balance Sheet: ​ ​ ​ ​ Trading balances due to KOAS ​ $ 813 ​ $ 1,304 Trading balances due to KNOT and affiliates ​ 783 ​ 902 Trade accounts payables to related parties ​ $ 1,596 ​ $ 2,206 ​ Trading balances from KNOT and affiliates are included in other current assets in the balance sheet. The balances from related parties consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, At December 31, (U.S. Dollars in thousands) ​ 2021 ​ 2020 Balance Sheet: ​ ​ Trading balances due from KOAS ​ $ 687 ​ $ 1,697 Trading balances due from KNOT and affiliates ​ ​ 543 ​ ​ 450 Other current assets from related parties ​ $ 1,230 ​ $ 2,147 ​ (e) Acquisitions from KNOT On December 31, 2020, the Partnership acquired KNOT’s 100% interest in KNOT Shuttle Tankers 34 AS, the company that owns and operates the Tove Knutsen The board of directors of the Partnership (the “Board”) and the Conflicts Committee of the Board approved the purchase price for the transaction described above. The Conflicts Committee retained a financial advisor to assist with its evaluation of each of the transaction. See Note 22—Acquisitions.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies
Commitments and Contingencies	18) Commitments and Contingencies Assets Pledged As of December 31, 2021 and 2020, Vessels with a book value of $1,598 million and $1,709 million, respectively, were pledged as security held as guarantee for the Partnership’s long-term debt and interest rate swap obligations. See Note 10—Derivative Instruments, Note 13—Vessels and Equipment and Note 15—Long-Term Debt. Claims and Legal Proceedings Under the Partnership’s time charters, claims to reduce the hire rate payments can be made if the Vessel does not perform to certain specifications in the agreements. No accrual for possible claim was recorded for the years ended December 31, 2021, 2020 and 2019. From time to time, the Partnership is involved in various claims and legal actions arising in the ordinary course of business. In the opinion of management, the ultimate disposition of these matters will not have a material adverse effect on the consolidated financial position, results of operations or cash flows. Insurance The Partnership maintains insurance on all the Vessels to insure against marine and war risks, which include damage to or total loss of the Vessels, subject to deductible amounts that average $0.15 million per Vessel, and loss of hire. Under the loss of hire policies, the insurer will pay a compensation for the lost hire rate agreed in respect of each Vessel for each day, in excess of 14 deductible days, for the time that the Vessel is out of service as a result of damage, for a maximum of 180 days. In addition, the Partnership maintains protection and indemnity insurance, which covers third-party legal liabilities arising in connection with the Vessels’ activities, including, among other things, the injury or death of third-party persons, loss or damage to cargo, claims arising from collisions with other vessels and other damage to other third-party property, including pollution arising from oil or other substances. This insurance is unlimited, except for pollution, which is limited to $1 billion per vessel per incident. The protection and indemnity insurance is maintained through a protection and indemnity association, and as a member of the association, the Partnership may be required to pay amounts above budgeted premiums if the member claims exceed association reserves, subject to certain reinsured amounts. If the Partnership experiences multiple claims each with individual deductibles, losses due to risks that are not insured or claims for insured risks that are not paid, it could have a material adverse effect on the Partnership’s results of operations and financial condition. Windsor Knutsen In December 2020, the Windsor Knutsen In addition, as of December 31, 2021, the Partnership had claimed and received payments of $4.1 million (net of deductible amounts) for hull and machinery recoveries. Tove Knutsen In March 2021, the Tove Knutsen In addition, as of December 31, 2021, the Partnership had claimed $0.1 million (net of deductible amounts) for hull and machinery recoveries. As of December 31, 2021, the Partnership has not received payment for this claim, resulting in an open insurance claim of $0.1 million. Bodil Knutsen In April 2021, the Bodil Knutsen Tordis Knutsen In July 2021, the Tordis Knutsen

Earnings per Unit and Cash Dist

Earnings per Unit and Cash Distributions	12 Months Ended
	Dec. 31, 2021
Earnings per Unit and Cash Distributions
Earnings per Unit and Cash Distributions	19) Earnings per Unit and Cash Distributions The calculations of basic and diluted earnings per unit (1) are presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands, except per unit data) 2021 2020 2019 Net income ​ $ 53,876 ​ $ 65,225 ​ $ 58,957 Less: Series A Preferred unitholders’ interest in net income ​ ​ 6,900 ​ ​ 7,200 ​ ​ 7,200 Net income attributable to the unitholders of KNOT Offshore Partners LP ​ ​ 46,976 ​ ​ 58,025 ​ ​ 51,757 Less: Distributions (2) ​ ​ 72,520 ​ ​ 72,136 ​ ​ 72,136 Under (over) distributed earnings ​ ​ (25,544) ​ ​ (14,111) ​ ​ (20,379) Under (over) distributed earnings attributable to: ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders (3) ​ ​ (24,927) ​ ​ (13,851) ​ ​ (20,003) Class B unitholders ​ ​ (147) ​ ​ — ​ ​ — General Partner ​ ​ (470) ​ ​ (261) ​ ​ (376) Weighted average units outstanding (basic) (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders ​ ​ 33,050 ​ ​ 32,694 ​ ​ 32,694 Class B unitholders ​ ​ 195 ​ ​ — ​ ​ — General Partner ​ ​ 623 ​ ​ 615 ​ ​ 615 Weighted average units outstanding (diluted) (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders (4) ​ ​ 37,064 ​ ​ 32,694 ​ ​ 32,694 Class B unitholders ​ ​ 195 ​ ​ — ​ ​ — General Partner ​ ​ 623 ​ ​ 615 ​ ​ 615 Earnings per unit (basic) ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders ​ $ 1.38 ​ $ 1.74 ​ $ 1.55 Class B unitholders ​ ​ 2.62 ​ ​ — ​ ​ — General Partner ​ ​ 1.38 ​ ​ 1.74 ​ ​ 1.55 Earnings per unit (diluted): ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders (4) ​ $ 1.38 ​ $ 1.74 ​ $ 1.55 Class B unitholders ​ ​ 2.62 ​ ​ — ​ ​ — General Partner ​ ​ 1.38 ​ ​ 1.74 ​ ​ 1.55 Cash distributions declared and paid in the period per unit (5) ​ $ 2.08 ​ $ 2.08 ​ $ 2.08 Subsequent event: Cash distributions declared and paid per unit relating to the period (6) ​ $ 0.52 ​ $ 0.52 ​ $ 0.52 (1) Earnings per unit have been calculated in accordance with the cash distribution provisions set forth in the Partnership’s partnership agreement (the “Partnership Agreement”). (2) This refers to distributions made or to be made in relation to the period irrespective of the declaration and payment dates and based on the numbers of units outstanding at the record date. This includes cash distributions to the IDR holder (KNOT) for the year ended December 31, 2021 of $2.1 million and for the years ended December 31, 2020 and 2019 of $2.8 million, respectively. (3) This includes the net income that was attributable to the IDR holder. The net income that was attributable to IDRs for the year ended December 31, 2021 was $2.1 million and for the years ended December 31, 2020 and 2019 was $2.8 million, respectively. (4) Diluted weighted average units outstanding and earnings per unit diluted for the years ended December 2021, 2021 and 2019 does not reflect any potential common units relating to the convertible preferred units since the assumed issuance of any additional units would be anti-dilutive. (5) Refers to cash distributions declared and paid during the period. (6) Refers to cash distributions declared and paid subsequent to December 31. On May 27, 2021, Tortoise Direct Opportunities Fund LP, the holder of 416,677 of the Partnership's Series A Preferred Units, sold 208,333 of its Series A Preferred Units to KNOT and converted 208,334 Series A Preferred Units to 215,292 common units based on a conversion rate of 1.0334. The Series A Preferred Units rank senior to the common units and Class B Units as to the payment of distributions and amounts payable upon liquidation, dissolution or winding up. The Series A Preferred Units have a liquidation preference of $24.00 per unit, plus any Series A unpaid cash distributions, plus all accrued but unpaid distributions on such Series A Preferred Unit with respect to the quarter in which the liquidation occurs to the date fixed for the payment of any amount upon liquidation. The Series A Preferred Units are entitled to cumulative distributions from their initial issuance date, with distributions being calculated at an annual rate of 8.0% on the stated liquidation preference and payable quarterly in arrears within 45 days after the end of each quarter, when, as and if declared by the Board. The Series A Preferred Units are generally convertible, at the option of the holders of the Series A Preferred Units, into common units at the applicable conversion rate. The conversion rate will be subject to adjustment under certain circumstances. In addition, the conversion rate will be redetermined on a quarterly basis, such that the conversion rate will be equal to $24.00 (the "Issue Price") divided by the product of (x) the book value per common unit at the end of the immediately preceding quarter (pro-forma for per unit cash distributions payable with respect to such quarter) multiplied by (y) the quotient of (i) the Issue Price divided by (ii) the book value per common unit on February 2, 2017. In addition, the Partnership may redeem the Series A Preferred Units at any time until February 2, 2027 at the redemption price specified in the Partnership Agreement, provided, however, that upon notice from the Partnership to the holders of Series A Preferred Units of its intent to redeem, such holders may elect, instead, to convert their Series A Preferred Units into common units at the applicable conversion rate. Upon a change of control of the Partnership, the holders of Series A Preferred Units will have the right to require cash redemption at 100% of the Issue Price. In addition, the holders of Series A Preferred Units will have the right to cause the Partnership to redeem the Series A Preferred Units on February 2, 2027 in, at the option of the Partnership, (i) cash at a price equal to 70% of the Issue Price or (ii) common units such that each Series A Preferred Unit receives common units worth 80% of the Issue Price (based on the volume-weighted average trading price, as adjusted for splits, combinations and other similar transactions, of the common units as reported on the NYSE for the 30 trading day period ending on the fifth trading day immediately prior to the redemption date) plus any accrued and unpaid distributions. In addition, subject to certain conditions, the Partnership has the right to convert the Series A Preferred Units into common units at the applicable conversion rate if the aggregate market value (calculated as set forth in the partnership agreement) of the common units into which the outstanding Series A Preferred Units are convertible, based on the applicable conversion rate, is greater than 130% of the aggregate Issue Price of the outstanding Series A Preferred Units. The Series A Preferred Units have voting rights that are identical to the voting rights of the common units and Class B Units, except they do not have any right to nominate, appoint or elect any of the directors of the Board, except whenever distributions payable on the Series A Preferred Units have not been declared and paid for four consecutive quarters (a "Trigger Event"). Upon a Trigger Event, holders of Series A Preferred Units, together with the holders of any other series of preferred units upon which like rights have been conferred and are exercisable, may replace one of the members of the Board appointed by the General Partner with a person nominated by such holders, such nominee to serve until all accrued and unpaid distributions on the preferred units have been paid. The Series A Preferred Units are entitled to vote with the common units and Class B Units as a single class so that the Series A Preferred Units are entitled to one vote for each common unit into which the Series A Preferred Units are convertible at the time of voting. On September 7, 2021, the Partnership entered into an exchange agreement with its general partner and KNOT whereby KNOT contributed to the Partnership all of KNOT’s IDRs in exchange for the issuance by the Partnership to KNOT of 673,080 common units and 673,080 Class B Units, whereupon the IDRs were cancelled (the “IDR Exchange”). The IDR Exchange closed on September 10, 2021. The Class B Units are a new class of limited partner interests which are not entitled to receive cash distributions in any quarter unless common unitholders receive a distribution of at least $0.52 for such quarter (the “Distribution Threshold”). When common unitholders receive a quarterly distribution at least equal to the Distribution Threshold, then Class B unitholders will be entitled to receive the same distribution as common unitholders. For each quarter (starting with the quarter ended September 30, 2021) that the Partnership pays distributions on the common units that are at or above the Distribution Threshold, one single class. After the payment of the Partnership’s quarterly cash distribution on November 10, 2021 with respect to the third quarter, 84,135 of the Class B Units converted to common units on a one-to-one basis. After the payment of the Partnership’s quarterly cash distribution on February 10, 2022 with respect to the quarter ended December 31, 2021, 84,135 of the Class B Units converted to common units on a one-to-one basis. As of December 31, 2021, 72.1% of the Partnership’s total number of common units outstanding representing limited partner interests were held by the public (in the form of 24,293,458 common units) and 27.7% of such units were held directly by KNOT (in the form of 9,324,715 common units). In addition, KNOT, through its ownership of the General Partner, held a 1.83% general partner interest (in the form of 640,278 general partner units) and a 0.3% limited partner interest (in the form of 90,368 common units). As of December 31, 2021, KNOT also held 208,333 Series A Preferred Units and 588,945 Class B Units. Earnings per unit—basic is determined by dividing net income, after deducting the amount of net income attributable to the Series A Preferred Units and the distribution paid or to be made in relation to the period by the weighted-average number of units outstanding during the applicable period. The computation of limited partners’ interest in net income per common unit – diluted assumes the issuance of common units for all potentially dilutive securities consisting of 3,541,666 Series A Preferred Units and 588,945 Class B Units as of December 31, 2021. Consequently, the net income attributable to limited partners’ interest is exclusive of any distributions on the Series A Preferred Units. In addition, the weighted average number of common units outstanding has been increased assuming the Series A Preferred Units and Class B Units have been converted to common units using the if-converted method. The computation of limited partners’ interest in net income per common unit – diluted does not assume the issuance of Series A Preferred Units and Class B Units if the effect would be anti-dilutive. The General Partner’s, Class B unitholders’ and common unitholders’ interest in net income was calculated as if all net income was distributed according to the terms of the Partnership Agreement, regardless of whether those earnings would or could be distributed. The Partnership Agreement does not provide for the distribution of net income. Rather, it provides for the distribution of available cash, which is a contractually defined term that generally means all cash on hand at the end of each quarter less the amount of cash reserves established by the Board to provide for the proper conduct of the Partnership’s business, including reserves for future capital expenditures, anticipated credit needs and capital requirements and any accumulated distributions on, or redemptions of, the Series A Preferred Units. Unlike available cash, net income is affected by non-cash items, such as depreciation and amortization, unrealized gains and losses on derivative instruments and unrealized foreign currency gains and losses.

Unit Activity

Unit Activity	12 Months Ended
	Dec. 31, 2021
Unit Activity
Unit Activity	20) Unit Activity The following table shows the movement in number of common units, Class B Units, general partner units and Series A Preferred Units from December 31, 2019 until December 31, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Series A ​ ​ ​ ​ ​ ​ General Partner ​ Convertible (in units) Common Units Class B Units Units Preferred Units December 31, 2020 32,694,094 — 615,117 3,750,000 May 27, 2021: Conversion of Series A Preferred Units 215,292 — — (208,334) September 10, 2021: IDR elimination 673,080 673,080 — — September 10, 2021: Issue of General Partner Units — — 25,161 — October 25, 2021: ATM program issue of common units 10,902 — — — October 26, 2021: ATM program issue of common units 31,038 — — — November 10, 2021: Quarterly conversion of Class B Units 84,135 (84,135) — — December 31, 2021 33,708,541 588,945 640,278 3,541,666 ​ On May 27, 2021 Tortoise Direct Opportunities Fund LP, the holder of 416,677 of the Partnership’s Series A Preferred Units sold 208,333 of its Series A Preferred Units to KNOT and converted 208,334 Series A Preferred Units to 215,292 common units based on a Series A conversion rate of 1.0334. On September 7, 2021, the Partnership entered into an exchange agreement with KNOT and the Partnership’s general partner whereby KNOT contributed to the Partnership all of KNOT’s IDRs, in exchange for the issuance by the Partnership to KNOT of 673,080 common units and 673,080 Class B Units, whereupon the IDRs were cancelled. The IDR Exchange closed on September 10, 2021. On September 10, 2021, the Partnership’s general partner contributed $0.45 million to the Partnership in exchange for the issuance of 25,161 general partner units in order to maintain its 1.83% general partner interest in the Partnership in connection with the IDR Exchange. In October 2021, the Partnership sold 41,940 common units under the ATM Program at an average gross sales price of $20.06 per unit and received net proceeds, after sale commissions, of $0.83 million. The Partnership paid an aggregate of $0.01 million in sales commissions to the Agent in connection with such sales. On November 10, 2021, 84,135 Class B units were converted to common units on a one-to-one basis pursuant to the Partnership’s partnership agreement.

