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                                                                    EXHIBIT 3.12

                               LEEVAC MARINE, INC.

                          AMENDED AND RESTATED BY-LAWS

                                FEBRUARY 17, 1998

                                    ARTICLE I

                                     Offices

         SECTION 1. Registered Office. The registered office of Leevac Marine,
Inc. (the "Company") in the State of Louisiana is located at 8550 United Plaza
Blvd., Baton Rouge, Louisiana.

         SECTION 2. Principal Office. The principal office of the Company will
be in Mandeville, Louisiana, or at such other place as the board of directors
may from time to time determine.

         SECTION 3. Other Offices. The Company may also have offices at such
other places as the board of directors may from time to time determine or the
business of the corporation may require.

                                   ARTICLE II

                             Meeting of Shareholders

         SECTION 1. Place of Meetings. All meetings of shareholders will be held
at the principal office of the Company, or at such other place as will be
determined by the board of directors and specified in the notice of the meeting.

         SECTION 2. Annual Meeting. The annual meeting of shareholders will be
held at such date and time as will be designated from time to time by the board
of directors and stated in the notice of meeting, at which such meeting the
shareholders will elect by written ballot a board of directors and transact such
other business as may properly be brought before the meeting.

         SECTION 3. Notice of Annual Meeting. Written or printed notice of the
annual meeting stating the place, day, and hour thereof, will be served upon or
mailed to each shareholder entitled to vote thereat at such address as appears
on the books of the Company, not less than ten (10) nor more than sixty (60)
days before the date of the meeting.

         SECTION 4. Special Meeting. Special meetings of shareholders will be
called by the chief executive officer or the board of directors, and will be
called by the chief executive officer or secretary at the request in writing of
the shareholders owning one-third of the outstanding shares of capital stock of
the Company. Such request will state the purpose or purposes of the proposed
meeting, and any purpose so stated will be conclusively deemed to be a "proper"
purpose.



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         SECTION 5. Notice of Special Meeting. Written or printed notice of a
special meeting stating the place, day, and hour thereof, will be served upon or
mailed to each shareholder entitled to vote thereat at such address as appears
on the books of the Company, not less than fifteen (15) nor more than sixty (60)
days before the date of the meeting.

         SECTION 6. Business at Special Meeting. Business transacted at all
special meetings of shareholders will be confined to the purpose or purposes
stated in the notice.

         SECTION 7. Shareholder List. At least ten (10) days before each meeting
of shareholders, a complete list of shareholders entitled to vote at each such
meeting or in any adjournment thereof, arranged in alphabetical order, with the
address of and number of shares held by each, will be prepared by the secretary.
Such list will be open to the examination of any shareholder, for any purpose
germane to the meeting, during any ordinary business hours for such ten (10) day
period either at a place within the city where the meeting is to be held, or, if
not so specified, at the place where the meeting is to be held. Such list will
also be produced and kept open at the time and place of the meeting and will be
subject to the inspection of any shareholder during the whole time of the
meeting.

         SECTION 8. Quorum. The holders of a majority of the shares of capital
stock issued and outstanding and entitled to vote thereat, represented in person
or by proxy, will constitute a quorum at all meetings of the shareholders for
the transaction of business. The shareholders present may adjourn the meeting
despite the absence of a quorum. When a meeting is adjourned for less than
thirty days in any one adjournment, it will not be necessary to give any notice
of the adjourned meeting if the time and place to which the meeting is adjourned
are announced at the meeting at which the adjournment is taken, and at the
adjourned meeting any business may be transacted which might have been
transacted on the original date of the meeting. When a meeting is adjourned for
thirty (30) days or more, notices of the adjourned meeting will be given as in
the case of an original meeting.

         SECTION 9. Proxies. At any meetings of the shareholders, every
shareholder having the right to vote will be entitled to vote in person or by
proxy appointed by an instrument in writing subscribed by such shareholder or by
his duly authorized attorney-in-fact and bearing a date not more than eleven
months prior to said meeting.

