Patent Publication Number: US-2009221196-A1

Title: Torsional control boat throttle system

Description:
FIELD OF THE INVENTION 
     The present invention relates to throttle controls for vehicles, particular watercraft. The invention also relates to the manner of converting user control input to output, as well as translation of that output to action at a remote location. 
     BACKGROUND OF THE INVENTION 
     A number of known throttle controls for watercraft employ a twist-grip type of interface connected to an electronic control unit. These are found in connection with electric trolling motors. Twist of the grip controls motor speed. Typically, the grip also serves as a tiller, in which its point dictates the direction of the motor connected thereto by a tube or shaft. 
     More sophisticated throttle control systems are shown in U.S. Pat. Nos. 6,053,781 and 6,776,671. In each patent, the tiller/throttle grip assembly is removed from the propeller tube and setup at a remote location. In the &#39;781 patent, the direction the propeller points is controlled by a separate lever arm with push-pull ropes/cables wrapped around a component connected to the motor tube. The motor control unit with its grip is located amidship oriented vertically. In the &#39;671 patent, the motor control head and throttle control grip are mounted alongside the pilot&#39;s seat. The control head is mounted on a rod so that it can rotate around the axis that is in-line with the boat to actuate a linkage assembly attached to propeller tube to effect steering. 
     While these systems offer benefits, their use is contemplated only in connection with electric trolling motors. Furthermore, neither system offers angular adjustability of the throttle grip independent of steering control. In the &#39;781 patent, no angular adjustability is available with the fixed unit. In the &#39;671 patent one cannot simply adjust the angle of the grip to a desirable position while operating the boat, since to do so would set an unintended course. Moreover, trolling motors are suited only for driving a small boat at a speed of a few knots/mph, and in calm water. The inventor hereof has appreciated the benefits of a throttle grip type system for use in a vastly different context. Particularly, the present invention finds use in high power speedboats as a means of control for the primary source of propulsion. Benefits and advantages of the current system are elaborated upon below. 
     SUMMARY OF THE INVENTION 
     The present invention is a throttle control assembly using a twist grip type user interface. The throttle control assembly is provided for use in connection with powerboats, especially those suited for use in rough (open ocean) water and/or at high speed (i.e., greater than, for example, 30 knots/35 mph) in racing, etc. The present invention may also be used in other types of vessels, vehicles and crafts. While the examples provided herein relate to watercraft, it is intended that the use of the word “boat” or similar terms, other than in the claims, refers to any type of vessel, vehicle or craft. 
     The throttle control assembly of the present invention typically controls at least one large internal combustion engine. The present invention offers particular advantages in connection with racing boats in which the user sits in a tight cockpit and the boat is planning across the water at very high speeds (upwards of 75 mph in a typical race). At such speeds, the wakes of other boats or wave action produces an extremely rough or “bumpy” ride. A grip-style throttle control assembly according to the present invention, then, provides a user something stable to hold onto in order to help maintain body position, and avoid injury as is common from banging fingers, elbows etc. while being tossed around in the cockpit of a scarab or another type of racing boat. 
     In one aspect of the invention, the grip drives a mechanical gear system that operates a control cable. The cable may be coupled directly to a lever arm attached to the throttle shaft of a marine engine or motor. Alternatively, the cable can actuate a rack in a rack-and-pinion arrangement in which the pinion is mounted on the throttle shaft itself. In this manner, truly linear throttle control can be achieved since change in lever arm angle is avoided. 
     In yet another aspect of the invention, the rotary motion caused by rotation of the grip is transmitted by a flexible shaft to a throttle cable. Rotation of the grip in the clockwise direction pulls the throttle cable forward, and rotation of the grip in the counter-clockwise direction pushes the throttle cable in the opposite direction. The pulling and pushing on the throttle cable serves to increase and decrease, respectively, the throttle of the boat engine. 
