
Exhibit 5.1
KNOT Offshore Partners LP
2 Queen’s Cross, Aberdeen
Aberdeenshire AB15 4YB
United Kingdom
Our reference: 28422.50007/ US/80621760v3
October 23, 2018
KNOT Offshore Partners LP: Registration Statement on FormF-3: Exhibit 5.1 Opinion
Ladies and Gentlemen:
We have acted as special counsel as to matters of the law of the Republic of the Marshall Islands (“Marshall Islands Law”) for KNOT Offshore Partners LP, a Marshall Islands limited partnership (the “Partnership”), in connection with the preparation of a Registration Statement on FormF-3 (the “Registration Statement”) filed by the Partnership with the Securities and Exchange Commission pursuant to the Securities Act of 1933, as amended, and the rules and regulations thereunder (the “Securities Act”), with respect to the registration of the sale by OMP AY Preferred Limited, Pierfront Capital Mezzanine Fund Pte. Ltd., and Tortoise Direct Opportunities Fund, LP (or such other persons as may be listed as selling unitholders in a supplement to the Prospectus) of up to 3,750,000 of the Partnership’s common units (the “Resale Units”) issuable upon the conversion of up to 3,750,000 Series A Convertible Preferred Units (the “Series A Units”) previously issued pursuant to a Series A Preferred Unit Purchase Agreement (as amended, the “Purchase Agreement”) dated December 6, 2016, as amended on December 20, 2016, February 2, 2017 and May 16, 2017.
The Resale Units will be sold from time to time as set forth in the Registration Statement and the prospectus contained therein (the “Prospectus”).
As such counsel, we have examined originals or copies (certified or otherwise identified to our satisfaction) of the following documents:

Watson Farley & Williams
ATHENS BANGKOK DUBAI FRANKFURT HAMBURG HONG KONG LONDON
MADRID MILAN MUNICH NEW YORK PARIS ROME SINGAPORE
Watson Farley & Williams LLP 250 West 55th Street New York New York 10019 T+1 212 922 2200 F+1 212 922 1512 wfw.com
Watson Farley & Williams LLP is a limited liability partnership that (or a WFW Affiliated Entity) has an office in each of the cities listed above.