         SECTION 10. Voting. Unless otherwise provided by statute, each
shareholder having the right to vote will be entitled to vote for each share of
stock having voting power registered in his name on the books of the Company.
Cumulative voting for directors is prohibited.

         SECTION 11. Comment of Shareholders in Lieu of Meeting. Any action
which may be taken at a special or annual meeting of the shareholders may be
taken without a meeting, without prior notice, and without a vote, if a consent
in writing, setting forth the action so taken, will be signed by all of the
holders of outstanding stock having not less than the minimum number of votes
which would be necessary to authorize or take such action at a meeting at which
all shares entitled to vote thereon were presented and voted. Prompt notice of
the taking of the



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corporate action without a meeting by less than unanimous written consent will
be given to those shareholders who have not consented in writing.

                                   ARTICLE III

                               Board of Directors

         SECTION 1. Number of Directors. The number of directors comprising the
full board of directors will be not less than one (1) nor more than five (5),
but the number of directors may be increased from time to time by action of the
shareholders or the board of directors, or, whenever the number of directors
comprising the full board exceeds one, decreased (provided such decrease does
not shorten the term of any incumbent director), from time to time by amendment
to these bylaws.

         SECTION 2. Election and Term. Except as provided in Section 3 of this
Article, directors will be elected at the annual meeting of the shareholders,
and each director will be elected to serve until the next annual meeting or
until his successor will have been elected and will qualify. Directors need not
be shareholders.

         SECTION 3. Vacancies and Newly Created Directorships. Vacancies and
newly created directorships resulting from any increase in the authorized number
of directorships resulting from any increase in the authorized number of
directors may be filled by a majority of the directors, although less than a
quorum, except where the vacancies have been created by removal of directors by
the owners of a majority of the outstanding shares of capital stock. In the
event of such removal, the resulting vacancies will be filled by the owners of
the majority of the outstanding shares of capital stock.

         SECTION 4. Resignation; Removal. Any director may resign at any time by
giving written notice thereof to the board of directors. Any such resignation
will take effect as of its date unless some other date is specified therein, in
which event it will be effective as of that date. The acceptance of such
resignation will not be necessary to make it effective. The board of directors
may, by majority vote of the directors then in office, remove a director for
cause. The owners of a majority of the outstanding shares of capital stock may
remove any director or the entire board of directors, with or without cause,
either by a vote at a special meeting or annual meeting, or by written consent.

                                   ARTICLE IV

                              Meetings of the Board

         SECTION 1. First Meeting. Upon the adjournment of the annual meeting of
shareholders, the board of directors will meet as soon as practicable to appoint
the members of such committees of the board of directors as the board may deem
necessary or advisable, to appoint officers for the ensuing year, and to
transact such other business as may properly come



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before the meeting. No notice of such meeting will be necessary to the newly
elected directors in order legally to constitute the meeting provided a quorum
will be present.

         SECTION 2. Meetings. Meetings of the board of directors will be held
whenever called by the chief executive officer or by any director. Notice of
each meeting will be given at least one (1) day prior to the date of the meeting
either personally, or by telephone or telegraph to each director, and will state
the purpose, place, day and hour of the meeting.

         SECTION 3. Quorum and Voting. At all meetings of the board of directors
(except in the case of a meeting convened for the purpose specified in Article
III, Section 3 of these bylaws) a majority of the directors will be necessary
and sufficient to constitute a quorum for the transaction of business and the
act of a majority of the directors present at any meeting at which there is a
quorum will be the act of the board of directors. If a quorum will not be
present at any such meeting of directors, the directors present thereat may
adjourn the meeting from time to time, without notice other than announcement at
the meeting, until a quorum will be present.

