Patent Publication Number: US-6341992-B1

Title: Boat steering torque compensator

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to mechanisms for countering the steering torque of a boat. 
     2. Prior Art 
     A typical prior art outboard motor  10  for a boat is shown in FIG.  1 . Motor  10  is pivoted about a vertical axle  11  on a motor mount  12  attached to the stern of a boat (not shown). A control shaft  13  is movably positioned through a sleeve  14  extending transversely through motor mount  12 . A follower shaft  15  is positioned through another sleeve  16  in parallel with control shaft  13 . A connecting bar  17  is connected between a first end  18  of control shaft  13  and a first end  19  of follower shaft  15 , so that when control shaft  13  is moved, follower shaft  15  is moved simultaneously. A link arm  20  is hinged between motor  10  and connecting bar  17 . Motor  10  is steered to turn right by moving control shaft  13  toward the right of the figure, and steered to turn left by moving control shaft  13  toward the left of the figure. 
     The torque generated by motor  10  tends to pivot motor  10  counterclockwise about axle  11  and steer the boat right, as shown in FIG.  2 . The driver of the boat must constantly resist the right-turning tendency by counter steering with the steering wheel. The constant application of counter steer is tiring. Further, if the driver releases the steering wheel, or if there is a failure in the steering linkage, the torque from motor  10  will automatically snap the boat into a sharp, uncontrolled right turn. 
     A steering mechanism disclosed in U.S. Pat. No. 4,263,994 to Hayes prevents outboard motor torque from feeding back to a steering wheel. It is a replacement for a preexisting steering mechanism, not an add-on. It requires numerous arms and links, so that it is complicated to make and install. 
     OBJECTS OF THE INVENTION 
     Accordingly, objects of the present boat steering torque compensator are: 
     to precisely counteract torque from an outboard motor; 
     to eliminate the need for a driver to apply counter steer on the steering wheel; 
     to eliminate a boat&#39;s natural tendency to turn even when the driver releases the steering wheel, or during steering linkage failure; and 
     to be easily retrofitted to a boat without modifying or dissembling an existing steering linkage. 
     Further objects of the present invention will become apparent from a consideration of the drawings and ensuing description. 
     BRIEF SUMMARY OF THE INVENTION 
     The present boat steering torque compensator is for being attached to a boat with a pivotable outboard motor, and a linearly movable control shaft with a first end connected to the outboard motor and a second end connected to a steering wheel. The compensator is comprised of a tube for being attached to the boat in a fixed position parallel to the control shaft. A compression spring positioned in the tube has a fixed first end adjacent the first end of the control shaft, and a movable second end. An elongated shaft positioned in the tube and through the spring has a first end connected to the first end of the control shaft by an adapter arm, and a second end positioned adjacent the movable second end of the spring. An engaging member on the second end of the elongated shaft engages the movable second end of the spring to compress the spring when the control shaft and elongated shaft are moved in the direction of the first end of the tube. As a result, the tendency of the motor to pivot under the influence of motor torque is opposed by the spring. The engaging member on the elongated shaft disengages and moves away from the movable second end of the spring when the control shaft and elongated shaft are moved in the direction of the second end of the tube, so that the control shaft is free to move independently of the spring. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     FIG. 1 is a top view of a prior art boat outboard motor in a neutral position. 
     FIG. 2 is a top view of the prior art outboard motor steered to turn right by motor torque. 
     FIG. 3 is a top view of the present torque compensator attached to the outboard motor. 
     FIG. 4 is a top view of the torque compensator opposing a right turn caused by motor torque. 
     FIG. 5 is a top view of the torque compensator allowing the motor to freely turn left. 
    
