Abstract:
A control mechanism for a watercraft is described herein said control mechanism comprising a steerable propulsion source, a steering controller for controlling said steerable propulsion source, a lid member connected to said steerable propulsion source, and at least one tab connected to said linking member, said at least one tab moveable between an inoperative position and an operative position whereby said at least one tab can be angled such that, in the operative position and when said watercraft is traveling upright in water in a substantially forward direction, a volume of water impinges on a top surface of said at least one tab thereby creating a downward and rearward force on said watercraft.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention pertains to a watercraft control mechanism and, more particularly, to a watercraft control mechanism that provides enhanced, integrated step decelerating and trimming.  
         BACKGROUND OF THE INVENTION  
         [0002]    In recent years, the demands of racers and recreational users alike for greater performance and maneuverability have driven the designers of personal watercraft to reconsider the control mechanisms traditionally used for steering, decelerating and trimming. In general, steering decelerating and trimming can be achieved in a variety of manners, either independently of one another or synergistically.  
           [0003]    Essentially, the steering of a boat can be achieved by either turning the source of propulsion, such as an outboard motor or a jet-boat nozzle, or by actuating the boat&#39;s control surfaces. These control surfaces can be substantially vertical such as the common rudder on a stern drive or they can be substantially horizontal, such as flaps and tabs. Examples of steering mechanisms involving vertical fins or rudders are found in U.S. Pat. Nos. 4,615,290 and 4,632,049, issued to Hall et. al., and in U.S. Pat. No. 4,352,666, issued to McGowan. Examples of steering mechanisms involving horizontal tabs or flaps are found in Mardikan&#39;s U.S. Pat. No. 5,193,479.  
           [0004]    Decelerating can generally be accomplished in one of three ways: by either reversing thrust, by redirecting the thrust toward the bow of the watercraft or by creating drag by introducing a control surface substantially perpendicular to the watercraft&#39;s direction of travel. Decelerating by reversing trust is perhaps the most common technique, simply requiring the propellor to turn backwards. The main problem associated with this technique is that decelerating is slow due to the time lag required to stop and then to reverse the propellor.  
           [0005]    Redirecting the thrust toward the bow is a braking technique currently employed by numerous personal watercraft. Examples of thrust-reversing buckets or reverse gate have been disclosed by Kobayashi et al. in U.S. Pat. Nos. 5,062,815, 5,474,007, 5,607,332, 5,494,464 as well as by Nakase in U.S. Pat. No. 5,154,650. Although these thrust-reversing buckets direct the water jet backwards, they also have a propensity to direct the water jet downwards. This downward propulsion lifts the stern of the watercraft and causes the bow to dive. The sudden plunging of the bow not only makes the watercraft susceptible to flooding and instability but also makes it difficult for the rider to remain comfortably seated and firmly in control of the steering column.  
           [0006]    Mardikian discloses in U.S. Pat. No. 5,092,260 a brake and control mechanism for personal waters involving a hinged, retractable flap mounted on each side of the hull capable of being angled into the water to slow the boat. However, when the actuator is extended, the flap pivots such that the trailing edge is lower than the leading edge, thereby creating an undesirable elevating force at the stern.  
           [0007]    Trimming or stabilizing of a watercraft is normally achieved by adjusting the angle of the tabs mounted aft on the hull. Trim-tabs are used to alter the running attitude of the watercraft, to compensate for changes in weight distribution and to provide the hull with a larger surface for planing. Examples of trim-tab systems for watercraft are disclosed in Cluett&#39;s U.S. Pat. No. 4,854,259, Sasawaga&#39;s U.S. Pat. No. 4,961,396 and Schermerhorn&#39;s U.S. Pat. No. 4,323,027. Typically, these trim-tabs are actuated by electronic feedback control systems capable of sensing the boat&#39;s pitch and roll as well as wave conditions and then making appropriate adjustments to the trim-tabs to stabilize the boat. Examples of trim-tab control systems are found in Davis&#39; U.S. Pat. No. 5,263,432, Ontolchik&#39;s U.S. Pat. No. 4,749,926 Atsumi&#39;s U.S. Pat. No. 4,759,732 and Takeuchi&#39;s U.S. Pat. No. 4,909,766. The foregoing trim-tab mechanisms deflect the water downward and thus elevate the saw The stabilizing system for watercraft disclosed by O&#39;Donnell in U.S. Pat. No. 4,967,682 attempts to address this problem by introducing a twin-tab mechanism capable of deflect the flow of water under the hull either upwards or downwards to either elevate or lower the stern of the watercraft. O&#39;Donnell&#39;s twin-tab mechanism, however, is designed expressly for stabilizing a watercraft and not for braking.  
