<PAGE>
                                                                   Exhibit 10.53

                              MAY 2004 AMENDMENT TO
                           LOAN AND SECURITY AGREEMENT


         THIS MAY 2004 AMENDMENT TO LOAN AND SECURITY AGREEMENT (the
"Amendment") is made and entered into as of the 1st day of May, 2004, by and
among FLEET CAPITAL CORPORATION, a Rhode Island corporation, successor in
interest by merger to FLEET CAPITAL CORPORATION, a Connecticut corporation,
formerly known as SHAWMUT CAPITAL CORPORATION, successor in interest by
assignment to BARCLAYS BUSINESS CREDIT, INC. ("Lender"), LOWRANCE ELECTRONICS,
INC., a Delaware corporation ("Lowrance"), LEI EXTRAS, INC., a Delaware
corporation ("LEI"), LOWRANCE CONTRACTS, INC., a Delaware corporation ("Lowrance
Contracts"), and SEA ELECTRONICS, INC., an Oklahoma corporation ("Sea
Electronics") (Lowrance, LEI, Lowrance Contracts and Sea Electronics are herein
individually and collectively called "Borrower").

                                    RECITALS


(A) Borrower, Lowrance Australia Pty Limited ("Lowrance Australia") and Lender
have entered into that certain Loan and Security Agreement, dated December 15,
1993, as such Loan and Security Agreement has been amended, including, without
limitation, as amended by (i) that certain First Amendment to Loan and Security
Agreement, dated October 16, 1995, by and among Lender, Borrower and Lowrance
Australia, (ii) that certain Second Amendment to Loan and Security Agreement,
dated November 1, 1996 by and among Lender and Borrower, (iii) that certain
Third Amendment to Loan and Security Agreement, dated December 30, 1996, by and
among Lender and Borrower, (iv) that certain Fourth Amendment to Loan and
Security Agreement, entered into effective as of April 1, 1997, by and among
Lender and Borrower, (v) that certain Fifth Amendment to Loan and Security
Agreement, entered into effective as of August 25, 1997, by and between Lender
and Borrower, (vi) that certain Sixth Amendment to Loan and Security Agreement
and Certain Other Loan Documents, entered into effective as of August 28, 1997,
by and between Lender and Borrower, (vii) that certain Seventh Amendment to Loan
and Security Agreement, entered into effective as of November 1, 1997, by and
between Lender and Borrower, (viii) that certain Eighth Amendment to Loan and
Security Agreement, made and entered into as of December 9, 1997, by and between
Lender and Borrower, (ix) that certain Ninth Amendment to Loan and Security
Agreement made and entered into as of September 14, 1998, by and between Lender
and Borrower, (x) that certain Tenth Amendment to Loan and Security Agreement
and Amendment to Certain Other Loan Documents, executed in November of 1998, by
Lender and Borrower; (xi) that certain Eleventh Amendment to Loan and Security
Agreement and Amendment to Certain Other Loan Documents, executed March 14,
2000, by Lender and Borrower, (xii) that certain Twelfth Amendment to Loan and
Security Agreement and Amendment to Certain Other Loan Documents, executed
October 15, 2000, by Lender and Borrower, (xiii) that certain Thirteenth
Amendment to Loan and Security Agreement and Amendment to Certain Other Loan
Documents and Limited Waiver entered into on October 19, 2001, by Lender and
Borrower, (xiv) that certain letter agreement, dated December 14, 2001, by and
between Lender and Borrower, (xv) that certain Fourteenth



                                       1
<PAGE>

Amendment to Loan and Security Agreement and Amendment to Certain Other Loan
Documents, entered into on March 11, 2002, by Lender and Borrower, (xvi) that
certain November 2002 Amendment to Loan and Security Agreement and Amendment to
Certain Other Loan Documents, entered into on November 26, 2002, by Lender and
Borrower, (xvii) that certain waiver and amendment letter agreement, dated May
29, 2003, entered into by Lender and Borrower, and (xviii) that certain
amendment letter agreement, dated September 10, 2003, executed by Lender and
Borrower (as amended, the "Loan Agreement").

         (B) Borrower has requested (i) that Lender consent to the $940,000
Distribution recently made by Lowrance to its shareholders in the form of a cash
dividend, such Distribution having been made in connection with the fiscal year
of Lowrance which will end July 31, 2004 (the "$940,000 Distribution"), and (ii)
that Lender waive the covenant embodied in Section 9.2(J) of the Loan Agreement
to the extent such covenant would be deemed violated solely due to the making of
the $940,000 Distribution by Lowrance.

