<PAGE>

                                                                    EXHIBIT 10.6
                                                                    ------------

                                    Form Of


                       INDENTURE OF FIRST NAVAL MORTGAGE
                       ---------------------------------


                                    between


                            R&B FALCON CORPORATION

                                   as Owner



                                    - and -



                     CHRISTIANIA BANK OG KREDITKASSE ASA,
                      NEW YORK BRANCH, Collateral Agent,

                                 as Mortgagee



                                 RANDOLPH YOST



       Executed August 31, 2000 to be effective as of September 6, 2000
<PAGE>

                                     INDEX
                                     -----

<TABLE>
<CAPTION>
CLAUSE     SUBJECT MATTER                                               PAGE
------     --------------                                               ----
<S>                                                                     <C>
1.   REPRESENTATIONS AND COVENANTS....................................     3
     -----------------------------

2.   DEFINITIONS AND INTERPRETATION...................................     5
     ------------------------------

3.   MORTGAGE.........................................................    10
     --------

4.   PAYMENT COVENANTS................................................    11
     -----------------

5.   PRESERVATION OF SECURITY.........................................    11
     ------------------------

6.   INSURANCE........................................................    13
     ---------

7.   RIG COVENANTS....................................................    16
     -------------

8.   PROTECTION OF SECURITY...........................................    20
     ----------------------

9.   ENFORCEABILITY AND MORTGAGEE'S POWERS............................    21
     -------------------------------------

10.  APPLICATION OF MONEYS............................................    23
     ---------------------

11.  FURTHER ASSURANCES...............................................    24
     ------------------

12.  POWER OF ATTORNEY................................................    25
     -----------------

13.  INDEMNITIES......................................................    25
     -----------

14.  EXPENSES.........................................................    26
     --------

15.  COMMUNICATIONS...................................................    27
     --------------

16.  ASSIGNMENTS......................................................    27
     -----------

17.  TOTAL AMOUNT, ETC................................................    28
     ------------------

18.  WAIVER: AMENDMENT................................................    28
     -----------------

19.  MISCELLANEOUS....................................................    28
     -------------

20.  JURISDICTION.....................................................    29
     ------------
</TABLE>

EXHIBIT 1 - FORM OF CREDIT AGREEMENT
<PAGE>

     THIS INDENTURE OF FIRST NAVAL MORTGAGE is executed on the 31/st/ day of
August, 2000, to be effective as of the 6/th/ day of September, 2000, between
R&B FALCON CORPORATION, a Delaware corporation with its principal office at 901
Threadneedle, Suite 200, Houston, Texas 77079 (hereinafter called the "Owner")
and CHRISTIANIA BANK OG KREDITKASSE ASA, NEW YORK BRANCH having its office at 11
West 42nd Street, New York, NY 10036, as Collateral Agent for the Banks (as
hereinafter defined) (hereinafter called the "Mortgagee"), on the Panamanian
flag offshore drilling vessel RANDOLPH YOST of 6,157 gross tons, 1,847 net tons
and with a length of 74.09 meters, a breadth of 61.11 meters and a depth of 7.92
meters and Provisional Patent of Navigation No. 27265-PEXT-3 (hereinafter called
the "Rig"), duly registered under the laws and flag of the Republic of Panama,
the detailed description of which is hereinafter more particularly set forth.

                                  WITNESSETH:

WHEREAS
-------

(A)   The Owner is the sole owner of the whole of the Rig; and

(B)   By a Letter of Credit and Reimbursement Agreement dated as of August 31,
      2000 (as modified, amended or supplemented from time to time, the "Credit
      Agreement") among (i) the Owner, (ii) the financial institutions listed
      from time to time on Schedule II to the Credit Agreement (the "Banks"),
      (iii) Credit Agricole Indosuez; (iv) Credit Lyonnais New York Branch, as
      Syndication Agent (the "Syndication Agent"); and (v) Christiania Bank og
      Kreditkasse ASA, New York Branch, as Administrative Agent (the
      "Administrative Agent" and, together with the Syndication Agent, the
      "Agents") (the form of which Credit Agreement, together with the
      schedules, the form of A Letter of Credit attached thereto as Exhibit A-1
      and the form of Letter of Credit Request attached thereto as Exhibit A-2
      but without the remaining exhibits, is attached hereto as Exhibit 1), it
      was agreed among other things that the Banks would make available to the
      Owner a letter of credit facility (the "Facility") under which the maximum
      aggregate principal amount of Letters of Credit (as defined in the Credit
      Agreement) at any one time outstanding shall be Seventy Million United
      States Dollars (US$70,000,000), including (i) an irrevocable single draw
      standby letter of credit in the form of Exhibit A-1 to the Credit
      Agreement and in the maximum principal amount of Fifty Million U.S.
      Dollars (US$50,000,000) issued by Credit Agricole Indosuez as the A
      Issuing Bank (the "A Issuing Bank") for the account of the Owner and for
      the benefit of Wilmington Trust Company (or any trustee, agent or other
      similar representative for Wilmington Trust Company) in support of the
      Deepwater Frontier Obligations (as defined in the Credit Agreement) and
      (ii) irrevocable standby letters of credit in the maximum aggregate
      principal amount outstanding at any time of Twenty Million U.S. Dollars
      (US$20,000,000) to be issued from time to time by Christiania Bank og
      Kreditkasse ASA, New York Branch, in its individual capacity as the B
      Issuing Bank (the "B Issuing Bank") for the account of the Owner or its
      Subsidiaries and for the benefit of any holders of B L/C Supportable
      Indebtedness (as defined in the Credit Agreement); and, as required by
      Article 1515 Section 3 of the Commercial Code of Panama, the dates on
      which the Owner is obligated to reimburse the A Issuing Bank or B Issuing
      Bank, respectively, the amount of any Unpaid Drawing (as defined in the
      Credit

                                      -1-
<PAGE>

      Agreement) may be determined from the provisions of the Credit Agreement,
      including, without limitation, Sections 1A.03(a) and 1B.04(a); and

(C)   The obligations of the Owner with respect to the Facility are evidenced by
      the Credit Agreement and the other Credit Documents (as defined in the
      Credit Agreement); and

(D)   This Mortgage is made for the benefit of the Mortgagee to secure (i) the
      full and prompt payment by the Owner when due of (x) all reimbursement
      obligations and Unpaid Drawings with respect to any Letter of Credit (as
      defined in the Credit Agreement) issued under the Credit Agreement,
      together with interest thereon as provided in the Credit Agreement and (y)
      all other obligations and indebtedness (including, without limitation,
      indemnities, Fees and interest thereon) of the Owner to the Secured
      Creditors (as hereinafter defined), whether now existing or hereafter
      incurred under, arising out of or in connection with the Credit Agreement
      and the other Credit Documents (or any of them) including, without
      limitation, this Mortgage, and the due performance and compliance by the
      Owner with all of the terms, conditions and agreements contained in the
      Credit Agreement and the other Credit Documents (or any of them),
      including, without limitation, this Mortgage; (ii) any and all sums
      advanced by the Mortgagee, either of the Agents or any of the other
      Secured Creditors in order to preserve the Collateral (as defined in the
      Credit Agreement) or to preserve the Security Interest in the Collateral
      granted by this Mortgage and the other Security Documents (or any of
      them); (iii) in the event of any proceeding for the collection or
      enforcement of any indebtedness, obligations, or liabilities of the Owner
      referred to in clause (i) above, after an Event of Default (as defined in
      the Credit Agreement) shall have occurred and be continuing, the
      reasonable expenses of the Mortgagee of re-taking, holding, preparing for
      sale or lease, selling or otherwise disposing of or realizing on the
      Collateral, including, without limitation, the Rig, or of any exercise by
      the Mortgagee of its rights hereunder or under any other Security
      Document, together with reasonable attorneys' fees of counsel to the
      Mortgagee and court costs; and (iv) all amounts paid by any Indemnitee as
      to which such Indemnitee has the right to reimbursement under Clause 13 of
      this Mortgage (all such obligations, liabilities, sums and expenses
      referred to in clauses (i) through (iv) above being collectively referred
      to as the "Obligations"). It is acknowledged and agreed that the
      "Obligations" shall include extensions of credit of the types described
      above, whether outstanding on the date of this Mortgage or extended from
      time to time after the date of this Mortgage; and

(E)   This Indenture of First Naval Mortgage is entered into by the Owner in
      consideration of the Banks agreeing to make the Facility available to the
      Owner and as a condition thereto and for other good and valuable
      consideration provided by the Banks (the sufficiency of which the Owner
      hereby acknowledges).

NOW, THEREFORE, the appearing parties, each in the name and on behalf of his
respective principal, state that they hereby execute this Indenture of First
Naval Mortgage pursuant to the following representations:

                                      -2-
<PAGE>

1.    REPRESENTATIONS AND COVENANTS
      -----------------------------

1.01  The Owner represents and covenants to the Mortgagee that:

      (a) The Rig is duly registered in the name of the Owner in the Public
          Registry of the City of Panama, Republic of Panama under Microjacket
          21669, Document 139314 as of August 16, 2000;

      (b) The Owner, as sole legal and beneficial owner of the Rig, has received
          and presently possesses a Provisional Patent of Navigation for the
          Rig, duly issued by the Republic of Panama under No. 27265-PEXT-3;

      (c) Neither the whole nor any share in the Rig is subject to any Security
          Interest (as defined herein) (except for Permitted Liens (as defined
          herein) and the lien of this Mortgage);

      (d) the Owner has not sold or transferred, or agreed to sell or transfer,
          title to the Rig or any share therein;

      (e) the Owner is a corporation duly organized and validly existing and in
          good standing under the laws of the State of Delaware;

      (f) the Owner has full power and authority (i) to execute and deliver this
          Mortgage, (ii) to mortgage the Rig as security for the Obligations and
          (iii) to comply with the provisions of, and perform all its
          obligations under, this Mortgage;

      (g) the Owner has complied with all statutory and other material
          requirements relative to the ownership, registration and operation of
          the Rig;