     In one aspect of the invention, the grip provides an electronic output for throttle control. A rotary encoder determines the angular position of the grip, and an electronic controller drives a motor or a servomechanism to pull and push on a throttle cable, which increases and decreases, respectively, the throttle of a boat engine. In other embodiments, the motor or servomechanism may be mechanically coupled directly to a throttle mechanism of the boat engine without the use of a cable. In still other embodiments, the motor or servomechanism itself may be eliminated by electronically coupling signals from the grip encoder (or other intervening circuitry) directly to electronic controls associated with the boat engine. 
     In yet another aspect of the invention, shifting the grip of the throttle control assembly in a fore-aft plane engages a transmission of a boat engine, for changing gears between forward, neutral and reverse. 
     One aspect of the invention concerns the engine-side rack-and-pinion itself alone or in combination with the throttle control assembly. Another aspect of the invention concerns a throttle control assembly that is adjustable by a user (in use or adjusted and then set to a position) relative to a fixed housing. The adjustment serves to optimize user comfort and/or available support. 
     Yet another aspect of the invention provides control features atop the throttle control assembly. These may be buttons, switches, etc. which may be positioned within reach of the user&#39;s thumb so that they may be actuated without changing grip on the throttle. These controls advantageously actuate right and/or left trim tabs and/or outboard motor or outdrive up/down adjustment. The throttle grip is advantageously shaped both to provide space for mounting the control features and for facilitating reach to actuate the controls. As such, the grip may have an ergonomic shape, with a surface for mounting the controls canted towards the thumb position for a user. 
     The invention also comprises methods, in which the methods may involve use of the subject devices. The methods may be practiced with other devices than those described herein. Yet, the acts associated with the use of such other devices will typically be in accordance with those associated with the devices described herein. 
     In any case, one method according to the present invention involves operating a boat in which the user grasping a steering wheel with one hand and the throttle control with the second hand, and substantially maintains a body position while effecting throttle control by supporting the body from forward and aft movement with the wheel and throttle control. The user is able to do so since throttle control merely requires twisting the grip. In comparison, where one or more levers are the means of throttle control, the back and forth movement of the levers alter body position. Further, it is not possible to support the body against forward and aft movement by grasping a throttle lever free to move in the same plane. The method may further comprise adjusting at least one of trim and motor up/down without releasing the throttle grip. 
     Another method according to the invention includes grasping a throttle control assembly with one hand and adjusting at least one of trim and motor up/down with that hand while grasping the throttle control. Typically, this will be accomplished using the thumb. The method advantageously further comprises grasping a steering wheel with the second hand while grasping the throttle control with the first hand. Most advantageously, the throttle is a grip-type twist throttle so that the user can maintain a stable position while operating the boat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: 
         FIG. 1A  is an oblique view of the type of boat with which the invention is advantageously used;  FIG. 1B  is a partial view of the stem of the boat;  FIG. 1C  is an aerial view of the helm of the boat, including a throttle controller according to aspects of one embodiment of the present invention; 
         FIG. 2A  shows an oblique overview of the throttle controller assembly;  FIG. 2B  details the interior of the throttle controller assembly in oblique cut-away view; 
         FIG. 3  illustrates an engine-side throttle control system; 
         FIG. 4A  shows an oblique overview of another embodiment of a throttle controller assembly according to aspects of the present invention;  FIG. 4B  details the interior of the throttle controller assembly in a front end cut-away view;  FIG. 4C  details the interior of the throttle controller assembly in a side cut away view with rotating arm  176  in an aft position;  FIG. 4D  details the interior of the throttle controller assembly in a side cut away view with rotating arm  176  in a forward position; and 
         FIG. 5  shows an oblique overview of another embodiment of a throttle grip according to aspects of the present invention; 
         FIG. 6  shows an oblique overview of another embodiment of a throttle grip according to aspects of the present invention. 
         FIG. 7  shows another oblique overview of the embodiment of the throttle grip illustrated in  FIG. 6 . 
