EXHIBIT 3.9.1



                            CERTIFICATE OF FORMATION

                                       OF

                         HORNBECK OFFSHORE SERVICES, LLC



         The undersigned natural person of the age of eighteen (18) years or
more, acting as organizer of Hornbeck Offshore Services, LLC, a Delaware limited
liability company (the "COMPANY"), under the Delaware Limited Liability Company
Act (the "ACT"), does hereby adopt the following Certificate of Formation for
the Company.

                                   ARTICLE I

         The name of the Company is Hornbeck Offshore Services, LLC.

                                   ARTICLE II

         The period of duration for the Company is perpetual.

                                  ARTICLE III

         The street address of the initial registered office of the Company is
1209 Orange Street, Wilmington, Delaware, and the name of its initial registered
agent at such address is The Corporation Trust Company.

                                   ARTICLE IV

         The management of the Limited Liability Company is hereby reserved to
its managers (the "MANAGERS"). The names and addresses of the initial Managers
are as follows:

<Table>
<Caption>
                  Name                                        Address
                  ----                                        -------

                                                           
                  Christian G. Vaccari                        414 North Causeway Blvd.
                                                              Mandeville, Louisiana  70448

                  Todd M. Hornbeck                            414 North Causeway Blvd.
                                                              Mandeville, Louisiana  70448
</Table>

                                   ARTICLE V

         The initial limited liability company agreement (the "LLC AGREEMENT")
will be adopted by the Members.

                                   ARTICLE VI

         The membership interests of the Company will be subject to restrictions
on their transferability as set out in the LLC Agreement of the Company, which
LLC Agreement will be




kept with the records of the Company. The Company will
provide a copy of the LLC Agreement without charge to any record holder of a
membership interest upon written request addressed to the Company at its
principal business office or its registered agent's address.

                                  ARTICLE VII

         This Certificate of Formation may be amended, modified, supplemented or
restated in any manner permitted by applicable law and as provided in the LLC
Agreement.

                                  ARTICLE VIII

         The name and address of the organizer is James O. Harp, Jr., 414 North
Causeway Blvd., Mandeville, Louisiana 70448.





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         IN WITNESS WHEREOF, I have hereunto set my hand this 17th day of
December, 2001.

                                     /s/ JAMES O. HARP, JR.
                                     ------------------------------------------
                                     James O. Harp, Jr.



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