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Publication numberUS3577948 A
Publication typeGrant
Publication dateMay 11, 1971
Filing dateApr 11, 1969
Priority dateApr 11, 1969
Publication numberUS 3577948 A, US 3577948A, US-A-3577948, US3577948 A, US3577948A
InventorsFrey Ellsworth J
Original AssigneeStar Tab Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Stabilizer trim attachment for power boats
US 3577948 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent Ellsworth J. Frey Logan, Ohio 815,404

Apr. 11, 1969 May 1 l, 1971 Star Tab, Inc. Logan, Ohio lnventor Appl. No. Filed Patented Assignee STABILIZER TRIM ATTACHMENT FOR POWER BOATS 1 Claim, 4 Drawing Figs US. Cl. 114/665 Int. Cl 1363b 1/22 Field of Search ll4/66.5

Relerenoes Cited UNITED STATES-PATENTS v 5/ l 944 Parker l l4/66.5X

3,399,643. 9/1968 Benn ett 1 14/665 3,404,651 l0/l968 Jensen etal. ll4/66.5- 3,468,278 9/l969 Kercheval Primary Examiner-Andrew H. Farrell Attorney-Mahoney, Miller & Stebens An attachment for a power boat which fits on the transom or stem of the boat and comprises a pair of trim tabs hinged at the transom and extending rearwardly therefrom, and which may be'swung vertically simultaneously to difi'erent angular positions to trim the boat so that it operates at the proper attitude regardless of its loading. The

- tabs are so formed that they also bring about lateral stability as well as impart the proper attitude to the boat. Furthermore, the tabs are positively moved vertically up or down to their selected angular positions.

PATENTEU-HAH I |97l 3577,534


1 STABILIZER TRIM ATTACHMENT FOR POWER BOATS BACKGROUND OF THE INVENTION Various trim tab attachments have been provided in the past for obtaining the proper attitude in the movement of the boats through the water under various loaded conditions.

However, these prior art attachments have not included means for obtaining lateral stability. Also, the operating means for these tabs have not been positive in both directions to permit a definite selection of angular position of the tabs. According to the present invention, lateral stability is accomplished as well as positive selection of the angular position of the tabs in order to obtain the desired attitude of the boat under various loaded conditions.

in the accompanying drawings, l have illustrated a preferred embodiment of my-invention and in these drawings:

FIG. 1 is a side elevational view of a portion of a boat at its stern, partly broken away, showing my attachment applied to the transom thereof.

FIG. 2 is a horizontal sectional view taken along line 2-2 of FIG. 1.

FIG. 3 is a rear view taken along line 3-3 of FIG. 1.

FIG. 4 is a schematic diagram of the hydraulic and electric control circuit for controlling the angular position of the trim With reference to the drawings, 1 have shown in FIG. 1, the stern portion of a power boat of the inboard motor type with the transom l and the bottom 11 converging at a lower corner 12. The trim tabs of this invention are indicated generally at 13 and 14 and are hinged about a transverse axis, indicated at 15, for vertical swinging movement. This axis is adjacent the corner 12. Y

The tabs 13 and 14 are hinged side by side, but with a space 16 therebetween. If the attachment is used on an outboard motor type boat this spacing could be increased if necessary. Each tab is made of relatively stiff sheet metal with a straight forward edge which is hinged to the transom 10, preferably by a piano-type hinge 17. The rear edge of the tab is turned upwardly at a transverse joint 18 parallel with the front or leading edge of the tab so as to provide an upwardly and rearwardly projecting angular extension which stiffens the tab and provides for smoother flow of water over its rear edge. It will be apparent that due to the location of the hinge 17, the main body of the tab is, in effect, an extension of the bottom of the boat being coplanar therewith. The extension 19 extends upwardly and rearwardly from the tab so as to reduce turbulence at the rear edge of the tab. It will be noted that the corners of the extension 19 are angled at 20 to further reduce turbulence.

To obtain lateral stability as the boat is passing through the water, each tab at each edge is provided with a depending stabilizing flange 21 which also reinforces the body of the tab to make it rigid. It will be noted that each flange 21 angles downwardly from the hinge 17, where its edge is substantially flush with the bottom 11, to its rear end 22, at the joint 18, where it depends from the body of the tab a substantial distance. Each depending flange 21 is in a vertical plane at a right angle to the flat plane of the body of the trim tab.

Each of the tabs 13 and 14 is moved up or down positively to a selected angular position by means of a double-acting hydraulic rarn or cylinder and piston unit 25. This unit 25 is pivotally connected to the transom 10 at 23, on its outer vertical surface, and to the tab at 24, on its upper surface rearwardly of the hinge axis 15 and adjacent the joint 18. The units 25 are preferably simultaneously activated by means of a combined motor and pump unit 26, located within the boat, preferably mounted on the inner surface of the transom, being connected to the units 25 bythe necessary flexible conduit 27.

As the boat passes through the water, the proper attitude may be obtained by operating the switch 30 to select the proper angle on the two tabs 13 and 14 simultaneously. The switch 30 will be of the double-throw, double-pole type and will normally be held spring biased into off" ition. It will control a reversible motor 26a of the unit 2 which Wlll, m

turn, control the reversible hydraulic pump 26b of that unit. Driving the motor 26a in one direction will actuate the rams 25 to swing the tabs 13 and 14 upwardly simultaneously and driving the motor in the other direction will actuate the rams 25 to swing them downwardly. As the boat is powered through the water, the water will pass beneath the flat bodies of the tabs 13 and 14, which will provide planing surfaces, and then over the rearwardly and upwardly angled extensions 19 with a minimum of turbulence. The flanges 21 projecting downwardly into the water will create lateral stability. This is especially true at the center where water is passing through the space 16, between the two tabs, which space is lined up with the keel or centerline of the boat and acts on both adjacent flanges 21 to obtain a high degree of lateral stabilization. Positive displacement of the tabs up or down, as described, may be obtained merely by moving the activating lever of the switch 30 in the proper. direction. By using two separate tabs they can be spaced apart as desired and angularly related relatively depending upon the transverse contour of the bottom of the boat and the transom.