         FIG. 8  shows another oblique overview of the embodiment of the throttle grip illustrated in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain specific details are set forth in the following description and figures to provide an understanding of various embodiments of the invention. Certain well-known details, associated electronics and devices are not set forth in the following disclosure to avoid unnecessarily obscuring the various embodiments of the invention. Further, those of ordinary skill in the relevant art will understand that they can practice other embodiments of the invention without one or more of the details described below. Finally, while various processes are described with reference to steps and sequences in the following disclosure, the description is for providing a clear implementation of particular embodiments of the invention, and the steps and sequences of steps should not be taken as required to practice this invention. 
       FIG. 1A  shows a “scarab” type speedboat  2  banking or turning at high speed across the water  4 . As shown, it produces a substantial wake  6 . An operator or pilot  8  sits in a seat  10  located at the starboard side  12  of the watercraft. A co-pilot (not shown) would typically sit to the port side  14  of the vessel. The present invention is advantageously used in connection with such a watercraft. However, the invention may be put to good use with other types of boats. 
       FIG. 1B  provides a partial view of the stem  16  of boat  2  opposite bow  18 . Trim tabs  20 , exhaust pipes  22 , and outboard engine  24  components are shown.  FIG. 1C  shows the cockpit of boat  26  including chairs  10 , wheel  28 , gauges  30 , switch bank  32 , ignition  34  and a control system  40  according to the present invention 
     In use, the pilot or captain of the vessel will steer with the left hand and control engine direction and speed with the right hand using control system  40 . Since the controller grip  42  is fixed in a forward-aft direction (in contrast to) the gear selector  44 , the throttle control grip offers a stable interface for support. 
     Further details of the subject throttle controller are better appreciated in reference to  FIGS. 2A and 2B . The former figure shows a fully assembled view of control system  40 ; the later figure a cutaway view of the throttle control portion of the device 
     The gear selector arm  44  allows the user to select the direction in which to propel the boat by switching the transmission (not shown) between forward and reverse. Selector  44  and its associated box  46  are not unique, and may be constructed as known in the art. However, in combination with the throttle control mechanism of the present invention, a unique control system  40  is hereby provided. 
     As for those features particular to the inventive controller, a throttle control assembly or subassembly  48  comprises throttle grip or handle  42 . The handle is mounted upon a shaft  50 . Multiple position locations  52  may be selected from which to secure the handle to the shaft by mating pins  54  to best accommodate a variety of uses or preferred positions. The adjustment holes may be offset around the body of the shaft to allow for selecting a position for the grip rotated around the Z-axis shown. To provide clearance for one another, the adjustment locations may be provided in a sort of “spiral staircase” arrangement as shown, Alternatively, a smooth shaft may be provided against which one or more setscrews are locked to secure position at different “heights” along a Z-axis or different rotated “home” or “start” grip positions around the shaft. 
     Shaft  50  may be received within a bracket  56  and be supported by a bearing  58 . Shaft  50  may be flexible, include a flexible section (as described later in an alternative embodiment), or include a U-joint (universal joint)  60  between a proximal section “A” and a distal section “B”. In the present embodiment, an input bevel gear  62  driven by the handle meshes with an output bevel gear  64  to transform the motion about the grip axis (Z-axis) to motion useful for throttle control. Additional support bearings  58  may be provided for the distal section of the shaft. 
     Providing a flexible shaft, shaft section or a U-joint  60  as shown allows for the grip to be adjusted about an axis Y in a plane relative to the fixed body of the device. As noted, such an adjustment offers improvement for user comfort in use as well as the option of moving the grip out of the way for cockpit entry or exit. The degree of adjustability provided may range from about 30 to about 90 degrees. By way of a pin  65  captured within a way  66 , or by some other stop means, travel may be limited to a desired range. Detent features may also be provided to releasable secure or give a tactile indication of movement or progression between positions. 
     When a U-joint is employed for angular adjustment, the system may employ a housing  68  to support the bracket  56  through which shaft  50  is rotationally received. Housing  68  may be mounted to a base  70 . Regardless, pins or shoulder bolts  72  supported by housing may be used to provide an axis of rotation for the referenced angular adjustment of the grip relative to base  70  and/or plates  74  to which the base is affixed. 