         SECTION 4. Telephone Meetings. At any meeting of the board of
directors, a member may attend by telephone, radio, television, or similar means
of communication which permits him to participate in the meeting, and a director
so attending will be deemed present at the meeting for all purposes including
the determination of whether a quorum is present.

         SECTION 5. Action by Written Consent. Any action required or permitted
to be taken by the board of directors may be taken without a meeting if a
consent in writing, setting forth the action so taken, is signed by all the
members of the board.

         SECTION 6. Attendance Fees. Directors will not receive any stated
salary, as such, for their services, but by resolution of the board of directors
a fixed sum and expenses of attendance may be allowed for attendance at each
regular or special meeting of the board; however, this provision will not
preclude any director from serving the Company in any other capacity and
receiving compensation therefor.

                                    ARTICLE V

                                   Committees

         SECTION 1. Executive Committee. The board of directors by resolution
may designate one or more directors to constitute an Executive Committee, which
committee, to the extent provided in such resolution, will have and may exercise
all of the powers and authority of the board of directors in the management of
the business and affairs of the Company, except where action of the board of
directors is required by statute.

         SECTION 2. Other Committees. The board of directors may by resolution
create other committees for such terms and with such powers and duties as the
board will deem appropriate.



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         SECTION 3. Organization of Committees. The chairman of each committee
of the board of directors will be chosen by the members thereof. Each committee
will elect a secretary. who will be either a member of the committee or the
secretary of the Company. The chairman of each committee will preside at all
meetings of such committee.

         SECTION 4. Meetings. Regular meetings of each committee may be held
without the giving of notice if a day of the week, a time, and a place will have
been established by the committee for such meetings. Special meetings (and, if
the requirements of the preceding sentence have not been met, regular meetings)
will be called as provided in Article IV, Section 3 with respect to notices of
special meetings of the board of directors.

         SECTION 5. Quorum and Manner of Acting. A majority of the members of
each committee will be present either in person or by telephone, radio,
television, or similar means of communication, at each meeting of such committee
in order constitute a quorum for the transaction of business. The act of a
majority of the members so present at a meeting at which a quorum is present
will be the act of such committee. The members of each committee will act only
as a committee, and will have no power or authority, as such, by virtue of their
membership on the committee.

         SECTION 6. Action by Written Consent. Any action required or permitted
to be taken by any committee may be taken without a meeting if a consent in
writing, setting forth the action so taken, is signed by all the members of the
committee.

         SECTION 7. Record of Committee Action; Reports. Each committee will
maintain a record, which need not be in the form of complete minutes, of the
action taken by it at each meeting, which record will include the date, time,
and place of the meeting, the names of the members present and absent, the
action considered, and the number of votes cast for and against the adoption of
the action considered. All action by each committee will be reported to the
board of directors at its meeting next succeeding such action, such report to be
in sufficient detail as to enable the board to be informed of the conduct of the
Company's business and affairs since the last meeting of the board.

         SECTION 8. Removal. Any member of any committee may be removed from
such committee, either with or without cause, at any time, by resolution adopted
by a majority of the whole board of directors at any meeting of the board.

         SECTION 9. Vacancies. Any vacancy in any committee will be filled by
the board of directors in the manner prescribed by these bylaws for the original
appointment of the members of such committee.



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                                   ARTICLE VI

                                    Officers

         SECTION 1. (a) Appointment and Term of Office. The officers of the
Company will consist of a chief executive officer, president, a secretary, and a
treasurer, and there may be one or more vice presidents, one or more assistant
secretaries, one or more assistant treasurers, and such other officers as may be
appointed by the board. One of the directors may also be chosen chairman of the
board. Each of such officers (except as may be appointed pursuant to Section
2(h) of this Article), will be chosen annually by the board of directors at its
regular meeting immediately following the annual meeting of shareholders and,
subject to any earlier resignation or removal, will hold office until the next
annual meeting of shareholders or until his successor is elected and qualified.
Two or more offices, other than the offices of president and secretary, may be
held by the same person.