      (h) the Owner has taken all necessary action to authorize the execution
          and delivery of this Mortgage and this Mortgage constitutes, the
          legal, valid and binding obligation of the Owner enforceable against
          the Owner in accordance with its terms (except to the extent limited
          by applicable bankruptcy, reorganization, insolvency, moratorium or
          other laws of general application relating to or affecting the
          enforcement of creditors' rights as from time to time in effect and
          general equitable principles) and when preliminarily recorded with the
          Public Registry in Panama or through the Panamanian Consulate in New
          York, New York or Houston, Texas will create a legal, valid and
          enforceable first priority mortgage lien on the Rig subject only to
          the permanent filing of this Mortgage in the Public Registry in Panama
          within six months of the date of the preliminary recorded filing;

      (i) the entry into and performance by the Owner of this Mortgage does not
          and will not during the Credit Facility Period (as defined herein)
          violate in any respect (i) any law or regulation of any governmental
          or official authority or body, or (ii) any of the constitutive
          documents of the Owner including the Certificate of

                                      -3-
<PAGE>

          Incorporation or By-laws, as amended from time to time, or (iii) any
          material agreement, contract or other undertaking to which the Owner
          is a party or which is binding upon the Owner or any of its assets;

      (j) all consents, licenses, approvals and authorizations required in
          connection with the entry into, performance, validity and
          enforceability of this Mortgage and the transactions contemplated
          hereby and thereby have been obtained and are in full force and effect
          and will be so maintained during the Credit Facility Period;

      (k) save for such registrations and filings as are referred to in this
          Mortgage, it is not necessary for the legality, validity,
          enforceability or admissibility in evidence of this Mortgage that it
          or any document relating thereto be registered, filed, recorded or
          enrolled with any court or authority in any relevant jurisdiction or
          that any stamp, registration or similar taxes be paid on or in
          relation to this Mortgage;

      (l) the Owner is in compliance with all applicable Environmental Laws (as
          defined herein) and all Environmental Approvals (as defined herein)
          relating to the Rig, its operation and management and the business of
          the Owner (as now conducted and as reasonably anticipated to be
          conducted in the future) have been obtained or complied with;

      (m) no Environmental Claim (as defined herein) has been made or threatened
          against the Owner or otherwise in connection with the Rig;

      (n) no Environmental Incident (as defined herein) which has resulted, or
          which could reasonably be expected to result, in an Environmental
          Claim in excess of US$200,000 has occurred;

      (o) a twenty year inspection of the Vessel is required as a condition to
          the issuance of a Permanent Patent of Navigation for the Rig, and the
          Owner shall take all necessary action to have such 20 year inspection
          performed within three (3) months of the date hereof; and

      (p) The Owner hereby affirms as its representations all of the statements
          contained in the "WHEREAS" clauses of this Mortgage.

1.02  The representations and warranties of the Owner set out in Clause 1.01
      shall survive the execution of this Mortgage and shall be deemed to be
      repeated at the time of the issuance of each Letter of Credit, with
      respect to the facts and circumstances existing at each such time, as if
      made at each such time.

1.03  The Mortgagee represents that the Banks have made the Facility available
      to the Owner, as evidenced by, inter alia, the Credit Agreement, the
                                     ----- ----
      Security Documents (as defined in the Credit Agreement), and the other
      Credit Documents and accepts the Mortgage constituted by this instrument
      upon the Rig as security for the due and prompt payment and performance of
      the Obligations (as defined herein).

                                      -4-
<PAGE>

1.04  Each of the contracting parties declares that it is satisfied with the
      representations and covenants made by the other and accepts them as true;
      and the parties mutually acknowledge their respective legal status as well
      as the authority of the persons representing them respectively in this
      instrument to sign the same on behalf of their respective principals.

2.    DEFINITIONS AND INTERPRETATION
      ------------------------------

2.01  In this Mortgage unless the context otherwise requires, the following
      expressions shall have the following meanings:

      "A Issuing Bank" shall have the meaning provided in Recital (B) hereto;

      "Administrative Agent" shall have the meaning provided in Recital (B)
      hereto;

      "Agents" shall have the meaning provided in Recital (B) hereto;

      "B Issuing Bank" shall have the meaning provided in Recital (B) hereto;

      "Bank" shall mean each financial institution listed from time to time on
      Schedule II to the Credit Agreement, as well as any person or entity which
      becomes a "Bank" under the Credit Agreement pursuant to Section 10.04 of
      the Credit Agreement (collectively, the "Banks");

      "Base Rate: shall have the same meaning for such term as set forth in the
      Credit Agreement;

      "Collateral" shall have the same meaning for such term as set forth in the
      Credit Agreement;

      "Credit Agreement" shall have the meaning provided in Recital (B) hereto;

      "Credit Documents" shall have the same meaning for such term as set forth
      in the Credit Agreement;

      "Credit Facility Period" shall mean the period commencing on the date
      hereof and ending on the date the Total Commitments have terminated, no
      Letter of Credit remains outstanding and the Unpaid Drawings together with
      interest, Fees and all other obligations  under the Credit Documents are
      paid in full;

      "Default Rate" shall mean the Base Rate in effect from time to time plus
      2%;

      "Environmental Approvals" means all approvals, licenses, permits,
      exemptions or authorization required under applicable Environmental Laws;

                                      -5-
<PAGE>

      "Environmental Claims" means any and all administrative, regulatory or
      judicial actions, suits, demands, demand letters, claims, liens, notices
      of noncompliance or violation, investigations (other than internal reports
      prepared by the Owner or any of its Subsidiaries solely in the ordinary
      course of such person's business and not in response to any third party
      action or request of any kind) or proceedings relating in any way to any
      Environmental Law or any permit issued, or any approval given, under any
      such Environmental Law (hereafter, "Claims"), including, without
      limitation, (a) any and all Claims by governmental or regulatory
      authorities for enforcement, cleanup, removal, response, remedial or other
      actions or damages pursuant to any applicable Environmental Law, and (b)
      any and all Claims by any third party seeking damages, contribution,
      indemnification, cost recovery, compensation or injunctive relief
      resulting from Hazardous Materials arising from alleged injury or threat
      of injury to health, safety or the environment;

      "Environmental Incident" means (i) any release of Hazardous Material from
      the Rig, (ii) any incident in which Hazardous Material is released from a
      vessel other than the Rig and which involves collision between the Rig and
      such other vessel or some other incident of navigation or operation, in
      either case, where the Rig or the Owner are actually or allegedly at fault
      or otherwise liable (in whole or in part) or (iii) any incident in which
      Hazardous Material is released from a vessel other than the Rig and where
      the Rig is actually or potentially liable to be arrested as a result
      and/or where the Owner is actually or allegedly at fault or otherwise
      liable (and, in each such case, "release" shall mean disposing,
      discharging, injecting, spilling, leaking, leaching, dumping, emitting,
      escaping, emptying, seeping, placing and the like, into or upon any land
      or water or air, or otherwise entering into the environment);

      "Environmental Law" means any applicable Federal, state, foreign or local
      statute, law, rule, regulation, ordinance, code, guide, policy or rule of
      common law now or hereafter in effect and in each case, as amended, and
      any judicial or administrative interpretation thereof, including any
      judicial or administrative order, consent decree or judgment, relating to
      the environment, health, safety or Hazardous Materials, including, without
      limitation, the Comprehensive Environmental Response, Compensation and
      Liability Act of 1980, as amended, 42 U.S.C. (S) 9601 et seq.; the
                                                            -- ---
      Resource Conservation and Recovery Act of 1976, as amended, 42 U.S.C. (S)
      6901 et seq.; the Federal Water Pollution Control Act, as amended, 33
           -- ---
      U.S.C. (S) 1251 et seq.; the Toxic Substances Control Act, as amended, 15
                      -- ---
      U.S.C. (S) 2601 et seq.; the Clean Air Act, as amended, 42 U.S.C. (S) 7401
                      -- ---
      et seq.; the Safe Drinking Water Act, as amended, 42 U.S.C. (S) 201 et
      -- ---                                                              --
      seq.; the Oil Pollution Act of 1990, as amended, 33 U.S.C. (S) 2701 et
      ---                                                                 --
      seq. and any applicable state and local or foreign counterparts or
      ---
      equivalents;

      "Event of Default" shall have the same meaning for such term as set forth
      in the Credit Agreement;

      "Facility" shall have the meaning provided in Recital (B) hereto;

      "Fees" shall have the same meaning for such term as set forth in the
      Credit Agreement;

                                      -6-
<PAGE>

      "Hazardous Material" means (a) any petroleum or petroleum products,
      radioactive materials, asbestos in any form that is or could become
      friable, urea formaldehyde foam insulation, transformers or other
      equipment that contained fluid containing polychlorinated biphenyls, and
      radon gas; (b) any chemicals, materials or substances defined as or
      included in the definition of "hazardous substances," "hazardous waste,"
      "hazardous materials," "extremely hazardous waste," "restricted hazardous
      waste," "toxic substances," "toxic pollutants," "contaminants," or
      "pollutants," or words of similar import, under any applicable
      Environmental Law; and (c) any other chemical, material or substance,
      exposure to which is prohibited, limited or regulated by any governmental
      authority;

      "Indemnitee" shall have the meaning provided in Section 13.01;

      "Insurances" includes all policies and contracts of insurance (which
      expression includes all entries of the Rig in a protection and indemnity
      association) which are from time to time required by Clause 6 hereof to be
      taken out or entered into in respect of the Rig or otherwise by the Owner
      (whether in the sole name of the Owner or in the joint names of the Owner
      and the Mortgagee) and all benefits thereof (including claims of
      whatsoever nature and return of premiums);

      "Letter of Credit" shall have the same meaning for such term as set forth
      in the Credit Agreement;

      "Major Casualty" means any casualty to the Rig in respect whereof the
      claim or the aggregate of the claims against all insurers, before
      adjustment for any relevant franchise or deductible, exceeds Five Hundred
      Thousand United States Dollars (US$500,000) or the equivalent in any other
      currency;

      "Mortgage" means this mortgage, as modified, amended or supplemented from
      time to time;

      "Obligations" shall have the meaning provided in Recital (D) hereto;

