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                                                                   EXHIBIT 10.18

                             UNCONDITIONAL GUARANTY

      FOR VALUE RECEIVED, SEA ELECTRONICS, INC., an Oklahoma corporation
("Guarantor"), guarantees unconditionally the full and prompt payment to SHAWMUT
CAPITAL CORPORATION, a Connecticut corporation ("Lender"), at Lender's office
in Dallas County, Texas, upon demand, of the following obligations and
indebtedness of LOWRANCE ELECTRONICS, INC., a Delaware corporation ("Lowrance"),
LEI EXTRAS, INC., a Delaware corporation ("LEI"), LOWRANCE AUSTRALIA PTY
LIMITED, a New South Wales, Australia corporation ("Lowrance Australia") (ACN
050 050 612), and LOWRANCE CONTRACTS, INC., a Delaware corporation ("Lowrance
Contracts") (individually and collectively referred to herein as "Borrower"):

      Any and all indebtedness and obligations, whether direct or indirect,
absolute or contingent, primary or secondary, joint or several, and all
renewals, modifications and extensions thereof for which Borrower, is now, or
hereafter may become liable or indebted to Lender, whether by lapse of time,
acceleration of maturity, on account of (i) the Obligations, as defined in that
certain Loan and Security Agreement, dated December 15, 1993, between Borrower
and Lender (as successor by assignment to Barclays Business Credit, Inc.) as
amended by the First Amendment to Loan and Security Agreement, dated as of
October 16, 1995 among Lender, Guarantor and Borrower (as amended, the "Loan
Agreement"), outstanding prior to the date hereof; (ii) any document executed in
connection with or as security for payment of such Obligations or any renewal,
extension, or modification thereof; and (iii) all costs, attorneys' fees, and
other expenses incurred by Lender by reason of any default by Borrower under any
of the foregoing (all of the foregoing are hereinafter referred to as the
"Obligations"). The Obligations referred to in clause (i) above shall be
determined in accordance with Section 1.6 of the Loan Agreement.

      At the time Guarantor pays any sum which may become due Lender under the
terms of this Unconditional Guaranty (this "Guaranty"), written notice of such
payment shall be delivered to Lender by Guarantor, and in the absence of such
notice, any sum received by Lender on account of any of the Obligations shall be
conclusively deemed paid by Borrower. All sums paid Lender by Guarantor may be
applied by Lender at its discretion upon any of the Obligations. To further
secure payment of the Obligations, Guarantor grants to Lender, in addition to
all other contractual, legal, and equitable rights of Lender, the right to
offset against any account, certificate of deposit, or other funds of Guarantor
in the possession of or under the control of Lender.

      Guarantor hereby waives notice of acceptance of this Guaranty and all
other notices in connection herewith or in connection with the Obligations,
including, without limitation, notice of intent to accelerate and notice of
acceleration, and waives diligence, presentment, demand, protest, and suit on
the part of Lender in the collection of any of the Obligations, and agrees that
Lender shall not be required to first endeavor to collect any of the Obligations
from Borrower, or any other party liable for payment of the Obligations
(hereinafter referred to as an "Obligated Party"), before requiring Guarantor to
pay the full amount of the Obligations. Without impairing

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the rights of Lender against Guarantor, Borrower or any other Obligated Party,
suit may be brought and maintained against Guarantor at the election of Lender
with or without joinder of Borrower, or any other Obligated Party, any right to
any such joinder being hereby waived by Guarantor.

      Guarantor acknowledges and represents to Lender that it is receiving
direct and indirect financial and other benefits as a result of this Guaranty;
represents to Lender that after giving effect to this Guaranty and the
contingent obligations evidenced hereby it is, and will be, solvent;
acknowledges that its liability hereunder shall be cumulative and in addition to
any other liability or obligation to Lender, whether the same is incurred
through the execution of a note, a similar guaranty, through endorsement, or
otherwise; and acknowledges that neither Lender nor any officer, employee,
agent, attorney or other representative of Lender has made any representation,
warranty or statement to Guarantor to induce it to execute this Guaranty.