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets	12 Months Ended
	Dec. 31, 2021
Impairment of Long-Lived Assets
Impairment of Long-Lived Assets	21) Impairment of Long-Lived Assets The carrying value of the Partnership’s fleet is regularly assessed as events or changes in circumstances may indicate that a vessel’s net carrying value exceeds the net undiscounted cash flows expected to be generated over its remaining useful life, and in such situation the carrying amount of the vessel is reduced to its estimated fair value. The Partnership considers factors related to vessel age, expected residual value, ongoing use of the vessels and equipment, shifts in market conditions and other impacting factors associated with the global oil and maritime transportation industries. This exercise in the second quarter of 2021 resulted in an impairment in respect of the Windsor Knutsen Windsor Knutsen Windsor Knutsen

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2021
Acquisitions
Acquisitions	22) Acquisitions During the year ended December 31, 2020, the Partnership acquired from KNOT equity interests in one subsidiary which owns and operates the Tove Knutsen. Tove Knutsen On December 31, 2020, the Partnership’s wholly owned subsidiary, KNOT Shuttle Tankers AS, acquired KNOT’s 100% interest in KNOT Shuttle Tankers 34 AS (“KNOT 34”), the company that owns and operates the Tove Knutsen The board of directors of the Partnership and the Conflicts Committee approved the purchase price for the transaction. The Conflicts Committee retained a financial advisor to assist with its evaluation of the transaction. The cost of the fee paid to the financial advisor was divided equally between the Partnership and KNOT. Acquisition related costs of $0.1 million as of December 31, 2020 were expensed as incurred under general and administrative expenses. The allocation of the purchase price to acquired identifiable assets was based on their estimated fair values at the date of acquisition. The purchase price of the acquisition has been allocated to the identifiable assets acquired. The details of the transaction are as follows: ​ ​ ​ ​ ​ ​ ​ Final ​ ​ Tove Knutsen ​ ​ December 31, (U.S. Dollars in thousands) 2020 Purchase consideration (1) ​ $ 21,898 Less: Fair value of net assets acquired: ​ ​ Vessels and equipment (2) ​ 117,978 Cash ​ 804 Inventories ​ 136 Derivatives assets (liabilities) ​ (3,537) Others current assets ​ 270 Amounts due from related parties ​ — Long-term debt ​ (93,139) Long-term debt from related parties ​ — Deferred debt issuance costs ​ 769 Trade accounts payable ​ (430) Accrued expenses ​ (622) Amounts due to related parties ​ (331) Total purchase consideration ​ 21,898 Difference between the purchase price and fair value of net assets acquired ​ $ — (1) The purchase consideration comprises the following: ​ ​ ​ ​ ​ ​ ​ Final ​ ​ Tove Knutsen ​ ​ December 31, (U.S. Dollars in thousands) 2020 Cash consideration paid to KNOT (from KNOP) ​ $ 25,430 Purchase price adjustments ​ (3,596) Acquisition-related costs ​ ​ 64 Purchase price ​ $ 21,898 (2) Vessel and equipment includes allocation to dry docking (in thousands) of $3,040 .

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2021
Subsequent Events
Subsequent Events	23) Subsequent Events The Partnership has evaluated subsequent events from the balance sheet date through March 17, 2022, the date at which the audited consolidated financial statements were available to be issued, and determined that there are no other items to disclose, except as follows: On February 10, 2022, the Partnership paid a quarterly cash distribution of $0.52 per common unit and Class B After the payment of the Partnership’s quarterly cash distribution with respect to the quarter ended December 31, 2021, 84,135 of the Class B Units converted to common units on a one-to-one basis. The Tordis Knutsen The Anna Knutsen Anna Knutsen The Vigdis Knutsen Although the Partnership has not experienced any direct impacts on its business from the Russian invasion of Ukraine, some of its vessels’ crew members are Russian or Ukrainian nationals. The Partnership continues to monitor this situation closely, and is mindful that there may be restrictions or logistical challenges in employing both nationalities in the near future. The invasion may also lead to further regional and international conflicts or armed action and it is possible that such conflicts could disrupt supply chains and cause instability in the global economy.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Summary of Significant Accounting Policies
Basis of Preparation	(a) Basis of Preparation The consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). All intercompany balances and transactions are eliminated on consolidation. The consolidated financial statements include the financial statements of the entities listed in Note 4—Subsidiaries.
Business Combinations and Asset Acquisitions	(b) Business Combinations and Asset Acquisitions Business combinations are accounted for under the purchase method of accounting. On acquisition, the identifiable assets, liabilities and contingent liabilities are measured at their fair values at the date of acquisition. Any excess of the cost of acquisition over the fair values of the identifiable net assets acquired is recognized as goodwill. The consideration transferred for an acquisition is measured at fair value of the consideration given. Acquisition related costs are expensed as incurred. The results of operations of the acquired businesses are included in the consolidated results as of the date of the applicable acquisition. Dependent on the facts and circumstances, the assessment of a transaction may be considered the acquisition of an asset, when substantially all of the fair value of assets acquired is concentrated in a single identifiable asset, rather than a business combination. Asset acquisitions are accounted for by allocating the cost of the acquisition to the individual assets acquired and liabilities assumed on a relative fair value basis. Acquisition related costs are capitalized as a component of the assets acquired. See Note 22- Acquisitions.
Reporting Currency	(c) Reporting Currency The consolidated financial statements are prepared in the reporting currency of U.S. Dollars. The functional currency of the vessel-owning Partnership subsidiaries is the U.S. Dollar, because the subsidiaries operate in the international shipping market, in which all revenues are U.S. Dollar-denominated and the majority of expenditures are made in U.S. Dollars. Transactions involving other currencies during the year are converted into U.S. Dollars using the exchange rates in effect at the time of the transactions. As of the balance sheet dates, monetary assets and liabilities that are denominated in currencies other than the U.S. Dollar are translated to reflect the year-end exchange rates. Resulting gains or losses are reflected separately in the accompanying consolidated statements of operations.
Use of Estimates	(d) Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. Significant items subject to such estimates and assumptions include the useful lives and impairment of Vessels, drydocking, purchase price allocation and income taxes.
Revenues and Operating Expenses	(e) Revenues and Operating Expenses The Partnership’s time charter contracts include both a lease component, consisting of the lease of the vessel, and non-lease component, consisting of operation of the vessel for the customers. The bareboat element is accounted for as an operating lease on a straight-line basis over the term of the charter, while the service element consisting of the operation of the vessel is recognized over time as the services are delivered. Revenue from time charters is recognized net of any commissions and is not recognized during days the Vessel is off-hire. Revenue is recognized from delivery of the Vessel to the charterer, until the end of the contract period. Under bareboat charters, the Partnership provides a specified Vessel for a fixed period of time at a specified day rate and the Partnership recognizes revenues from bareboat charters as operating leases on a straight-line basis over the term of the charter, net of any commissions. Where the term of the contract is based on the duration of a single voyage, the partnership evaluates whether the voyage contain leases and, if so, recognizes lease revenue as described above, and if not, recognizes revenue in accordance with ASC 606 upon the satisfaction of the performance obligations in the contract, i.e, when the underlying transportation service is provided to the customer. Voyage expenses are all expenses unique to a particular voyage, including bunker fuel expenses, port fees, cargo loading and unloading expenses, canal tolls and agency fees. Voyage expenses are paid by the customer under time charter and bareboat charters. Voyage expenses are paid by the Partnership for spot contracts and during periods of off-hire and are recognized when incurred. Vessel operating expenses include crewing, repairs and maintenance, insurance, stores, lube oils and communication expenses. Vessel operating expenses are paid by the Partnership for time charters, spot contracts and during off-hire and are recognized when incurred. The Partnership directly employs one onshore employee and no seagoing employees. Related parties have provided the management services for the Vessels and employ the crews that work on the Vessels. The Partnership is not liable for any pension or post-retirement benefits. See Note 17—Related Party Transactions.
Financial Income (Expense)	(f) Financial Income (Expense) Other finance expense includes external bank fees and commitment fees paid on undrawn revolving credit facility.
Cash and Cash Equivalents	(g) Cash and Cash Equivalents The Partnership considers all highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents.
Trade Accounts Receivable	(h) Trade Accounts Receivable Accounts receivable are recorded at the invoiced amount and do not bear interest. Under terms of the current time charters and bareboat charters, the customers are committed to pay for the full month’s charter the first day of each month. See Note 2(s)—Prepaid Charter. The allowance for expected credit losses is the Partnership’s best estimate of the expected credit losses over the remaining lives of the assets. Expected credit losses are estimated using historical credit loss experience, relevant available information, from internal and external sources, relating to current conditions and reasonable and supportable forecasts of economic conditions impacting the collectability of the assets. There was no allowance for expected credit loss or amounts written off against the allowance as of December 31, 2021 and 2020. The Partnership does not have any off-balance-sheet credit exposure related to its customers.
Inventories	(i) Inventories Inventories, which are comprised of lubricating oils and, for vessels not operating on time charter or bareboat charter, also bunkers, are stated at the lower of cost or net realizable value. For vessels on time charters or bareboat charters, there are no bunkers, as the charterer supplies the bunkers, which principally consist of fuel oil. Cost is determined using the first-in, first-out method for all inventories.
Other Current Assets	(j) Other Current Assets Other current assets principally consist of prepaid expenses and other receivables.
Vessels and Equipment	(k) Vessels and Equipment Vessels and equipment are stated at the historical acquisition or construction cost, including capitalized interest, supervision and technical and delivery cost, net of accumulated depreciation and impairment loss, if any. Expenditures for subsequent conversions and major improvements are capitalized, provided that such costs increase the earnings capacity or improve the efficiency or safety of the vessels. Generally, the Partnership drydocks each vessel every 60 months until the vessel is 15 years old and every 30 months thereafter, as required for the renewal of certifications issued by classification societies. For vessels operating on time charters, the Partnership capitalizes the costs directly associated with the classification and regulatory requirements for inspection of the vessels and improvements incurred during drydocking. Drydock cost is depreciated on a straight-line basis over the period until the next planned drydocking takes place. The Partnership expenses costs related to routine repairs and maintenance performed during drydocking or as otherwise incurred. For vessels that are newly built or acquired, an element of the cost of the vessel is initially allocated to a drydock component and depreciated on a straight-line basis over the period until the next planned drydocking. When significant dry-docking expenditures occur prior to the expiration of this period, the Partnership expenses the remaining balance of the original drydocking cost in the month of the subsequent drydocking. For vessels operating on bareboat charters, the charter-party bears the cost of any drydocking. Depreciation on vessels and equipment is calculated on a straight-line basis over the asset’s estimated useful life, less an estimated residual value, as follows: ​ ​ ​ ​ ​ Useful Life Hull 23 years Anchor-handling, loading and unloading equipment 23 years Main/auxiliary engine 23 years Thruster, dynamic positioning systems, cranes and other equipment 23 years Drydock costs 2.5 – 5 years ​ A Vessel is depreciated to its estimated residual value, which is calculated based on the weight of the ship and estimated steel price. Any cost related to the disposal is deducted from the residual value. Historically, the useful life of the Partnership’s vessels and equipment was assessed as 25 years commencing from the date the vessel and equipment were delivered from the shipyard. As of June 30, 2021, the Partnership considered factors related to the ongoing use of the vessels and equipment, gradual shifts in market conditions and other long-term factors associated with the global oil and maritime transportation industries and based on this has reassessed the useful life as being 23 years. This change in estimate was applied prospectively from July 1, 2021 and impacted the entire fleet of shuttle tanker vessels. The change in estimate resulted in an increase in depreciation diluted
Right-of-use assets and lease liabilities	(l) Right-of-use assets and lease liabilities The Partnership assesses whether a contract contains a lease at inception of the contract. The assessment involves the exercise of judgement about whether it depends on a specified asset, whether the Partnership obtains substantially all the economic benefits from the use of that asset, and whether the Partnership has the right to direct the use of the asset. The Partnership does not separate lease components from non-lease components as lessee. The Partnership recognizes a right-of-use asset and a lease liability at the lease commencement date, except for short-term leases of 12 months or less, which are expensed on a straight-line basis over the lease term.
Capitalized Interest	(m) Capitalized Interest Interest expense incurred on the Partnership’s debt during the construction of the Vessels exceeding one year is capitalized during the construction period.
Impairment of Long-Lived Assets	(n) Impairment of Long-Lived Assets Vessels and equipment, vessels under construction and intangible assets subject to amortization are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require a long-lived asset or asset group to be tested for possible impairment, the Partnership first compares undiscounted cash flows expected to be generated by that asset or asset group to its carrying value. If the carrying value of the long-lived asset or asset group is not recoverable on an undiscounted cash flow basis, impairment is recognized to the extent that the carrying value exceeds its fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. See Note 21—Impairment of Long-Lived Assets
Intangibles	(o) Intangibles Intangible assets represent contractual rights for charters obtained in connection with business and asset acquisitions that have favorable contractual terms relative to market as of the acquisition dates. Contract liabilities represent contractual rights obtained in connection with business acquisitions that have unfavorable contractual terms relative to market as of the acquisition dates. The favorable and unfavorable contract rights have definite lives and are amortized to revenues over the period of the related contracts. Intangible assets with a definite life are tested for impairment whenever events or circumstances indicate that their carrying amount may not be recoverable. An impairment loss is recognized if the carrying amount exceeds the estimated fair value of the asset. The contract related intangible assets and liabilities and their amortization periods at acquisition dates are as follows: ​ ​ ​ ​ ​ ​ Amortization Intangible category Period Above market time charter— Tordis Knutsen 4.8 years Above market time charter— Vigdis Knutsen 4.9 years Unfavorable contractual rights— Fortaleza Knutsen 12 years Unfavorable contractual rights— Recife Knutsen 12 years ​ The intangible for the above market value of the time charter contract associated with the Tordis Knutsen Vigdis Knutsen The unfavorable contractual rights for charters associated with Foraleza Knutsen Recife Knutsen Fortaleza Knutsen Recife Knutsen Fortaleza Knutsen Recife Knutsen
Debt Issuance Costs	(p) Debt Issuance Costs Debt issuance costs, including fees, commissions and legal expenses, are deferred and presented net of debt. Debt issuance costs of term loans are amortized over the term of the relevant loan. Amortization of debt issuance costs is included in interest expense. These costs are presented as a deduction from the corresponding liability, consistent with debt discount.
Derivative Instruments	(q) Derivative Instruments The Partnership uses derivatives to reduce market risks associated with its operations. The Partnership uses interest rate swaps for the management of interest risk exposure. The interest rate swaps effectively convert a portion of the Partnership’s debt from a floating to a fixed rate over the life of the transactions without an exchange of underlying principal. The Partnership seeks to reduce its exposure to fluctuations in foreign exchange rates through the use of foreign currency forward contracts. All derivative instruments are initially recorded at fair value as either assets or liabilities in the accompanying consolidated balance sheets and subsequently measured to fair value. The Partnership does not apply hedge accounting to its derivative instruments. Changes in the fair value of the derivative instruments are recognized in earnings. Gains and losses from the interest rate swap contracts of the Partnership related to long-term mortgage debt and foreign exchange forward contracts are recorded in realized and unrealized gain (loss) on derivative instruments in the consolidated statements of operations. Cash flows related to interest rate swap contracts are presented as cash flows provided by operating activities. Cash flows related to foreign exchange forward contracts entered into to economically hedge operating expenses in currencies other than U.S. Dollars are presented as cash flows provided by operating activities in the consolidated statements of cash flows, while cash flows related to foreign exchange forward contracts entered into to hedge contractual obligations to pay the shipyard in currencies other than functional currency of U.S. Dollars are presented as cash flows used in investing activities in the consolidated statements of cash flows.
Income Taxes	(r) Income Taxes Historically, part of the Partnership’s activities were subject to ordinary taxation and taxes were paid on taxable income (including operating income and net financial income and expense), while part of the activities were subject to the Norwegian Tonnage Tax Regime (the “tonnage tax regime”). Under the tonnage tax regime, tax is based on the tonnage of the vessel, and not operating income. Net financial income and expense remain taxable as ordinary income at the regular corporate income tax rate. Income taxes arising from the part of activities subject to ordinary taxation are included in income tax expense in the consolidated statements of operations. For the portion of activities subject to the tonnage tax regime, tonnage taxes are classified as vessel operating expenses, while the current and deferred taxes arising on net financial income and expense are reflected as income tax expense in the consolidated statements of operations. See Note 16—Income Taxes. The Partnership accounts for deferred income taxes using the liability method. Under the liability method, deferred tax assets and liabilities are recognized for the anticipated future tax effects of temporary differences between the financial statement basis and the tax basis of the Partnership’s assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. A valuation allowance for deferred tax assets is recorded when it is more likely than not that some or all of the benefit from the deferred tax asset will not be realized. Recognition of uncertain tax positions is dependent upon whether it is more-likely-than-not that a tax position taken or expected to be taken in a tax return will be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. If a tax position meets the more-likely-than-not recognition threshold, it is measured to determine the amount of benefit to recognize in the financial statements based on U.S. GAAP guidance. The Partnership recognizes interest and penalties related to uncertain tax positions in income tax expense.
Prepaid Charter	(s) Prepaid Charter Under terms of the time charters and bareboat charters, the customer pays for the month’s charter the first day of each month that is recorded as prepaid charter revenues.
Commitments, Contingencies and Insurance Proceeds	(t) Commitments, Contingencies and Insurance Proceeds Liabilities for loss contingencies arising from claims, assessments, litigation, fines and penalties and other sources are recorded when it is probable that a liability has been incurred and the amount can be reasonably estimated. Legal costs incurred in connection with loss contingencies are expensed as incurred. See Note 18—Commitments and Contingencies. Insurance claims for property damage for recoveries up to the amount of loss recognized are recorded when the claims submitted to insurance carriers are probable of recovery. Claims for property damage in excess of the loss recognized and for loss of hire are considered gain contingencies, which are generally recognized when the proceeds are received.
Fair Value Measurements	(u) Fair Value Measurements The Partnership utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. The Partnership determines fair value based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels: ● Level 1 Inputs: Unadjusted quoted prices in active markets for identical assets or liabilities accessible to the reporting entity at the measurement date. ● Level 2 Inputs: Other than quoted prices included in Level 1 inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability. ● Level 3 Inputs: Unobservable inputs for the asset or liability used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date.
Recently Adopted Accounting Standards and New Accounting Standards Not Yet Adopted	(v) Recently Adopted Accounting Standards There are no recent accounting standards whose adoption had a material impact on the consolidated financial statements in the current year. (w) New Accounting Standards Not Yet Adopted In March 2020, the Financial Accounting Standards Board (“FASB”) issued ASU 2020-04 Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Reporting. In August 2020, the FASB issued ASU 2020-06 Debt—Debt with conversion and other options (subtopic 470-20) and Derivatives and Hedging—contracts in entity’s own equity (subtopic 815-40): Accounting for convertible instruments and contracts in an entity’s own equity Other recently issued accounting pronouncements are not expected to materially impact the Partnership.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2021
Summary of Significant Accounting Policies
Schedule of estimated useful life of vessels and equipment	​ ​ ​ ​ ​ Useful Life Hull 23 years Anchor-handling, loading and unloading equipment 23 years Main/auxiliary engine 23 years Thruster, dynamic positioning systems, cranes and other equipment 23 years Drydock costs 2.5 – 5 years
Summary of contract related intangible assets and liabilities and their amortization periods at acquisition dates	​ ​ ​ ​ ​ ​ Amortization Intangible category Period Above market time charter— Tordis Knutsen 4.8 years Above market time charter— Vigdis Knutsen 4.9 years Unfavorable contractual rights— Fortaleza Knutsen 12 years Unfavorable contractual rights— Recife Knutsen 12 years