      "Oil Pollution Act 1990" means the Oil Pollution Act 1990 (33 U.S.C. (S)
      2701 et seq.), as amended;
           -- ---

      "Other Rigs" means, individually or collectively, (i) the jackup offshore
      drilling vessel J. T. ANGEL owned by the Owner and documented under the
      laws and flag of the Republic of Panama with Provisional Patent of
      Navigation Number 27302-PEXT-3 of 5,286 gross registered tons and 1,585
      net registered tons; (ii) the jackup offshore drilling vessel D. R.
      STEWART owned by the Owner documented under the laws and flag of the
      Republic of Panama with Provisional Patent of Navigation Number
      26724-PEXT-3 of 6,634 gross registered tons and 1,990 net registered tons;
      (iii) the semisubmersible offshore drilling rig J. W. MCLEAN owned by the
      Owner documented under the laws and flag of the Republic of Panama with
      Provisional Patent of Navigation Number 25384-PEXT-3 of 15,453 gross
      registered tons and 4,636 net registered tons; and (iv) the

                                      -7-
<PAGE>

      jackup offshore drilling vessel GEORGE H. GALLOWAY owned by the Owner
      documented under the laws and flag of the United States of America with
      Official Number 651646 of 3,729 gross registered tons and 2,496 net
      registered tons;

      "Permitted Charters" means (i) drilling and other service contracts
      entered into in the ordinary course of the Owner's business, (ii) charters
      to Subsidiaries of the Owner, and (iii) charters expressly subordinated to
      the lien of this Mortgage on terms satisfactory to the Mortgagee.

      "Permitted Liens" means: (1) liens incident to expenses of current
      operations, other than for master's and crew's wages, incurred in the
      ordinary course of business of the Owner and due and payable for not more
      than thirty (30) days (or being contested in good faith, provided such
      liens in the aggregate are not in excess of Five Million United States
      Dollars (US$5,000,000), or if in excess thereof the Owner has given the
      Mortgagee written notice of the existence of such liens and, upon the
      written request of the Mortgagee, has provided a bond or other security
      satisfactory to the Mortgagee); (2) liens for master's and crew's wages
      not yet due and payable; (3) liens for taxes, assessments, governmental
      charges, fines and penalties not at the time delinquent (unless being
      contested in good faith, provided such liens in the aggregate are not in
      excess of Five Million United States Dollars (US$5,000,000), or if in
      excess thereof the Owner has given the Mortgagee written notice of the
      existence of such liens and, upon the written request of the Mortgagee,
      has provided a bond or other security satisfactory to the Mortgagee); (4)
      liens for general average and salvage (including contract salvage); (5)
      liens for claims covered by valid policies of insurance meeting the
      requirements of Clause 6 hereof (provided a lien shall be deemed covered
      by insurance to the extent insurance in force would cover the amount
      secured by the lien but for any applicable deductible amount approved by
      the Mortgagee); (6) liens arising pursuant to any judgment or to an order
      of attachment, distraint or similar legal process arising in connection
      with legal proceedings, but only for a maximum period of thirty (30) days
      and only if and so long as the execution or other enforcement thereof is
      stayed; (7) any lien for which the Owner has made provision for payment or
      discharge satisfactory to the Mortgagee, as evidenced by the Mortgagee's
      written consent to such lien; (8) any lien in favor of the Banks; provided
                                                                        --------
      that Permitted Liens shall not include any liens described in sub-clauses
      (1) through (7) above unless they: (i) are subordinate to the lien of this
      Mortgage or (ii) constitute a maritime lien which would in any event be
      entitled as such to priority over this Mortgage under the United States
      shipping laws or other applicable laws relating to the Rig's trading
      pattern. Nothing herein shall be deemed a waiver of the priority preferred
      lien status of this Mortgage;

      "Protection and Indemnity Risks" means the usual risks covered by
      protection and indemnity associations of international repute including
      the proportion not recoverable in case of collision under the ordinary
      running-down clause (unless such is recoverable under the relevant hull
      and machinery coverage);

                                      -8-
<PAGE>

      "Requisition Compensation" means all moneys or other compensation payable
      during the Credit Facility Period by reason of requisition for title or
      other compulsory acquisition of the Rig, including requisition for hire;

      "Rig" shall have the meaning provided in the first paragraph of this
      Mortgage and shall include any share or interest in such vessel and shall
      include such vessel's engines, machinery, boats, tackle, outfit, spare
      gear, fuel, consumable or other stores, belongings and appurtenances
      whether on board or ashore and whether now owned or hereafter acquired
      (but excluding therefrom any leased equipment owned by third parties
      unaffiliated with the Owner);

      "Secured Creditors" means the A Issuing Bank, the B Issuing Bank, the
      Banks, the Agents, the Collateral Agent and the Mortgagee;

      "Security Documents" shall have the same meaning for such term as set
      forth in the Credit Agreement;

      "Security Interest" means a mortgage, charge (whether fixed or floating),
      pledge, lien, hypothecation, assignment, trust arrangement, title
      retention or other security interest or arrangement of any kind
      whatsoever;

      "Syndication Agent" shall have the meaning provided in Recital (B) hereto;

      "Taxes" shall have the same meaning for such term as set forth in the
      Credit Agreement;

      "Total Commitment" shall have the same meaning for such term as set forth
      in the Credit Agreement;

      "Total Loss" means (a) the actual, constructive, arranged, agreed, or
      compromised total loss of the Rig; (b) the requisition for title or other
      compulsory acquisition or forfeiture of the Rig otherwise than by
      requisition for hire; (c) the capture, seizure, arrest, detention or
      confiscation of the Rig by any government or by persons acting or
      purporting to act on behalf of any government unless the Rig is released
      from such capture, seizure, arrest or detention within ninety (90) days
      after the occurrence thereof;

      "United States Dollars" and "US$" means the lawful currency of the United
      States of America;

      "Unpaid Drawing" shall have the same meaning for such term as set forth in
      the Credit Agreement;

      "War Risks" includes the risk of mines and all risks excluded from the
      standard form of English marine policy by the free of capture and seizure
      clause.

                                      -9-
<PAGE>

2.02  Except where otherwise expressly provided or unless the context otherwise
      requires, words and expressions defined in the Credit Agreement shall bear
      the same meanings when used in this Mortgage.

2.03  In this Mortgage:

      (a) Clause headings are inserted for convenience only and shall not affect
          the construction of this Mortgage and, unless otherwise specified, all
          references to Clauses are to clauses of this Mortgage;

      (b) unless the context otherwise requires, words denoting the singular
          number shall include the plural and vice versa;

      (c) references to persons include bodies corporate and unincorporated;

      (d) references to assets include property, rights and assets of every
          description;

      (e) references to any document are to be construed as references to such
          document as amended or supplemented from time to time; and

      (f) references to any enactment include re-enactments, amendments and
          extensions thereof.

3.    MORTGAGE
      --------

3.01  In order to secure the Obligations the Owner has granted, conveyed and
      mortgaged and does by these presents grant, convey and mortgage unto the
      Mortgagee, its successors and assigns, in accordance with the provisions
      of Chapter V, Title IV of Book Second of the Code of Commerce and
      pertinent provisions of the Civil Code and other legislation of the
      Republic of Panama, the whole of the Rig, the detailed description of
      which is as follows:

          the Panama flag jackup offshore drilling vessel RANDOLPH
          YOST; gross tonnage approximately 6,157; net tonnage
          approximately 1,847; length overall 74.09 meters, breadth
          61.11 meters; depth 7.92 meters; built in 1979 by Marathon
          LeTourneau in Brownsville, Texas; Provisional Patent of
          Navigation Number 27265-PEXT-3; radio call letters HP-9319;

      TO HAVE AND TO HOLD the same unto the Mortgagee, its successors and
      assigns forever, upon the terms herein set forth, to secure the payment
      and performance of the Obligations, including the Unpaid Drawings and
      interest thereon and such additional sums as the Owner may be obligated to
      pay under the agreements, covenants, terms and conditions contained in
      this Mortgage, and to secure the performance and observance of and
      compliance with all the agreements, covenants, terms and conditions
      contained in the Credit Agreement, this Mortgage and the other Credit
      Documents (or any of them).

                                      -10-
<PAGE>

     PROVIDED ONLY and the condition of these presents is such that if the Owner
     or its successors and assigns shall pay or cause to be paid to the Secured
     Creditors or their respective successors and assigns the Obligations as and
     when the same shall become due and payable in accordance with the terms of
     the Credit Agreement, this Mortgage and the other Credit Documents and
     shall observe and comply with the covenants, terms and conditions contained
     in the Credit Agreement, this Mortgage and the other Credit Documents (or
     any of them), expressed or implied to be performed, observed or complied
     with by and on the part of the Owner or its successors and assigns, then
     these presents and the rights hereunder shall cease, determine and be void
     and, in such event, the Mortgagee agrees to furnish, execute and record, at
     the expense of the Owner, all such documents as the Owner may reasonably
     require to discharge this Mortgage, otherwise to be and remain in full
     force and effect.

     Notwithstanding anything to the contrary herein it is not intended that any
     provision of this Mortgage shall waive the preferred status of this
     Mortgage and that if any provision or part thereof herein shall be
     construed as waiving the preferred status of this Mortgage then such
     provision shall to such extent be void and of no effect.

3.02 The Owner shall remain liable to perform all the obligations assumed by it
     in relation to the Rig and none of the Secured Creditors shall be under any
     obligation of any kind whatsoever in respect thereof or be under any
     liability whatsoever in event of any failure by the Owner to perform its
     obligations in respect thereof.

3.03 This Mortgage, when it shall have been duly executed and signed on behalf
     of the parties, shall be provisionally recorded through the Public Registry
     in Panama or the Panamanian Consulate at New York, New York or Houston,
     Texas and thereafter within six months permanently recorded in the Public
     Registry in Panama.