      Guarantor hereby agrees that, except as hereinafter provided, its
obligations under this Guaranty shall be continuing, absolute and unconditional,
irrespective of (i) the validity or enforceability of the Obligations or of any
promissory note or other document evidencing all or any part of the Obligations,
(ii) the absence of any attempt to collect the Obligations from Borrower or any
other Obligated Party or other action to enforce the same, (iii) the waiver or
consent by Lender with respect to any provision of any instrument evidencing the
Obligations, or any part thereof, or any other agreement now or hereafter
executed by Borrower and delivered to Lender, (iv) failure by Lender to take any
steps to perfect and maintain its security interest in, or to preserve its
rights to, any security or collateral for the Obligations, (v) the surrender,
release, exchange, or alteration by Lender of any security or collateral for the
Obligations, (vi) Lender's election, in any proceeding instituted under Chapter
11 of Title 11 of the United States Code (11 U.S.C. (S)101 et seq.) (as amended,
the "Bankruptcy Code"), of the application of Section 1111(b)(2) of the
Bankruptcy Code, (vii) any borrowing or grant of a security interest by
Borrower, as debtor-in-possession, under Section 364 of the Bankruptcy Code,
(viii) the disallowance of all or any portion of Lender's claim(s) for repayment
of the Obligations under Section 502 of the Bankruptcy Code, or (ix) any other
circumstance which might otherwise constitute a legal or equitable discharge or
defense of a guarantor.

      No release, waiver, or discharge of Borrower or any other Obligated Party
from liability for payment of any of the Obligations, nor any renewal,
supplementation, modification, rearrangement or acceleration of any of the
Obligations, nor any amendment of any document evidencing any of the
Obligations, either express or implied, shall relieve Guarantor from liability
for payment of the full amount of the Obligations; and Guarantor will
immediately pay all Obligations to Lender or other person entitled thereto,
regardless of any defense, right of set-off or counterclaim which Borrower or
any other Obligated Party may have or assert, and regardless of whether Lender
or any other party shall have taken any steps to enforce any rights against
Borrower, any other Obligated Party, or any other party to collect such sum, and
regardless of any other condition or contingency, including, without limitation,
any neglect, delay or omission of Lender. Lender is hereby authorized, without
notice or demand and without affecting the liability of Guarantor, to, from time
to time: (i) accept partial payments on the Obligations; (ii) take and hold
security or collateral for the payment of this Guaranty or any other

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guarantees of the Obligations, and exchange, enforce, waive and release any such
security or collateral; and (iii) apply such security or collateral therefor in
any manner, without affecting or impairing the obligations of Guarantor
hereunder.

      Notwithstanding anything to the contrary contained herein, Guarantor shall
not have any right, claim or action, now or hereafter, against Borrower or any
other Obligated Party arising out of or in connection with this Guaranty or any
other document evidencing or securing the Obligations, including, without
limitation, any right or claim of subrogation, contribution, reimbursement,
exoneration, or indemnity, all such rights and claims being hereby expressly and
absolutely waived.

      Guarantor is familiar with, and has independently reviewed the financial
condition of, Borrower and hereby assumes responsibility for keeping itself
informed of the financial condition of Borrower, and any and all endorsers or
other guarantors of any instrument or document evidencing all or any part of the
Obligations and of all other circumstances bearing upon the risk of nonpayment
of the Obligations or any part thereof that diligent inquiry would reveal.
Guarantor hereby agrees that Lender shall have no duty to advise Guarantor of
information known to Lender regarding such condition or any such circumstances.
Guarantor is not relying on the financial condition of Borrower or the value of
any collateral for the Obligations as an inducement to enter into this Guaranty.
If Lender, in its sole discretion, undertakes at any time or from time to time
to provide any such information to Guarantor, Lender shall be under no
obligation (i) to undertake any investigation not a part of its regular business
routine, (ii) to disclose any information which, pursuant to accepted or
reasonable commercial finance practices, Lender wishes to maintain confidential,
or (iii) to make any other or future disclosures of such information or any
other information to Guarantor.