         (b) Removal. Any officer or agent elected or appointed by the board of
directors may be removed by the board of directors whenever in its judgment the
best interests of the corporation will be served thereby, but such removal will
be without prejudice to the contact rights, if any, of the person so removed.
Election as appointment of an officer or agent will not of itself create
contract rights.

         (c) Vacancies. A vacancy in the office of any officer may be filled by
vote of a majority of the directors for the unexpired portion of the term.

         (d) Salaries. The salaries of all officers of the Company will be fixed
by the board of directors except as otherwise directed by the board.

         SECTION 2. Power and Duties. The powers and duties of the officers will
be those usually pertaining to their respective officers, subject to the general
direction and supervision of the board of directors. Such powers and duties will
include the following:

                  (a) Chairman of the Board. The chairman of the board, if there
         be one, will preside at all meetings of the board of directors and will
         perform such other duties as will be assigned to him from time to time
         by the board.

                  (b) Chief Executive Officer. The chief executive officer shall
         be subject to the control of the board of directors, and shall in
         general supervise and control all business and affairs of the
         Corporation. The chief executive officer may sign, with the secretary
         or any other proper officer of the Company thereunto authorized by the
         board of directors, certificates for shares of the Company, deeds,
         mortgages, bonds, contracts, and other obligations in the name of the
         Company, which the board of directors has authorized to be executed,
         except in cases where the signing and execution thereof shall be
         expressly delegated by the board of directors or by these Bylaws to
         some other officer or agent of the Company, or shall be required by law
         to be otherwise signed and executed; and



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         in general shall perform all duties incident to the office of chief
         executive officer and such other duties as may be prescribed by the
         board of directors from time to time. In the absence of the Chairman,
         or if the directors neglect or fail to elect a Chairman, then the chief
         executive officer of the Company, if he is a member of the Board of
         Directors, shall automatically serve as Chairman of the Board of
         Directors.

                  (c) President. In the absence of the chief executive officer,
         or in the event of his death or inability to act or refusal to act, the
         president shall perform the duties of the chief executive officer and
         when so acting shall have all of the powers of and be subject to all of
         the restrictions upon the chief executive officer. In general, he shall
         perform all duties incident to the office of President and such other
         duties as may be prescribed by the chief executive or the board of
         directors from time to time.

                  (d) Vice Chairmen of the Board. Vice chairmen will perform the
         duties assigned to them by the board of directors, and at the request
         of the president, will perform as well the duties of the office of the
         president. Each vice chairman will have power also to execute and
         deliver in the name and on behalf of the Company, deeds, mortgages,
         leases, assignments, bonds, contracts or other instruments authorized
         by the board of directors.

                  (e) Executive Vice Presidents. Executive vice presidents will
         perform the duties assigned to them by the board of directors, and, in
         the order designated by the president, at the request of the president
         or in the absence of the president will perform as well the duties of
         the president's office. Each executive vice president will have power
         also to execute and deliver in the name and on behalf of the Company,
         deeds, mortgages, leases, assignments, bonds, contracts, or other
         instruments authorized by the board of directors.

                  (f) Vice Presidents. Vice presidents will perform the duties
         assigned to them by the board of directors, and at the request of the
         president, will perform as well the duties of the president's office.
         Each vice president will have the power also to execute and deliver in
         the name and on behalf of the Company, deeds, mortgages, leases,
         assignments, bonds, contracts, and other instruments authorized by the
         board of directors.

                  (g) Secretary. The secretary will keep the minutes of all
         meetings of the board of directors and the minutes of all meetings of
         the stockholders and will be the custodian of all corporate records and
         of the seal of the Company. He will see that all notices required to be
         given to the stockholders and to the board of directors are duly given
         in accordance with these bylaws or as required by law.