           [0008]    Steering, braking and trimming can also be performed synergistically. Mardikian&#39;s U.S. Pat. No. 5,193,478 discloses an adjustable brake and control flaps for steering, braking and trimming a watercraft. The flaps, located at the stern, in their fully declined position act as powerful brakes for the boat. Differential declination of the flaps results in trimming and steering of the boat. The laps provide steering, braking and trimming in a manner analogous to the flaps and ailerons of an aircraft. During braking, however, the downward sweep of the tabs causes the stern to rise and the bow of the personal watercraft to plunge, often creating the potential for flooding and instability. Not only is the plunging of the bow uncomfortable for the rider but the watercraft is more difficult to control during hard braking maneuvers.  
           [0009]    Finally, Korcak&#39;s U.S. Pat. No. 3,272,171 discloses a control and steering device for watercraft fib, a pair of vanes that can be pivotally opened below the hull of the watercraft to which they are mounted. The vanes are hinged at the ends closest to the stern and open toward the bow of the watercraft. As water is scooped by the opening vanes, the force of the water impinging on the vanes forces the vanes to open even more. In order to prevent the vanes is from being violently flung open against the underside of the watercraft, a ducting system has been incorporated into the vanes to channel scooped water through the rear of the vanes to cushion the hull from the impact of the rear of the vanes One of the shortcomings of this control mechanism, however, is that the scooping action of the vanes induces a great deal of turbulence on the underside of the watercraft especially when beam at high speeds. Secondly, the amount of that is channeled through the ducts of the vanes is minimal and thus braking might, in some conditions, be too harsh. Thirdly, the presence of the vanes (even when full retracted) and their associated attachment bases on the underside of the watercraft create drag at high speeds. Fourthly, the vanes are not integrated with a main steering mechanism (such as a rudder or steerable node) to provide better cornering. Fifthly, the vanes may scoop up seaweed, flotsam or other objects floating in the water that may prevent the vanes from closing or may clog the ducts in the vanes. Finally, to close the vanes when they are scooping water requires large gears whose weight causes the rear of the watercraft to sag.  
           [0010]    Thus, there is a need for an improved watercraft control mechanism capable of steering and/or decelerating and/or trimming a watercraft without causing the stern to elevate and the bow to plunge.  
         OBJECT AND STATEMENT OF THE INVENTION  
         [0011]    It is thus the object of the present invention to provide an apparatus or mechanism for steering and/or decelerating and/or trimming a watercraft without causing the stem of the watercraft to elevate and the bow to plunge, therefore optimizing stability, control and comfort.  
           [0012]    It is another object of the present invention to provide an apparatus to steer a watercraft when the throttle is cut and no steerable thrust is available.  
           [0013]    It is another object of the present invention to provide an apparatus for steering and/or trimming and/or decelerating a watercraft that can be stowed or retracted to minimize hydrodynamic drag at high speeds.  
           [0014]    It is another object of the preset invention to provide an apparatus for steering, trimming and decelerating a watercraft that does not become clogged or jammed by seaweed or flotsam or foreign objects floating in the water.  
           [0015]    It is another object of the present invention to provide an apparatus for decelerating a watercraft in a smooth and stable fashion when the waters is travelling at high speeds.  
           [0016]    As embodied and broadly described herein the invention provides a control mechanism for a watercraft, said mechanism comprising a steerable propulsion source, a steering controller for controlling said steerable propulsion source, a linking member connected to said steerable propulsion source and at least one tab connected to said linking member, said at least one tab moveable between an inoperative position and an operative position whereby said at least one tab can be angled such that, in the operative position and when said watercraft is traveling upright in water in a substantially forward direction, a volume of water impinges on a top surface of said at least one tab thereby creating a downward and rearward force on said watercraft.  
