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A trim adjustment system includes a means for sensing the depth of the water over which a power boat is traversing and automatic means for raising the propeller and shaft of the boat motor out of danger of the propeller and shaft from becoming damaged by contact with the bed of the water.

Heromin, Dexter (Huron, TN, US)
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1. A system for automatically moving a motor of a boat to a position to avoid damage to the motor in response to change in the depth of the water over which the boat is traveling, said system comprising: a) means for sensing the depth of the water being traversed and b) means for calculating the necessary position of the motor to extend into the water at a safe depth less than the depth sensed by the sensing means and c) means for moving said motor to said position.

2. The system as defined in claim 1 and in which said moving means includes trim adjustment means for moving the motor away from and toward the boat.



This application claims priority of U.S. Provisional Patent Application Ser. No. 60/983, 344, filed Oct. 29, 2007, which is incorporated herein by reference.


The present invention relates to power boats and more particularly to a system for automatically trimming the boat by raising the engine propeller when obstacles such as shallow water are encountered by the boat.


Damage to propellers and shafts of power boat engines is a common problem encountered by power boat users and is caused by accidentally bringing the power boat into shallow water causing the propeller and shaft to strike the ground. The present invention provides a means of solving this problem by providing a system for automatically sensing approaching danger and causing the shaft of the engine and the propeller to be lifted out of harms way.


Trim apparatus in this form of means for raising the propeller of an outboard engine to change the trim angle of a power boat is well known in the boating industry. The present invention is directed to modifying such an apparatus to provide a system which will sense changes in the depth of the water and which will use the trim system to automatically raise the propeller of the boat sufficiently to avoid contact between the engine and the bed of the water being traversed.


A better understanding of the present invention will be achieved by referring to the drawings in wherein

FIG. 1 is diagrammatic view of a boat including an engine for powering the boat and the automatic trim system of this present invention; and

FIG. 2 is a fragmentary diagrammatic view showing a portion of the boat of FIG. 1 and with the engine in a position to avoid encountering the bottom of the body of water over which the boat is traveling.


As can next be seen in FIG. 1 the system of the present invention is intended for use in a boat 12 powered by an outboard motor 14. As is common the hull 16 of the boat 12 is intended to ride along the top of the water 18 with the forward portion of the hull 16 upwardly and above the water 18. The outboard motor 14 generally includes a hydraulic system 20 or the like to enable the motor 14 to be rotated about a horizontal axis to increase or decrease the angle A between the water 18 and the bottom of the hull 16 to thereby facilitate changing the speed of the power boat.

The primary purpose of the changing the trim angle of the boat is to control the speed of the power boat. By raising and lowering the outboard motor by rotation to extend the propeller and shaft further into or further away from the bottom of the water over which the boat is traveling the speed of the boat can be changed. The motor can of course be moved manually upwardly out of the water to avoid contact with the bed of the water.

What has been described except for the system 10 is conventional for power boats. The system 10 as part of the means for controlling the trim angle of the motor is the present invention. The system 10 includes a depth finder 30 mounted to the boat 12 forwardly of the motor 14. The depth finder 30 is electronically connected to a computer 32 which receives the information from the depth finder 30 as to the depth of the water 18 and calculates as to whether or not the motor 14 has to be raised to avoid dragging on the bottom of the water 18.

The computer 32 determines whether or not the motor 14 needs to be raised and how much it needs to be raised. This information is sent to the trim adjustment 34 which is generally a part of the control system of the boat 12 and the motor 14 is then rotated to the proper position to bring the propeller 40 and the housing 42 to a position to avoid the obstacle in the form of the water bottom 18.

The control system for the operation of the motor 14 may or may not include a trim adjustment means as a part of the system. If it does not, the automatic trim system of the present invention will include means for rotating the motor in response to instructions received from the computer 30.

It should be apparent that the present invention provides a system for avoiding the damage to outboard motors ordinarily encountered when a boat moves from an area if safe depth to an area where obstacles are provided because of the shallow depths of the water being traversed.

It should also be apparent that changes can be made to the system as described without departing from the spirit of the invention as set forth in the following claim.