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                                                                   EXHIBIT 10.43


                               FOURTH AMENDMENT TO
                       AMENDED AND RESTATED LOAN AGREEMENT

         This Fourth Amendment to Amended and Restated Loan Agreement is entered
into effective November 19, 2003, and is executed in connection with that
certain Amended and Restated Loan Agreement effective as of December 20, 2002
(as the same may be amended, restated, modified or supplemented from time to
time, the "Loan Agreement") among Torch Offshore, Inc. ("Borrower") and Regions
Bank ("Bank").

         WHEREAS, Borrower and Bank desire to further amend the Loan Agreement.

         NOW THEREFORE, for good and adequate consideration the receipt of which
is hereby acknowledged, the parties hereto do hereby agree as follows:

         1. As used herein, capitalized terms not defined herein shall have the
meanings attributed to them in the Loan Agreement.

         2. The definitions of "Applicable Margin", "Receivables Borrowing Base"
and "Receivables Line of Credit Note" in Section 1.01 of the Loan Agreement are
hereby amended and restated to read as follows:

                  "Applicable Margin" shall mean, the rate of interest per annum
         shown in the applicable column below:

<Table>
<Caption>
                                                Level I          Level II        Level III
                                                -------          --------        ---------
<S>                                           <C>              <C>             <C>
                  Consolidated Leverage                               >1.00
                  Ratio                       < or = 1.00       < or = 1.50          >1.50

                  Applicable Margin for
                  LIBOR Rate Loans                   2.50%             3.00%          3.50%

                  Origination Fee                    .150%             .300%          .500%

                  Unused Fee                         .200%             .350%          .500%
</Table>

         The Applicable Margin shall commence at Level II and shall be adjusted
         on the first day of each March, June, September and December (or, if
         such day is not a Business Day, on the next succeeding Business Day),
         based on the Consolidated Leverage Ratio as of the end of the
         immediately preceding fiscal quarter. If Borrower should fail to
         deliver the certificate required by Section 5.02(a)(vi) hereof within
         the time period set forth in Section 5.02(a)(vi), then, until Borrower
         shall have provided such certificate, it shall be presumed that the
         Consolidated Leverage Ratio as of the end of the immediately preceding
         fiscal quarter was greater than 1.5 (and, from the date of the delivery
         of such certificate, the Applicable Margin shall be determined by
         reference to such certificate).

         "Receivables Borrowing Base" shall mean, as of the date of
         determination thereof, an amount equal to the lesser of (a)
         $15,000,000.00 or (b) eighty-five (85%) percent of the base amounts
         owed on all Eligible Receivables as of such date.

         "Receivables Line of Credit Note" shall mean that certain promissory
         note made payable to the order of Bank in the principal sum of
         $15,000,000.00, a copy of which is attached hereto as Exhibit A(1).

         3. Clause (ix) of the definition of "Eligible Receivables" in Section
1.01 of the Loan Agreement is hereby amended and restated to read as follows:


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         (ix) Receivables with respect to which the Account Debtor does not
         maintain its chief executive office in the United States of America or
         is not organized under the laws of the United States of America, except
         to the extent such Receivables are supported by letters of credit
         satisfactory to Bank which letters of credit are subject to a first
         security interest in favor of Bank; provided that, Receivables due from
         Blue Marine S.A. de C.V. not exceeding $1,000,000.00 in the aggregate
         at any one time outstanding will not be considered ineligible solely
         because such Account Debtor is a foreign company unless Bank notifies
         Borrower to the contrary;

         4. The Loan Agreement is hereby amended to reflect that the obligation
of the Borrower to repay the Receivables Line of Credit Loans shall be evidenced
by a promissory note made payable to the order of Bank in the principal sum of
$15,000,000.00, a copy of which is attached hereto as Exhibit A(1) (as the same
may from time to time be amended, modified extended or renewed, the "Receivables
Line of Credit Note").

         5. The second to last sentence of Section 3.07 of the Loan Agreement is
hereby amended and restated to read as follows:

         The unused Receivables Line of Credit shall be defined as (x)
         $15,000,000.00 minus (y) the sum of (1) the aggregate outstanding
         principal amount of the Receivables Line of Credit Loans and (2) the
         Stated Amount of all outstanding Receivables Line of Credit Letters of
         Credit.

         6. In connection with the foregoing and only in connection with the
foregoing, the Loan Agreement is hereby amended, but in all other respects all
of the terms, conditions and provisions of the Loan Agreement remain unaffected.

         7. Except as may be specifically set forth herein, this Fourth
Amendment to Amended and Restated Loan Agreement shall not constitute a waiver
of any Default(s) under the Loan Agreement or any documents executed in
connection therewith, all rights and remedies of Bank being preserved and
maintained.

         8. This Fourth Amendment to Amended and Restated Loan Agreement may be
executed in two or more counterparts, and it shall not be necessary that the
signatures of all parties hereto be contained on any one counterpart hereof;
each counterpart shall be deemed an original, but all of which together shall
constitute one and the same instrument.

                   REMAINDER OF PAGE INTENTIONALLY LEFT BLANK


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IN WITNESS WHEREOF, the parties have caused this instrument to be duly executed.

                                             TORCH OFFSHORE, INC.


                                             By:
                                                 -------------------------------
                                                 Robert E. Fulton
                                                 Its Chief Financial Officer
                                                 401 Whitney Avenue, Suite 400
                                                 Gretna, Louisiana 70056
                                                 Telecopy number: (504) 367-7075

                                             REGIONS BANK


                                             By:
                                                 -------------------------------
                                                 Jorge E. Goris
                                                 Its Senior Vice President
                                                 301 St. Charles Avenue
                                                 New Orleans, LA 70130
                                                 Telecopier: (504) 584-2165