           [0017]    Such a control mechanism provides a very efficient way of steering and/or decelerating and/or trimming a watercraft and simultaneously acting to maintain or force the stern of the watercraft downwardly. The maneuverability and stability of the watercraft is thus enhanced. The watercraft is able to corner more sharply and to decelerate more rapidly than before. This arrangement also allows the watercraft to be steered when the throttle is cut. The tabs can also function as trimming devices for stabilizing the watercraft and/or for augmenting the planing sure of the hull of the watercraft.  
           [0018]    Advantageously, the tab is translationally displaceable between the inoperative position and the operative position.  
           [0019]    Such an arrangement is very cost-effective, simple and reliable.  
           [0020]    In an advantageous variant, the tab is pivotally displaceable between the inoperative position and the operative position.  
           [0021]    This arrangement provides a plurality of angular positions for improving steering and trimming capabilities.  
           [0022]    In another advantageous variant, the tab has a variable surface.  
           [0023]    This provides a single and efficient means for reducing the force acting on a tab at high speeds to enhance ride comfort to provide more controlled, stable decelerations.  
           [0024]    Advantageously, the variable su includes a section that is moveable with respect to said at least one tab to allow a volume of water to pass through said at least one tab.  
           [0025]    Such an arrangement avoids overpressure when the watercraft travels at high speeds. By alleviating the force of the water impinging on the tab, the stresses in the tab-actuating mechanism can thus be reduced. Tis means tat components of the tab-actuating mechanism can be made smaller and lighter than would otherwise be necessary to support the forces associated with a tab without such a moveable section.  
           [0026]    Advantageously, the at least one tab is hooked.  
           [0027]    This provides a cost-effective and easily manufactured tab that occupies little space and can be used to create a drag force on the watercraft.  
           [0028]    Advantageously, the watercraft further comprises a decelerating actuation mechanism for displacing at least one tab from the inoperative position to the operative position for creating a downward and rearward force on said watercraft.  
           [0029]    Such a tab is preferably centrally disposed. An arrangement pith a plurality of symmetrical tabs is also possible. The tab(s) in the operative position create(s) a drag force acting in a direction substantially opposite to the travelling direction of the boat when the latter is travelling in a substantially forward direction. The tab(s) will decelerate the boat if the drag force exerted by the tab(s) exceeds the propulsive force.  
           [0030]    As embodied and broadly described herein, the Invasion also provides a control mechanism for a watercraft, said mechanism comprising a decelerating anon mechanism and least one tab capable of being activated by said decelerating actuation mechanism, said at least one tab moveable between an mop inoperative position and an operative position whereby said at least one tab can be angled such that, in the operative position and when said watercraft is traveling in substantially in a s forward direction, a volume of water impinges on a top surface of said at least one tab thereby creating a downward and rearward force on said watercraft.  
           [0031]    Such a tab is preferably centrally disposed. An arrangement with a plurality of symmetrical tabs is also possible. The tab(s) in the optative position create(s) a drag force acting in a direction substantially opposite to the travelling direction of the boat when the latter is traveling in a substantially forward direction. The tab(s) will decelerate the boat if the drag force exerted by the tab(s) exceeds the propulsive force.  
           [0032]    As embodied and broadly described herein, the invention also provides a control mechanism for a watercraft, said mechanism comprising a steerable propulsion source, a steering controller for controlling said steerable propulsion source, a linking member connected to said steerable propulsion source, and at least one tab connected to said linking member, said tab moveable between an inoperative position and a plurality of operative positions whereby said at least one tab can be aged such that, in the operative positions and when said watercraft is travelling upright in water in a substantially forward direction, a volume of water impinges on a top surface of said at least one tab thereby crag a downward rearward force on said watercraft.  
           [0033]    With a plurality of operative positions, the user of such a watercraft control mechanism would be able to steer and/or decelerate and/or rim the watercraft to varying degrees thereby affording the driver a much greater degree of control.  