Significant Risks and Uncerta_2

Significant Risks and Uncertainties Including Business and Credit Concentrations (Tables)	12 Months Ended
	Dec. 31, 2021
Significant Risks and Uncertainties Including Business and Credit Concentrations
Schedule consolidated revenues and percentages of revenues for customers	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ (U.S. Dollars in thousands) ​ 2021 ​ 2020 ​ 2019 ​ Eni Trading and Shipping S.p.A. $ 43,823 16 % $ 44,175 16 % $ 44,610 16 % Fronape International Company, a subsidiary of Petrobras Transporte S.A. ​ 45,115 17 % 45,235 16 % 45,116 16 % Repsol Sinopec Brasil, B.V., a subsidiary of Repsol Sinopec Brasil, S.A. ​ 37,030 14 % 33,947 12 % 36,346 13 % Brazil Shipping I Limited, a subsidiary of Royal Dutch Shell ​ 59,825 22 % 76,959 28 % 66,199 23 % Galp Sinopec Brasil Services BV ​ 35,622 13 % 35,684 13 % 35,541 13 %

Operating Leases (Tables)

Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Operating Leases
Schedule of Partnership's revenues by time charter and bareboat charters and other revenues	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) ​ 2021 ​ 2020 ​ 2019 Time charter revenues (service element included) ​ $ 224,191 ​ $ 233,346 ​ $ 237,387 Bareboat revenues ​ ​ 45,115 ​ ​ 45,235 ​ ​ 45,115 Other revenues (loss of hire insurance recoveries and other income) ​ ​ 11,823 ​ ​ 641 ​ ​ 59 Total revenues ​ $ 281,129 ​ $ 279,222 ​ $ 282,561
Schedule of minimum contractual future revenues	​ ​ ​ ​ ​ (U.S. Dollars in thousands) ​ ​ 2022 ​ $ 198,385 2023 ​ ​ 99,805 2024 ​ ​ 102,560 2025 ​ ​ 94,803 2026 ​ ​ 51,088 2027 and thereafter ​ ​ 13,672 Total $ 560,313
Schedule of maturity analysis of partnership's lease liabilities	​ ​ ​ ​ ​ (U.S. Dollars in thousands) ​ 2022 ​ $ 703 2023 ​ 703 2024 ​ ​ 703 2025 ​ ​ 703 2026 ​ ​ 59 2027 and thereafter ​ ​ — Total ​ $ 2,871 Less imputed interest ​ 130 Carrying value of operating lease liabilities ​ $ 2,741

Other Finance Expenses (Tables)

Other Finance Expenses (Tables)	12 Months Ended
	Dec. 31, 2021
Other Finance Expenses
Schedule of components of interest cost	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Interest expense ​ $ 24,546 ​ $ 29,142 ​ $ 48,118 Amortization of debt issuance cost and fair value of debt assumed ​ 3,519 ​ 2,503 ​ 2,617 Total interest cost ​ $ 28,065 ​ $ 31,645 ​ $ 50,735
Schedule of components of other finance expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Bank fees, charges ​ $ 463 ​ $ 441 ​ $ 597 Commitment fees ​ 548 264 248 Total other finance expense ​ $ 1,011 $ 705 $ 845

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2021
Derivative Instruments
Schedule of realized and unrealized gains and losses recognized in earnings	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Realized gain (loss): ​ ​ ​ Interest rate swap contracts ​ $ (10,094) ​ $ (3,528) ​ $ 3,812 Foreign exchange forward contracts ​ — ​ (109) ​ (2,933) Total realized gain (loss): ​ (10,094) ​ (3,637) ​ 879 Unrealized gain (loss): ​ ​ ​ ​ ​ Interest rate swap contracts ​ 20,054 ​ (21,795) ​ (20,663) Foreign exchange forward contracts ​ — ​ (247) ​ 1,987 Total unrealized gain (loss): ​ 20,054 ​ (22,042) ​ (18,676) Total realized and unrealized gain (loss) on derivative instruments: ​ $ 9,960 ​ $ (25,679) ​ $ (17,797)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Measurements
Carrying amounts and estimated fair values of financial instruments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ December 31, 2020 ​ Carrying Fair Carrying Fair (U.S. Dollars in thousands) Amount Value Amount Value Financial assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 62,293 ​ $ 62,293 ​ $ 52,583 ​ $ 52,583 Non-current derivative assets: ​ ​ ​ ​ ​ ​ Interest rate swap contracts ​ 1,015 ​ 1,015 ​ — ​ — Financial liabilities: ​ ​ ​ ​ Current derivative liabilities: ​ ​ ​ ​ ​ ​ Interest rate swap contracts ​ 6,754 ​ 6,754 ​ 10,695 ​ 10,695 Non-current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 4,260 ​ 4,260 ​ 19,358 ​ 19,358 Long-term debt, current and non-current ​ 974,596 ​ 974,596 ​ 1,036,118 ​ 1,036,118
Schedule of assets and liabilities measured at fair value on recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements ​ ​ ​ ​ at Reporting Date Using ​ ​ ​ ​ ​ Quoted Price ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ in Active ​ Significant ​ ​ ​ ​ ​ Carrying ​ Markets for ​ Other ​ Significant ​ ​ Value ​ Identical ​ Observable ​ Unobservable ​ ​ December 31, ​ Assets ​ Inputs ​ Inputs (U.S. Dollars in thousands) 2021 (Level 1) (Level 2) (Level 3) Financial assets: ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 62,293 ​ $ 62,293 ​ $ — ​ $ — Non-current derivative assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest rate swap contracts ​ ​ 1,015 ​ ​ — ​ ​ 1,015 ​ ​ — Financial liabilities: ​ ​ ​ ​ Current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 6,754 ​ — ​ 6,754 ​ — Non-current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 4,260 ​ — ​ 4,260 ​ — Long-term debt, current and non-current ​ 974,596 ​ — ​ 974,596 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements ​ ​ ​ ​ at Reporting Date Using ​ ​ ​ ​ ​ Quoted Price ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ in Active ​ Significant ​ ​ ​ ​ ​ Carrying ​ Markets for ​ Other ​ Significant ​ ​ Value ​ Identical ​ Observable ​ Unobservable ​ ​ December 31, ​ Assets ​ Inputs ​ Inputs (U.S. Dollars in thousands) 2020 (Level 1) (Level 2) (Level 3) Financial assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 52,583 ​ $ 52,583 ​ $ — ​ $ — Financial liabilities: ​ ​ ​ ​ Current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 10,695 ​ — ​ 10,695 ​ — Non-current derivative liabilities: ​ ​ ​ ​ Interest rate swap contracts ​ 19,358 ​ — ​ 19,358 ​ — Long-term debt, current and non-current ​ 1,036,118 ​ — ​ 1,036,118 ​ — ​

Trade Accounts Receivable and_2

Trade Accounts Receivable and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2021
Trade Accounts Receivable and Other Current Assets
Schedule of Other Current Assets	​ ​ ​ ​ ​ ​ ​ ​ (U.S. Dollars in thousands) At December 31, 2021 At December 31, 2020 Insurance claims for recoveries ​ $ 124 ​ $ — Refund of value added tax ​ ​ 1,805 ​ ​ 1,429 Prepaid expenses ​ 1,158 ​ 1,050 Other receivables ​ 2,540 ​ 3,032 Total other current assets ​ $ 5,627 ​ $ 5,511

Vessels and Equipment (Tables)

Vessels and Equipment (Tables)	12 Months Ended
	Dec. 31, 2021
Vessels and Equipment
Schedule of vessels and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ Accumulated ​ ​ ​ (U.S. Dollars in thousands) Vessels & equipment depreciation impairment Net Vessels Vessels, December 31, 2019 ​ $ 2,129,012 ​ $ (451,524) ​ $ — ​ $ 1,677,488 Additions ​ 115,277 ​ — ​ ​ — ​ 115,277 Drydock costs ​ 5,764 ​ — ​ ​ — ​ 5,764 Disposals ​ — ​ — ​ ​ — ​ — Depreciation for the year ​ — ​ (89,743) ​ ​ — ​ (89,743) Vessels, December 31, 2020 ​ $ 2,250,053 ​ $ (541,267) ​ $ — ​ $ 1,708,786 Additions (1) ​ 14,065 ​ — ​ ​ — ​ 14,065 Drydock costs ​ 4,235 ​ — ​ ​ — ​ 4,235 Disposals ​ (2,641) ​ 2,641 ​ ​ — ​ — Depreciation and impairment for the period (2) ​ — ​ (99,559) ​ ​ (29,421) ​ (128,980) Vessels, December 31, 2021 ​ $ 2,265,712 ​ $ (638,185) ​ $ (29,421) ​ $ 1,598,106 (1) During the scheduled second renewal survey drydocking of the Bodil Knutsen a ballast water treatment system was installed on the vessel. A Volatile Organic Compounds (VOC) recovery system was installed on the Bodil Knutsen during the fourth quarter of 2021. ​ (2) The carrying value of the Windsor Knutsen was written down to its estimated fair value as of June 30, 2021. See Note 21—Impairment of Long-Lived Assets.
Schedule of drydocking activity	​ ​ ​ ​ ​ ​ ​ ​ (U.S. Dollars in thousands) At December 31, 2021 At December 31, 2020 Balance at the beginning of the year ​ $ 17,106 ​ $ 18,523 Costs incurred for dry docking ​ 4,235 ​ 2,724 Costs allocated to drydocking as part of acquistion of asset ​ — ​ 3,040 Drydock amortization ​ (7,883) ​ (7,181) Balance at the end of the year ​ $ 13,458 ​ $ 17,106