     Adjustment of the grip assembly about an X-axis as shown is also contemplated. Housing  68  and/or base  70  may be adjusted to a desired position and locked down to one or more of the control body plate(s)  74 . In order to serve the desired support function, fixing the position about the X-axis by pins, set screws, etc. is important in order to avoid inadvertent movement or slippage of the grip  42  in the direction of movement when a user is bracing his/herself with it (possibly in combination with wheel  28 ). Likewise, rotation about axis X should not be so great as to result in turning axis Y far from horizontal. In other words, adjustment around the X-axis should be limited to about +/−15 degrees. 
     Regarding grip  42  configuration, three buttons are shown upon a canted head  76  of the handle. Button  78  operates the left trim tab, button  80  manipulates outdrive in and out, and button  82  operates the right trim tab. The grip body is shaped to mimic the natural curve of the human hand to provide better grip and allow reach to actuate the buttons with the thumb while maintaining a grip on the handle. Wiring is routed within hollows  84  of the grip or as otherwise convenient. 
     As for throttle assembly output, the system is set to pull a throttle cable  86  within a cable housing  88 . The cable housing may be attached to plate  74  by a clamp block  90 . In a variation of the invention, the end of cable  86  may be connected at a block  92  to a slide  94 . The cable may comprise a threaded end fitting or section  96 . A jam nut  98  may be provided to lock the threaded section within threading inside block  92 . 
     In the arrangement shown, slide  94  forms part of a rack and pinion assembly  100 . Rack gear teeth  102  mesh with pinion gear teeth  104 . The pinion gear itself  106  may comprise a section or sector of a full round gear. It may include lightening holes  108 . It may include holes or depressions  110  to interface with a spring loaded ball  112  to provide a detent means. The detent means provides tactile feedback providing a user with an indication of advancement across the range of throttle grip rotation. Alternatively, a damped or smooth frictional feel to grip rotation may be desired. Naturally, any type of action may be employed. 
     Regarding the action produced by grip rotation, reference to  FIG. 2B  illustrates how rotation of bevel gear  62  turns bevel gear  64 , that—in turn—rotates pinion  106  to translate rack/slider  94 , to push and pull throttle cable  86 . Alternatively, pinion  104  could be replaced by a cam or lever arm attached to the throttle cable. Other output options exist as well. In any case, at some stage, output from the second bevel gear drives cable pull. 
     Another noteworthy option concerns the manner in which the throttle control and/or gear selector assembly is installed in a boat. The control system  40  may simply be mounted to existing boat hardware or to custom brackets using mounting bosses  114 . Alternatively, an existing gear selector setup may be employed and only the throttle control section  48  of the system retrofitted to the existing setup. Still further, the system may be integrated into the original control design of a boat. In which case, significant variation to the configuration of at least the device housing is contemplated. Still further, any boat may be modified by supplying a custom combing or wall insert to better accommodate a stock throttle control system according to the present invention. Such a wall insert to the boat would allow a user to better recess the subject control housing or box. It is also contemplated that the control housing can be adapted to be mounted in a seat, bolster or on the floor of the boat. In these arrangements, the control housing can be located towards the center of the boat, or outboard of the driver as shown in  FIG. 1C . 
     Another aspect of the invention concerns the manner in which cable pull from the control side of systems is handled at the engine side. The cable can actuate the motor throttle in a conventional manner. However,  FIG. 3  shows an approach where a transfer mechanism  150  according to the present invention operates an engine throttle shaft  152 . Here, cable  86  is affixed to throttle rack  154 . As the rack is pulled by the throttle cable, rack teeth  156  engage throttle pinion gear teeth  158 , causing throttle pinion gear  160  to rotate. The throttle pinion gear is affixed to throttle shaft  152  by a setscrew, a splined connection or other conventional means. Throttle shaft  152  may be affixed to butterfly valve  162 . As the butterfly valve position is open, airflow to the engine is increased, resulting in increased combustion in the engine, and higher boat speed. An extension spring  164  may be provided in the system to bias cable pull and help return the rack and pinion to its previous configuration when the cable is “pushed” within the housing. The system in  FIG. 3  is especially advantageous for use with the system as illustrated in  FIGS. 2A and 2B  because it offers a 1:1 correspondence of user input to engine throttle action. 