 4.  PAYMENT COVENANTS
     -----------------

4.01 The Owner hereby covenants with the Secured Creditors:

     (a)  to pay, and indemnify the Secured Creditors against, all expenses,
          claims, liabilities, losses, costs, duties, fees, charges or other
          moneys as are stated in this Mortgage to be payable by the Owner to,
          or recoverable from the Owner by, the Secured Creditors (or in respect
          of which the Owner agrees in this Mortgage to indemnify any of the
          Secured Creditors) at the times and in the manner specified in this
          Mortgage;

     (b)  to pay interest on any such expenses, claims, liabilities, losses,
          costs, duties, fees, charges or other moneys referred to in Clause
          4.01(a) from the date on which the relevant expense, claim, liability,
          loss, cost, duty, fee, charge or other money is paid by any Secured
          Creditor (both before and after any relevant judgment) at the Default
          Rate; and

                                      -11-
<PAGE>

     (c)  to pay and perform its obligations which may be or become due or owing
          to any Secured Creditor, as the case may be, under the Credit
          Agreement, this Mortgage and the other Credit Documents (or any of
          them) at the times and in the manner specified herein or therein.

 5.  PRESERVATION OF SECURITY
     ------------------------

5.01 It is declared and agreed that:

     (a)  the security created by this Mortgage shall be held by the Mortgagee
          as a continuing security for the performance of the Obligations and
          that the security so created shall not be satisfied by any
          intermediate payment or satisfaction of any part of the Obligations;

     (b)  the security so created shall be in addition to and shall not in any
          way be prejudiced or affected by any of the other Security Documents;

     (c)  the Mortgagee shall not have to wait for the enforcement of any of the
          other Security Documents before enforcing the security created by this
          Mortgage;

     (d)  no failure or delay on the part of the Mortgagee in exercising any
          right, power, privilege or remedy hereunder and no course of dealing
          between Owner and Mortgagee or any of the Secured Creditors shall
          operate as a waiver thereof; nor shall any single or partial exercise
          of any right, power, privilege or remedy hereunder preclude any other
          or further exercise thereof or the exercise of any other right, power
          or privilege hereunder. The rights and remedies herein expressly
          provided are cumulative and not exclusive of any rights or remedies
          which the Mortgagee or any of the Secured Creditors would otherwise
          have. No notice to or demand on the Owner in any case shall entitle
          the Owner to any other or further notice or demand in similar or other
          circumstances or constitute a waiver of the rights of the Mortgagee or
          any of the Secured Creditors to any other or further action in any
          circumstances without notice or demand; and

     (e)  any waiver by the Mortgagee of any terms of this Mortgage or any
          consent given by the Mortgagee under this Mortgage shall only be
          effective if given in writing and then only for the purpose and upon
          the terms for which it is given.

5.02 Any settlement or discharge under this Mortgage between the Mortgagee and
     the Owner shall be conditional upon no security or payment to the Secured
     Parties or any of them by the Owner or any other person being avoided or
     set-aside or ordered to be refunded or reduced by virtue of any provision
     or enactment relating to bankruptcy, insolvency, administration or
     liquidation for the time being in force and, if such condition is not
     satisfied, the Mortgagee shall be entitled to recover from the Owner on
     demand the value of such security or the amount of any such payment as if
     such settlement or discharge had not occurred.

                                      -12-
<PAGE>

5.03 The rights of the Mortgagee under this Mortgage and the security hereby
     constituted shall not be affected by any act, omission, matter or thing
     which, but for this provision, might operate to impair, affect or discharge
     such rights and security, in whole or in part, including without
     limitation, and whether or not known to or discoverable by the Owner, the
     Secured Creditors or any other person:

     (a)  any waiver granted to or composition with the Owner or any other
          person; or

     (b)  the taking, variation, compromise, renewal or release of or refusal or
          neglect to perfect or enforce any rights, remedies or securities
          against the Owner or any other person; or

     (c)  any legal limitation, disability, incapacity or other circumstances
          relating to the Owner or any other person; or

     (d)  any amendment or supplement to the Credit Agreement, any of the other
          Credit Documents or any other document or security; or

     (e)  the dissolution, liquidation, amalgamation, reconstruction or
          reorganization of the Owner or any other person; or

     (f)  the unenforceability, invalidity or frustration of any obligations of
          the or any other person under the Credit Agreement, any of the other
          Credit Documents or any other document or security.

6.   INSURANCE
     ---------

6.01 The Owner covenants with the Mortgagee that throughout the Credit Facility
     Period:

     (a)  The Owner shall, at its own expense, when and so long as any
          Obligation remains outstanding, insure the Rig and keep her insured,
          or cause the Rig to be insured, in lawful money of the United States,
          in such amounts, for such risks (including without limitation, hull
          and machinery/increased value, Protection and Indemnity Risks,
          pollution liability, and War Risks), in such form (including without
          limitation, the form of the loss payable clause and the designation of
          named assureds) and with such first class insurance companies,
          underwriters, funds, mutual insurance associations or clubs, as shall
          be reasonably satisfactory to the Mortgagee. With respect to hull and
          machinery/increased value insurance, including war risk, the Owner
          shall insure the Rig and keep her insured, or cause the Rig to be
          insured, for an amount which is at least the agreed value of the Rig,
          and when such amount is aggregated with the total amount of such
          insurance coverage on the Other Rigs, such aggregate amount shall be
          at least 110% of the aggregate amount of the Total Commitment. Such
          insurance shall cover marine and war risk perils, on hull and
          machinery, with per occurrence deductibles not in excess of Five
          Hundred Thousand United States Dollars (US$500,000) (such deductibles
          not to apply in the case of Total Loss of the Rig), and shall be

                                      -13-
<PAGE>

          maintained in the broadest forms available in the American, British
          and Scandinavian insurance markets or in such other major
          international markets acceptable to the Mortgagee. The Owner shall
          maintain protection and indemnity insurance, including war risk
          protection and indemnity coverage and coverage against pollution
          liability, in an amount not less than One Hundred Million United
          States Dollars (US$100,000,000) (or, with respect to pollution
          liability coverage, such greater amount as may be at least equal from
          time to time to the limitation of liability amount applicable to the
          Rig under the Oil Pollution Act 1990 or other Environmental Laws),
          through underwriters or associations acceptable to the Mortgagee. In
          addition, the Owner shall, at its own expense, furnish to the
          Mortgagee a mortgagee's interest policy providing coverage which, when
          aggregated with the mortgagee's interest insurance furnished to the
          Mortgagee in respect of the Other Rigs, shall be in an amount equal to
          at least 110% of the Total Commitment (or in lieu of such mortgagee's
          interest insurance Owner shall cause the hull and machinery/increased
          value insurance to be endorsed to afford breach of warranty coverage
          for the benefit of the Mortgagee). Such mortgagee's interest insurance
          and any additional insurance policies for the benefit of the Mortgagee
          shall be maintained in the broadest form available in the American,
          British and Scandinavian markets or other major international markets
          acceptable to the Mortgagee through underwriters acceptable to the
          Mortgagee. The Rig shall not operate in or proceed into any area then
          excluded by trading warranties under its marine or war risk policies
          (including protection and indemnity) without satisfying the conditions
          of the relevant policies evidence of which shall be furnished to the
          Mortgagee.

     (b)  The policy or policies of insurance shall be issued by responsible
          underwriters reasonably acceptable to the Mortgagee, shall contain
          conditions, terms, stipulations and insuring covenants satisfactory to
          the Mortgagee, and shall be kept in full force and effect by the Owner
          during the Credit Facility Period. All such policies, binders and
          other interim insurance contracts shall be executed and issued in the
          name of the Owner and shall, to the extent required herein, provide
          that the Mortgagee shall be the loss payee for distribution by it to
          itself, the other Secured Creditors and the Owner as their interests
          may appear.  All such insurance shall provide for at least ten days
          prior notice to be given to the Mortgagee by the underwriters or
          association in the event of (i) cancellation, or (ii) failure of the
          Owner to pay any premium or call which would suspend coverage under
          the policy or the payment of a claim thereunder, except for war risk
          coverage, which shall provide at least seven (7) days prior notice to
          the Mortgagee. The Mortgagee and the other Secured Creditors shall be
          named as co-assureds on all such policies and insurance contracts, but
          without liability of the Mortgagee or the other Secured Creditors for
          premiums or calls. Complete certified copies or originals, at the
          option of the Mortgagee, of all such policies, binders and other
          interim insurance contracts shall be delivered to the Mortgagee upon
          the request of the Mortgagee. The Owner shall furnish to the Mortgagee
          annually a detailed report signed by a firm of marine insurance
          brokers satisfactory to the Mortgagee as to the insurance maintained
          in respect of the Rig,

                                      -14-
<PAGE>

          as to their opinion as to the adequacy thereof and as to compliance
          with the provisions of this Clause 6.01.

          Unless otherwise required by the Mortgagee, by notice to the
          underwriters, although the following insurance is payable to the
          Mortgagee, (i) any loss under any insurance on the Rig with respect to
          Protection and Indemnity Risks may be paid directly to the Owner to
          reimburse it for any loss, damage or expense incurred by it and
          covered by such insurance or to the person to whom any liability
          covered by such insurance has been incurred and (ii) in the case of
          any loss (other than a loss covered by (i) above or by the next
          following paragraph of this Clause 6.01(b)) under any insurance with
          respect to the Rig involving any damage to the Rig, the underwriters
          may pay directly for the repair, salvage or other charges involved or,
          if the Owner shall have first fully repaired the damage or paid the
          salvage or other charges, may pay the Owner as reimbursement therefor;
          provided, however, that if such damage involves a before deductible
          --------  -------
          loss in excess of Five Million United States Dollars (US$5,000,000),
          the underwriters shall not make such payment without first obtaining
          the written consent thereto of the Mortgagee (which consent shall not
          be unreasonably withheld). Any loss covered by this paragraph which is
          paid to the Mortgagee but which might have been paid, in accordance
          with the provisions of this paragraph, directly to the Owner or
          others, shall be paid by the Mortgagee to, or as directed by, the
          Owner, and all other payments to the Mortgagee of losses covered by
          this paragraph shall be applied by the Mortgagee in accordance with
          Clause 10.01 without regard to the reference to this Clause 6.01(b).
          Notwithstanding any other provision in this Mortgage, any amounts
          received by the Mortgagee under any Mortgagee's interest policy or
          endorsement shall not be applied towards discharge or satisfaction of
          any of the Obligations.