Intangible Assets and Contrac_2

Intangible Assets and Contract Liabilities (Tables)	12 Months Ended
	Dec. 31, 2021
Intangible Assets and Contract Liabilities
Schedule of intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Above market ​ Above market time ​ ​ ​ ​ time charter charter Total (U.S. Dollars in thousands) ​ Tordis Knutsen ​ Vigdis Knutsen ​ intangibles Intangibles, December 31, 2019 ​ $ 608 ​ $ 678 ​ $ 1,286 Additions ​ — ​ — ​ — Amortization for the year ​ (303) ​ (302) ​ (605) Intangibles, December 31, 2020 ​ $ 305 ​ $ 376 ​ $ 681 Additions ​ — ​ — ​ — Amortization for the period ​ (305) ​ (301) ​ (606) Intangibles, December 31, 2021 ​ $ — ​ $ 75 ​ $ 75
Schedule of estimated future amortization of intangible assets	​ ​ ​ ​ ​ (U.S. Dollars in thousands) ​ ​ 2022 ​ ​ 75 Total ​ $ 75
Schedule of contract liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance of Amortization for Balance of Amortization for Balance of ​ ​ December 31, ​ the year ended ​ December 31, ​ the year ended ​ December 31, (U.S. Dollars in thousands) ​ 2021 ​ December 31, 2021 ​ 2020 ​ December 31, 2020 ​ 2019 Contract liabilities: ​ ​ ​ ​ ​ Unfavourable contract rights ​ $ (2,169) ​ $ 1,517 ​ $ (3,686) ​ $ 1,517 ​ $ (5,203) Total amortization income ​ ​ $ 1,517 ​ ​ $ 1,517 ​ ​ ​
Schedule of expected amortization of contract liabilities	​ ​ ​ ​ ​ (U.S. Dollars in thousands) ​ 2022 $ 1,517 2023 ​ ​ 652 2024 ​ ​ — 2025 ​ ​ — 2026 ​ ​ — 2027 ​ ​ — Total ​ $ 2,169

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2021
Long-Term Debt
Schedule of long-term debt	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, (U.S. Dollars in thousands) Vessel 2021 2020 $345 million loan facility ​ Anna Knutsen, Tordis Knutsen, Vigdis Knutsen, Brasil Knutsen, Lena Knutsen ​ $ 338,726 ​ $ — $320 million loan facility ​ Windsor Knutsen, Bodil Knutsen, Carmen Knutsen, Fortaleza Knutsen, Recife Knutsen, Ingrid Knutsen ​ ​ 222,133 ​ ​ 252,245 $55 million revolving credit facility ​ ​ ​ — ​ 34,279 Hilda loan facility Hilda Knutsen ​ 72,308 ​ 78,462 Torill loan facility Torill Knutsen ​ 75,000 ​ 81,667 $172.5 million loan facility Dan Cisne, Dan Sabia ​ 45,340 ​ 58,340 Raquel loan facility Raquel Knutsen ​ — ​ 52,725 Tordis loan facility Tordis Knutsen ​ — ​ 75,871 Vigdis loan facility Vigdis Knutsen ​ — ​ 77,136 Lena loan facility Lena Knutsen ​ — ​ 75,950 Brasil loan facility Brasil Knutsen ​ — ​ 50,997 Anna loan facility Anna Knutsen ​ — ​ 62,196 Tove loan facility ​ Tove Knutsen ​ ​ 81,883 ​ ​ 86,250 $25 million revolving credit facility with NTT ​ 25,000 ​ 25,000 $25 million revolving credit facility with Shinsei ​ ​ ​ ​ 25,000 ​ ​ 25,000 Raquel Sale & Leaseback ​ Raquel Knutsen ​ ​ 89,206 ​ ​ — Total long-term debt ​ $ 974,596 ​ $ 1,036,118 Less: current installments ​ 90,956 ​ 186,723 Less: unamortized deferred loan issuance costs ​ 2,378 ​ 2,535 Current portion of long-term debt ​ 88,578 ​ 184,188 Amounts due after one year ​ 883,640 ​ 849,395 Less: unamortized deferred loan issuance costs ​ 5,092 ​ 3,238 Long-term debt, less current installments, and unamortized deferred loan issuance costs ​ $ 878,548 ​ $ 846,157
Schedule of partnership's outstanding debt repayable	The Partnership’s outstanding debt of $974.6 million as of December 31, 2021 is repayable as follows : ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (U.S. Dollars in thousands) Sale & Leaseback Period repayment Balloon repayment Total 2022 ​ $ 4,960 $ 85,996 $ — $ 90,956 2023 ​ ​ 5,177 ​ 79,768 ​ 225,906 ​ 310,851 2024 ​ ​ 5,418 ​ 38,107 ​ 123,393 ​ 166,918 2025 ​ ​ 5,640 ​ ​ 28,372 ​ ​ 65,506 ​ ​ 99,518 2026 and thereafter ​ ​ 68,010 ​ ​ 18,822 ​ ​ 219,521 ​ ​ 306,353 Total ​ $ 89,205 ​ $ 251,065 ​ $ 634,326 ​ $ 974,596

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Taxes
Schedule of significant components of current and deferred Income tax expense attributable to Income from continuing operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Current tax benefit (expense) ​ $ (488) ​ $ (10) ​ $ (9) Deferred tax benefit (expense) ​ — ​ — ​ — Income tax benefit (expense) ​ $ (488) ​ $ (10) ​ $ (9)
Schedule of taxation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (U.S. Dollars in thousands) 2021 2020 2019 Income tax benefit (expense) within Norway ​ $ (479) ​ $ — ​ $ — ​ Income tax benefit (expense) within UK ​ (9) ​ (10) ​ (9) ​ Income tax benefit (expense) ​ $ (488) ​ $ (10) ​ $ (9) ​ Effective tax rate ​ (1) % 0 % 0 %
Schedule of components of deferred tax assets and liabilities	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities as of December 31, 2021 and 2020 are presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (U.S. Dollars in thousands) 2021 2020 Deferred tax assets: ​ ​ ​ ​ Financial derivatives ​ $ — ​ $ — Financial loss carry forwards for tonnage tax ​ 23,485 ​ 20,863 Total deferred tax asset ​ 23,485 ​ 20,863 Less valuation allowance ​ (23,485) ​ (20,863) Net deferred tax asset ​ — ​ — Deferred tax liabilities: ​ ​ ​ ​ Entrance tax ​ 228 ​ 295 Total deferred tax liabilities ​ ​ 228 ​ ​ 295 ​ ​ $ 228 ​ $ 295 ​ The net deferred tax liability is classified in the consolidated balance sheets as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (U.S. Dollars in thousands) 2021 2020 Current deferred tax asset ​ $ — ​ $ — Non-current deferred tax liabilities ​ 228 ​ 295 Net deferred tax liabilities ​ $ 228 ​ $ 295 ​ Changes in the net deferred tax liabilities at December 31, 2021 and 2020 are presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (U.S. Dollars in thousands) 2021 2020 Net deferred tax liabilities at January 1, ​ $ 295 ​ $ 357 Change in temporary differences ​ (58) ​ (72) Translation differences ​ (9) ​ 10 Net deferred tax liabilities at December 31, ​ $ 228 ​ $ 295

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2021
Related Party Transactions
Schedule of Related Party Costs and Expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands) 2021 2020 2019 Statements of operations: ​ ​ ​ ​ ​ ​ Time charter and bareboat revenues: ​ ​ ​ ​ ​ ​ ​ ​ ​ Time charter income from KNOT (1) ​ $ 6,427 ​ $ 4,883 ​ $ 15,910 Operating expenses: ​ ​ ​ Vessel operating expenses (2) ​ ​ 16,812 ​ ​ 14,693 ​ ​ 14,489 Technical and operational management fee from KNOT to Vessels (3) ​ 8,429 ​ 7,342 ​ 6,954 Operating expenses from other related parties (4) ​ ​ 866 ​ ​ 515 ​ ​ 487 General and administrative expenses: ​ ​ ​ ​ Administration fee from KNOT Management (5) ​ 1,277 ​ 1,131 ​ 1,280 Administration fee from KOAS (5) ​ 780 ​ 654 ​ 663 Administration fee from KOAS UK (5) ​ 80 ​ 118 ​ 116 Administration and management fee from KNOT (6) ​ 58 ​ 49 ​ 170 Total income (expenses) ​ $ (21,875) ​ $ (19,619) ​ $ (8,249) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, ​ At December 31, ​ At December 31, (U.S. Dollars in thousands) 2021 2020 2019 Balance Sheet: ​ ​ ​ ​ ​ ​ ​ ​ ​ Vessels: ​ ​ ​ ​ ​ ​ ​ ​ ​ Drydocking supervision fee from KNOT (7) ​ $ 134 ​ $ 47 ​ $ — Equipment purchased from KOAS (8) ​ ​ 1,840 ​ ​ — ​ ​ — Total ​ $ 1,974 ​ $ 47 ​ $ — (1) Time charter income from KNOT: On December 17, 2018, the Partnership’s subsidiary that owns the Windsor Knutsen and Royal Dutch Shell (“Shell”) agreed to suspend the vessel’s time charter contract. The suspension period commenced March 4, 2019, and ended April 5, 2020, when the vessel was redelivered to Shell. During the suspension period, the Windsor Knutsen operated under a time charter contract with Knutsen Shuttle Tankers Pool AS, a subsidiary of KNOT, on the same terms as the existing time charter contract with Shell. After completing its drydock in the second quarter of 2021, the Bodil Knutsen has operated under a time charter with Knutsen Shuttle Tankers Pool AS. The charter expires in April 2022, with two one-month extensions at the charterer’s option. (2) Vessel operating expenses: KNOT Management or KNOT Management Denmark provides technical and operational management of the vessels on time charter including crewing and crew training services. (3) Technical and operational management fee, from KNOT Management or KNOT Management Denmark to Vessels : KNOT Management or KNOT Management Denmark provides technical and operational management of the vessels on time charter including crewing, purchasing, maintenance and other operational service. In addition, there is also a charge for 24-hour emergency response services provided by KNOT Management for all vessels managed by KNOT Management. (4) Operating expenses from other related parties : Simsea Real Operations AS, a company jointly owned by the Partnership’s Chairman of the Board, Trygve Seglem, and by other third-party shipping companies in Haugesund, provides simulation, operational training assessment and other certified maritime courses for seafarers. The cost is course fees for seafarers. Knutsen OAS Crewing AS, a subsidiary of TSSI, provides administrative services related to East European crew on vessels operating on time charter contracts. The cost is a fixed fee per month per East European crew onboard the vessel. (5) Administration fee from KNOT Management, Knutsen OAS Shipping AS (“KOAS”) and Knutsen OAS (UK) Ltd. (“KOAS UK”) : Administration costs include compensation and benefits of KNOT Management’s management and administrative staff as well as other general and administration expenses. Some benefits are also provided by KOAS and KOAS UK. Net administration costs are total administration cost plus a 5% margin, reduced for the total fees for services delivered by the administration staffs and the estimated shareholder costs for KNOT that have not been allocated. As such, the level of net administration costs as a basis for the allocation can vary from year to year based on the administration and financing services offered by KNOT to all the vessels in its fleet each year. KNOT Management also charges each subsidiary a fixed annual fee for the preparation of the statutory financial statement. (6) Administration and management fee from KNOT Management and KNOT Management Denmark : For bareboat charters, the shipowner is not responsible for providing crewing or other operational services and the customer is responsible for all vessel operating expenses and voyage expenses. However, each of the vessels under bareboat charters is subject to a management and administration agreement with either KNOT Management or KNOT Management Denmark, pursuant to which these companies provide general monitoring services for the vessels in exchange for an annual fee. (7) Drydocking supervision fee from KNOT and KOAS : KNOT and KOAS provide supervision and hire out service personnel during drydocking of the vessels. The fee is calculated as a daily fixed fee. (8) During the scheduled second renewal survey drydocking of the Bodil Knutsen a ballast water treatment system was installed on the vessel. Parts of the system were purchased from Knutsen Ballast Water AS, a subsidiary of TSSI, for $1.84 million.
Schedule of amounts due from and due to related parties	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, ​ At December 31, (U.S. Dollars in thousands) 2021 2020 Balance Sheet: ​ ​ Trading balances due from KOAS ​ $ 290 ​ $ 170 Trading balances due from KNOT and affiliates (1) ​ 2,378 ​ 5,556 Amount due from related parties ​ $ 2,668 ​ $ 5,726 Trading balances due to KOAS ​ $ 1,205 ​ $ 1,596 Trading balances due to KNOT and affiliates ​ 219 ​ 544 Amount due to related parties ​ $ 1,424 ​ $ 2,140 (1) On December 31, 2020, the Partnership’s wholly owned subsidiary, KNOT Shuttle Tankers AS, acquired KNOT’s 100% interest in KNOT Shuttle Tankers 34 AS, the company that owns and operates the Tove Knutsen. Trading balances due from KNOT and affiliates as of December 31, 2020 includes the post-closing settlement amount of $3.6 million related to the acquisition of the Tove Knutsen .
Schedule of Trade accounts payable and other current assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, ​ At December 31, (U.S. Dollars in thousands) 2021 2020 Balance Sheet: ​ ​ ​ ​ Trading balances due to KOAS ​ $ 813 ​ $ 1,304 Trading balances due to KNOT and affiliates ​ 783 ​ 902 Trade accounts payables to related parties ​ $ 1,596 ​ $ 2,206
Schedule of other current asset balances from related parties	​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, At December 31, (U.S. Dollars in thousands) ​ 2021 ​ 2020 Balance Sheet: ​ ​ Trading balances due from KOAS ​ $ 687 ​ $ 1,697 Trading balances due from KNOT and affiliates ​ ​ 543 ​ ​ 450 Other current assets from related parties ​ $ 1,230 ​ $ 2,147

Earnings per Unit and Cash Di_2

Earnings per Unit and Cash Distributions (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings per Unit and Cash Distributions
Schedule of calculations of basic and diluted earnings per unit	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (U.S. Dollars in thousands, except per unit data) 2021 2020 2019 Net income ​ $ 53,876 ​ $ 65,225 ​ $ 58,957 Less: Series A Preferred unitholders’ interest in net income ​ ​ 6,900 ​ ​ 7,200 ​ ​ 7,200 Net income attributable to the unitholders of KNOT Offshore Partners LP ​ ​ 46,976 ​ ​ 58,025 ​ ​ 51,757 Less: Distributions (2) ​ ​ 72,520 ​ ​ 72,136 ​ ​ 72,136 Under (over) distributed earnings ​ ​ (25,544) ​ ​ (14,111) ​ ​ (20,379) Under (over) distributed earnings attributable to: ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders (3) ​ ​ (24,927) ​ ​ (13,851) ​ ​ (20,003) Class B unitholders ​ ​ (147) ​ ​ — ​ ​ — General Partner ​ ​ (470) ​ ​ (261) ​ ​ (376) Weighted average units outstanding (basic) (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders ​ ​ 33,050 ​ ​ 32,694 ​ ​ 32,694 Class B unitholders ​ ​ 195 ​ ​ — ​ ​ — General Partner ​ ​ 623 ​ ​ 615 ​ ​ 615 Weighted average units outstanding (diluted) (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders (4) ​ ​ 37,064 ​ ​ 32,694 ​ ​ 32,694 Class B unitholders ​ ​ 195 ​ ​ — ​ ​ — General Partner ​ ​ 623 ​ ​ 615 ​ ​ 615 Earnings per unit (basic) ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders ​ $ 1.38 ​ $ 1.74 ​ $ 1.55 Class B unitholders ​ ​ 2.62 ​ ​ — ​ ​ — General Partner ​ ​ 1.38 ​ ​ 1.74 ​ ​ 1.55 Earnings per unit (diluted): ​ ​ ​ ​ ​ ​ ​ ​ Common unitholders (4) ​ $ 1.38 ​ $ 1.74 ​ $ 1.55 Class B unitholders ​ ​ 2.62 ​ ​ — ​ ​ — General Partner ​ ​ 1.38 ​ ​ 1.74 ​ ​ 1.55 Cash distributions declared and paid in the period per unit (5) ​ $ 2.08 ​ $ 2.08 ​ $ 2.08 Subsequent event: Cash distributions declared and paid per unit relating to the period (6) ​ $ 0.52 ​ $ 0.52 ​ $ 0.52 (1) Earnings per unit have been calculated in accordance with the cash distribution provisions set forth in the Partnership’s partnership agreement (the “Partnership Agreement”). (2) This refers to distributions made or to be made in relation to the period irrespective of the declaration and payment dates and based on the numbers of units outstanding at the record date. This includes cash distributions to the IDR holder (KNOT) for the year ended December 31, 2021 of $2.1 million and for the years ended December 31, 2020 and 2019 of $2.8 million, respectively. (3) This includes the net income that was attributable to the IDR holder. The net income that was attributable to IDRs for the year ended December 31, 2021 was $2.1 million and for the years ended December 31, 2020 and 2019 was $2.8 million, respectively. (4) Diluted weighted average units outstanding and earnings per unit diluted for the years ended December 2021, 2021 and 2019 does not reflect any potential common units relating to the convertible preferred units since the assumed issuance of any additional units would be anti-dilutive. (5) Refers to cash distributions declared and paid during the period. (6) Refers to cash distributions declared and paid subsequent to December 31.