     As indicated above, a flexible shaft may be utilized to transmit torsional movement about the Z-axis from throttle grip  42  to an engine throttle, while permitting shaft  50  to be adjusted about the X and Y axes shown in  FIGS. 2A and 2B . An example of such an alternative embodiment will now be described with reference to  FIGS. 4A-4D . 
     Referring first to  FIGS. 4A and 4B , an embodiment is shown that is similar to that of  FIGS. 2A and 2B . In the alternative embodiment of  FIGS. 4A and 4B , controller grip  42  is mounted on shaft  50  as previously described. Shaft  50  in turn is rotably mounted to shaft bracket  56  with bearing  58 , as shown in  FIG. 2B . One end of a flexible shaft  170  is attached to the lower end of shaft  50 , such as with one or more set screw  172  mounted in a flexible shaft coupling  174 . The other end of flexible shaft  170  is attached to rotating arm  176  at its pivot point. The distal end  178  of arm  176  is coupled to throttle cable  86 . 
     When grip  42  is rotated clockwise about the Z-axis, the rotary motion is transmitted from shaft  50  to arm  176  by flexible shaft  170 . This motion causes the distal end  178  of arm  176  to move in the fore plane, which pulls throttle cable  86  forward with respect to cable housing  88 . Conversely, when grip  42  is rotated counter-clockwise about the Z-axis, flexible shaft  170  rotates in the opposite direction. This motion causes the distal end  178  of arm  176  to move in the aft plane, pushing throttle cable  86  rearward with respect to cable housing  88 . The pulling and pushing on throttle cable  86  serves to increase and decrease, respectively, the throttle of the boat engine, such as described above in reference to  FIG. 3 . 
     In this exemplary embodiment, the lower end of flexible shaft  170  may be directly connected to arm  176  with a coupling similar to coupling  174  at the upper end. Alternatively, the lower end of flexible shaft  170  can be affixed within an opening of a transfer shaft  180 , as shown in  FIG. 4B , such as with one or more set screws. Shaft  180  may be rotably attached to plate  74 . Arm  176  can be attached to the opposite end of shaft  180 , such as with a pin  182 . 
     Referring now to  FIGS. 4C and 4D , the operation of rotating arm  176  and throttle cable  86  are more clearly shown. Cable housing  88  may be secured from longitudinal movement by pivot bracket  184 . In this example, clamp screw  186  adjustably secures cable housing  88  to pivot bracket  184 . Pivot bracket  184  in turn is pivotably secured to plate  74  with shoulder bolt  188 . With this arrangement, pivot bracket  184  and the end of cable housing  88  are allowed to pivot around shoulder bolt  88  as arm  176  is moved between the aft position shown in  FIG. 4C  and the fore position shown in  FIG. 4D . This alleviates throttle cable  86  from bending or binding in its housing  88  as the distal end  178  of arm  176  rotates through the bottom of its travel arc. 
     As with the embodiment depicted by  FIGS. 2A and 2B , the embodiment depicted by  FIGS. 4A-4D  allows the longitudinal Z-axis of grip  42  to be rotated about the X-axis (fore and aft) and about the Y-axis (pivoting up or down), as described above. In this embodiment, the orientation of the longitudinal Z-axis can also be locked in place after adjustments about the X and Y axes, as also described above. 
     As can be seen by comparing  FIGS. 4A and 4B  with  FIGS. 2A and 2B , the use of flexible shaft  170  and rotating arm  176  permits various components shown in  FIGS. 2A and 2B  to be eliminated, such as universal joint  60 , bevel gears  62  and  64 , shaft  50 B, bearings  58 , slide  94 , rack  102  and pinion gear  106 . These components are relatively complex, so their elimination can increase reliability of control system  40  and reduce its size and cost. In alternative embodiments, some or all of these components can be used in combination with a flexible shaft. For example, rotating arm  176  of  FIGS. 4A-4D  can be replaced with a pinion gear  106  as part of a rack and pinion assembly  100 , similar to that of  FIG. 2B , with the rack  102  mounted on a horizontal slide  94 . Alternatively, just the detent means of pinion gear  106  (i.e. holes or depressions  110  and a spring loaded ball  112 ) can be incorporated into arm  176  and plate  74 , or provided elsewhere, to provide tactile feedback to a user with an indication of advancement across the range of throttle grip rotation. 