         (C) Borrower has requested (i) that Lender consent to the secondary
public offering of the capital stock of Lowrance which is anticipated to close
during the summer of 2004 (the "Lowrance Secondary Offering"), (ii) that Lender
waive any covenants embodied in the Loan Agreement to the extent such covenants
would be deemed violated solely due to the consummation of the Lowrance
Secondary Offering, and (iii) that effective upon the consummation of the
Lowrance Secondary Offering, Borrower and Lender delete Section 11.1(K) Change
of Ownership of the Loan Agreement.

         (D) Pursuant to the terms and conditions of this Amendment, (i) Lender
is willing to consent to the making of the $940,000 Distribution by Lowrance and
to waive the covenant embodied in Section 9.2(J) of the Loan Agreement to the
extent such covenant would be deemed violated solely due to the making of the
$940,000 Distribution by Lowrance, (ii) Lender is willing to consent to the
consummation of the Lowrance Secondary Offering and to waive any covenants
embodied in the Loan Agreement to the extent they would be deemed violated
solely due to the consummation of the Lowrance Secondary Offering, and effective
upon consummation of the Lowrance Secondary Offering, to agree with Borrower to
the deletion of Section 11.1(K) Change of Ownership of the Loan Agreement, and
(iii) Borrower and Lender are willing to further amend the Loan Agreement, all
as hereinafter set forth.

         NOW, THEREFORE, in consideration of the premises herein contained and
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties, intending to be legally bound, agree as
follows:

                                   ARTICLE I
                                   DEFINITIONS

         1.01 Capitalized terms used in this Amendment are defined in the Loan
Agreement, as amended hereby, unless otherwise stated.



                                       2
<PAGE>

                                   ARTICLE II
                                   AMENDMENTS

         2.01 AMENDMENT TO SECTION 3.1(A) OF THE LOAN AGREEMENT. Effective as of
May 1, 2004, Section 3.1(A) of the Loan Agreement is hereby deleted in its
entirety and the following substituted in lieu thereof:

         "Outstanding principal on the Loans shall bear interest, calculated
         daily, at the following rates per annum (individually called, as
         applicable, an 'Applicable Annual Rate'): (i) (a) each Term Loan which
         is a LIBOR Loan shall bear interest at a rate per annum equal to 2.50%
         above the LIBOR Base Rate and (b) each Term Loan which is a Base Rate
         Loan shall bear interest at a rate per annum equal to 0.25% above the
         Base Rate, and (ii) (a) each Revolving Credit Loan which is a LIBOR
         Loan shall bear interest at a rate per annum equal to 2.50% above the
         LIBOR Base Rate and (b) each Revolving Credit Loan which is a Base Rate
         Loan shall bear interest at a fluctuating rate per annum equal to 0.25%
         above the Base Rate. Interest rate on each Base Rate Loan shall be
         increased or decreased, as the case may be, by an amount equal to any
         increase or decrease in the Base Rate, with such adjustments to be
         effective as of the opening of business on the day that any such change
         in the Base Rate becomes effective. The Base Rate in effect on the date
         hereof shall be the Base Rate effective as of the opening of business
         on the date hereof, but if this Agreement is executed on a day that is
         not a Business Day, the Base Rate on the date hereof shall be the Base
         Rate effective as of the opening of business on the last Business Day
         immediately preceding the date hereof. The interest rate on each Loan
         shall be calculated daily, based on the actual days elapsed over a 360
         day year. Further, for the purpose of computing interest, all items of
         payment received by Lender shall be applied by Lender (subject to final
         payment of all drafts and other items received in form other than
         immediately available funds) against the Obligations on the first
         Business Day after receipt. The determination of when a payment is
         received by Lender will be made in accordance with Section 3.6."

         2.02 DELETION OF SECTION 11.1(K) OF THE LOAN AGREEMENT. Effective as of
the date of consummation of the Lowrance Secondary Offering, Section 11.1(K) of
the Loan Agreement is hereby deleted in its entirety; provided, however, that in
addition to any of the other terms and conditions of this Amendment, a condition
precedent to the deletion of Section 11.1(K) of the Loan Agreement is
consummation of the Lowrance Secondary Offering and that until the date, if
ever, of the consummation of the Lowrance Secondary Offering, Section 11.1(K) of
the Loan Agreement shall remain in full force and effect.