Unit activity (Tables)

Unit activity (Tables)	12 Months Ended
	Dec. 31, 2021
Unit Activity
Schedule of movement in number of common units, general partner units and Series A Preferred Units	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Series A ​ ​ ​ ​ ​ ​ General Partner ​ Convertible (in units) Common Units Class B Units Units Preferred Units December 31, 2020 32,694,094 — 615,117 3,750,000 May 27, 2021: Conversion of Series A Preferred Units 215,292 — — (208,334) September 10, 2021: IDR elimination 673,080 673,080 — — September 10, 2021: Issue of General Partner Units — — 25,161 — October 25, 2021: ATM program issue of common units 10,902 — — — October 26, 2021: ATM program issue of common units 31,038 — — — November 10, 2021: Quarterly conversion of Class B Units 84,135 (84,135) — — December 31, 2021 33,708,541 588,945 640,278 3,541,666

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2021
Acquisitions
Schedule of purchase price for the transaction	​ ​ ​ ​ ​ ​ ​ Final ​ ​ Tove Knutsen ​ ​ December 31, (U.S. Dollars in thousands) 2020 Purchase consideration (1) ​ $ 21,898 Less: Fair value of net assets acquired: ​ ​ Vessels and equipment (2) ​ 117,978 Cash ​ 804 Inventories ​ 136 Derivatives assets (liabilities) ​ (3,537) Others current assets ​ 270 Amounts due from related parties ​ — Long-term debt ​ (93,139) Long-term debt from related parties ​ — Deferred debt issuance costs ​ 769 Trade accounts payable ​ (430) Accrued expenses ​ (622) Amounts due to related parties ​ (331) Total purchase consideration ​ 21,898 Difference between the purchase price and fair value of net assets acquired ​ $ — (1) The purchase consideration comprises the following: ​ ​ ​ ​ ​ ​ ​ Final ​ ​ Tove Knutsen ​ ​ December 31, (U.S. Dollars in thousands) 2020 Cash consideration paid to KNOT (from KNOP) ​ $ 25,430 Purchase price adjustments ​ (3,596) Acquisition-related costs ​ ​ 64 Purchase price ​ $ 21,898 (2) Vessel and equipment includes allocation to dry docking (in thousands) of $3,040 .

Description of Business (Detail

Description of Business (Details) $ in Millions	1 Months Ended
	Apr. 30, 2013item	Mar. 17, 2022USD ($)	Dec. 31, 2021item
Ownership interest in shuttle tankers acquired at formation (as a percent)	100.00%
Number of shuttle tankers acquired at formation	4
Number of operating vessels			17
Subsequent Event [Member]
Undrawn portion of revolving credit facilities | $		$ 55

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Revenues and Operating Expenses (Details)	12 Months Ended
	Dec. 31, 2021employee
Summary of Significant Accounting Policies
Number of onshore employees	1

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Trade Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Summary of Significant Accounting Policies
Allowance for doubtful accounts	$ 0	$ 0

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Vessels and Equipment (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2021		Dec. 31, 2020	Dec. 31, 2019
Vessels and Equipment
Drydocking interval until a vessel is 15 years old		60 months
Age of vessels to switch from 60 to 30 month drydocking interval		15 years
Drydocking interval after a vessel is 15 years old		30 months
Asset's estimated useful life	25 years
Amount of increase in depreciation and amortization		$ 99,559	[1]	$ 89,743	$ 89,844
Amount of increase in net loss		53,876		$ 65,225	$ 58,957
Useful life of vessels and equipment [Member]
Vessels and Equipment
Asset's estimated useful life	23 years
Amount of increase in depreciation and amortization		5,670
Amount of increase in net loss		$ 5,670
Increase in basic common unit		$ 0.17
Increase in diluted common unit		$ 0.17
Hull [Member]
Vessels and Equipment
Asset's estimated useful life		23 years
Anchor-Handling, Loading and Unloading Equipment [Member]
Vessels and Equipment
Asset's estimated useful life		23 years
Main/Auxiliary Engine [Member]
Vessels and Equipment
Asset's estimated useful life		23 years
Thruster, Dynamic Positioning Systems, Cranes and Other Equipment [Member]
Vessels and Equipment
Asset's estimated useful life		23 years
Drydock Costs [Member] | Minimum
Vessels and Equipment
Asset's estimated useful life		2 years 6 months
Drydock Costs [Member] | Maximum
Vessels and Equipment
Asset's estimated useful life		5 years
[1]	The carrying value of the Windsor Knutsen was written down to its estimated fair value as of June 30, 2021. See Note 21—Impairment of Long-Lived Assets.

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Intangibles (Details)	1 Months Ended		12 Months Ended
	Aug. 31, 2011	Mar. 31, 2011	Dec. 31, 2021
Fortaleza Knutsen
Intangible Assets
Amortization Period, Unfavorable contractual rights		12 years
Term of bareboat charter		12 years
Recife Knutsen
Intangible Assets
Amortization Period, Unfavorable contractual rights	12 years
Term of bareboat charter	12 years
Above Market Value Of Time Charter [Member] | Tordis Knutsen [Member]
Intangible Assets
Amortization Period, Above market time charter			4 years 9 months 18 days
Above Market Value Of Time Charter [Member] | Vigdis Knutsen [Member]
Intangible Assets
Amortization Period, Above market time charter			4 years 10 months 24 days
Unfavorable contractual rights [Member] | Fortaleza Knutsen
Intangible Assets
Amortization Period, Unfavorable contractual rights			12 years
Unfavorable contractual rights [Member] | Recife Knutsen
Intangible Assets
Amortization Period, Unfavorable contractual rights	12 years		12 years

Formation Transactions and In_2

Formation Transactions and Initial Public Offering - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 10, 2021	Apr. 30, 2013	Dec. 31, 2021	Dec. 31, 2020
Formation Transactions and Initial Public Offering
Number of general partner units issued			640,278	615,117
Repayment of outstanding debt		$ 118,900
One-time entrance tax into Norwegian tonnage tax regime		3,000
Revolving credit facility, outstanding		$ 20,000
KNOT [Member] | Bodil Knutsen [Member]
Formation Transactions and Initial Public Offering
Period of related party guarantee of payment of hire rate		5 years
IPO [Member]
Formation Transactions and Initial Public Offering
Gross proceeds received		$ 179,900
Net proceeds from the offering		160,700
KNOT [Member]
Formation Transactions and Initial Public Offering
Cash distribution		$ 21,950
General Partner [Member]
Formation Transactions and Initial Public Offering
Number of general partner units issued		349,694
Subordinated Units | KNOT [Member]
Formation Transactions and Initial Public Offering
Limited partners' capital account, units issued		8,567,500
Common Units [Member]
Formation Transactions and Initial Public Offering
Limited partners' capital account, units issued			33,708,541	32,694,094
Limited Partner [Member] | Common Units [Member] | IPO [Member]
Formation Transactions and Initial Public Offering
Common units sold and issued		8,567,500
Common unit, per share amount		$ 21
Limited Partner [Member] | Common Units [Member] | Underwriters' option to purchase additional units
Formation Transactions and Initial Public Offering
Common units sold and issued		1,117,500
General Partner Unit [Member]
Formation Transactions and Initial Public Offering
Number of general partner units issued	25,161
IDR Holders
Formation Transactions and Initial Public Offering
Threshold quarterly distribution for increasing percentages allocated to the IDRs		$ 0.43125
Partnership [Member] | General Partner Unit [Member]
Formation Transactions and Initial Public Offering
Percentage of partnership interest held by General Partner	1.83%
KNOT Offshore Partners UK LLC [Member] | KNOT Shuttle Tankers AS
Formation Transactions and Initial Public Offering
Percentage of contribution to subsidiary		100.00%
KNOT [Member] | Partnership [Member]
Formation Transactions and Initial Public Offering
Percentage of limited partner interest		49.00%	27.70%
KNOT [Member] | Incentive Distribution Rights [Member]
Formation Transactions and Initial Public Offering
Percentage of limited partner interest		100.00%
General Partner [Member] | Partnership [Member]
Formation Transactions and Initial Public Offering
Percentage of partnership interest held by General Partner		2.00%
Public | Partnership [Member]
Formation Transactions and Initial Public Offering
Percentage of limited partner interest		49.00%	72.10%

Significant Risks and Uncerta_3

Significant Risks and Uncertainties Including Business and Credit Concentrations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Significant Risks and Uncertainties Including Business and Credit Concentrations
Revenues	$ 281,129	$ 279,222	$ 282,561
Customer Concentration Risk [Member] | Revenues [Member] | Eni Trading and Shipping S.p.A.
Significant Risks and Uncertainties Including Business and Credit Concentrations
Revenues	$ 43,823	$ 44,175	$ 44,610
Percentage of partnership's consolidated revenues	16.00%	16.00%	16.00%
Customer Concentration Risk [Member] | Revenues [Member] | Fronape International Company, a subsidiary of Petrobras Transporte S.A.
Significant Risks and Uncertainties Including Business and Credit Concentrations
Revenues	$ 45,115	$ 45,235	$ 45,116
Percentage of partnership's consolidated revenues	17.00%	16.00%	16.00%
Customer Concentration Risk [Member] | Revenues [Member] | Repsol Sinopec Brasil, B.V., a subsidiary of Repsol Sinopec Brasil, S.A.
Significant Risks and Uncertainties Including Business and Credit Concentrations
Revenues	$ 37,030	$ 33,947	$ 36,346
Percentage of partnership's consolidated revenues	14.00%	12.00%	13.00%
Customer Concentration Risk [Member] | Revenues [Member] | Brazil Shipping I Limited, a subsidiary of Royal Dutch Shell
Significant Risks and Uncertainties Including Business and Credit Concentrations
Revenues	$ 59,825	$ 76,959	$ 66,199
Percentage of partnership's consolidated revenues	22.00%	28.00%	23.00%
Customer Concentration Risk [Member] | Revenues [Member] | Galp Sinopec Brasil Services BV
Significant Risks and Uncertainties Including Business and Credit Concentrations
Revenues	$ 35,622	$ 35,684	$ 35,541
Percentage of partnership's consolidated revenues	13.00%	13.00%	13.00%

Operating Leases (Details)

Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Leases
Revenue from contract with customers	$ 269,306	$ 278,581	$ 282,502
Other revenues (loss of hire insurance recoveries and other income)	11,823	641	59
Total revenues	281,129	279,222	282,561
Time charter revenues (service element included)
Operating Leases
Revenue from contract with customers	224,191	233,346	237,387
Bareboat revenues
Operating Leases
Revenue from contract with customers	$ 45,115	$ 45,235	$ 45,115

Operating Leases - Minimum Cont

Operating Leases - Minimum Contractual Future Revenues (Details) $ in Thousands	Dec. 31, 2021USD ($)
Minimum contractual future revenues
2022	$ 198,385
2023	99,805
2024	102,560
2025	94,803
2026	51,088
2027 and thereafter	13,672
Total	$ 560,313

Operating Leases - Additional I

Operating Leases - Additional Information (Details) - item	Feb. 23, 2022	Feb. 11, 2022	Dec. 31, 2021	Aug. 31, 2011	Mar. 31, 2011
Fortaleza Knutsen
Operating Leases
Current bareboat charter expiration year			2023
Recife Knutsen
Operating Leases
Current bareboat charter expiration year			2023
Bodil Knutsen [Member]
Operating Leases
Option to extend term			one-year
Number of options to extend one year periods			2
Current time charter expiration year			2022
Windsor Knutsen [Member]
Operating Leases
Current bareboat charter expiration year			2022
Option to extend term			one-year
Number of options to extend one year periods			2
Current time charter expiration year			2024
Carmen Knutsen [Member]
Operating Leases
Current time charter expiration year			2023
Time charter expiration year under options to extend			2026
Hilda Knutsen
Operating Leases
Current time charter expiration year			2022
Time charter expiration year under options to extend			2025
Torill Knutsen [Member]
Operating Leases
Fixed term of contract			3 years
Current time charter expiration year			2022
Time charter expiration year under options to extend			2024
Dan Cisne [Member]
Operating Leases
Current bareboat charter expiration year			2023
Dan Sabia [Member]
Operating Leases
Current bareboat charter expiration year			2024
Ingrid Knutsen [Member]
Operating Leases
Current time charter expiration year			2024
Time charter expiration year under options to extend			2029
Raquel Knutsen [Member]
Operating Leases
Current time charter expiration year			2025
Time charter expiration year under options to extend			2030
Tordis Knutsen [Member]
Operating Leases
Current time charter expiration year			2022
Extension period for new time charter contract			1 month
Time charter expiration year under options to extend			2023
Vigdis Knutsen [Member]
Operating Leases
Fixed term of contract			3 years
Current time charter expiration year			2022
Time charter expiration year under options to extend			2023
Lena Knutsen [Member]
Operating Leases
Fixed term of contract			3 years
Current time charter expiration year			2022
Time charter expiration year under options to extend			2023
Brasil Knutsen [Member]
Operating Leases
Current time charter expiration year			2022
Time charter expiration year under options to extend			2028
Tove Knutsen [Member]
Operating Leases
Current time charter expiration year			2027
Time charter expiration year under options to extend			2040
Fortaleza Knutsen
Operating Leases
Fixed term of contract					12 years
Recife Knutsen
Operating Leases
Fixed term of contract				12 years
Minimum | Bodil Knutsen [Member] | Vessel
Operating Leases
Fixed term of contract			1 year
Minimum | Windsor Knutsen [Member] | Vessel
Operating Leases
Fixed term of contract			1 year
Maximum | Bodil Knutsen [Member] | Vessel
Operating Leases
Fixed term of contract			2 years
Maximum | Windsor Knutsen [Member] | Vessel
Operating Leases
Fixed term of contract			2 years
Subsequent Event [Member] | Tordis Knutsen [Member]
Operating Leases
Extension period for new time charter contract	1 month
Subsequent Event [Member] | Anna Knutsen [Member]
Operating Leases
Option to extend term		one-year
Subsequent Event [Member] | Minimum | Anna Knutsen [Member]
Operating Leases
Fixed term of contract		1 year
Option to extend term		one-year
Number of options to extend one year periods		4
Subsequent Event [Member] | Maximum | Anna Knutsen [Member]
Operating Leases
Fixed term of contract		2 years
Option to extend term		one-year
Number of options to extend one year periods		3