          In the event of a Total Loss, all insurance payments therefor shall be
          paid to the Mortgagee and shall be applied by the Mortgagee in
          accordance with Clause 10.01 without regard to the reference to this
          Clause 6.01(b). The Owner shall not declare or agree with the
          underwriters that the Rig is a Total Loss without the prior written
          consent of the Mortgagee.

     (c)  The Owner shall comply with and satisfy all of the provisions of any
          applicable law, regulation, proclamation or order concerning financial
          responsibility for liabilities imposed on the Owner or the Rig with
          respect to the carriage of passengers or pollution, and will maintain,
          or cause to be maintained, all certificates or other evidence of
          financial responsibility as may be required by any such law,
          regulation, proclamation or order with respect to the trade in which
          the Rig from time to time is engaged.

     (d)  The Owner shall renew all such insurances as they expire and so as to
          insure that there is no gap in coverage, keep the Mortgagee advised of
          the progress of such renewals, and shall provide evidence of such
          renewal in writing to the Mortgagee as and when each such renewal is
          effected.

                                      -15-
<PAGE>

     (e)  The Owner shall punctually pay all premiums, calls, contributions or
          other sums payable in respect of all such insurances and produce all
          relevant receipts when so required by the Mortgagee.

     (f)  The Owner shall arrange for the execution of such guarantees as may
          from time to time be required by any protection and indemnity or war
          risks association.

     (g)  The Owner shall not employ the Rig or suffer the Rig to be employed
          otherwise than in conformity with the terms of the instruments of
          insurance aforesaid relative to the Rig (including any warranties,
          express or implied, therein) without first obtaining the consent to
          such employment of the insurers and complying with such requirements
          as to extra premium or otherwise as the insurers may prescribe.

7.   RIG COVENANTS
     -------------

7.01 The Owner covenants with the Mortgagee that throughout the Credit Facility
     Period the Owner will:

     (a)  keep the Rig documented in the Owner's name as a Panamanian flag
          vessel and do or allow to be done nothing whereby such documentation
          may be forfeited or imperilled;

     (b)  not without the previous consent in writing of the Mortgagee change
          the name of the Rig or make any modification to the Rig which would
          materially alter the structure, type or performance characteristics of
          the Rig and which would materially reduce the value of the Rig;

     (c)  keep the Rig in a good and efficient state of repair consistent with
          first-class ownership and management practice employed by owners of
          drilling rigs of similar size and type and so as to maintain her
          present class (namely A1 Self Elevating Drilling Unit) at American
          Bureau of Shipping free of recommendations and qualifications and
          change of class, save those approved in writing by the Mortgagee and
          so as to comply with all applicable laws, treaties and conventions of
          the Republic of Panama and other applicable jurisdictions, and rules
          and regulations issued thereunder, and have on board as and when
          required thereby valid certificates showing compliance therewith;

     (d)  repair or replace any damaged, worn or lost parts or equipment in such
          manner (both as regards workmanship and quality of materials) as to
          not materially diminish the value of the Rig and not remove any
          material part of the Rig, or item of equipment owned by the Owner or
          its Subsidiaries installed on the Rig, unless (i) the part or item so
          removed is forthwith replaced by a suitable part or item which is in
          the same condition as, or better condition than, the part or item
          removed, is free from any Security Interest (other than Permitted
          Liens) in favor of any person and becomes on installation on the Rig
          the property of the Owner

                                      -16-
<PAGE>

          and subject to the security constituted by this Mortgage or (ii) the
          removal will not materially diminish the value of the Rig;

     (e)  submit the Rig to such periodical or other surveys as may be required
          for classification purposes and if so required to supply to the
          Mortgagee copies of all survey reports issued in respect thereof;

     (f)  permit the Mortgagee by independent surveyors to board the Rig at all
          reasonable times and upon reasonable notice for the purpose of
          inspecting her condition or for the purpose of satisfying themselves
          in regard to proposed or executed repairs and to afford all proper
          facilities for such inspections, provided that unless an Event of
          Default shall have occurred and be continuing, the cost of any such
          inspection shall be for the account of the Mortgagee;

     (g)  promptly pay and discharge all debts, damages and liabilities
          whatsoever which have given or may give rise to maritime or possessory
          liens (other than Permitted Liens) on or claims enforceable against
          the Rig and all tolls, dues, taxes, assessments, governmental charges,
          fines and penalties lawfully charged on or in respect of the Rig and
          all other outgoings whatsoever in respect of the Rig and in the event
          of arrest of the Rig pursuant to legal process, or in the event of her
          detention in exercise or purported exercise of any such lien or claim
          as aforesaid, procure the release of the Rig from such arrest or
          detention forthwith upon receiving notice thereof by providing bail or
          otherwise as the circumstances may require;

     (h)  not employ the Rig or allow her employment in any trade or business
          which is unlawful under the laws of any relevant jurisdiction or in
          carrying illicit or prohibited goods or in any manner whatsoever which
          can reasonably be expected to render her liable to destruction,
          seizure or confiscation and in the event of hostilities in any part of
          the world (whether war be declared or not) not employ the Rig or
          suffer her employment in carrying any contraband goods and not allow
          the Rig to enter or trade to any zone which is declared a war zone by
          any government or by the War Risks insurers of the Rig unless there
          shall have been effected by the Owner (at its expense) such special,
          additional or modified insurance cover as the Mortgagee may reasonably
          require;

     (i)  promptly furnish to the Mortgagee all such information as it may from
          time to time require regarding the Rig, her employment, position and
          engagements, particulars of all towages and salvages and, upon the
          request of the Mortgagee in writing, copies of all charters and other
          contracts for her employment or otherwise howsoever concerning her;

     (j)  notify the Mortgagee forthwith by telecopy thereafter confirmed by
          letter of:

          (i)   any casualty to the Rig which is or is likely to be a Major
                Casualty; and

                                      -17-
<PAGE>

          (ii)  any occurrence in consequence whereof the Rig has become or is,
                by the passing of time or otherwise, likely to become a Total
                Loss; and

          (iii) any requirement or recommendation made by any insurer or
                classification society or by any competent authority which is
                not complied with; and

          (iv)  any arrest of the Rig or the exercise or purported exercise of
                any lien or other Security Interest on the Rig or any
                requisition for title, other compulsory acquisition or
                requisition for hire of the Rig; and

          (v)   any intended dry docking of the Rig, as to which the Owner shall
                give the Mortgagee 30 days prior notice, provided, that in the
                                                         --------
                event of any emergency dry docking of the Rig, the Owner shall
                immediately notify the Mortgagee; and

          (vi)  any intended deactivation or lay-up of the Rig (other than for
                normal periods of inactivity between contracts for the Rig
                during which periods the Rig remains manned) and obtain the
                prior written consent of the Mortgagee;

     (k)  keep proper books of account in respect of the Rig and as and when the
          Mortgagee may so reasonably require make such books available for
          inspection on behalf of the Mortgagee and furnish satisfactory
          evidence that the wages and allotments and the insurance of the master
          and crew are being regularly paid and that all deductions from crew's
          wages in respect of tax and/or social security liability are being
          properly accounted for and that the master has no claim for
          disbursements other than those incurred by him in the ordinary course
          of trading on the voyage then in progress;

     (l)  observe the obligations contained in Section 6 of the Credit Agreement
          which apply to the Rig, and in pursuance thereof such obligations
          shall be incorporated in and deemed to form part of this Mortgage
          mutatis mutandis;

     (m)  not without the previous consent in writing of the Mortgagee (such
          consent not to be unreasonably withheld), put the Rig into the
          possession of any person for the purpose of work being done upon her
          in an amount exceeding or likely to exceed Two Million Five Hundred
          Thousand United States Dollars (US$2,500,000.00) (or the equivalent in
          any other currency) unless (i) such person shall first have given to
          the Mortgagee in terms satisfactory to the Mortgagee a written
          undertaking not to exercise any lien on the Rig for the cost of such
          work or otherwise or (ii) the cost of such work shall be fully covered
          by applicable insurance;

     (n)  comply with and satisfy all the provisions of applicable laws and
          regulations of the Republic of Panama, as at any time amended, in
          order to establish and maintain this Mortgage as a first priority
          naval mortgage thereunder upon the Rig

                                      -18-
<PAGE>

          and upon all renewals, important and replacements made in or to the
          same, and promptly to furnish to the Mortgagee from time to time such
          proofs as the Mortgagee may request for its satisfaction with respect
          to the compliance by the Owner with the provisions of this sub-clause,
          including appropriate certificates of the Public Registry of the
          Republic of Panama showing that this Mortgage has been duly registered
          and filed and is a first and absolute lien on the Rig;

     (o)  place, and use due diligence to retain, a properly certified copy of
          this Mortgage on board the Rig with her papers and cause such
          certified copy of this Mortgage to be exhibited to any and all persons
          having business with the Rig which might give rise to any lien thereon
          other than a lien for crew's wages, general average and salvage and to
          any representative of the Mortgagee on demand and to place and keep
          prominently displayed in the chart room and in the master's cabin of
          the Rig a framed printed notice in plain type in English of such size
          that the paragraph of reading matter shall cover a space not less than
          6 inches wide and 9 inches high reading as follows:

                                   "NOTICE OF MORTGAGE

               This Rig is subject to an Indenture of First Naval Mortgage in
               favor of CHRISTIANIA BANK OG KREDITKASSE ASA, NEW YORK BRANCH, as
               Collateral Agent for the Secured Creditors defined in said
               Mortgage, in conformity with the provisions of Chapter V, Title
               IV of Book Second of the Code of Commerce, and the pertinent
               provisions of the Civil Code and other legislation of the
               Republic of Panama. Under the terms of said Mortgage neither the
               owner, any charterer, the master of the Rig nor any other person
               shall have the right, power or authority to create, incur or
               permit to be placed upon the Rig any other lien whatsoever other
               than for current crew's wages and salvage and Permitted Liens (as
               that term is defined in said Mortgage)."