     Referring to  FIG. 4B , a flexible shaft arrangement should be chosen so that the bend radius of flexible shaft  170  is not so small as to cause binding or excessive stress to flexible shaft  170  in any orientation of grip handle  42 . In some embodiments, the bend radius is about three or four inches. Flexible shaft  170  can be bare, as shown in  FIGS. 4A and 4B , or can be jacketed with a sleeve or housing. If a jacketed flexible shaft is employed, one or both ends may be secured to surrounding structures so that only the core of the flexible shaft rotates as grip  42  is twisted. A jacketed shaft can protect the shaft core from harsh marine environments. A jacketed shaft may also be able to traverse tighter spaces within the throttle control assembly  48 ′ without rubbing on adjacent parts. By securing one or more midpoints of a longer jacketed shaft, excessive “helixing” or side-to-side movement can be eliminated, thereby creating a more responsive throttle system. In some embodiments, the length of flexible shaft  170  is about six inches. An example of a suitable flexible shaft that can be used is part number FR187SMRAB00600 manufactured by S.S. White Technologies, Inc., Piscataway, N.J. (www.sswhite.net). 
     According to an aspect of yet another embodiment of the present invention, the rotational motion of flexible shaft  170  need not be converted into a linear push-pull motion at the throttle control assembly  48 ′. Rather, a flexible shaft may be run directly from throttle grip  42  to the boat engine or engine compartment. There the rotational motion may be converted into linear motion with a rotary arm similar to that shown in  FIGS. 4C and 4D , a rack and pinion assembly or other suitable mechanism. The rotational motion of grip  42  need not ever be converted into linear motion, but can instead be coupled directly or through reduction gearing to throttle shaft  152  to drive the rotational movement of a butterfly valve, such as shown in  FIG. 3 . Such an arrangement can reduce the cost and complexity of a throttle system. Additionally, it can provide direct control of the engine throttle without the backlash that can accumulate in other throttle systems, particularly after various components begin to wear. If a flexible shaft is run between grip  42  and the engine throttle, the flexible shaft should have high torsional rigidity to preserve responsiveness, and low friction for ease of operation. Biasing a long flexible shaft in one direction can also improve responsiveness. 
     According to an aspect of still another embodiment of the present invention, switches  78 ,  80  and  82  atop grip  42 ′ can be arranged in a fan-like manner, as best shown in  FIG. 5 . With such an arrangement, a user&#39;s thumb can more easily travel from one switch to another. In some embodiments, the angle formed between adjacent switches is between about 1 and 10 degrees. In other embodiments, the angle is between about 2 and 7.5 degrees. In still other embodiments, the angle is about 5 degrees. Two, three or four switches can be used atop grip  42 ′ in this embodiment of the invention. As indicated above, each switch or button may have a momentary forward position, a momentary rearward position and a neutral center position. 
     Rather than being flat, top surface  190  may be arcuate as shown in  FIG. 5  to more closely match the arcuate movement of a user&#39;s thumb. In some embodiments, the arc of surface  190  has a radius between about 1 and 36 inches. In other embodiments it is between about 2 and 12 inches, and in still other embodiments the radius is about 8 inches. Additionally, top surface  190  may be canted as shown with respect to the longitudinal Z-axis of the grip shaft  50 . In some embodiments, the centerline of surface  190  is canted between about 10 and 60 degrees. In other embodiments it is between about 20 and 40 degrees. In still other embodiments it is about 30 degrees. 
