WASHINGTON, D.C. 20549

                                                     SCHEDULE 13G

                                      Under the Securities Exchange Act of 1934

                                             Cal Dive International, Inc.

                                                   (Name of Issuer)

                                              Common Stock, No Par Value
                                            (Title of Class of Securities)

                                                    (CUSIP NUMBER)

                                             Cambridge Investments, Ltd.
                                                600 Montgomery Street
                                                      43rd Floor
                                               San Francisco, CA 94111
                                                 Tel No. 415-781-0866

                                (Name, Address and Telephone Number of Person
                               Authorized to Receive Notices and Communications)

                                                  - with copies to -

                                             Michael G. Tannenbaum, Esq.
                                Newman Tannenbaum Helpern Syracuse & Hirschtritt
                                            900 Third Avenue - 13th Floor
                                               New York, New York 10022
                                                    (212) 508-6700

Filed on May 12, 1998 For the Purpose of Converting From 13D to 13G filing 
                                            (Date of event which requires
                                              filing of this statement)

Check the  appropriate box to designate the rule pursuant to which this Schedule
is filed:

                  |X|  Rule 13d-1-(b)

                  |_|  Rule 13d-1-(c)

                  |_|  Rule 13d-1-(d)

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act.

                                                 Page 1 of 6 Pages

CUSIP No. 0001279141

1.  Names of Reporting Persons I.R.S. Identification Nos. of Above Persons
    (entities only)

    Cambridge Investments, Ltd.

2.  Check the Appropriate Box if a Member of a Group (See Instructions)



3.  SEC Use Only

4.  Citizenship or Place of Organization:  State of California, USA

  Number of Shares   5.  Sole Voting Power 800,888 Shares
    Owned by         6.  Shared Voting Power
   Reporting         7.  Sole Dispositive Power 800,888 Shares
    With             8.  Shared Dispositive Power

9.   Aggregate Amount Beneficially Owned by Each Reporting Person 800,888 Shares

10.  Check if the Aggregate Amount in Row (9) Excludes Certain Shares
     (See Instructions)

11.  Percent of Class Represented by Amount in Row 9 6.21%

12.  Type of Reporting Person (See Instructions)   CO, IA

                                                 Page 2 of 6 Pages

CUSIP No. 0001279141

Item 1(a) Name of Issuer:

Cal Dive International, Inc.

Item 1(b) Address of Issuer:

Cal Dive International, Inc.
13430 Northwest Freeway
Suite 350
Houston, TX  77040

Item 2(a) Name of Person Filing:

Cambridge Investments, Ltd.

Item 2(b) Address of Principal Business Office or, if none, Residence:

The principal business address of the reporting person is:

Cambridge Investments, Ltd.
600 Montgomery Street
43rd Street
San Francisco, California 94111

Item 2(c) Citizenship:

Cambridge Investments, Ltd. was formed under the laws of the State of 

Item 2(d) Title of Class of Securities:

Common Stock, no par value

Item 2(e) CUSIP Number:


Item 3 If this statement is filed pursuant to Rules 13d-1(b) or 13d-2(b) or
       13d-2(c) promulgated under the Securities Exchange Act of 1934, check
       whether the filing person is a:

                                                 Page 3 of 6 Pages

CUSIP No. 0001279141

 a.       |_|      Broker or dealer registered under Section 15 of the Act,
 b.       |_|      Bank as defined in Section 3(a)(6) of the Act,
 c.       |_|      Insurance Company as defined in Section 3(a)(19) of the Act,
 d.       |_|      Investment Company registered under Section 8 of the
                   Investment Company Act,
 e.       |X|      Investment Adviser in accordance with Rule 13d-1(b)(1)(ii)
 f.       |_|      Employee Benefit Plan, or Endowment Fund in accordance with 
                   Rule 13d-1(b)(1)(ii)(F),
 g.       |_|      Parent Holding Company or Control Person, in accordance with
                   Rule 13d-1(b)(ii)(G); (Note:  see Item 7)
 h.       |_|      A savings association as defined in Section 3(b) of the 
                   Federal Deposit Insurance Act (12 U.S.C. 1813);
 i.       |_|      A church plan that is excluded from the
                   definition of an  investment company under section
                   3(c)(14) of the Investment Company Act of 1940;
 j.       |_|      Group, in accordance with Rule 13d-1(b)(1)(ii)(J).

Item 4 Ownership:

       (a)    Amount Beneficially Owned:

              As of April 5, 1998,  800,888 Shares were  beneficially
              owned by the filing person.

       (b)    Percent of Class:  5.41%

       (c)    Number of shares as to which such person has:

             (i)    sole power to vote or to direct the vote:


             (ii)   shared power to vote or direct the vote:


            (iii)   sole power to dispose or to direct the disposition of:


                                                 Page 4 of 6 Pages

CUSIP No. 0001279141

            (iv) shared power to dispose or direct the disposition of:


Item 5 Ownership of Five Percent or Less of a Class:
- ------                                                         

       If this statement is being filed to report the fact that as of
       the date  hereof  the  reporting  person  has ceased to be the
       beneficial  owner of more  than five  percent  of the class of
       securities, check the following |_|

Item 6 Ownership of More than Five Percent on Behalf of Another Person:
- ------                                                                      

       Not applicable

Item 7 Identification and Classification of the Subsidiary which Acquired the
- ------                                                                    
       Security Being Reported on By the Parent Holding Company:

        Not applicable

Item 8  Identification and Classification of Members of the Group:
- ------                                                                      
        Not applicable

Item 9  Notice of Dissolution of Group:
- ------                                           

        Not applicable

Item 10  Certification:
- -------

By signing below I certify  that,  to the best of my knowledge  and belief,  the
securities  referred to above were acquired and are held in the ordinary  course
of business  and were not  acquired  and are not held for the purpose of or with
the  effect of  changing  or  influencing  the  control  of the  insurer  of the
securities  and were not  acquired and are not held in  connection  with or as a
participant in any transaction having that purpose or effect.

                                                 Page 5 of 6 Pages

CUSIP No. 0001279141


After  reasonable  inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

May 12, 1998
- -------------------------------------------------------------------------------

/s/ John R. Tozzi, President
- -------------------------------------------------------------------------------

John R. Tozzi, President
- -------------------------------------------------------------------------------

                                                 Page 6 of 6 Pages