     (p)  comply or procure compliance with all Environmental Laws and
          Environmental Approvals relating to the Rig, its operation or
          management and the business of the Owner from time to time;

     (q)  notify the Mortgagee forthwith upon:

          (i)  any Environmental Claim which could reasonably be expected to
               result in damages in excess of Two Hundred Thousand United States
               Dollars (US$200,000) being made against the Owner, or otherwise
               in connection with the Rig; or

          (ii) any Environmental Incident occurring, and keep the Mortgagee
               advised, in writing on such regular basis and in such detail as
               the Mortgagee shall

                                      -19-
<PAGE>

               require, of the Owner's response to such Environmental Claim or
               Environmental Incident.

     (r)  not sell, charter (other than Permitted Charters), mortgage or
          transfer the Rig without the written consent of the Mortgagee having
          first been obtained, and any such written consent to any one such
          sale, charter, mortgage or transfer shall not be construed to be a
          waiver of this provision with respect to any subsequent proposed sale,
          charter, mortgage or transfer. Any such sale, charter, mortgage or
          transfer shall be subject to the provisions of this Mortgage and the
          lien it creates. The Owner shall not charter the Rig to, or permit the
          Rig to serve under any contract with, a person included within the
          definition of (i) "national" of a "designated foreign country," or
          "specially designated national" of a "designated foreign country," in
          the Foreign Assets Control Regulations or the Cuban Assets Control
          Regulations of the United States Treasury Department, 31 C.F.R. Parts
          500 and 515, in each case as amended, (ii) "Government of Libya",
          "entity of the Government of Libya" or "Libyan entity" in the Libyan
          Sanctions Regulations of the United States Treasury Department, 31
          C.F.R. Part 550, as amended, or (iii) "Government of Iraq", "entity of
          the Government of Iraq" or "Iraqi Government entity" in the Iraqi
          Sanctions Regulations, 31 C.F.R. Part 575, as amended, all within the
          meaning of said Regulations or of any regulations, interpretations or
          rulings issued thereunder, or sail in Cuban waters or enter any Cuban
          port for any purpose or engage in any transaction that violates any
          provision of said Regulations or that violates any provision of the
          Office of Foreign Assets Control Regulations, 31 C.F.R. Parts 500
          through 597, as amended, or Executive Orders 12810, 12831 and/or
          12846; if such transaction or violation would (i) expose the Mortgagee
          to any penalty, sanction or investigation or (ii) jeopardize the lien
          created by this Mortgage or (iii) have a material adverse effect on
          the Owner or the operation of the Rig;

     (s)  shall not cause or permit the Rig to be operated in any manner
          contrary to law (except where the failure to operate in compliance
          with any law would not have a material adverse effect on the Owner,
          the Rig or the lien of this Mortgage), shall not abandon the Rig in a
          foreign port and shall not engage in any unlawful trade or violate any
          law or carry any cargo that shall expose the Rig to forfeiture or
          capture.

8.   PROTECTION OF SECURITY
     ----------------------

8.01 The Mortgagee shall without prejudice to its other rights and powers under
     the Credit Agreement, this Mortgage and the other Credit Documents (or any
     of them) be entitled (but not bound) at any time and as often as may be
     necessary (but unless an Event of Default shall have occurred and be
     continuing with prior written notice to the Owner) to take any such action
     as it may in the reasonable exercise of its discretion think fit for the
     purpose of protecting or maintaining the security created by this Mortgage
     and the other Credit Documents (or any of them) (including, without
     limitation, such action as is referred to in Clause 8.02) and each and
     every expense, liability, or loss (including,

                                      -20-
<PAGE>

     without limitation, reasonable legal fees) so incurred by the Mortgagee in
     or about the protection or maintenance of the said security together with
     interest payable thereon under Clause 4.01 (b) shall be payable to the
     Mortgagee by the Owner on demand.

8.02 Without prejudice to the generality of Clause 8.01:

     (a)  if the Owner does not comply in any material respect with the
          provisions of Clause 6 or any of them the Mortgagee shall be entitled
          (but not bound) to effect or to replace and renew and thereafter to
          maintain the Insurances in such manner it, in its discretion, may
          think fit and to require that all policies, contracts and other
          records relating to the Insurances (including details of any
          correspondence concerning outstanding claims) be forthwith delivered
          to such brokers as the Mortgagee may nominate and, upon the direction
          of the Mortgagee to collect, recover, compromise and give a good
          discharge for all claims then outstanding or thereafter arising under
          the Insurances or any of them and to take over or institute (if
          necessary using the name of the Owner) all such proceedings in
          connection therewith as the Mortgagee in its absolute discretion, may
          think fit and to permit the brokers through whom the collection or
          recovery is effected to charge the usual brokerage therefor;

     (b)  if the Owner does not comply with the provisions of Clause 7.01(d) and
          7.01(f) or any of them the Mortgagee shall be entitled (but not bound)
          to arrange for the carrying out of such repairs to and/or surveys of
          the Rig as it deems expedient or necessary; and

     (c)  if the Owner does not comply with the provisions of Clause 7.01 (g) or
          any of them, the Mortgagee shall be entitled (but not bound) to pay
          and discharge all such debts, damages and liabilities and all such
          tolls, dues, taxes, assessments, charges, fines, penalties and other
          outgoings as are therein mentioned and/or to take any such measures as
          it deems expedient or necessary for the purpose of securing the
          release of the Rig.

9.   ENFORCEABILITY AND MORTGAGEE'S POWERS
     -------------------------------------

9.01 Upon the happening of any of the Events of Default specified in the Credit
     Agreement but without the necessity for any court order or declaration in
     any jurisdiction to the effect that an Event of Default has occurred (and
     whether prior to or after any notice referred to in Section 7 of the Credit
     Agreement) the security constituted by this Mortgage shall become
     immediately enforceable and the Mortgagee shall be entitled, as and when it
     may see fit, to put into force and exercise all or any of the powers
     possessed by it as mortgagee of the Rig or otherwise and in particular:

     (a)  to exercise all the rights and remedies in foreclosure and otherwise
          given to mortgagees by the laws of the Republic of Panama or other
          applicable laws;

                                      -21-
<PAGE>

     (b)  to take possession of the Rig whether actually or constructively
          and/or otherwise to take control of the Rig wherever the Rig may be
          and cause the Owner or any other person in possession of the Rig
          forthwith upon demand to surrender the same to the Mortgagee without
          legal process and without liability of the Mortgagee for any losses or
          damages incurred thereby and without having to render accounts to the
          Owner in connection therewith;

     (c)  to require that all policies, contracts, certificates of entry and
          other records relating to the Insurances (including details of and
          correspondence concerning outstanding claims) be forthwith delivered
          to or to the order of the Mortgagee;

     (d)  to collect, recover, compromise and give a good discharge for or
          procure that the Mortgagee collect, recover, compromise and give good
          discharge for any and all moneys or claims for moneys then outstanding
          or thereafter arising under the Insurances or any Requisition
          Compensation and to permit any brokers through whom collection or
          recovery is effected to charge the usual brokerage therefor;

     (e)  to take over or institute (if necessary using the name of the Owner)
          all such proceedings in connection with the Rig, the Insurances, or
          any Requisition Compensation as the Mortgagee in its absolute
          discretion thinks fit and to discharge, compound, release or
          compromise claims against the Owner in respect of the Rig which have
          given or may give rise to any charge or lien or other Security
          Interest on the Rig or which are or may be enforceable by proceedings
          against the Rig;

     (f)  to sell the Rig or any share therein with or without prior notice to
          the Owner free from any claim of or by the Owner of any nature
          whatsoever, and with or without the benefit of any charter or other
          contract for her employment, by public auction or private contract at
          such place and upon such terms (including, without limitation, on
          terms such that payment of some or all of the purchase price be
          deferred) as the Mortgagee in its absolute discretion may determine
          with power to postpone any such sale, without being answerable for any
          loss occasioned by such sale or resulting from postponement thereof,
          and/or itself to purchase the Rig at any such public auction and to
          set off the purchase price against all or any part of the Obligations,
          subject to notice of sale being given by the Mortgagee to the Owner
          and other mortgagees of record, if any, by airmail, postage pre-paid
          and by publication once in a newspaper of general circulation in the
          City of Panama, Republic of Panama, not less than twenty (20) calendar
          days in advance of the sale, to satisfy the requirement of notice of
          sale contained in Article 1527 of the Panama Code of Commerce. Such
          notice shall be necessary only in respect of the initial date of sale;

     (g)  to manage, insure, maintain and repair the Rig and to charter, employ,
          sail or lay up the Rig in such manner, upon such terms and for such
          period as the Mortgagee in its absolute discretion deems expedient and
          for the purposes aforesaid the Mortgagee shall be entitled to do all
          acts and things incidental or conducive

                                      -22-
<PAGE>

          thereto and in particular to enter into such arrangements respecting
          the Rig, and the insurance, management, maintenance, repair,
          classification, chartering and employment of the Rig, in all respects
          as if the Mortgagee were the owner of the Rig and without being
          responsible for any loss thereby incurred;

     (h)  to recover from the Owner on demand any expenses, liabilities or
          losses as may be incurred by the Mortgagee in or about the exercise of
          the power vested in the Mortgagee under Clause 9.01(g);

     (i)  generally, to recover from the Owner on demand each and every expense,
          liability or loss incurred by the Mortgagee in or about or incidental
          to the exercise by it of any of the powers aforesaid.

9.02 The Mortgagee shall not be obliged to make any enquiry as to the nature or
     sufficiency of any payment received by it under this Mortgage or to make
     any claim, take any action or enforce any rights and benefits assigned to
     the Mortgagee by this Mortgage or to which the Mortgagee may at any time be
     entitled hereunder.

9.03 Neither the Mortgagee, any other Secured Creditor, nor their respective
     agents, managers, officers, employees, delegates and advisers shall be
     liable for any expense, claim, liability, loss, cost, damage or expense
     incurred or arising in connection with the exercise or purported exercise
     of any rights, powers and discretions under this Mortgage in the absence of
     gross negligence or wilful misconduct.