      Guarantor consents and agrees that Lender shall be under no obligation to
marshall any assets in favor of Guarantor or against or in payment of any or all
of the Obligations. Guarantor further agrees that, to the extent that Borrower
makes a payment or payments to Lender, or Lender receives any proceeds of
collateral, which payment or payments or any part thereof are subsequently
invalidated, declared to be fraudulent or preferential, set aside and/or
required to be repaid to Borrower, any of its estate, trustee, receiver or any
other party, including, without limitation, Guarantor, under any bankruptcy law,
state or federal law, common law or equitable cause, then to the extent of such
payment or repayment, the Obligations or part thereof which has been paid,
reduced or satisfied by such amount shall be reinstated and continued in full
force and effect as of the date such initial payment, reduction or satisfaction
occurred.

      Lender may, without notice to Guarantor or any other party, assign its
rights hereunder to any holder of the Obligations, in whole or in part, and upon
any such assignment all the terms and provisions of this Guaranty shall inure to
the benefit of such assignee, to the extent so assigned.

      Lender is relying and is entitled to rely upon each and all of the
provisions of this Guaranty; and, accordingly, if any provision of this Guaranty
should be held to be invalid or ineffective, then all other provisions shall
continue in full force and effect notwithstanding.

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      Any and all notices, requests and demands to or upon Guarantor to be
effective shall be in writing and shall be deemed to have been validly served,
given or delivered as follows: (a) if sent by certified or registered mail
return receipt requested, three business days after deposit in the mail, postage
prepaid, or, if earlier, when delivered against receipt; or (b) in the case of
telegraphic notice, when delivered to the telegraph company; or (c) in the case
of telex notice, when sent, answerback received; or (d) if sent by any other
method, upon actual delivery; in each case addressed to the address set forth
opposite Guarantor's signature below or at such other address as Guarantor shall
hereafter notify Lender.

      It is the intention of Borrower, Guarantor and Lender to conform strictly
to applicable usury laws. Accordingly, no agreements, conditions, provisions or
stipulations contained in this Guaranty or any other instrument, document or
agreement between Guarantor or Borrower and Lender or default of Guarantor or
Borrower, or the exercise by Lender of the right to accelerate the payment of
the maturity of principal and interest, or to exercise any option whatsoever
contained in this Guaranty or any other agreement between Guarantor or Borrower
and Lender, or the arising of any contingency whatsoever, shall entitle Lender
to collect, in any event, interest exceeding the maximum rate of interest
permitted by applicable state or federal law in effect from time to time
hereafter (the "Maximum Legal Rate") and in no event shall Guarantor be
obligated to pay interest exceeding such Maximum Legal Rate and all agreements,
conditions or stipulations, if any, which may in any event or contingency
whatsoever operate to bind, obligate or compel Guarantor to pay a rate of
interest exceeding the Maximum Legal Rate, shall be without binding force or
effect, at law or in equity, to the extent only of the excess of interest over
such Maximum Legal Rate. In the event any interest is charged in excess of the
Maximum Legal Rate ("Excess"), Guarantor acknowledges and stipulates that any
such charge shall be the result of an accident and bona fide error, and such
Excess shall be, first, applied to reduce the principal then unpaid hereunder;
second, applied to reduce the Obligations; and third, returned to Guarantor, it
being the intention of the parties hereto not to enter at any time into a
usurious or otherwise illegal relationship. Guarantor recognizes that, with
fluctuations in the applicable rate on the Obligations and the Maximum Legal
Rate, such an unintentional result could inadvertently occur. By the execution
of this Guaranty, Guarantor covenants that the credit or return of any Excess
shall constitute the acceptance by Guarantor of such Excess.

      If any sum due Lender by Guarantor hereunder is placed in the hands of an
attorney for collection, or is collected through probate, bankruptcy, or other
court proceeding, then Guarantor promises to pay Lender all costs, attorneys'
fees, and other expenses incurred by Lender pursuant to such collection efforts.