           [0034]    As embodied and broadly described herein, the invention also provides a control mechanism for a waters said mechanism comprising rising at least one tab provided with a variable surface.  
           [0035]    Such an arrangement avoids overpressure when the waters travels at high speeds. By alleviating the force of the water impinging on the tab, the stresses in the tab-actuating mechanism can thus be reduced. This means that components of the tab-actuating mechanism can be made smaller and lighter would otherwise be necessary to support the forces associated with a tab without such a moveable section.  
           [0036]    As embodied and broadly described herein, this invention also provides a control mechanism for a watercraft, said control mechanism comprising at least two tabs each having a leading edge, a trailing edge and a pivoting point, and an actuator pivotally connected to said at least two tabs, said actuator capable of pivoting said at lea two tabs about said pivoting point, said at least two tabs moveable between an inoperative position and an operative position whereby said at least two tabs can be angled such that, in the operative position and when said watercraft is traveling upright in water in a substantially forward direction, a volume of water impinges on a top surface of said at least two tabs thereby creating a downward and rearward force on said watercraft.  
           [0037]    Such an arrangement provides advantageous steering and/or decelerating and/or trimming effects. An actuator activates the tab. This actuator is advantageously connected to said tab at a point distant from the pivoting axis. This provides a better force ratio and an enhanced efficiency.  
           [0038]    Advantageously, each said tab can be actuated either asymmetrically, to produce an asymmetrical force for steering said watercraft, or symmetrically, to produce a symmetrical force in a direction substantially opposite to the direction of travel of said watercraft.  
           [0039]    The control mechanism preferably further comprises a steerable propulsion source linked to said actuators whereby turning of said steerable propulsion source actuates at least one of said tabs.  
           [0040]    The control mechanism preferably ether comprises resiliently-biased flaps, said flaps having resilient members such that at high speeds a momentum of water impinging on said flaps forces open said flaps when said momentum exceeds a force generated by said resilient member.  
           [0041]    As embodied and broadly described herein, the invention also provides a control mechanism kit for a watercraft, said kit comprising a linking member connectable to a steerable propulsion source and at least one tab connectable to said lining member, said at least one tab movable between an inoperative position and an operative position whereby said at least one tab can be angled such that, in the operative position and when said watercraft is traveling upright in water in a substantially forward direction, a volume of water impinges on a top surface of said at least one tab thereby creating a downward and reward force on said watercraft.  
           [0042]    Such a kit may be retrofitted on an existing watercraft. Linking members would be attached to a modified or existing steerable propulsion source. Tabs would be fitted under the hull or on the ride plate. Such a retrofit kit would be useful to any owner of a personal watercraft who wishes to improve the performance and control of his or her watercraft. Owners of personal watercraft may thus benefit from the present invention at low cost.  
           [0043]    As embodied and broadly described herein, the invention also provides a watercraft control mechanism comprising a steerable propulsion source, a starboard actuating linkage connected to said steerable propulsion source, a port actuating linkage connected to said steerable propulsion source, a starboard tab connected to said starboard acne linkage, a port tab connected to said port actuating linkage, a ride plate to which said starboard tab and says port tab are hingedly connected whereby turning of the steerable propulsion source to starboard causes said starboard tab to pivot below said ride plate thereby drag-steering to starboard and whereby turning of the steerable propulsion source to port causes said port tab to pivot below said ride plate thereby drag-steering to port, and a deceleration actuation linkage capable of causing said starboard tab and said port tab to pivot symmetrically below said ride plate thereby creating a force opposite a direction of travel of the watercraft.  