     Referring to  FIG. 6 , an embodiment of control system  40  is shown that is similar to that of  FIGS. 2A ,  2 B, and  4 A. Control system  40  includes shaft  50  which engages encoder shaft adapter  192  to be rotably mounted to encoder shaft  194  of rotary encoder  196 . The top portion of shaft  50  includes a grip  42  (not shown) which can be mounted to shaft  50  as described in detail above. Rotary encoder  196 , encoder shaft adapter  192 , and the lower portion of shaft  50  are enclosed by top  198 , encoder housing  200 , and encoder cap  202 , to protect the sensitive rotary and electronic components of the throttle control assembly from sun, wind, and water damage. Encoder housing  200  is pivotably mounted to pivot bracket  206 . Since rotary encoder  196  does not offer any resistance to the movement of shaft  50 , control system  40  may also include a friction mechanism on the shaft (not shown) to add tactile feedback to rotation of shaft  50 . A set screw can push against shaft  50  to provide resistance, for example. 
     Control system  40  further includes control body plate  274 , which can be mounted in a boat in either the vertical (as shown) or horizontal positions. Shift base  204  is disposed between pivot bracket  206  and shift arm  208 , and is mounted to control body plate  274 . When grip  42  and shaft  50  are rotated in the fore-aft plane (i.e. about the x-axis shown), pivot bracket  206  and shift arm  208  rotate together as shift base  204  remains fixedly mounted to control body plate  274 . Control system  40  also includes electronic controller  210  which is electronically coupled to rotary encoder  196 . Electronic controller  210  is enclosed in controller base  212  and controller top  214 , which are mounted to control body plate  274 . Control system  40  further includes solenoid  216 , lockout catch  218 , and solenoid switch  220 , which will be discussed in more detail below. Cover plate  230  is attached to control body plate  274  to encase control system  40  into a single unit. 
     When shaft  50  is rotated clockwise about the Z-axis, the rotary motion is transmitted from shaft  50  to rotary encoder  196 , which converts the angular position of shaft  50  to an electronic signal as known in the art. In some embodiments, the range of rotary motion is about 60 degrees. Rotary encoder  196  outputs this electronic signal to electronic controller  210 , which in turn provides an electronic output for throttle control to the boat engine. For example, electronic controller  210  can be configured to control an electric motor (not shown) which may be located on or adjacent to the boat engine. In one embodiment, both electronic controller  210  and the electric motor are situated in a single housing adjacent to the boat engine and separate from the rest of the control system. There, the rotational motion of the electric motor&#39;s shaft may drive a rotary throttle control on or adjacent to the engine. In some embodiments, rotational motion of the electric motor may be converted into linear motion with either a rotary arm similar to that shown in  FIGS. 4C and 4D , a rack and pinion assembly similar to that shown in  FIG. 2B , or another suitable mechanism. 
     For example, when the arm  176  and throttle cable  86  of  FIGS. 4C and 4D  are coupled to the shaft of an electric motor, the rotary motion of the shaft is transmitted to arm  176 . This causes the distal end  178  of arm  176  to move in the fore or aft plane, which pulls or pushes, respectively, throttle cable  86  with respect to cable housing  88 . As previously described, the pulling and pushing on throttle cable  86  serves to increase and decrease, respectively, the throttle of the boat engine. In some embodiments, a return spring is provided to close the engine throttle if there is a power loss or other malfunction in the controller. One embodiment may include a cruise control system (not shown) to maintain a desired engine throttle or speed. The cruise control system may be implemented electronically or by mechanically fixing the shaft in a desired position, for example. 
     An example of a suitable rotary encoder that can be used is part number RE30E-300-213-1 manufactured by Nidec Copal Electronics Corp. However, other types of rotary encoders can be utilized, such as an analog or digital rotary encoders or potentiometers. Also, an example of a suitable controller that can be used is part number EZHR17EN EZ Stepper Motor Controller/Driver manufactured by All Motion Inc., and an example of a suitable electric motor that can be used is part number 57BYGH801 stepper motor manufactured by Jameco Electronics. However, other embodiments can employ another type of electric motor or even a servomechanism or to convert the electronic output from electronic controller  210  into a mechanical means for controlling engine throttle. In yet another embodiment, electronic controller  210  can be electronically coupled to an engine control unit (ECU) to provide for fully electronic engine throttle control. 