      Notwithstanding any other provision of this Guaranty, the Guarantor's
liability hereunder shall be limited to the lesser of the following amounts
minus, in either case, $1.00:

            a.    the lowest amount which would render this Guaranty a
      fraudulent transfer under Section 548 of the Bankruptcy Code; or

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            b.    if this Guaranty is subject to the Uniform Fraudulent Transfer
      Act (the "UFTA") or the Uniform Fraudulent Conveyance Act (the "UFCA") or
      any similar or analogous statute or rule of law, then the lowest amount
      which would render this Guaranty a fraudulent transfer or fraudulent
      conveyance under the UFTA, the UFCA, or any such similar or analogous
      statute or rule of law.

The amount of the limitation imposed upon the Guarantor's liability under the
terms of the preceding sentence shall be subject to redetermination as of each
date a "transfer" is deemed to have been made on account of this Guaranty under
applicable law. The Guarantor acknowledges that information concerning the
Guarantor's financial condition is under the control of the Guarantor and is
more readily available to the Guarantor than to Lender, and for that reason the
Guarantor agrees that should the Guarantor claim that the amount of its
liability under this Guaranty is less than the full amount of the Obligations
because of the provisions of this paragraph, then the burden of proving the
facts which would result in such limitation shall be upon the Guarantor.

      This Guaranty shall be terminated at such time as the Obligations are
satisfied in full.

      THIS GUARANTY HAS BEEN NEGOTIATED AND SHALL BE DEEMED TO HAVE BEEN MADE IN
THE STATE OF TEXAS. THIS GUARANTY SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE INTERNAL LAWS OF THE STATE OF TEXAS AND NOT THE LAWS OF
CONFLICTS OF THE STATE OF TEXAS. AS PART OF THE CONSIDERATION FOR NEW VALUE AND
BENEFIT THIS DAY RECEIVED BY GUARANTOR, GUARANTOR HEREBY CONSENTS TO THE
JURISDICTION OF ANY STATE OR FEDERAL COURT LOCATED WITHIN DALLAS COUNTY OF THE
STATE OF TEXAS AND WAIVES PERSONAL SERVICE OF ANY AND ALL PROCESS UPON IT AND
CONSENTS THAT ALL SUCH SERVICE OF PROCESS BE MADE BY CERTIFIED OR REGISTERED
MAIL DIRECTED TO GUARANTOR AT THE ADDRESS STATED HEREIN AND SERVICE SO MADE
SHALL BE DEEMED TO BE COMPLETED UPON ACTUAL RECEIPT THEREOF. GUARANTOR WAIVES
ANY OBJECTION TO JURISDICTION AND VENUE OF ANY ACTION INSTITUTED AGAINST IT AS
PROVIDED HEREIN AND AGREES NOT TO ASSERT ANY DEFENSE BASED ON LACK OF
JURISDICTION OR VENUE.

      EXCEPT AS OTHERWISE PROVIDED FOR IN THIS GUARANTY, GUARANTOR WAIVES THE
RIGHT TO TRIAL BY JURY (WHICH LENDER HEREBY ALSO WAIVES) IN ANY ACTION, SUIT,
PROCEEDING OR COUNTERCLAIM OF ANY KIND ARISING OUT OF OR RELATED TO THIS
GUARANTY OR THE OBLIGATIONS.

      THIS WRITTEN GUARANTY, TOGETHER WITH ALL OTHER INSTRUMENTS, AGREEMENTS AND
CERTIFICATES EXECUTED BY THE PARTIES IN CONNECTION WITH THE OBLIGATIONS OR WITH
REFERENCE HERETO OR THERETO, REPRESENT THE FINAL AGREEMENT BETWEEN THE

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PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR
SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL
AGREEMENTS BETWEEN THE PARTIES.

            Executed and delivered as of October 16, 1995

                                        SEA ELECTRONICS, INC.

                                        By: /s/ Steven L. Schneider
                                            ----------------------------------
                                            Steven L. Schneider, President

                                        Address:

                                        12000 E. Skelly Drive
                                        Tulsa, Oklahoma 74128

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