9.04 The Mortgagee shall not by reason of the taking possession of the Rig be
     liable to account as mortgagee-in-possession or for anything except actual
     receipts or be liable for any loss or for any default or omission for which
     a mortgagee-in-possession might be liable.

9.05 Upon any sale of the Rig or any share therein by the Mortgagee the
     purchaser shall not be bound to see or enquire whether the power of sale of
     the Mortgagee has arisen in the manner provided in this Mortgage and the
     sale shall be deemed to be within the power of the Mortgagee and the
     receipt of the Mortgagee for the purchase money shall effectively discharge
     the purchaser who shall not be concerned with the manner of application of
     the proceeds of sale or be in any way answerable therefor.

 10. APPLICATION OF MONEYS
     ---------------------

10.01

     (a)  Except as otherwise provided in Clause 6.01(b) hereof, all moneys
          received by the Mortgagee or any other Secured Creditor in connection
          with this Mortgage, including, without limitation, in respect of sale
          of the Rig or any part thereof, in respect of recovery under the
          Insurances, or in respect of Requisition Compensation, shall be
          applied in the following manner:

                                      -23-
<PAGE>

          (i)   first, to the payment of all amounts owing the Mortgagee of the
                type described in sub-clauses (ii) and (iii) of Recital (D);

          (ii)  second, to the extent moneys remain after the application
                pursuant to the preceding sub-clause (i), an amount equal to the
                outstanding Obligations shall be paid to the Secured Creditors
                as provided in Clause 10.01(c), with each Secured Creditor
                receiving an amount equal to such Obligations held by it or, if
                the proceeds are insufficient to pay in full all such
                Obligations, its Pro Rata Share (as defined below) of the amount
                remaining to be distributed; and

          (iii) third, to the extent moneys remain after the application
                pursuant to the preceding sub-clauses (i) and (ii), and
                following the termination of this Mortgage pursuant to Clause
                3.01, any surplus then remaining shall be paid to the Owner,
                subject, however, to the rights of the holder of any then
                existing Lien (as defined in the Credit Agreement) of which the
                Mortgagee has actual notice (without investigation).

     (b)  For purposes of this Mortgage "Pro Rata Share" shall mean, when
          calculating a Secured Creditor's portion of any distribution or amount
          in respect of any Obligations, the amount (expressed as a percentage)
          equal to a fraction the numerator of which is the then unpaid amount
          of such Obligations owing to or held by such Secured Creditor and the
          denominator of which is the then outstanding amount of all
          Obligations. For purposes of determining the amount payable to each
          Secured Creditor, the Mortgagee shall be entitled to request each
          Secured Creditor to furnish it with written notice of the amount of
          Obligations then owed to it and shall be entitled to rely upon the
          amounts stated therein in making such distribution.

     (c)  All payments required to be made to Secured Creditors hereunder shall
          be made to the Administrative Agent under the Credit Agreement for the
          account of the Secured Creditors.

     (d)  For purposes of applying payments received in accordance with this
          Clause 10.01, the Mortgagee  shall be entitled to rely upon (i) the
          Administrative Agent under the Credit Agreement and (ii) the Secured
          Creditors for a determination (which the Administrative Agent and each
          Secured Creditor, by their acceptance of the benefits of this Mortgage
          shall be obligated to provide upon request of the Mortgagee) of the
          outstanding Obligations owed to the Secured Creditors. Unless it has
          actual knowledge (including by way of written notice from a Secured
          Creditor) to the contrary, the Administrative Agent under the Credit
          Agreement, in furnishing information pursuant to the preceding
          sentence, and the Mortgagee, in acting hereunder, shall be entitled to
          assume that no obligations other than principal, interest and
          regularly accruing fees are owing to any Secured Creditor.

                                      -24-
<PAGE>

10.02     It is understood and agreed that the Owner shall remain liable to the
          extent of any deficiency between the amount of the proceeds of the Rig
          or other amounts received hereunder and the aggregate amount of the
          Obligations.

11.       FURTHER ASSURANCES
          ------------------

11.01     The Owner shall execute and do all such assurances, acts and things as
          the Mortgagee in its absolute discretion may require for:

          (a)  perfecting or protecting the security created (or intended to be
               created) by this Mortgage; or

          (b)  preserving or protecting any of the rights of the Mortgagee and
               the other Secured Creditors under this Mortgage; or

          (c)  ensuring that the security constituted by this Mortgage and the
               covenants and obligations of the Owner under this Mortgage shall
               inure to the benefit of any transferee, successor or assignee of
               the Mortgagee; or

          (d)  enforcing the security constituted by this Mortgage on or at any
               time after the same shall have become enforceable; or

          (e)  the exercise of any power, authority or discretion vested in the
               Mortgagee under this Mortgage, in any such case, forthwith upon
               demand by the Mortgagee and at the expense of the Owner.

12.       POWER OF ATTORNEY
          -----------------

12.01     The Owner, by way of security and in order to more fully secure the
          performance of the Obligations under this Mortgage, hereby irrevocably
          appoints the Mortgagee as its attorney for the duration of the Credit
          Facility Period for the purposes of:

          (a)  doing in its name all acts and executing, signing and (if
               required) registering in its name all documents which the Owner
               itself could do, execute, sign or register in relation to the Rig
               (including without limitation, transferring title to the Rig to a
               third party), provided, however, that such power shall not be
               exercisable by or on behalf of the Mortgagee until this Mortgage
               shall have become immediately enforceable pursuant to Clause
               9.01; and

          (b)  executing, signing, perfecting, doing and (if required)
               registering every such further assurance document, act or thing
               as is referred to in Clause 11.

12.02     The exercise of such power as is referred to in Clause 12.01(a) by or
          on behalf of the Mortgagee shall not put any person dealing with the
          Mortgagee upon any enquiry as to whether this Mortgage has become
          enforceable nor shall such person be in any way affected by notice
          that this Mortgage has not become enforceable and, in relation to both

                                      -25-
<PAGE>

          Clauses 12.01(a) and 12.01(b), the exercise by the Mortgagee of such
          power shall be conclusive evidence as against third parties of its
          right to exercise the same.

13.       INDEMNITIES
          -----------

13.01     The Owner will indemnify and save harmless each of the Mortgagee, the
          other Secured Creditors and their respective officers, directors,
          employees, attorneys and agents (each an "Indemnitee") from and
          against any and all expenses, claims, liabilities, losses, taxes,
          costs, duties, fees and charges suffered, incurred or made by any
          Indemnitee in good faith:

          (a)  in the exercise or purported exercise of any rights, powers or
               discretions vested in them pursuant to this Mortgage; or

          (b)  in the preservation or enforcement of the rights of the Mortgagee
               under this Mortgage; or

          (c)  on the release of the Rig from the security created by this
               Mortgage,

          and the Indemnitees may retain and pay all sums in respect of the same
          out of money received under the powers conferred by this Mortgage. All
          such amounts recoverable by an Indemnitee shall be recoverable on a
          full indemnity basis.

13.02     Without limiting the foregoing Clause 13.01, the Owner hereby further
          indemnifies and holds harmless each of the Indemnitees from and
          against any and all liabilities, losses, obligations, claims, damages,
          penalties, causes of action, costs and expenses (including, without
          limitation, reasonable attorneys' fees and expenses, consultant fees,
          investigation and laboratory fees) imposed upon or incurred by or
          asserted against them, or any of them, by reason of (a) an actual,
          alleged or threatened Environmental Incident; (b) any personal injury
          (including wrongful death) or property damage (real or personal) or
          economic damage arising out of or related to such Environmental
          Incident; (c) any Environmental Claim brought or threatened, or
          settlement reached; or (d) any violation of laws, orders, regulations,
          requirements or demands of government authorities relating to
          Hazardous Materials at, or discharged from, the Rig.

13.03     If, under any applicable law or regulation, and whether pursuant to a
          judgment being made or registered against the Owner or the liquidation
          of the Owner or for any other reason, any payment under or in
          connection with this Mortgage is made or fails to be satisfied in a
          currency (the "payment currency") other than the currency in which
          such payment is due under or in connection with this Mortgage (the
          "contractual currency"), then to the extent that the amount of such
          payment actually received by the Mortgagee, when converted into the
          contractual currency at the rate of exchange, falls short of the
          amount due under or in connection with this Mortgage, the Owner, as a
          separate and independent obligation, shall indemnify and hold harmless
          the Mortgagee against the amount of such shortfall. For the purposes
          of this Clause 13.03, "rate of exchange" means the rate at which the
          Mortgagee is able on the date of such payment (or, if it is not

                                      -26-
<PAGE>

          practicable for the Mortgagee to purchase the contractual currency
          with the payment currency on the date of such payment, at the rate of
          exchange as soon afterwards as is practicable for the Mortgagee to do
          so) to purchase the contractual currency with the payment currency and
          shall take into account any premium and other costs of exchange with
          respect thereto.

14.       EXPENSES
          --------

14.01     The Owner shall pay to the Mortgagee and any other Secured Creditor on
          demand all costs, fees and expenses, including, but not limited to,
          legal fees and expenses and valuation fees and Taxes thereon incurred
          by the Mortgagee or any other Secured Creditor or for which the
          Mortgagee or any other Secured Creditor may become liable in
          connection with:

          (a)  the negotiation, preparation and execution of the Credit
               Agreement, this Mortgage and the other Credit Documents (or any
               of them); and/or

          (b)  the preserving or enforcing of, or attempting to preserve or
               enforce, any rights under the Credit Agreement, this Mortgage and
               the other Credit Documents (or any of them).

14.02     The Owner shall pay to the Mortgagee or any other Secured Creditor on
          demand all costs, fees and expenses (including, but not limited to,
          legal fees and expenses) and Taxes thereon incurred by the Mortgagee
          or any other Secured Creditor in connection with:

          (a)  any variation of, or amendment or supplement to, any of the terms
               of the Credit Agreement, this Mortgage and the other Credit
               Documents (or any of them) requested by the Owner, necessary or
               advisable under applicable law or relating to the syndication of
               the Facility, or initiated during the occurrence and continuation
               of an Event of Default; and/or

          (b)  any consent or waiver required from the Mortgagee in relation to
               the Credit Agreement, this Mortgage and the other Credit
               Documents (or any of them), and in each case, regardless of
               whether the same is actually implemented, completed or granted,
               as the case may be.