                  (h) Treasurer. The treasurer will be the principal financial
         officer of the Company and will have charge of the corporate funds and
         securities and will keep



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         a record of the property and indebtedness of the Company. He will, if
         required by the board of directors, give bond for the faithful
         discharge of his duties in such sum and with such surety or sureties as
         the board may require.

                  (i) Other Officers. The board of directors may appoint such
         other officers, agents, or employees as it may deem necessary for the
         conduct of the business of the Company. In addition, the board may
         authorize the president or some other officers to appoint such agents
         or employees as they deem necessary for the conduct of the business of
         the Company.

         SECTION 3. Resignations. Any officer may at any time by giving written
notice thereof to the board of directors. Any such resignation will take effect
as of its date unless some other date is specified therein, in which event it
will be effective as of that date. The acceptance of such resignation will not
be necessary to make it effective.

         SECTION 4. Vacancies. A vacancy in any office arising at any time from
any cause, may be filled by the board of directors or by the officer authorized
by the board to fill the vacancy in that office.

                                   ARTICLE VII

                    Shares of Stock and Their Transfer; Books

         SECTION 1. Forms of Certificates. Shares of the capital stock of the
Company will be represented by certificates in such form, not inconsistent with
law or with the certificate of incorporation of the Company, as will be approved
by the board of directors, and will be signed by the president or a vice
president and the secretary or an assistant secretary or the treasurer or an
assistant treasurer and sealed with the seal of the Company. Such seal may be
facsimile, engraved or printed. Where any such certificate is countersigned by a
transfer agent or by a registrar, the signature of such president, vice
president, secretary, assistant secretary, treasurer or assistant treasurer upon
such certificate may be facsimiles, engraved or printed.

         SECTION 2. Transfer of Shares. Shares of stock of the Company will be
transferred only on the stock books of the Company by the holder of record
thereof in person, or by his duly authorized attorney, upon surrender of the
certificate therefor.

         SECTION 3. Shareholders of Record. Shareholders of record entitled to
vote at any meeting of shareholders or entitled to receive payment of any
dividend or to all allotment of rights or to exercise the rights in respect of
any change or conversion or exchange of capital stock will be determined
according to the Company's record of shareholders and, if so determined by the
board of directors in the manner provided by statute, will be such shareholders
of record (a) at the date fixed for closing the stock transfer books, or (b) as
of the date of record.



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         SECTION 4. Lost, Stolen or Destroyed Certificates. The board of
directors may direct the issuance of new or duplicate stock certificates in
place of lost, stolen, or destroyed certificates, upon being furnished with
evidence satisfactory to it of the loss, theft, or destruction and upon being
furnished with indemnity satisfactory to it. The board of directors may delegate
to any officer authority to administer the provisions of this Section.

         SECTION 5. Closing of Transfer Books. The board of directors will have
power to close the stock transfer books of the Company for a period not
exceeding sixty (60) days preceding the date of any meeting of shareholders, or
the date for the payment of any dividend, or the day for the allotment of
rights, or the date when change or conversion or exchange of capital stock will
go into effect, or for a period not exceeding sixty (60) days in connection with
obtaining the consent of shareholders for any purpose; or the board may, in its
discretion, fix a date, not more than sixty (60) days before any shareholders'
meeting, or the date for the payment of any dividend, or the date for the
allotment of rights, or the date when any change or conversion or exchange of
capital stock will go into effect as a record date for the determination of the
shareholders entitled to notice of, and to vote at, any such meeting and at any
adjournment thereof, or entitled to receive payment of any such dividend, or to
any such allotment of rights, or to exercise the rights in respect of any such
change, conversion, or exchange of capital stock, or to give such consent, and
in such case such shareholders and only such shareholders as will be
shareholders of record on the date so fixed will be entitled to notice of and to
vote at such meeting and at any adjournment thereof, or to receive payment of
such dividend, or to exercise rights, or to give such consent as the case may
be, notwithstanding any transfer of any stock on the books of the Company after
such record date fixed as aforesaid.