         2.03 AMENDMENT FEE. In consideration for the agreements of Lender
contained herein but subject to Section 3.1(D) of the Loan Agreement, Borrower
agrees to pay Lender a fee of $5,000. Such fee shall be due and payable and
shall be fully earned as of the date of execution of this Amendment.



                                       3
<PAGE>

                                  ARTICLE III
                              CONDITIONS PRECEDENT

         3.01 CONDITIONS PRECEDENT. The effectiveness of this Amendment is
subject to the satisfaction of the following conditions precedent, unless
specifically waived in writing by Lender:

                  (a) Lender shall have received each of the following, each in
         form and substance satisfactory to Lender: (i) this Amendment, duly
         executed by Borrower; and (ii) such additional documents, instruments
         and information as Lender or its legal counsel may request;

                  (b) The representations and warranties contained herein, in
         the Loan Agreement and in the other Loan Documents, as each is amended
         hereby, shall be true and correct as of the date hereof, as if made on
         the date hereof;

                  (c) After giving effect to this Amendment, no Default or Event
         of Default shall have occurred and be continuing, unless such Default
         or Event of Default has been specifically waived in writing by Lender;

                  (d) All corporate proceedings taken in connection with the
         transactions contemplated by this Amendment and all documents,
         instruments and other legal matters incident thereto shall be
         satisfactory to Lender and its legal counsel; and

                  (e) Lender shall have received, in immediately available
         funds, payment of the fee described in Section 2.03 of this Amendment.

                                   ARTICLE IV
                     CONSENT TO $940,000 DISTRIBUTION AND TO
                   CONSUMMATION OF LOWRANCE SECONDARY OFFERING

         4.01 CONSENT TO $940,000 DISTRIBUTION. Subject to the satisfaction of
the conditions precedent specified in Article III of this Amendment and the
other terms, conditions and provisions of this Amendment, Lender (a) consents to
the $940,000 Distribution, and (b) waives the covenant embodied in Section
9.2(J) of the Loan Agreement to the extent that such covenant would be violated
solely due to the consummation of the $940,000 Distribution.

         4.02 CONSENT TO LOWRANCE SECONDARY OFFERING. Subject to the
satisfaction of the conditions precedent specified in Article III of this
Amendment, and the other terms, conditions and provisions of this Amendment,
Lender (a) consents to the consummation of the Lowrance Secondary Offering and
(b) waives the covenants embodied in the Loan Agreement to the extent that such
covenants would be violated solely due to the consummation of the Lowrance
Secondary Offering.

         4.03 LIMITED NATURE OF CONSENTS. The making of the $940,000
Distribution and consummation of the Lowrance Secondary Offering (collectively,
the "Transactions") in



                                       4
<PAGE>

accordance with the terms, conditions and provisions of this Amendment shall not
constitute a Default or an Event of Default. The foregoing consents described
above in Section 4.01 and Section 4.02 are strictly limited to the Transactions
as described and limited by this Amendment, and, except as otherwise
specifically provided for in this Amendment, nothing contained in this Amendment
shall be construed as a waiver by Lender of any covenant or provision of the
Loan Agreement, the other Loan Documents, this Amendment, or of any other
contract or instrument between Borrower and Lender, and the failure of Lender at
any time or times hereafter to require strict performance by Borrower of any
provision thereof shall not waive, affect or diminish any right of Lender to
thereafter demand strict compliance therewith. Lender hereby reserves all rights
granted under the Loan Agreement, the other Loan Documents, this Amendment and
any other contract or instrument between Borrower and Lender.

                                   ARTICLE V
                  RATIFICATIONS, REPRESENTATIONS AND WARRANTIES

         5.01 RATIFICATIONS. The terms and provisions set forth in this
Amendment shall modify and supersede all inconsistent terms and provisions set
forth in the Loan Agreement and the other Loan Documents, and, except as
expressly modified and superseded by this Amendment, the terms and provisions of
the Loan Agreement and the other Loan Documents are ratified and confirmed and
shall continue in full force and effect. Borrower and Lender agree that the Loan
Agreement and the other Loan Documents, as amended hereby, shall continue to be
legal, valid, binding and enforceable in accordance with their respective terms.