14.03     The Owner shall pay promptly all stamp, documentary and other like
          duties and Taxes to which the Credit Agreement, this Mortgage and the
          other Credit Documents (or any of them) may be subject or give rise
          and shall indemnify the Mortgagee on demand against any and all
          liabilities with respect to or resulting from any delay or omission on
          the part of the Owner to pay any such duties or Taxes.

15.  COMMUNICATIONS
     --------------

15.01     All notices required to be given to the Mortgagee shall be made to the
     following address:

                                      -27-
<PAGE>

               Christiania Bank og Kreditkasse ASA, New York Branch
               11 West 42nd Street
               7th Floor
               New York, New York 10036
               Attention:  Loan Administration
               Telephone:  (212) 827-4800
               Telefax:    (212) 827-4888

          with a copy to Robert Friedrich, Esquire, White & Case LLP, 1155
          Avenue of the Americas, New York, NY 10036, Telecopier No. 212-354-
          8113 and with a copy to Richard L. Lionberger, Esquire, Royston,
          Rayzor, Vickery & Williams, L.L.P., 600 Travis Street, Suite 2200,
          Houston, Texas 77002, Telecopier No. 713-225-9945. All other notices
          shall be made to the addresses provided for in Section 10.03 of the
          Credit Agreement.

16.       ASSIGNMENTS
          -----------

16.01     This Mortgage shall be binding upon and shall inure to the benefit of
          the Owner, the Mortgagee and the other Secured Creditors and their
          respective transferees, successors and permitted assigns, and
          references in this Mortgage to any of them shall be construed
          accordingly.

16.02     The Owner may not assign or transfer all or any part of its rights
          and/or obligations under this Mortgage.

16.03     Pursuant to Section 10.04 of the Credit Agreement, each Bank has the
          right to assign or transfer all or any part of its rights and/or
          obligations under the Credit Agreement on the terms therein provided.
          The Mortgagee shall notify the Owner promptly following any such
          assignment, transfer or change.

17.       TOTAL AMOUNT, ETC.
          ------------------

17.01     For the purposes of recording this Mortgage, as required by the
          Panamanian Maritime Law, the total principal amount of the direct or
          contingent obligations that are or may be secured by the Mortgage is
          Seventy Million United States Dollars (US$70,000,000), and, in
          addition, interest, fees, court costs, collection expenses, amounts
          resulting from fluctuation in exchange rates and any additional
          amounts agreed upon which are secured in accordance with Article 1515
          of the Code of Commerce of the Republic of Panama for which the Owner
          may become liable in connection with the performance of the covenants
          of the Credit Agreement, this Mortgage and any other Credit Document
          (or any of them). The total discharge amount is the same as the total
          amount.

18.       WAIVER: AMENDMENT
          -----------------

18.01     None of the terms and conditions of this Mortgage may be changed,
          waived, modified or varied in any manner whatsoever unless in writing
          duly signed by the Owner and the

                                      -28-
<PAGE>

          Mortgagee (with the consent of any Secured Creditor required by
          Section 10.14 of the Credit Agreement).

19.       MISCELLANEOUS
          -------------

19.01     This Mortgage shall be governed by the laws of the Republic of Panama.

19.02     If at any time any one or more of the provisions in this Mortgage is
          or becomes invalid, illegal or unenforceable in any respect under any
          law or regulation, the validity, legality and enforceability of the
          remaining provisions of this Mortgage shall not be in any way affected
          or impaired thereby.

19.03     The Mortgagee, at any time and from time to time, may delegate by
          power of attorney or in any other manner to any person or persons all
          or any of the powers, authorities and discretions which are for the
          time being exercisable by the Mortgagee under this Mortgage in
          relation to the Rig. Any such delegation may be made upon such terms
          and subject to such regulations as the Mortgagee may think fit. The
          Mortgagee shall not be in any way liable or responsible to the Owner
          for any loss or damage arising from any act, default, omission or
          misconduct on the part of any such delegate.

19.04     The appearing parties hereby confer a special power of attorney on (i)
          Benedetti & Benedetti, lawyers of Panama, Republic of Panama, (ii)
          White & Case LLP, and (iii) Royston, Rayzor, Vickery & Williams,
          L.L.P. and/or any lawyers in any such firm authorizing any such firm
          or any such lawyer to take all necessary steps to record this
          Indenture of First Naval Mortgage in the appropriate registries of the
          Republic of Panama, including, without limitation, through the
          Panamanian Consulate in New York, New York or Houston, Texas, and to
          substitute the power of attorney herein granted.

19.05     A certification or determination by the Mortgagee as to any matter
          provided for in this Mortgage shall, in the absence of manifest error,
          be conclusive and binding on the Owner.

19.06     The Mortgagee declares that it accepts the naval mortgage hereby
          created under the terms above set forth.

19.07     This Mortgage may be executed by the parties hereto in separate
          counterparts, each of which when so executed and delivered shall be
          deemed an original, but all such counterparts shall together
          constitute one and the same instrument. Each counterpart may consist
          of a number of copies hereof each signed by less then all, but
          together signed by all, the parties hereto.

20.       JURISDICTION
          ------------

20.01     The Owner agrees that the Mortgagee shall have the liberty but shall
          not be obliged to take any proceedings in the courts of any country to
          protect or enforce the security constituted by this Mortgage or to
          enforce any provisions of this Mortgage or to enforce the Obligations
          and for the purpose of any proceedings for such enforcement the Owner

                                      -29-
<PAGE>

          hereby submits to the jurisdiction of the courts of any country of the
          choice of the Mortgagee.

20.02     Without prejudice to the generality of Clause 20.01, the Mortgagee
          shall have the right to arrest and take action against the Rig at
          whatever place the Rig shall be found lying and for the purpose of any
          action which the Mortgagee may bring before the courts of such
          jurisdiction or other judicial authority and for the purpose of any
          action which the Mortgagee may bring against the Rig, any writ,
          notice, judgment or other legal process or documents may (without
          prejudice to any other method of service under applicable law) be
          served upon the master of the Rig (or upon anyone acting as the
          master) and such service shall be deemed good service on the Owner for
          all purposes.

20.03     The Owner agrees that should the Mortgagee bring a legal action or
          proceeding against it or its assets in relation to any matters arising
          out of or in connection with this Mortgage, no immunity from such
          legal action or proceeding (which shall be deemed to include, without
          limitation, suit, attachment prior to judgment, other attachment, the
          obtaining of judgment, execution or other enforcement) shall be
          claimed by or on behalf of the Owner or with respect of its assets,
          and the Owner hereby irrevocably waives any such right of immunity
          which it or its assets now has or may hereafter acquire and the Owner
          hereby consents generally in respect of any legal action or
          proceedings arising out of or in connection with this Mortgage to the
          giving out of any relief or the issue of any process in connection
          with such action or proceedings including, without limitation, the
          making, enforcement or execution or attachment against any property
          whatsoever of any order or judgment which may be made or given in such
          action or proceedings.

            [The remainder of this page intentionally left blank.]

                                      -30-
<PAGE>

IN WITNESS WHEREOF, the parties have executed this Mortgage on the 31/st/ day of
August, 2000 to be effective as of the 6/th/ day of September, 2000.

                         R&B FALCON CORPORATION


                         By:  ________________________________
                         Name:________________________________
                         Title:________________________________



                           ACKNOWLEDGMENT OF MORTGAGE
                           --------------------------

STATE OF TEXAS      )
                    ) ss:
COUNTY OF HARRIS    )

On this 31/st/ day of August, 2000 before me personally appeared _____________,
to me known and whose address is 901 Threadneedle, Suite 200, Houston, Texas
77079; who submitted evidence to me that he is the ____________________________
of R&B FALCON CORPORATION, the corporation described in and which executed the
foregoing mortgage; and that he signed his name thereto pursuant to authority
granted to him by the Board of Directors of said corporation.


                              _________________________
                              Notary Public

<PAGE>

                         CHRISTIANIA BANK OG KREDITKASSE ASA,
                         NEW YORK BRANCH, as Collateral Agent


                         By:   ________________________________
                         Name: ________________________________
                         Title:________________________________


                         By:   ________________________________
                         Name: ________________________________
                         Title:________________________________

                           ACKNOWLEDGMENT OF MORTGAGE
                           --------------------------

STATE OF NEW YORK   )
                    ) ss:
COUNTY OF NEW YORK  )

On this 31/st/ day of August, 2000, before me personally appeared _____________
to me known and whose address is 11 West 42/nd/ Street, New York, NY 10036; and
who submitted evidence to me that he/she is _____________________________ of
CHRISTIANIA BANK OG KREDITKASSE ASA, NEW YORK BRANCH, the corporation described
in and which executed the foregoing mortgage; and that he/she signed his/her
name thereto pursuant to authority granted to him/her by the Board of Directors
of said corporation.


                              __________________________
                              Notary Public

                           ACKNOWLEDGMENT OF MORTGAGE
                           --------------------------

STATE OF NEW YORK   )
                    ) ss:
COUNTY OF NEW YORK  )

On this 31/st/ day of August, 2000, before me personally appeared
_________________________ to me known and whose address is 11 West 42/nd/
Street, New York, NY 10036; and who submitted evidence to me that he/she is
______________________________ of CHRISTIANIA BANK OG KREDITKASSE ASA, NEW YORK
BRANCH, the corporation described in and which executed the foregoing mortgage;
and that he/she signed his/her name thereto pursuant to authority granted to
him/her by the Board of Directors of said corporation.


                                    ________________________
                                    Notary Public

<PAGE>

                      EXHIBIT 1 - FORM OF CREDIT AGREEMENT

(Credit Agreement together with the schedules, the form of A Letter of Credit
attached thereto as Exhibit A-1 and the form of Letter of Credit Request
attached thereto as Exhibit A-2 but without the remaining exhibits)