           [0044]    Other objects and features of the invention will become apparent by reference to the following description and drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0045]    A detailed description of the preferred embodiments of the present invention is provided hereinbelow with reference to the following drawings in which:  
         [0046]    [0046]FIG. 1 is a perspective view of a watercraft control mechanism;  
         [0047]    [0047]FIG. 2 is a perspective view of a varmint nozzle arm of the watercraft control mechanism of FIG. 1 wherein the nozzle arm is provided with a slot therein;  
         [0048]    [0048]FIG. 3 is a side elevational view of a watercraft control mechanism with a watercraft shown in stippled lines;  
         [0049]    [0049]FIG. 4 is a top plan view of a watercraft control mechanism with a watercraft shown in stippled lines;  
         [0050]    [0050]FIG. 5 is a side elevational view of a waters control mechanism illustrating the integration of a decelerator cable mechanism;  
         [0051]    [0051]FIG. 6 is a top plan view of the watercraft control mechanism of FIG. 5;  
         [0052]    [0052]FIG. 7 is a side elevational view of another embodiment of the watercraft control mechanism, illustrating the use of telescopic linkages in lieu of slots;  
         [0053]    [0053]FIG. 8 shows a typical tab disposed with three small ramps which ensure that the tab remains closed at high speeds;  
         [0054]    [0054]FIG. 9 shows a side elevational view of the tab of FIG. 8;  
         [0055]    [0055]FIG. 10 shows a side view of an alternative embodiment of a watercraft control mechanism having a pivot lock capable of keeping the tab closed at high speeds and which can only be unlocked by actuation of either the decelerator linkage or the steering linkage;  
         [0056]    [0056]FIG. 11 is a rear elevational view of another embodiment of the watercraft control mechanism in which the linkages coupling the tabs to the nozzle are substantially perpendicular to the thrust vector of the propulsion source;  
         [0057]    [0057]FIG. 12 is a top plan view of the embodiment of the watercraft control mechanism of FIG. 11;  
         [0058]    [0058]FIG. 13 is a top plan view of a variant of the embodiment of FIG. 12, wherein the transverse linkages are attached to the nozzle near the inlet of the nozzle,  
         [0059]    [0059]FIG. 14 is a perspective view of a tab for a watercraft control mechanism having a spring-loaded flap that is forced open at high flow velocity;  
         [0060]    [0060]FIG. 15 is a side elevational view of the tab of FIG. 14 shown in its neutral position flush with the ride plate;  
         [0061]    [0061]FIG. 16 is a side elevational view of the tab of FIG. 15 shown in its decelerating position with its leading edge declined into the flow and the spring-loaded flap open;  
         [0062]    [0062]FIG. 17 is a side elevational view of the tab of FIG. 15 shown in its trimming position with its trailing edge declined into the flow;  
         [0063]    [0063]FIG. 18 is a side elevational view of a trim-tab mounted flush-fitted underneath the hull at the stern of the watercraft;  
         [0064]    [0064]FIG. 19 is rear view illustrating the integration of the flush-fitted trim-tabs of FIG. 18 to the hull;  
         [0065]    [0065]FIG. 20 is a perspective view of a variant of the tab having a spring-loaded flap of FIG. 14;  
         [0066]    [0066]FIG. 21 is a side elevational view of the tab of FIG. 20;  
         [0067]    [0067]FIG. 22 is a perspective view of another variant of the tab of FIG. 14;  
         [0068]    [0068]FIG. 23 is a top plan view of the tab of FIG. 22;  
         [0069]    [0069]FIG. 24 is a cross-sectional view of the tab of FIG. 23 taken along line  23 — 23  in its open position;  
         [0070]    [0070]FIG. 25 is a cross-sectional view of the tab of FIG. 23 taken along, line  23 — 23  in its closed position;  
         [0071]    [0071]FIG. 26 is a side elevational view of a hooked tab capable of exerting a downward force on the stern of a watercraft when in contact with the water;  
         [0072]    [0072]FIG. 27 is a side elevation view of another embodiment of a pivoting watercraft control mechanism shown in its deployed configuration and in its retracted configuration;  
         [0073]    [0073]FIG. 28 is a side elevation view of another embodiment of a translational waters control mechanism shown in its deployed position and in its retracted position;  
         [0074]    [0074]FIG. 29 is a geometric analysis in a plan view shoving how the motion of the tabs is coupled to that of the nozzle when the point of fixation is offset on the nozzle;  