         5.02 REPRESENTATIONS AND WARRANTIES. Borrower hereby represents and
warrants to Lender that (a) the execution, delivery and performance of this
Amendment and any and all other Loan Documents executed and/or delivered in
connection herewith have been authorized by all requisite corporate action on
the part of Borrower and will not violate the Certificate of Incorporation or
Bylaws of Borrower; (b) the representations and warranties contained in the Loan
Agreement, as amended hereby, and any other Loan Documents are true and correct
on and as of the date hereof and on and as of the date of execution hereof as
though made on and as of each such date; (c) no Default or Event of Default
under the Loan Agreement, as amended hereby, has occurred and is continuing; (d)
Borrower is in full compliance with all covenants and agreements contained in
the Loan Agreement and the other Loan Documents, as amended hereby; (e) the
Borrower's Certificate of Incorporation and Bylaws are in full force and effect
on and as of the date hereof without modification or amendment in any respect
since November 1, 1996; (f) as of the date hereof, (i) Borrower is in existence
and in corporate and tax good standing in the State of its organization, (ii)
the Borrower is qualified to do business as a foreign corporation and is in
corporate and tax good standing in each jurisdiction where Borrower is doing
business and is required to be so qualified, (iii) Borrower does not owe
franchise taxes or other taxes required to maintain its corporate existence and
no franchise tax reports are due, and (iv) no proceedings are pending for
forfeiture of the Borrower's charter or for its dissolution either voluntarily
or involuntarily; and (g) the officer of Borrower executing this Amendment has
been duly elected and is, at present, qualified and acting in the office
indicated below such officer's name and is duly authorized to execute this
Amendment on behalf of Borrower.



                                       5
<PAGE>

                                   ARTICLE VI
                            MISCELLANEOUS PROVISIONS

         6.01 SURVIVAL OF REPRESENTATIONS AND WARRANTIES. All representations
and warranties made in the Loan Agreement or any other Loan Document, including,
without limitation, any document furnished in connection with this Amendment,
shall survive the execution and delivery of this Amendment and the other Loan
Documents, and no investigation by Lender or any closing shall affect the
representations and warranties or the right of Lender to rely upon them.

         6.02 REFERENCE TO LOAN AGREEMENT. Each of the Loan Agreement and the
other Loan Documents, and any and all other agreements, documents or instruments
now or hereafter executed and delivered pursuant to the terms hereof or pursuant
to the terms of the Loan Agreement, as amended hereby, are hereby amended so
that any reference in the Loan Agreement and such other Loan Documents to the
Loan Agreement shall mean a reference to the Loan Agreement, as amended hereby.

         6.03 EXPENSES OF LENDER. As provided in the Loan Agreement, Borrower
agrees to pay on demand all costs and expenses incurred by Lender in connection
with the preparation, negotiation and execution of this Amendment and the other
Loan Documents executed pursuant hereto and any and all amendments,
modifications, and supplements thereto, including, without limitation, the costs
and fees of Lender's legal counsel, and all costs and expenses incurred by
Lender in connection with the enforcement or preservation of any rights under
the Loan Agreement, as amended hereby, or any other Loan Documents, including,
without, limitation, the costs and fees of Lender's legal counsel.

         6.04 SEVERABILITY. Any provision of this Amendment held by a court of
competent jurisdiction to be invalid or unenforceable shall not impair or
invalidate the remainder of this Amendment and the effect thereof shall be
confined to the provision so held to be invalid or unenforceable.

         6.05 SUCCESSORS AND ASSIGNS. This Amendment is binding upon and shall
inure to the benefit of Lender and Borrower and their respective successors and
assigns, except that Borrower may not assign or transfer any of its rights or
obligations hereunder without the prior written consent of Lender.

         6.06 COUNTERPARTS. This Amendment may be executed in one or more
counterparts, each of which when so executed shall be deemed to be an original,
but all of which when taken together shall constitute one and the same
instrument.

         6.07 EFFECT OF WAIVER. No consent or waiver, express or implied, by
Lender to or for any breach of or deviation from any covenant or condition by
Borrower shall be deemed a consent to or waiver of any other breach of the same
or any other covenant, condition or duty.

         6.08 HEADINGS. The headings, captions, and arrangements used in this
Amendment are for convenience only and shall not affect the interpretation of
this Amendment.



                                       6
<PAGE>

         6.09 APPLICABLE LAW. THIS AMENDMENT AND ALL OTHER LOAN DOCUMENTS
EXECUTED PURSUANT HERETO SHALL BE DEEMED TO HAVE BEEN MADE AND TO BE PERFORMABLE
IN AND SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE
STATE OF TEXAS.