Operating Leases - Lease obliga

Operating Leases - Lease obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Lessor Lease Description Line Items
Right-of-use asset	$ 2,742	$ 1,490
Lease liability	2,741
Lease cost	$ 700
Weighted average discount rate (as a percent)	2.30%
Partnership's lease liabilities from leased-in equipment
2022	$ 703
2023	703
2024	703
2025	703
2026	59
Total	2,871
Less imputed interest	130
Carrying value of operating lease liabilities	$ 2,741
Tove Knutsen [Member]
Lessor Lease Description Line Items
Weighted average remaining lease term	4 years 1 month 6 days

Segment Information (Details)

Segment Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)itemsegment	Dec. 31, 2020USD ($)item	Dec. 31, 2019USD ($)
Segment Information
Revenues | $	$ 281,129	$ 279,222	$ 282,561
Number Of Vessels	17
Number of reportable segments | segment	1
Number of time charters	12	12
Number of bareboat charters	4
Minimum | Revenues [Member] | Customer Concentration Risk [Member]
Segment Information
Benchmark percentage of revenues and combined revenues concentration	10.00%
Concentration Risk, Percentage	10.00%

Insurance Proceeds (Details)

Insurance Proceeds (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Insurance Proceeds
Deductible period under business interruption insurance		14 days
Loss of hire insurance payments recorded as a component of total revenues		$ 11,450
Net vessel operating expense		$ 72,114	$ 61,005	$ 60,129
Maximum
Insurance Proceeds
Deductible period under business interruption insurance		180 days
Windsor Knutsen [Member]
Insurance Proceeds
Deductible period under business interruption insurance	14 days		14 days
Loss of hire insurance payments recorded as a component of total revenues		$ 8,700
Amount of claimed and received payments		4,100
Windsor Knutsen [Member] | Maximum
Insurance Proceeds
Deductible period under business interruption insurance	180 days		180 days
Tove Knutsen [Member]
Insurance Proceeds
Loss of hire insurance payments recorded as a component of total revenues		1,500
Amount of claimed and received payments		100
Amount claimed for insurance		100
Bodil Knutsen [Member]
Insurance Proceeds
Amount of claimed and received payments		100
Tordis Knutsen [Member]
Insurance Proceeds
Amount of claimed and received payments		$ 1,200

Other Finance Expenses - Compon

Other Finance Expenses - Components Interest Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Finance Expenses
Interest expense	$ 24,546	$ 29,141	$ 48,117
Amortization of debt issuance cost and fair value of debt assumed	3,519	2,503	2,617
Total interest cost	$ 28,065	$ 31,645	$ 50,735

Other Finance Expenses - Comp_2

Other Finance Expenses - Components of other finance expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Finance Expenses
Bank fees, charges	$ 463	$ 441	$ 597
Commitment fees	548	264	248
Total other finance expense	$ 1,011	$ 705	$ 845

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Details) - Interest Rate Swap Contracts [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments
Notional amount	$ 462.3	$ 516.2
Carrying amount of derivative liabilities	$ 10	$ 30.1

Derivative Instruments - Realiz

Derivative Instruments - Realized and Unrealized Gains and Losses Recognized in Earnings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net gain (loss) on derivative instruments
Realized gain (loss)	$ (10,094)	$ (3,637)	$ 879
Unrealized gain (loss)	20,054	(22,042)	(18,676)
Total realized and unrealized gain (loss) on derivative instruments	9,960	(25,679)	(17,797)
Interest Rate Swap Contracts [Member]
Net gain (loss) on derivative instruments
Realized gain (loss)	(10,094)	(3,528)	3,812
Unrealized gain (loss)	$ 20,054	(21,795)	(20,663)
Foreign Exchange Forward Contracts [Member]
Net gain (loss) on derivative instruments
Realized gain (loss)		(109)	(2,933)
Unrealized gain (loss)		$ (247)	$ 1,987

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Amounts and Estimated Fair Values of Partnership 's Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financial assets:
Non-current derivative assets	$ 1,015
Financial liabilities:
Current derivative liabilities	6,754	$ 10,695
Non-current derivative liabilities	4,260	19,358
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	62,293	52,583
Financial liabilities:
Long-term debt, current and non-current	974,596	1,036,118
Carrying Amount [Member] | Interest Rate Swap Contracts [Member]
Financial assets:
Non-current derivative assets	1,015
Financial liabilities:
Current derivative liabilities	6,754	10,695
Non-current derivative liabilities	4,260	19,358
Fair Value [Member]
Financial assets:
Cash and cash equivalents	62,293	52,583
Financial liabilities:
Long-term debt, current and non-current	974,596	1,036,118
Fair Value [Member] | Interest Rate Swap Contracts [Member]
Financial assets:
Non-current derivative assets	1,015
Financial liabilities:
Current derivative liabilities	6,754	10,695
Non-current derivative liabilities	$ 4,260	$ 19,358

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Fair Value, assets and liabilities measured on recurring and nonrecurring basis
Impairment	[1]	$ 29,421
Deferred debt issuance cost		7,500	$ 5,800
Restricted cash		$ 0	$ 0
Interest Rate Swap Contracts [Member]
Fair Value, assets and liabilities measured on recurring and nonrecurring basis
Weighted average remaining terms		3 years 4 months 24 days	4 years 3 months 18 days
Interest Rate Swap Contracts [Member] | Minimum
Fair Value, assets and liabilities measured on recurring and nonrecurring basis
Notional amount per contract		$ 5,200	$ 7,000
Fixed interest rate		0.71%	0.71%
Interest Rate Swap Contracts [Member] | Maximum
Fair Value, assets and liabilities measured on recurring and nonrecurring basis
Notional amount per contract		$ 37,500	$ 40,100
Fixed interest rate		2.90%	2.90%
[1]	The carrying value of the Windsor Knutsen was written down to its estimated fair value as of June 30, 2021. See Note 21—Impairment of Long-Lived Assets.

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financial assets:
Non-current derivative assets	$ 1,015
Financial liabilities:
Current derivative liabilities	6,754	$ 10,695
Non-current derivative liabilities	4,260	19,358
Vessels	1,598,106	1,708,786	$ 1,677,488
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	62,293	52,583
Financial liabilities:
Long-term debt, current and non-current	974,596	1,036,118
Fair Value [Member]
Financial assets:
Cash and cash equivalents	62,293	52,583
Financial liabilities:
Long-term debt, current and non-current	974,596	1,036,118
Interest Rate Swap Contracts [Member] | Carrying Amount [Member]
Financial assets:
Non-current derivative assets	1,015
Financial liabilities:
Current derivative liabilities	6,754	10,695
Non-current derivative liabilities	4,260	19,358
Interest Rate Swap Contracts [Member] | Fair Value [Member]
Financial assets:
Non-current derivative assets	1,015
Financial liabilities:
Current derivative liabilities	6,754	10,695
Non-current derivative liabilities	4,260	19,358
Quoted Price in Active Markets for Identical Assets (Level 1) [Member] | Fair Value [Member]
Financial assets:
Cash and cash equivalents	62,293	52,583
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member]
Financial liabilities:
Long-term debt, current and non-current	974,596	1,036,118
Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Swap Contracts [Member] | Fair Value [Member]
Financial assets:
Non-current derivative assets	1,015
Financial liabilities:
Current derivative liabilities	6,754	10,695
Non-current derivative liabilities	$ 4,260	$ 19,358

Fair Value Measurements - Fai_2

Fair Value Measurements - Fair Value transfers into or out of Level 1, Level 2 or Level 3 (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value Measurements
Transfers amount Fair value assets level 1 to level 2	$ 0	$ 0

Trade Accounts Receivable and_3

Trade Accounts Receivable and Other Current Assets - Trade Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Trade Accounts Receivable and Other Current Assets
Provision for Doubtful Accounts	$ 0	$ 0

Trade Accounts Receivable and_4

Trade Accounts Receivable and Other Current Assets - Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Trade Accounts Receivable and Other Current Assets
Insurance claims for recoveries	$ 124
Refund of value added tax	1,805	$ 1,429
Prepaid expenses	1,158	1,050
Other receivables	2,540	3,032
Total other current assets	$ 5,626	$ 5,511

Vessels and Equipment - Pledged

Vessels and Equipment - Pledged Assets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Vessels and Equipment
Book value of assets pledged as security for long-term debt	$ 1,598	$ 1,709

Vessels and Equipment - Long-Te

Vessels and Equipment - Long-Term Debt (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020	Dec. 31, 2019
Vessels & equipment - Activity
Vessels and equipment, beginning balance		$ 2,250,053		$ 2,129,012
Additions		14,065	[1]	115,277
Drydock costs		4,235		5,764
Disposals		(2,641)
Vessels and equipment, ending balance		2,265,712		2,250,053	$ 2,129,012
Accumulated depreciation - Activity
Accumulated depreciation, beginning balance		(541,267)		(451,524)
Accumulated depreciation, disposals		2,641
Depreciation and impairment for the period		(99,559)	[2]	(89,743)	(89,844)
Accumulated depreciation, ending balance		(638,185)		(541,267)	(451,524)
Accumulated impairment - Activity
Depreciation and impairment for the period	[2]	(29,421)
Accumulated impairment, ending balance		(29,421)
Net Vessels - Activity
Net vessel, beginning balance		1,708,786		1,677,488
Additions		14,065	[1]	115,277
Drydock costs		4,235		5,764
Depreciation and impairment for the period		(128,980)	[2]	(89,743)
Net vessel, ending balance		$ 1,598,106		$ 1,708,786	$ 1,677,488
[1]	During the scheduled second renewal survey drydocking of the Bodil Knutsen a ballast water treatment system was installed on the vessel. A Volatile Organic Compounds (VOC) recovery system was installed on the Bodil Knutsen during the fourth quarter of 2021.
[2]	The carrying value of the Windsor Knutsen was written down to its estimated fair value as of June 30, 2021. See Note 21—Impairment of Long-Lived Assets.

Vessels and Equipment - Drydock

Vessels and Equipment - Drydocking Activity (Details) - Vessels & Equipment - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Movement in Capitalized Drydocking Costs [Roll Forward]
Balance at the beginning of the year	$ 17,106	$ 18,523
Costs incurred for drydocking	4,235	2,724
Costs allocated to drydocking as part of acquisition of asset		3,040
Drydock amortization	(7,883)	(7,181)
Balance at the end of the year	$ 13,458	$ 17,106

Intangible Assets and Contrac_3

Intangible Assets and Contract Liabilities - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Intangible Assets
Intangibles assets, beginning balance	$ 681	$ 1,286
Amortization for the year	(606)	(605)
Intangibles assets, ending balance	75	681
Above Market Value Of Time Charter [Member] | Tordis Knutsen [Member]
Intangible Assets
Intangibles assets, beginning balance	305	608
Amortization for the year	(305)	(303)
Intangibles assets, ending balance		305
Above Market Value Of Time Charter [Member] | Vigdis Knutsen [Member]
Intangible Assets
Intangibles assets, beginning balance	376	678
Amortization for the year	(301)	(302)
Intangibles assets, ending balance	$ 75	$ 376

Intangible Assets and Contrac_4

Intangible Assets and Contract Liabilities - Additional information (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2011	Mar. 31, 2011	Dec. 31, 2021	Dec. 31, 2020
Intangible Assets
Accumulated amortization for contract liabilities			$ 16	$ 14.5
Recife Knutsen
Intangible Assets
Period for amortization of unfavorable contractual rights	12 years
Recife Knutsen | Unfavorable contractual rights [Member]
Intangible Assets
Period for amortization of unfavorable contractual rights	12 years		12 years
Fortaleza Knutsen
Intangible Assets
Period for amortization of unfavorable contractual rights		12 years
Fortaleza Knutsen | Unfavorable contractual rights [Member]
Intangible Assets
Period for amortization of unfavorable contractual rights			12 years
Tordis Knutsen [Member] | Above Market Value Of Time Charter [Member]
Intangible Assets
Remaining term of the contract			4 years 9 months 18 days
Vigdis Knutsen [Member] | Above Market Value Of Time Charter [Member]
Intangible Assets
Remaining term of the contract			4 years 10 months 24 days

Intangible Assets and Contrac_5

Intangible Assets and Contract Liabilities - Summary of Estimated Future Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Estimated future amortization of intangible assets
2022	$ 75
Total	$ 75	$ 681	$ 1,286

Intangible Assets and Contrac_6

Intangible Assets and Contract Liabilities - Schedule of Contract Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Contract liabilities:
Unfavorable contract rights, Beginning Balance	$ (3,686)	$ (5,203)
Amortization income	1,517	1,517
Unfavorable contract rights, Ending Balance	$ (2,169)	$ (3,686)

Intangible Assets and Contrac_7

Intangible Assets and Contract Liabilities - Amortization of Contract Liabilities Classified Under Time Charter and Bareboat Revenues (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Amortization of contract liabilities
2022	$ 1,517
2023	652
2024	0
2025	0
2026	0
2027	0
Total	$ 2,169	$ 3,686	$ 5,203

Long-Term Debt - Components (De

Long-Term Debt - Components (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2018	Jan. 31, 2018	May 31, 2017	Dec. 31, 2014	Apr. 30, 2014
Long-Term Debt
Long-term debt	$ 974,596		$ 1,036,118
Less: current installments	90,956		186,723
Less: unamortized deferred loan issuance costs	2,378		2,535
Current portion of long-term debt	88,578		184,188
Amounts due after one year	883,640		849,395
Less: unamortized deferred loan issuance costs	5,092		3,238
Long-term debt, less current installments, and unamortized deferred loan issuance costs	878,548		846,157
$345 million loan facility
Long-Term Debt
Long-term debt	338,726
Debt instrument face amount	345,000	$ 345,000	345,000
$320 million loan facility
Long-Term Debt
Long-term debt	222,133		252,245
Debt instrument face amount	320,000			$ 320,000
$55 million revolving credit facility
Long-Term Debt
Long-term debt			34,279
Debt instrument face amount	55,000
Hilda Loan Facility [Member]
Long-Term Debt
Long-term debt	72,308		78,462
Debt instrument face amount						$ 100,000
Torill Loan Facility [Member]
Long-Term Debt
Long-term debt	75,000		81,667
Debt instrument face amount					$ 100,000
$172.5 million loan facility
Long-Term Debt
Long-term debt	45,340		58,340
Debt instrument face amount	172,500						$ 172,500	$ 172,500
Raquel Loan Facility [Member]
Long-Term Debt
Long-term debt			52,725
Tordis Loan Facility [Member]
Long-Term Debt
Long-term debt			75,871
Vigdis Loan Facility [Member]
Long-Term Debt
Long-term debt			77,136
Lena Loan Facility [Member]
Long-Term Debt
Long-term debt			75,950
Brasil Loan Facility [Member]
Long-Term Debt
Long-term debt			50,997
Anna loan facility
Long-Term Debt
Long-term debt			62,196
Tove loan facility
Long-Term Debt
Long-term debt	81,883		86,250
$25 million revolving credit facility | NTT Finance Corporation [Member]
Long-Term Debt
Long-term debt	25,000		25,000
Debt instrument face amount	25,000
$25 million revolving credit facility | Shinsei
Long-Term Debt
Long-term debt	25,000		$ 25,000
Debt instrument face amount	25,000
Raquel Sale & Leaseback
Long-Term Debt
Long-term debt	$ 89,206