1. In combination with a power boat having a bottom and a transom connected together at a joint at the stern of the boat; a pair of trim-tabs hinged to the boat adjacent said joint and on opposite sides of the centerline thereof;

said trim tabs comprising substantially flat body portions which are hinged at their forward edges to the boat and provide planing surfaces extending rearwardly from the boat bottom,

said tabs being spaced on each side of the centerline of the boat to provide a space therebetween, said tabs having stabilizing flanges which project from the planing surfaces of the tabs at both the inner and outer edges of the respective tabs, each tab having an upwardly angled extension at its rear edge, and means for positively raising and lowering the hinged tabs, said means for positively raising and lowering the tabs comprising a double-acting hydraulic ram connected between each of said tabs and the transom of the boat, and means for activating both of said rams simultaneously in the same direction, said activating means comprising a single selector switch movable from a normal off position into contact with either of two contacts, said contacts being connected to a reversible electric motor which drives a reversible hydraulic pump that supplies actuating fluid to said rams.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2347841 *May 14, 1941May 2, 1944Parker James FSeaplane
US3399643 *Mar 20, 1967Sep 3, 1968Charles H. BennettTrim attachment for power boats
US3404651 *May 5, 1967Oct 8, 1968Rexall Drug ChemicalBoat-trimming vane mechanism
US3468278 *May 18, 1967Sep 23, 1969Kercheval Frank TBoat leveler mechanism piston construction
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3828713 *Oct 19, 1972Aug 13, 1974C DuryeaBoat flanking rudder system
US4026231 *Jan 26, 1976May 31, 1977Fedorko Irvin EDevice for controlling boat speed
US4854259 *Oct 14, 1988Aug 8, 1989Sta-Rite Industries, Inc.Improved trim-tab control system for power boats
US4909175 *Oct 5, 1988Mar 20, 1990Arnseson Howard MBoat with trimmable bottom
US4967682 *Jul 12, 1989Nov 6, 1990Donnell Kenneth P OStabilizing system for a boat
US5549071 *Jul 3, 1995Aug 27, 1996Tige BoatsSki tow boat with wake control device and method for operation
US5832863 *Jun 3, 1997Nov 10, 1998Sherlock; JohnTrue track trim blades
US6095077 *Oct 10, 1997Aug 1, 2000Deagro; John EApparatus for motorized boat attitude adjustment
US6138601 *Feb 26, 1999Oct 31, 2000Brunswick CorporationBoat hull with configurable planing surface
US6167830Dec 6, 1999Jan 2, 2001Don T. PilgerBoat trim tabs
US6425341 *Aug 30, 1999Jul 30, 2002Neville John DevinBoat hull
US6805068Aug 5, 2003Oct 19, 2004Raimer TossavainenHydrofoil system for lifting a boat partially out of water an amount sufficient to reduce drag
US7434531 *May 3, 2007Oct 14, 2008Pivotal Designs Inc.Device for adjusting boat wake
US8047152Apr 27, 2009Nov 1, 2011Ultraflex S.P.A.Hinge joint for cylinder actuators of watercraft trim tabs, trim tab and trim tab control system
US8216007Feb 27, 2006Jul 10, 2012Steven Clay MooreMethods and arrangements for rapid trim adjustment
US8631753 *Feb 18, 2011Jan 21, 2014Robert A. MorvilloVariable trim deflector system and method for controlling a marine vessel
US9174703Feb 19, 2015Nov 3, 2015Mastercraft Boat Company, LlcWake-modifying device for a boat
US9233740Feb 7, 2014Jan 12, 2016Robert A. MorvilloVariable trim deflector system with protruding foil and method for controlling a marine vessel
US9260161Jul 10, 2012Feb 16, 2016Malibu Boats, LlcSurf wake system for a watercraft
US9315235Sep 21, 2015Apr 19, 2016Scott WoodWake adjustment system for boats
US9334022Jan 24, 2013May 10, 2016Malibu Boats, LlcSurf wake system for a watercraft
US9446823Nov 25, 2015Sep 20, 2016Mastercraft Boat Company, LlcWake-modifying device for a boat
US9481441Nov 27, 2013Nov 1, 2016Robert A. MorvilloVariable trim deflector system and method for controlling a marine vessel
US9505464Sep 4, 2015Nov 29, 2016Scott WoodWake adjustment system for boats
US9580147Nov 15, 2013Feb 28, 2017Malibu Boats, LlcSurf wake system for a watercraft
US20070202757 *Feb 27, 2006Aug 30, 2007Moore Steven CMethods and arrangements for rapid trim adjustment
US20080271660 *May 3, 2007Nov 6, 2008Pivotal Designs Inc.Device for adjusting boat wake
US20090277369 *Apr 27, 2009Nov 12, 2009Ultraflex SpaHinge joint for cylinder actuators of watercraft trim tabs, trim tab and trim tab control system
US20110011326 *Jun 7, 2010Jan 20, 2011M Ship Co., Llc.Powerboat rooster tail depressor
US20110320072 *Feb 18, 2011Dec 29, 2011Morvillo Robert AVariable trim deflector system and method for controlling a marine vessel
U.S. Classification114/286
International ClassificationB63B39/00, B63B39/06
Cooperative ClassificationB63B39/061
European ClassificationB63B39/06B