         6.10 FINAL AGREEMENT. THE LOAN AGREEMENT AND THE OTHER LOAN DOCUMENTS,
EACH AS AMENDED HEREBY, REPRESENT THE ENTIRE EXPRESSION OF THE PARTIES WITH
RESPECT TO THE SUBJECT MATTER HEREOF ON THE DATE THIS AMENDMENT IS EXECUTED. THE
LOAN AGREEMENT AND THE OTHER LOAN DOCUMENTS, AS AMENDED HEREBY, 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. NO
MODIFICATION, RESCISSION, WAIVER, RELEASE OR AMENDMENT OF ANY PROVISION OF THIS
AMENDMENT SHALL BE MADE, EXCEPT BY A WRITTEN AGREEMENT SIGNED BY BORROWER AND
LENDER.

         6.11 RELEASE. BORROWER HEREBY ACKNOWLEDGES THAT IT HAS NO DEFENSE,
COUNTERCLAIM, OFFSET, CROSS-COMPLAINT, CLAIM OR DEMAND OF ANY KIND OR NATURE
WHATSOEVER THAT CAN BE ASSERTED TO REDUCE OR ELIMINATE ALL OR ANY PART OF ITS
LIABILITY TO REPAY THE "OBLIGATIONS" OR TO SEEK AFFIRMATIVE RELIEF OR DAMAGES OF
ANY KIND OR NATURE FROM LENDER. BORROWER HEREBY VOLUNTARILY AND KNOWINGLY
RELEASES AND FOREVER DISCHARGES LENDER, ITS PREDECESSORS, OFFICERS, DIRECTORS,
AGENTS, EMPLOYEES, SUCCESSORS AND ASSIGNS, FROM ALL POSSIBLE CLAIMS, DEMANDS,
ACTIONS, CAUSES OF ACTION, DAMAGES, COSTS, EXPENSES, AND LIABILITIES WHATSOEVER,
KNOWN OR UNKNOWN, ANTICIPATED OR UNANTICIPATED, SUSPECTED OR UNSUSPECTED, FIXED,
CONTINGENT, OR CONDITIONAL, AT LAW OR IN EQUITY, ORIGINATING IN WHOLE OR IN PART
ON OR BEFORE THE DATE THIS AMENDMENT IS EXECUTED, WHICH THE BORROWER MAY NOW OR
HEREAFTER HAVE AGAINST LENDER, ITS PREDECESSORS, OFFICERS, DIRECTORS, AGENTS,
EMPLOYEES, SUCCESSORS AND ASSIGNS, IF ANY, AND IRRESPECTIVE OF WHETHER ANY SUCH
CLAIMS ARISE OUT OF CONTRACT, TORT, VIOLATION OF LAW OR REGULATIONS, OR
OTHERWISE, AND ARISING FROM ANY "LOANS", INCLUDING, WITHOUT LIMITATION, ANY
CONTRACTING FOR, CHARGING, TAKING, RESERVING, COLLECTING OR RECEIVING INTEREST
IN EXCESS OF THE HIGHEST LAWFUL RATE APPLICABLE, THE EXERCISE OF ANY RIGHTS AND
REMEDIES UNDER THE LOAN AGREEMENT OR OTHER LOAN DOCUMENTS, AND THE NEGOTIATION
OF AND EXECUTION OF THIS AMENDMENT.


                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]




                                       7
<PAGE>

         IN WITNESS WHEREOF, this Amendment has been executed and is effective
as of the date first above-written.


                                    "LENDER"

                                    FLEET CAPITAL CORPORATION


                                    By:
                                       -----------------------------------------
                                    Name:
                                         ---------------------------------------
                                    Title:
                                          --------------------------------------


                                    "BORROWER"

                                    LOWRANCE ELECTRONICS, INC.


                                    By:
                                       -----------------------------------------
                                    Name:
                                         ---------------------------------------
                                    Title:
                                          --------------------------------------


                                    LEI EXTRAS, INC.


                                    By:
                                       -----------------------------------------
                                    Name:
                                         ---------------------------------------
                                    Title:
                                          --------------------------------------


                                    LOWRANCE CONTRACTS, INC.


                                    By:
                                       -----------------------------------------
                                    Name:
                                         ---------------------------------------
                                    Title:
                                          --------------------------------------


                                    SEA ELECTRONICS, INC.


                                    By:
                                       -----------------------------------------
                                    Name:
                                         ---------------------------------------
                                    Title:
                                          --------------------------------------