Long-Term Debt - Summary of Par

Long-Term Debt - Summary of Partnership's Outstanding Debt Repayable (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument, Redemption [Line Items]
2022	$ 90,956
2023	310,851
2024	166,918
2025	99,518
2026 and thereafter	306,353
Total	974,596	$ 1,036,118
Sale & Leaseback
Debt Instrument, Redemption [Line Items]
2022	4,960
2023	5,177
2024	5,418
2025	5,640
2026 and thereafter	68,010
Total	89,205
Periodic repayment
Debt Instrument, Redemption [Line Items]
2022	85,996
2023	79,768
2024	38,107
2025	28,372
2026 and thereafter	18,822
Total	251,065
Balloon Repayment [Member]
Debt Instrument, Redemption [Line Items]
2023	225,906
2024	123,393
2025	65,506
2026 and thereafter	219,521
Total	$ 634,326

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - Partnership's Loan Agreements [Member] - London Interbank Offered Rate (LIBOR) [Member]	12 Months Ended
	Dec. 31, 2021
Minimum
Long-Term Debt
Long-term debt, fixed margin percentage	1.75%
Maximum
Long-Term Debt
Long-term debt, fixed margin percentage	2.40%

Long-Term Debt - 345 Million Te

Long-Term Debt - 345 Million Term Loan Facility (Details) - $345 million loan facility $ in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)item	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Long-Term Debt
Loan facility amount	$ 345	$ 345	$ 345
Number of consecutive quarterly installments | item	20
Balloon payment to be paid	$ 220
Minimum liquidity of Partnership		15
Incremental minimum liquidity, first 8 vessels with less than 12 months employment contract remaining		1.5
Incremental minimum liquidity, next 12 vessels with less than 12 months employment contract remaining		$ 1
Minimum book equity ratio for Partnership		30.00%
Minimum EBITDA to interest ratio for Partnership		2.50%
Maximum market value of vessels as percentage of outstanding loan (in percent)		125.00%
London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt
Interest margin percentage	2.05%

Long-Term Debt - 320 Million Te

Long-Term Debt - 320 Million Term Loan Facility and 55 Million Revolving Credit Facility (Details) $ in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2018USD ($)item	Dec. 31, 2021USD ($)	Apr. 30, 2013USD ($)
Long-Term Debt
Credit facility amount			$ 20
Multi-Vessels Facility
Long-Term Debt
Minimum liquidity of Partnership		$ 15
Incremental minimum liquidity, first 8 vessels with less than 12 months employment contract remaining		1.5
Incremental minimum liquidity, next 12 vessels with less than 12 months employment contract remaining		$ 1
Minimum book equity ratio for Partnership		30.00%
Minimum EBITDA to interest ratio for Partnership		2.50%
Maximum market value of vessels as percentage of outstanding loan (in percent)		125.00%
$320 million loan facility
Long-Term Debt
Loan facility amount	$ 320	$ 320
Number of consecutive quarterly installments | item	20
Balloon payment to be paid	$ 177
$320 million loan facility | London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt
Interest margin percentage	2.125%
$55 million revolving credit facility
Long-Term Debt
Loan facility amount		$ 55
Credit facility amount	$ 55
Commitment fee percentage	0.85%
$55 million revolving credit facility | London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt
Interest margin percentage	2.125%

Long-Term Debt - Hilda Loan Fac

Long-Term Debt - Hilda Loan Facility (Details) - Hilda Loan Facility [Member] $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2017USD ($)item	Dec. 31, 2021USD ($)
Long-Term Debt
Loan facility amount	$ 100
Amount of previous loan facility, replaced by new facility	$ 117
Number of consecutive quarterly installments | item	28
Balloon payment to be paid	$ 58.5
Minimum liquidity of Partnership		$ 15
Incremental minimum liquidity, in excess of 8 vessels with less than 12 months employment contract remaining		1
Incremental minimum liquidity, first 8 vessels with less than 12 months employment contract remaining		$ 1.5
Minimum book equity ratio for Partnership		30.00%
Minimum EBITDA to interest ratio for Partnership		2.50%
First Two Years [Member]
Long-Term Debt
Maximum market value of vessels as percentage of outstanding loan for first two years (in percent)		110.00%
Third and Fourth Years [Member]
Long-Term Debt
Maximum market value of vessels as percentage of outstanding loan for third and fourth years (in percent)		120.00%
Thereafter [Member]
Long-Term Debt
Maximum market value of vessels as percentage of outstanding loan thereafter (in percent)		125.00%
London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt
Interest margin percentage	2.20%

Long-Term Debt - Torill Loan Fa

Long-Term Debt - Torill Loan Facility (Details) - Torill Loan Facility [Member] $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2018USD ($)item	Dec. 31, 2021USD ($)
Long-Term Debt
Loan facility amount	$ 100
Amount of previous loan facility, replaced by new facility	$ 117
Number of consecutive quarterly installments | item	24
Balloon payment to be paid	$ 60
Minimum liquidity of Partnership		$ 15
Incremental minimum liquidity, first 8 vessels with less than 12 months employment contract remaining		1.5
Incremental minimum liquidity, in excess of 8 vessels with less than 12 months employment contract remaining		$ 1
Minimum book equity ratio for Partnership		30.00%
Minimum EBITDA to interest ratio for Partnership		2.50%
First Two Years [Member]
Long-Term Debt
Maximum market value of vessels as percentage of outstanding loan for first two years (in percent)		110.00%
Third and Fourth Years [Member]
Long-Term Debt
Maximum market value of vessels as percentage of outstanding loan for third and fourth years (in percent)		120.00%
Thereafter [Member]
Long-Term Debt
Maximum market value of vessels as percentage of outstanding loan thereafter (in percent)		125.00%
London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt
Interest margin percentage	2.10%

Long-Term Debt - 172.5 Million

Long-Term Debt - 172.5 Million Secured Loan Facility (Details) - USD ($) $ in Millions	Apr. 01, 2014	Dec. 31, 2021	Dec. 31, 2014	Apr. 30, 2014
$172.5 million loan facility
Long-Term Debt
Loan facility amount		$ 172.5	$ 172.5	$ 172.5
$172.5 million loan facility | London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt
Interest margin percentage	2.40%
Raquel Loan Facility [Member]
Long-Term Debt
Minimum liquidity of Partnership		15
Incremental minimum liquidity, in excess of 8 vessels with less than 12 months employment contract remaining		1
Incremental minimum liquidity, first 8 vessels with less than 12 months employment contract remaining		$ 1.5
Minimum book equity ratio for Partnership		30.00%
Raquel Loan Facility [Member] | First Three Years [Member]
Long-Term Debt
Maximum market value of vessels as percentage of outstanding loan for first three years (in percent)		125.00%

Long-Term Debt - Tove Loan Faci

Long-Term Debt - Tove Loan Facility (Details) - Tove loan facility - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2019	Dec. 31, 2021
Long-Term Debt
Final balloon payment to be paid	$ 65.5
Minimum liquidity of Partnership		$ 15
Incremental minimum liquidity, first 8 vessels with less than 12 months employment contract remaining		1.5
Incremental minimum liquidity, in excess of 8 vessels with less than 12 months employment contract remaining		$ 1
Minimum book equity ratio for Partnership		30.00%
Minimum EBITDA to interest ratio for Partnership		2.50%
Maximum market value of vessels as percentage of outstanding loan (in percent)		110.00%
London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt
Interest margin percentage	1.75%

Long-Term Debt - 25 Million Rev

Long-Term Debt - 25 Million Revolving Credit Facility (Details) - USD ($) $ in Millions	1 Months Ended
	Nov. 30, 2020	Jun. 30, 2019	Jun. 30, 2021	Apr. 30, 2013
Long-Term Debt
Credit facility amount				$ 20
$25 million revolving credit facility | NTT Finance Corporation [Member]
Long-Term Debt
Credit facility amount			$ 25
Interest margin percentage		1.80%
Commitment fee percentage		0.50%
$25 million revolving credit facility | Shinsei
Long-Term Debt
Interest margin percentage	1.75%
Commitment fee percentage	0.70%

Long-Term Debt - Raquel Sale an

Long-Term Debt - Raquel Sale and Leaseback (Details) - Knutsen Shuttle Tankers 19 AS - Raquel Sale & Leaseback $ in Millions	1 Months Ended
	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Lease period	10 years
Gross sales price	$ 94.3
Net proceeds	$ 38

Income Taxes - Significant Comp

Income Taxes - Significant Components of Current and Deferred Income Tax Expense Attributable to Income from Continuing Operations (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Taxes
Current tax benefit (expense)	$ (488,000)	$ (10,000)	$ (9,000)
Income tax benefit (expense)	$ 488,000	$ 10,000	$ 9,000
Effective tax rate	(1.00%)	0.00%	0.00%

Income Taxes - Additional infor

Income Taxes - Additional information (Details) - USD ($)	12 Months Ended			24 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021	Sep. 30, 2017	Mar. 31, 2013
Income Tax Rate Reconciliation
Tonnage tax included in operating expenses	$ 300,000	$ 200,000	$ 200,000
Valuation allowances	23,485,000	20,863,000		$ 23,485,000
Entrance tax	$ 228,000	295,000		228,000		$ 3,000,000
Entrance tax, annual decline in gain	20.00%
Deferred tax assets	$ 0			0
Entrance tax payable	300,000	400,000	$ 400,000
Entrance tax payable	$ 290,000	$ 380,000
Ordinary income tax rate	22.00%
Income tax rate, deferred tax liabilities	22.00%	22.00%
Estimated income tax payable	$ 600,000	$ 100,000		600,000
Entrance tax payable, current	60,000	80,000
Entrance tax payable, non current	230,000	$ 300,000		230,000
Entrance tax payable related to acquisition					$ 100,000
Unrecognized tax benefits	0			0
Interest or penalties on tax return	$ 0			$ 0
Period for income tax returns	10 years
Minimum percentage of ownership/control required to constitute a related party	25.00%
KNOT [Member]
Income Tax Rate Reconciliation
Ownership interest in partnership	25.00%
Norwegian Ordinary Tax Regime [Member]
Income Tax Rate Reconciliation
Ordinary income tax rate				22.00%
Period for income tax returns	10 years
UK tax
Income Tax Rate Reconciliation
Ordinary income tax rate	19.00%	19.00%
Income tax expense	$ 8,997,000	$ 10,233,000

Income Taxes - Summary of Taxat

Income Taxes - Summary of Taxation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Rate Reconciliation
Income tax benefit (expense)	$ (488,000)	$ (10,000)	$ (9,000)
Effective tax rate	(1.00%)	0.00%	0.00%
Norwegian Tonnage Tax Regime [Member]
Income Tax Rate Reconciliation
Effective tax rate	22.00%	22.00%	22.00%
Norway
Income Tax Rate Reconciliation
Income tax benefit (expense)	$ (479,000)
UK tax
Income Tax Rate Reconciliation
Income tax benefit (expense)	$ (9,000)	$ (10,000)	$ (9,000)
Effective tax rate	19.00%	19.00%	20.00%

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2013
Deferred tax assets:
Financial derivatives	$ 0	$ 0
Financial loss carryforwards for tonnage tax	23,485,000	20,863,000
Total deferred tax asset	23,485,000	20,863,000
Less valuation allowance	(23,485,000)	(20,863,000)
Net deferred tax asset	0
Deferred tax liabilities:
Entrance tax	228,000	295,000		$ 3,000,000
Deferred Tax Liabilities, Gross, Total	228,000	295,000
Net deferred tax liabilities	$ 228,000	$ 295,000	$ 357,000

Income Taxes - Classification o

Income Taxes - Classification of Net Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Taxes
Non-current deferred tax liabilities	$ 228	$ 295
Net deferred tax liabilities	$ 228	$ 295	$ 357

Income Taxes - Changes in Net D

Income Taxes - Changes in Net Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Taxes
Net deferred tax liabilities at January 1,	$ 295	$ 357
Change in temporary differences	(58)	(72)
Translation differences	(9)	10
Net deferred tax liabilities at December 31,	$ 228	$ 295

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - item	1 Months Ended	12 Months Ended
	Apr. 30, 2013	Dec. 31, 2021
Bodil Knutsen [Member]
Related Party Transaction
Current time charter expiration year		2022
Windsor Knutsen [Member]
Related Party Transaction
Current time charter expiration year		2024
KNOT Offshore Partners UK LLC [Member] | Administrative Services Agreement
Related Party Transaction
Period of notice for termination of agreement		90 days
KNOT [Member]
Related Party Transaction
Number of extension options		2
Extension term of charter		1 month
KNOT [Member] | Bodil Knutsen [Member]
Related Party Transaction
Period of related party guarantee of payment of hire rate	5 years
TSSI [Member] | KNOT [Member]
Related Party Transaction
Percentage ownership in joint venture		50.00%
NYK [Member] | KNOT [Member]
Related Party Transaction
Percentage ownership in joint venture		50.00%
KNOT [Member] | KNOT Management
Related Party Transaction
Ownership percentage acquired		100.00%
KNOT [Member] | KNOT Management Denmark AS
Related Party Transaction
Ownership percentage acquired		100.00%
Seglem Holding AS [Member] | TSSI [Member]
Related Party Transaction
Ownership percentage acquired		100.00%

Related Party Transactions - Re

Related Party Transactions - Related Party Costs and Expenses (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2013	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction
Operating expenses from other related parties		$ 866	$ 515	$ 487
Total income (expenses)		(21,875)	(19,619)	(8,249)
KNOT Management
Related Party Transaction
Administration fee		1,277	1,131	1,280
KOAS [Member]
Related Party Transaction
Administration fee		780	654	663
KOAS UK [Member]
Related Party Transaction
Administration fee		80	118	116
KNOT [Member]
Related Party Transaction
Time charter income from KNOT		6,427	4,883	15,910
Vessel operating expenses		16,812	14,693	14,489
Technical and operational management fee from KNOT to Vessels		8,429	7,342	6,954
Administration fee		$ 58	$ 49	$ 170
KNOT [Member] | Bodil Knutsen [Member]
Related Party Transaction
Period of related party guarantee of payment of hire rate	5 years

Related Party Transactions - Sc

Related Party Transactions - Schedule of Dues Payables to Related Party (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction
Total	$ 1,974	$ 47
KNOT | Drydocking supervision fee
Related Party Transaction
Total	$ 134	$ 47
KOAS [Member]
Related Party Transaction
Margin rate on administration cost	5.00%
KOAS [Member] | Equipment purchased
Related Party Transaction
Total	$ 1,840
Amount of parts purchased	$ 1,840

Related Party Transactions - Am

Related Party Transactions - Amounts Due from and Due to Related Parties (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2021
Related Party Transaction
Amount due from related parties	$ 5,726	$ 2,668
Amount due to related parties	$ (2,140)	(1,424)
Acquisitions from KNOT | Tove Knutsen [Member]
Related Party Transaction
Percentage of interest acquired	100.00%
KOAS [Member]
Related Party Transaction
Amount due from related parties	$ 170	290
Amount due to related parties	(1,596)	(1,205)
KNOT and affiliates
Related Party Transaction
Amount due from related parties	5,556	2,378
Amount due to related parties	$ (544)	(219)
KNOT and affiliates | Vigdis Knutsen [Member]
Related Party Transaction
Amount due from related parties		$ 3,600

Related Party Transactions - Tr

Related Party Transactions - Trade Accounts Payable (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction
Trade accounts payables to related parties	$ 1,596	$ 2,206
KOAS [Member]
Related Party Transaction
Trade accounts payables to related parties	813	1,304
KNOT and affiliates
Related Party Transaction
Trade accounts payables to related parties	$ 783	$ 902

Related Party Transactions - Ot

Related Party Transactions - Other current assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Other current assets from related parties	$ 1,230	$ 2,147
KOAS [Member]
Related Party Transaction [Line Items]
Trading balances	687	1,697
KNOT and affiliates
Related Party Transaction [Line Items]
Trading balances	$ 543	$ 450