         SECTION 6. Regulations. The board of directors may make such rules and
regulations as it may deem expedient concerning the issuance, transfer, and
registration of certificates of stock. It may appoint one or more transfer
agents or registrars, or both, and may require all certificates of stock to bear
the signature of either or both.

         SECTION 7. Examination of Books by Shareholders. The original or
duplicate stock ledger of the Company containing the names and addresses of the
shareholders and the number of shares held by them and the other books and
records of the Company will, at all times during the usual hours of business, be
available for inspection at its principal office, and any shareholder, upon
compliance with the conditions set forth in and to the extent authorized by
Section 220 of the General Corporation Laws of Delaware, will have the right to
inspect such books and records.

                                  ARTICLE VIII

                            Execution of Instruments

         SECTION 1. Contracts, Etc. The board of directors or any committee
thereunto duly authorized may authorize any officer or officers, agent or
agents, to enter into any contract or to execute and deliver in the name and on
behalf of the Company any contract or other



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instruments, except certificates representing shares of stock of the Company,
and such authority may be general or may be confined to specific instances.

         SECTION 2. Checks, Drafts, Etc. All checks, drafts or other orders for
the payment of money, notes acceptances or other evidence of indebtedness issued
by or in the name of the Company will be signed by such officer or officers,
agent or agents of the Company and in such manner as will be determined from
time to time by resolution of the board of directors. Unless otherwise provided
by resolution of the board, endorsements for deposits to the credit of the
Company in any of its duly authorized depositories may be made by hand-stamped
legend in the name of the Company or by written endorsement of any officer with
countersignature.

         SECTION 3. Loans. No loans will be contracted on behalf of the Company
unless authorized by the board of directors, but when so authorized, unless a
particular officer or agent is directed to negotiate the same, may be
negotiated, up to the amount so authorized, by the chief executive officer, the
president, or a vice president or the treasurer; and such officers are hereby
severally authorized to execute and deliver in the name and on behalf of the
Company, notes or other evidences of indebtedness for the amount of such loans
and to give security for the payment of any and all loans, advances, and
indebtedness by hypothecating, pledging or transferring any part or all of the
property of the Company, real or personal, at any time owned by the Company.

         SECTION 4. Sale or Transfer of Securities Held by the Company. Stock
certificates, bonds, or other securities at any time owned by the Company may be
held on behalf of the Company or sold, transferred, or otherwise disposed of
pursuant to authorization by the board of directors, or of any committee
thereunto duly authorized, and, when so authorized to be sold, transferred, or
otherwise disposed of, may be transferred from the name of the Company by the
signature of the president or a vice president and the treasurer or the
assistant treasurer or the secretary or the assistant secretary.

                                   ARTICLE IX

                                  Miscellaneous

         SECTION 1. Fiscal Year. Until otherwise determined by the board of
directors, the fiscal year of the Company will be the calendar year.

         SECTION 2. Methods of Notice. Whenever any notice is required to be
given in writing to any shareholder or director pursuant to any statute, the
certificate of incorporation, or these bylaws, it will not be construed to
require personal or actual notice, and such notice will be deemed for all
purposes to have been sufficiently given at the time the same is deposited in
the United States mail with postage thereon prepaid, addressed to the
shareholder or director at such address as appears on the books of the Company.
Whenever any notice may be or is required to be given by telegram to any
director, it will be deemed for all purposes to have been



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sufficiently given at the time the same is filed with the telegraph or cable
office, properly addressed.

         SECTION 3. Waiver of Notice. The giving of any notice of the time,
place, or purpose of holding any meeting of shareholders or directors and any
requirement as to publication thereof, whether statutory or otherwise, will be
waived by the attendance at such meeting by any person entitled to receive such
notice and may be waived by such person by an instrument in writing executed and
filed with the records of the meeting, either before or after the holding
thereof.



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