Exhibit 10.20

                                  INTEREST ONLY
                           NONRECOURSE PROMISSORY NOTE
                             AND SECURITY AGREEMENT

$400,000.00                                                 2/27/03
                                                            Portsmouth, Virginia

     FOR VALUE RECEIVED, H.E.R.C. Products Incorporated, a Delaware corporation,
("Maker" or "Debtor") promises to pay to R. John Armstrong ("Holder" or "Secured
Party"),   or  order,  the  principal  sum  of  Four  Hundred  Thousand  Dollars
($400,000.00) with interest from the date of this Note on unpaid principal owing
from time to time at the rate of eight  percent  (8.0%)  per annum  until  fully
paid.  Maker shall make  interest  only  payments on the first day of each month
from the date of this  Note  until  the date one (1) year  from the date of this
Note ("Maturity  Date").  Principal plus all accrued and unpaid interest on such
principal shall be due and payable on the Maturity Date.

     Maker  shall make all  payments  in lawful  money of the  United  States of
America and in immediately  available  funds.  Computations of interest shall be
based on a year of 360 days but shall be  calculated  for the  actual  number of
days in the period for which interest is charged.

     This  Note may be  prepaid  in whole or in part,  without  penalty,  at the
option of Maker and without the consent of Holder. All payments shall be applied
first  to  accrued  and  unpaid  interest  and  then  to the  principal  balance
outstanding.  All  payments  under  this Note shall be paid to Holder at Seaward
Marine Services,  Inc.,  Attention:  R. John Armstrong,  3975 University  Drive,
Suite 400,  Fairfax,  Virginia 22030 marked "PERSONAL and  CONFIDENTIAL",  or at
such other address as Holder shall direct Maker in writing.

     This Note is  nonrecourse  as to Maker,  except as to those assets of Maker
described  in the  Security  Agreement  between  Maker as Debtor  and  Holder as
Secured Party ("Security  Agreement") included herein and made a part hereof and
a  UCC-1   Financing   Statement,   both  dated  the  same  date  as  this  Note
("Collateral").  In the event  Holder is  entitled  to  proceed  against  Maker,
Holder's sole recourse shall be to proceed  against the  Collateral  pursuant to
the  terms set  forth in the  Security  Agreement.  Holder  shall  have no other
recourse  against Maker or any assets of Maker other than the  Collateral.  This
provision is not intended to constitute a discharge or release of any obligation
contained  in this Note or security  that  secures  such  obligations,  but is a
covenant by Holder not to sue Maker for a deficiency.

     In the event of any  failure to pay when due any  installment  of  interest
under this note, and the  continuance of that failure to pay for a period of ten
(10) days after  written  notice,  by  certified or  registered  mail or by hand
delivery,  of this failure,  this  promissory  note shall be considered to be in
default and the entire unpaid  principal  sum,  together with accrued  interest,
shall at the option of the holder become immediately due and payable in full.

     The laws of the State of  Virginia  excluding  its  conflict  of laws rules
shall govern this Note. The exclusive jurisdiction and venue of any legal action
instituted by any party to this Note shall be Fairfax, Virginia.

     Maker waives presentment,  protest and demand, notice of protest, notice of
demand and  dishonor,  and notice of nonpayment  of this Note.  Maker  expressly
agrees that Holder may extend this Note or any payment under this Note from time
to time without in any way affecting the liability of Maker.

     Maker shall pay all costs and expenses,  including attorney fees,  incurred
(i) in collecting payment on this Note, (ii) in connection with any dispute that
arises as to its enforcement, validity, or interpretation,  whether or not legal
action is  instituted  or  prosecuted  to judgment,  or (iii) in  enforcing  any
judgment obtained in any related legal proceeding.

     If any  provision or any word,  term,  clause,  or part of any provision of
this Note shall be invalid for any reason,  the same shall be  ineffective,  but
the remainder of this Note and of the provision  shall not be affected and shall
remain in full force and effect.

     Any of the terms and  conditions of this Note may be waived by Holder,  but
no such  waiver  shall  affect  or  impair  the  rights  of  Holder  to  require
observance, performance, or satisfaction, either of that term or condition as it
applies on a subsequent occasion or of any other term or condition of this Note.
<PAGE>
     This Note shall be secured by Collateral in the Security  Agreement  made a
part hereof as follows:

                                  SECTION ONE

                          CREATION OF SECURITY INTEREST

     Debtor  grants,  and secured  party  retains a security  interest in all of
company's present and future inventory,  accounts,  account and contract rights,
contracts, drafts, acceptances,  documents,  instruments, chattel paper, deposit
accounts,  general intangibles and all products and proceeds  therefrom,  all of
which are in this  instrument  referred  to as  "collateral,"  subject  to prior
encumbrance  and security  interest under that certain  agreement by and between
debtor and KBK Financial,  Inc. dated September 22, 1997, as amended,  to secure
payment of the following:

     A. The debt evidenced by this instrument.

     B. All costs and expenses  incurred by secured  party in the  collection of
the debt.

     C. All future advances made by secured party for taxes,  levies,  insurance
and repairs to or maintenance of collateral.

     D. All other future  advances that may, at the option of secured party,  be
made or given by secured party to or for the account of debtor.