Related Party Transactions - Ac

Related Party Transactions - Acquisitions from KNOT (Details)	Dec. 31, 2020
Acquisitions from KNOT | Tove Knutsen [Member]
Related Party Transaction
Percentage of interest acquired	100.00%

Commitments and Contingencies -

Commitments and Contingencies - Assets Pledged, Claims and Legal Proceedings (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies
Book value of assets pledged as security for long-term debt and interest rate swap obligations	$ 1,598,000,000	$ 1,709,000,000
Accrued claim	$ 0	$ 0	$ 0

Commitments and Contingencies_2

Commitments and Contingencies - Insurance (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Insurance Proceeds
Insurance coverage deductible amount per vessel		$ 150
Deductible period under business interruption insurance		14 days
Limit of protection and indemnity insurance for pollution, per vessel per incident		$ 1,000,000
Loss of hire insurance payments recorded as a component of total revenues		$ 11,450
Maximum
Insurance Proceeds
Deductible period under business interruption insurance		180 days
Windsor Knutsen [Member]
Insurance Proceeds
Deductible period under business interruption insurance	14 days		14 days
Loss of hire insurance payments recorded as a component of total revenues		$ 8,700
Amount of claimed and received payments		4,100
Windsor Knutsen [Member] | Maximum
Insurance Proceeds
Deductible period under business interruption insurance	180 days		180 days
Tove Knutsen [Member]
Insurance Proceeds
Loss of hire insurance payments recorded as a component of total revenues		1,500
Amount of claimed and received payments		100
Amount claimed for insurance		100
Bodil Knutsen [Member]
Insurance Proceeds
Amount of claimed and received payments		100
Tordis Knutsen [Member]
Insurance Proceeds
Amount of claimed and received payments		$ 1,200

Earnings per Unit and Cash Di_3

Earnings per Unit and Cash Distributions - Calculations of Basic and Diluted Earnings per Unit (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings per Unit and Cash Distributions
Net income	$ 53,876	$ 65,225	$ 58,957
Less: Series A Preferred unitholders' interest in net income	6,900	7,200	7,200
Net income attributable to the unitholders of KNOT Offshore Partners LP	46,976	58,025	51,757
Less: Distributions	72,520	72,136	72,136
Under (over) distributed earnings	$ (25,544)	$ (14,111)	$ (20,379)
Weighted average units outstanding (basic):
General Partner	623	615	615
Weighted average units outstanding (diluted):
General Partner	623	615	615
Earnings per unit (basic):
General Partner	$ 1.38	$ 1.74	$ 1.55
Earnings per unit (diluted):
General Partner	1.38	1.74	1.55
Cash distributions declared and paid in the period per unit	2.08	2.08	2.08
Subsequent event: Cash distributions declared and paid per unit relating to the period	$ 0.52	$ 0.52	$ 0.52
Common Units [Member]
Earnings per Unit and Cash Distributions
Net income attributable to the unitholders of KNOT Offshore Partners LP	$ 45,466	$ 56,953	$ 50,801
Weighted average units outstanding (basic):
Common and subordinated unitholders	33,050	32,694	32,694
Weighted average units outstanding (diluted):
Common and subordinated unitholders	37,064	32,694	32,694
Earnings per unit (basic):
Earnings per unit (basic)	$ 1.38	$ 1.74	$ 1.55
Earnings per unit (diluted):
Earnings per unit (diluted)	$ 1.38	$ 1.74	$ 1.55
Class B Units [Member]
Weighted average units outstanding (basic):
Common and subordinated unitholders	195
Weighted average units outstanding (diluted):
Common and subordinated unitholders	195
Earnings per unit (basic):
Earnings per unit (basic)	$ 2.62
Earnings per unit (diluted):
Earnings per unit (diluted)	$ 2.62
Limited Partner [Member] | Common Units [Member]
Earnings per Unit and Cash Distributions
Under (over) distributed earnings	$ (24,927)	$ (13,851)	$ (20,003)
Limited Partner [Member] | Class B Units [Member]
Earnings per Unit and Cash Distributions
Under (over) distributed earnings	(147)
General Partner Unit [Member]
Earnings per Unit and Cash Distributions
Net income attributable to the unitholders of KNOT Offshore Partners LP	862	1,072	956
Under (over) distributed earnings	(470)	(261)	(376)
IDR Holders
Earnings per Unit and Cash Distributions
Net income	2,100	2,800	2,800
Less: Distributions	$ 2,100	$ 2,800	$ 2,800

Earnings per Unit and Cash Di_4

Earnings per Unit and Cash Distributions - Additional Information (Details)	Dec. 31, 2021$ / sharesshares	Nov. 10, 2021shares	Sep. 10, 2021	Sep. 07, 2021$ / sharesshares	May 27, 2021shares	Oct. 31, 2021shares	Apr. 30, 2013	Dec. 31, 2021$ / sharesshares	Sep. 30, 2021shares	Dec. 31, 2021Vote$ / sharesshares	Dec. 31, 2020shares
Distribution Made to Limited Partner
Number of general partner units outstanding	640,278							640,278		640,278	615,117
Series A Preferred Stock
Distribution Made to Limited Partner
Potentially dilutive preferred units										208,333
Potentially dilutive preferred units	3,541,666
General Partner Unit [Member]
Distribution Made to Limited Partner
Issue of Units										25,161
Common Units [Member]
Distribution Made to Limited Partner
Issue of Units						41,940
Conversion of Units										215,292
Number of units in exchange of IDRs	673,080			673,080				673,080		673,080
Number of units converted										215,292
Partners' Capital Account, Units, Converted										215,292
Number of common units and subordinated units outstanding	33,708,541							33,708,541		33,708,541	32,694,094
Common Units [Member] | Minimum
Distribution Made to Limited Partner
Distributions to each unitholder, Per unit | $ / shares				$ 0.52
Common Units [Member] | KNOT [Member]
Distribution Made to Limited Partner
Number of common units and subordinated units outstanding	9,324,715							9,324,715		9,324,715
Class B Units [Member]
Distribution Made to Limited Partner
Conversion of Units	84,135	84,135
Number of units in exchange of IDRs				673,080
Units to be converted into common units for distribution that are at or above the Distribution Threshold									0.125
Units conversion ratio									1
Number of units converted	84,135	84,135
Partners' Capital Account, Units, Converted	84,135	84,135
Potentially dilutive preferred units										588,945
Potentially dilutive preferred units										588,945
Class B Units [Member] | Minimum
Distribution Made to Limited Partner
Conversion of Units								84,135
Number of units converted								84,135
Partners' Capital Account, Units, Converted								84,135
Series A Preferred Unit
Distribution Made to Limited Partner
Preferred units liquidation preference | $ / shares	$ 24							$ 24		$ 24
Percentage of annual rate										8.00%
Cash redemption rate as percentage of Issue Price, upon redemption eligibility date	100.00%							100.00%		100.00%
Percentage of Cash issue price										70.00%
Percentage of common unit issue price										80.00%
Aggregate issue price of outstanding										130.00%
Preferred units number of votes for each units | Vote										1
Partnership [Member] | General Partner Unit [Member]
Distribution Made to Limited Partner
Percentage of general partner interest			1.83%
Tortoise Direct Opportunities Fund LP | Series A Preferred Stock
Distribution Made to Limited Partner
Shares held					416,677
Issue of Units					208,333
Conversion of Units					208,334
Conversion rate					1.0334
Number of units converted					208,334
Partners' Capital Account, Units, Converted					208,334
Tortoise Direct Opportunities Fund LP | Common Units [Member]
Distribution Made to Limited Partner
Conversion of Units					215,292
Conversion rate					1.0334
Number of units converted					215,292
Partners' Capital Account, Units, Converted					215,292
Public | Partnership [Member]
Distribution Made to Limited Partner
Percentage of limited partner interest							49.00%			72.10%
Number of common units and subordinated units outstanding	24,293,458							24,293,458		24,293,458
KNOT [Member] | Partnership [Member]
Distribution Made to Limited Partner
Percentage of limited partner interest							49.00%			27.70%
KNOT | Partnership [Member] | Limited Partner [Member]
Distribution Made to Limited Partner
Percentage of limited partner interest										0.30%
Number of general partner units outstanding	90,368							90,368		90,368
KNOT | Partnership [Member] | General Partner Unit [Member]
Distribution Made to Limited Partner
Percentage of general partner interest										1.83%
Number of general partner units outstanding	640,278							640,278		640,278
General Partner [Member] | Partnership [Member]
Distribution Made to Limited Partner
Percentage of general partner interest							2.00%

Unit activity (Details)

Unit activity (Details)	Nov. 10, 2021shares	May 27, 2021shares	Oct. 31, 2021shares	Dec. 31, 2021shares	Sep. 07, 2021shares
General Partner Unit [Member]
Limited Partners' Capital Account [Line Items]
Units, Beginning balance				615,117
Issue of Units				25,161
Units, Ending balance				640,278
Common Units [Member]
Limited Partners' Capital Account [Line Items]
Units, Beginning balance				32,694,094
Conversion of Units				215,292
IDR elimination				673,080	673,080
Issue of Units			41,940
Conversion of unit				84,135
Units, Ending balance				33,708,541
Common Units [Member] | ATM October 25 2021
Limited Partners' Capital Account [Line Items]
Issue of Units				10,902
Common Units [Member] | ATM October 26 2021
Limited Partners' Capital Account [Line Items]
Issue of Units				31,038
Class B Units
Limited Partners' Capital Account [Line Items]
Conversion of Units	84,135
IDR elimination				673,080	673,080
Conversion of unit				(84,135)
Units, Ending balance				588,945
Series A Convertible Preferred Units
Limited Partners' Capital Account [Line Items]
Conversion of Units				(208,334)
Convertible Preferred Units, Beginning balance				3,750,000
Convertible Preferred Units, End balance				3,541,666
Tortoise Direct Opportunities Fund LP | Common Units [Member]
Limited Partners' Capital Account [Line Items]
Conversion of Units		215,292
Conversion rate		1.0334
Tortoise Direct Opportunities Fund LP | Series A Convertible Preferred Units
Limited Partners' Capital Account [Line Items]
Conversion of Units		208,334
Issue of Units		208,333
Shares held		416,677

Unit Activity - Additional info

Unit Activity - Additional information (Details) $ / shares in Units, $ in Thousands	Nov. 10, 2021shares	Sep. 10, 2021USD ($)shares	Oct. 31, 2021USD ($)$ / sharesshares	Dec. 31, 2021USD ($)shares	Sep. 07, 2021shares	Dec. 31, 2020shares
Limited Partners' Capital Account [Line Items]
Number of general partner units issued				640,278		615,117
General Partner Unit [Member]
Limited Partners' Capital Account [Line Items]
Amount of contribution | $		$ 450
Number of general partner units issued		25,161
Number of units sold				25,161
Amount of net proceeds, after sale commissions | $				$ 451
General Partner Unit [Member] | Partnership [Member]
Limited Partners' Capital Account [Line Items]
Ownership interest (in percent)		1.83%
Common Units [Member]
Limited Partners' Capital Account [Line Items]
Number of units in exchange of IDRs				673,080	673,080
Number of units sold			41,940
Average gross sales price per unit | $ / shares			$ 20.06
Amount of net proceeds, after sale commissions | $			$ 830
Amount of sales commissions paid | $			$ 10
Number of units converted				215,292
Class B Units
Limited Partners' Capital Account [Line Items]
Number of units in exchange of IDRs				673,080	673,080
Number of units converted	84,135
Units conversion ratio	1

Impairment of Long-Lived Asse_2

Impairment of Long-Lived Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Impairment of Long-Lived Assets
Impairment	$ 29,421	[1]
[1]	The carrying value of the Windsor Knutsen was written down to its estimated fair value as of June 30, 2021. See Note 21—Impairment of Long-Lived Assets.

Acquisitions - Purchase Price A

Acquisitions - Purchase Price Allocation (Details) - Tove Knutsen [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Acquisitions
Purchase consideration	$ 21,898
Less: Fair value of net assets acquired:
Vessels and equipment	117,978
Cash	804
Inventories	136
Derivatives assets (liabilities)	(3,537)
Others current assets	270
Long-term debt	(93,139)
Deferred debt issuance	769
Trade accounts payable	(430)
Accrued expenses	(622)
Amounts due to related parties	(331)
Total purchase consideration	$ 21,898

Acquisitions - Purchase Conside

Acquisitions - Purchase Consideration (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Acquisitions
Acquisition-related costs	$ 100
Tove Knutsen [Member]
Acquisitions
Cash consideration paid to KNOT (from KNOP)	25,430
Purchase price adjustments	(3,596)
Acquisition-related costs	64
Purchase price	21,898
Allocation to drydocking included in property, plant and equipment	$ 3,040

Acquisitions - Additional Infor

Acquisitions - Additional Information (Details) $ in Millions	Dec. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Additional information
Acquisition related costs		$ 0.1
Tove Knutsen [Member] | Acquisitions from KNOT
Additional information
Percentage of interest acquired	100.00%
Tove Knutsen [Member] | Non-Recurring
Additional information
Vessel and equipment in purchase price	$ 117.8	117.8
Outstanding indebtedness	93.1	93.1
Certain capitalized financing fees	$ 0.8	0.8
Purchase price adjustments		$ 3.6

Subsequent Events (Details)

Subsequent Events (Details) $ / shares in Units, $ in Millions	Nov. 27, 2022	Mar. 05, 2022	Feb. 23, 2022	Feb. 14, 2022	Feb. 11, 2022item	Feb. 10, 2022USD ($)$ / sharesshares	Nov. 10, 2021shares	Sep. 07, 2021$ / shares	Dec. 31, 2021shares
Tordis Knutsen [Member]
Subsequent Events
Planned special survey drydocking period	5 years
Extension period for new time charter contract									1 month
Vigdis Knutsen [Member]
Subsequent Events
Fixed term of contract									3 years
Common Units [Member]
Subsequent Events
Number of units converted | shares									215,292
Common Units [Member] | Minimum
Subsequent Events
Cash distributions paid in the period per unit | $ / shares								$ 0.52
Class B Units
Subsequent Events
Number of units converted | shares							84,135
Units conversion ratio							1
Subsequent Event [Member] | Tordis Knutsen [Member]
Subsequent Events
Fixed period for new time charter contract			5 months
Extension period for new time charter contract			1 month
Subsequent Event [Member] | Vigdis Knutsen [Member]
Subsequent Events
Planned special survey drydocking period		5 years
Subsequent Event [Member] | Anna Knutsen [Member]
Subsequent Events
Planned special survey drydocking period				5 years
Option to extend term					one-year
Subsequent Event [Member] | Anna Knutsen [Member] | Minimum
Subsequent Events
Fixed term of contract					1 year
Number of options to extend one year periods | item					4
Option to extend term					one-year
Subsequent Event [Member] | Anna Knutsen [Member] | Maximum
Subsequent Events
Fixed term of contract					2 years
Number of options to extend one year periods | item					3
Option to extend term					one-year
Subsequent Event [Member] | Series A Preferred Unit
Subsequent Events
Cash distributions | $						$ 1.7
Subsequent Event [Member] | Common Units [Member]
Subsequent Events
Cash distributions paid in the period per unit | $ / shares						$ 0.52
Units conversion ratio						1
Subsequent Event [Member] | Class B Units
Subsequent Events
Cash distributions paid in the period per unit | $ / shares						$ 0.52
Number of units converted | shares						84,135