     Further shown in  FIG. 6 , shaft  50  may be adjusted about a Y-axis in a plane relative to the fixed body of the device. As noted previously, such an adjustment offers improvement for user comfort and support in use as well as the option of moving the grip out of the way for cockpit entry or exit. The degree of adjustability provided may be approximately 30 to 90 degrees. 
     Another aspect of the invention concerns the manner in which the user selects the direction in which to propel the boat. As shown in  FIG. 7 , shaft  50 , encoder housing  200  (not shown), pivot bracket  206 , and shift arm  208  can be rotated about an X-axis to switch the transmission between forward, neutral and reverse. Rotating about the X-axis in the forward direction (counterclockwise in  FIG. 7 ) causes the protruding portion of shift arm  208  to rotate in the counterclockwise direction, which pulls transmission cable  224  upward with respect to transmission cable housing  226  and mechanically switches the transmission into forward gear. Conversely, rotating about the X-axis in the aft direction (clockwise) causes the protruding portion of shift arm  208  to rotate in the clockwise direction, which pushes transmission cable  224  in the opposite direction and mechanically switches the transmission into reverse gear. Rotation about axis X should not be so great as to result in turning axis Y far from horizontal, so rotation about the X-axis for gear selection should be limited to about +/−15 degrees as previously described. As can be seen in  FIGS. 6 and 7 , transmission cable housing  226  is mounted to control body plate  274  by shift link block  228 , which reduces strain on transmission cable  224  and transmission cable housing  226  by allowing them to pivot slightly as shift arm  208  rotates in the forward and aft directions. 
     Also shown in  FIGS. 7 and 8  are solenoid  216 , lockout arm  218 , and solenoid switch  220 . When shaft  50  is rotated about the X-axis to switch the transmission, as described above, lockout arm  218  aligns with slots  232 ,  234 , and  236  in shift arm  208  corresponding to the forward, neutral, and reverse gears, respectively. Solenoid switch  220  is coupled to shaft  50 , and detects when throttle is being actively applied to the boat engine as shaft  50  is rotated about the Z-axis, as described above. Solenoid  216  pulls on lockout arm  218  when active throttle is detected by solenoid switch  220 , causing lockout arm  218  to engage the appropriate slot in shift arm  208 . As long as throttle is being actively applied to the boat engine, the coupling of lockout arm  218  and shift arm  208  prevents a user from accidentally shifting gears while operating the boat. Thus, to shift gears, the user must return shaft  50  to zero throttle, at which point solenoid switch  220  detects that no throttle is being applied to the boat engine and causes solenoid  218  to push on lockout arm  218  and disengage from shift arm  208 . In an alternative embodiment, a transmission lockout switch (not shown) is situated on the grip. Thus, a user can disengage lockout arm  218  from shift arm  208  to switch the transmission by manipulating the lockout switch. Also shown in  FIG. 7  is startup switch  222 , which allows the engine to be started only when the transmission is in the neutral position. 
     Thus, various embodiments of the present invention, some of which were specifically described above, result in a significantly improved assembly for controlling the throttle and transmission of a boat with a twist grip interface. For example, adjustment of the throttle control assembly along the X and Y axes provides a user a stable throttle control grip to hold onto in order to help maintain body position while piloting a boat at high speeds. Additionally, various embodiments of the present invention have increased versatility for installation in boats by using a simplified design that can be mounted in small places and easily be coupled to the boat&#39;s engine and transmission. Furthermore, some embodiments of the present invention allow a user to advantageously control both engine throttle and transmission gear selection without taking a hand off the throttle control assembly grip. 
     As for additional details pertinent to the present invention, materials and manufacturing techniques may be employed as within the level of those with skill in the relevant art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts commonly or logically employed. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. Likewise, reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “and,” “said,” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The breadth of the present invention is not to be limited by the subject specification, but rather only by the plain meaning of the claim terms employed. 
     It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.