     E. All other past,  present,  future,  direct or contingent  liabilities of
debtor to secured party.

                                   SECTION TWO

                                 PURPOSE OF LOAN

     Secured  party has  loaned  the  above  sum to  debtor to enable  debtor to
provide  operational  working capital to expand its business,  and other general
corporate purposes.

                                  SECTION THREE

                         PERFECTION OF SECURITY INTEREST

     Debtor  shall pay all filing  fees with  respect to the  security  interest
created by this agreement,  and secured party is by this agreement appointed the
attorney-in-fact  of debtor to  perform  all acts  that  secured  party may deem
necessary to perfect and continue perfecting such security interest.

                                  SECTION FOUR

                         LOCATION OF BUSINESS OF DEBTOR

     The place of business  of debtor is at 1420  Columbus  Avenue,  Portsmouth,
Virginia 23704. Debtor has no other place of business in Virginia.  Debtor shall
promptly notify secured party in writing of:

     A. Any change in location of any place of business.

     B. Establishment of any new place of business.

     C. Discontinuance of any established place of business.

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<PAGE>
                                  SECTION FIVE

                            PROTECTION OF COLLATERAL

     Debtor shall maintain collateral in good condition and repair and shall pay
and discharge all taxes,  levies and other impositions levied on collateral,  as
well as the cost of repairs to or maintenance of collateral.  If debtor fails to
do so,  secured party may pay the cost of such  maintenance  or repairs and such
taxes,  levies and impositions  for the account of debtor,  adding the amount of
the same to the debt secured by this  agreement.  Debtor  shall  permit  secured
party to inspect  collateral  and the books and records of debtor  pertaining to
the collateral at any reasonable time. Debtor shall not lease, mortgage,  pledge
or encumber  collateral,  permit its identity to be lost, permit it to be levied
on or attached under any legal process,  or create any security  interest in the
collateral other than the security  interest created by this agreement,  subject
to prior encumbrance and security interest referenced in Section One hereof.

                                   SECTION SIX

                                  RISK OF LOSS

     Risk of loss, damage to or destruction of collateral is on debtor.

                                  SECTION SEVEN

                        RIGHTS AND REMEDIES UNDER STATUTE

     In addition to all rights given to secured  party by this  promissory  note
and security agreement,  secured party shall have all the rights and remedies of
a  secured  party  under VA ST T.  8.9A  and  otherwise  accorded  by the law in
Virginia.

                                  SECTION EIGHT

                             CONFESSION OF JUDGMENT

     Debtor  empowers  any  attorney  of any court of record  within  the United
States to appear  for debtor  and,  with or without  one or more  complaints  or
declarations  filed,  confess a judgment or judgments against debtor in favor of
the holder of this note and  agreement,  as of any term,  for the above sum plus
accrued interest,  together with costs of suit and attorney fees of 1.0%. Debtor
waives all errors and stays of  execution.  The  exemption of all property  from
levy and sale on any execution is also waived, and no benefit of exemption shall
be  claimed  under or by  virtue of any  exemption  law now in force or that may
later be enacted.

                                  SECTION NINE

                                  SEVERABILITY

     If any provision of this instrument shall for any reason be held invalid or
unenforceable,  such invalidity or  unenforceability  shall not affect any other
provision of this  instrument,  but this promissory note and security  agreement
shall be construed as if such invalid or unenforceable  provision had never been
contained in this instrument.

                                   SECTION TEN

                              EFFECT OF INSTRUMENT

     The rights and  privileges  of secured  party under this  instrument  shall
inure to the benefit of the  successors  and assigns of secured  party,  and the
duties and  obligations  of debtor under this  instrument  shall bind the heirs,

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<PAGE>
personal  representatives,  successors  and assigns of debtor.  If there is more
than one debtor, the warranties, covenants and agreements of debtor contained in
this instrument,  including the foregoing confession of judgment, shall be joint
and several.

     Executed at Portsmouth, Virginia the day and year first above written.


MAKER/DEBTOR

H.E.R.C. Products, Incorporated,
a Delaware corporation

BY: S. Steven Carl, CEO
    -----------------------------

[SIGNATURE]

/s/ S. Steven Carl
---------------------------------

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