    
     DRAWING REFERENCE NUMERALS 
       10 . Outboard Motor 
       11 . Axle 
       12 . Motor Mount 
       13 . Control Shaft 
       14 . Sleeve 
       15 . Follower Shaft 
       16 . Sleeve 
       17 . Connecting Bar 
       18 . First End 
       19 . First End 
       20 . Link Arm 
       30 . Tube 
       31 . First End 
       32 . Second End 
       33 . Mounting Bracket 
       34 . Spring 
       35 . First End 
       36 . Second End 
       37 . End Cap 
       38 . Washer 
       39 . End Cap 
       40 . Washer 
       41 . Elongated Shaft 
       42 . First End 
       43 . Adapter Arm 
       44 . Second End 
       45 . Nut 
       46 . Engaging Member 
       47 . U-Bolts 
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG.  3 : 
     A preferred embodiment of the present boat steering torque compensator is shown in a top view in FIG.  3 . It includes a tube  30  with a first end  31  adjacent first end  18  of control shaft  13 , and an opposite second end  32 . Mounting brackets  33  are attached to opposite ends of tube  30 . Tube  30  is for being attached to the boat in a fixed position generally parallel to control shaft  13  adjacent motor  10 . Tube  30  is preferably attached to motor mount  12  with U-bolts  47  wrapped around opposite ends of sleeve  14  and attached to mounting brackets  33 . 
     A compression spring  34  in tube  10  has a fixed first end  35  and a movable second end  36  in corresponding positions with first and second ends  31  and  32 , respectively, of tube  10 . Fixed first end  35  of spring  34  is abutting a first end cap  37  and a fixed first washer  38  at first end  31  of tube  10 . The extension limit for movable second end  36  of spring  34  is defined by a second end cap  39  and a movable second washer  40  at second end of  32  of tube  10 . 
     An elongated shaft  41  positioned in tube  10  and through spring  34  has a first end  42  connected to first end  18  of control shaft  13  and connecting bar  17  by an adapter arm  43 , and a second end  44  positioned adjacent movable second end  36  of spring  34 . During installation, elongated shaft  41  and motor  10  are arranged in the neutral positions shown, and adapter arm  43  is adjusted along elongated shaft  41  by adjusting a nut  45  thereon to meet first end  18  of control shaft  13 . An engaging member  46  near second end  44  of elongated shaft  41  engages movable second washer  40  and movable second end  36  of spring  34 . 
     The torque compensator is thus easily retrofitted to an existing outboard motor without modifying or dissembling the existing steering linkage on the boat. 
     FIG.  4 : 
     When control shaft  13  and elongated shaft  41  are moved in the direction of first end  31  of tube  30  under the influence of motor torque, their movement is resisted by spring  34 , as shown in FIG.  4 . Spring  34  is selected to have a strength just enough to counter the torque of a selected motor or a range of motors. The driver of the boat is relieved from constantly applying counter steer on the steering wheel against the torque-induced turning tendency. Steering is thus much easier and less fatiguing. If the steering wheel is released by the driver, or if there is a failure in the steering linkage during a right turn, spring  34  will gently return to its maximum extension and return the boat to a straight ahead course. 
     FIG.  5 : 
     When control shaft  13  and elongated shaft  41  are moved in the direction of second end  31  of tube  30 , such as during a controlled left turn, engaging member  46  on elongated shaft  41  is disengaged from washer  40  and spring  34 , so that control shaft  13  and elongated shaft  41  are free to move independently of spring  34 , as shown in FIG.  5 . 
     SUMMARY AND SCOPE 
     Accordingly, the present boat steering torque compensator precisely counteracts torque from an outboard motor. It eliminates the need for a driver to constantly apply counter steer on the steering wheel. It eliminates a boat&#39;s natural tendency to turn even when the driver releases the steering wheel, or during steering linkage failure. It is also easily retrofitted to a boat without dissembling or modifying the steering linkage. 
     Although the above description is specific, it should not be considered as a limitation on the scope of the invention, but only as an example of the preferred embodiment. Many variations are possible within the teachings of the invention. For example, the compensator may be provided as a built-in part of a motor mount. The spring may be an extension spring, and the elongated shaft may be rearranged to engage the extension spring. The spring may comprise any type of resilient resistance device, such as a hydraulic cylinder. Therefore, the scope of the invention should be determined by the appended claims and their legal equivalents, not by the examples given.