         [0075]    [0075]FIG. 30 is a side view of the geometric analysis of FIG. 29;  
         [0076]    [0076]FIG. 31 is a geometric analysis in a plan view showing how the motion of the tabs is coupled to that of the nozzle when the point of ion is offset on the tabs;  
         [0077]    [0077]FIG. 32 is a side view of the geometric analysis of FIG. 31;  
         [0078]    In the drawing the preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are only for purposes of illustration and to facilitate understanding, and are not intended to be a definition of the limits of the invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0079]    Referring to FIG. 1, a watercraft control mechanism  10  comprises a steerable nozzle  20  located at the stern of the watercraft. Attached to the steerable nozzle  20  is an L-shaped starboard nozzle arm  30   a  and an L-shaped port nose arm  30   b . A spherical rod-end bearing  40   a  connects the starboard nozzle arm  30   a  to a starboard rod  42   a  . Symmetrically, a spherical rod-end bearing  40   b  connected the port nozzle arm  30   b  to a port rod  42   b . The starboard rod  42   a  is connected to a reactive spherical rod-end bearing  44   a  while the port rod  42   b  is also connected to a reactive spherical rod-end bearing  44   b . The reactive spherical rod-end bearings  44   a  and  44   b  are fastened to a starboard slider  46   a  and to a port slider  46   b . The starboard slider  46   a  is constrained to translate within a starboard slot  48   a  which is machined from a starboard tab bracket  50   a . Similarly, the port slider  46   b  is constrained to translate&amp;ate within a port slot  49   b  which is machined from a port tab bracket  50   b . The starboard tab bracket  50   a  is attached to a starboard tab  52   a . The starboard tab  52   a  is disposed with a plurality of holes  56   a  and is connected to a ride plate  60  by a hinge  54   a . Similarly, the port tab bracket  50   b  is fixed to a port tab  52   b . The tabs  52   a  and  52   b  are disposed with a plurality of holes  56   a  and  56   b  to dissipate the pressure gradient that might arise at high speeds (due to the Bernoulli effect) between the top side of the tab and the underside. The port tab  52   b  is also connected to the ride plate  60  by a hinge  54   b . Springs  58   a  and  53   b  are connected to the top sides of the starboard tab bracket  50   a  and the port tab bracket  50   b , respectively. A push-pull steering cable  70  is fixed to the starboard nozzle arm  30   a  at a steering joint  72 .  
         [0080]    Alternatively, as shown in FIG. 2, the starboard nozzle arm  30   a  and the port nozzle arm  30   b  may have a slot  49 . The purpose of the slots is to create non-proportional actuation of the tabs  52   a  and  52   b . It should be apparent to one skilled in the art that the push-pull steering cable could have been equivalently mounted on the port nozzle arm or on a separate steering arm rigidly connected to the steerable nozzle  20 . Furthermore, it should also be apparent to one skilled in the art that two pull-only cables mounted to both the starboard nozzle arm  30   a  and the port nozzle arm  30   b  would achieve the same objective. Pneumatic or hydraulic actuators, solenoids or mechanical linkages could function in a manner equivalent to the push-pull cable illustrated in FIG. 1.  
         [0081]    To operate the watercraft control mechanism  10 , the driver simply actuates the push-pull steering cable  70  which causes the steerable nozzle  20  to turn. As the steerable nozzle  20  turns the starboard slider  46   a  and the port slider  46   b  translate in opposite directions within the starboard slot  48   a  and the port slot  48   b , respectively. To turn to starboard, for example, the push-pull steering cable  70  is pulled toward the bow, causing the steerable nozzle  20  to deflect towards starboard, creating a primary steering effect. As the steerable nozzle  20  turns to starboard, the starboard nozzle arm  30   a  exerts a force on the starboard rod  42   a  via the spherical rod-end bearing  40   a  which causes the reactive spherical rod-end bearing  44   a  and the starboard slider  46   a  to translate within the starboard slot  48   a . When the starboard slider  46   a  contacts the front-lower end of the starboard slot  48   a , the starboard slider  46   a  then exerts a force on the starboard tab bracket  50   a . The force exerted on the starboard tab bracket  50   a  causes the starboard tab  52   a  to pivot about the lie  54   a  and to decline below the plate  60 . The declination of the starboard tab  52   a  induces a drag on the starboard side which creates a secondary steering effect.  
         [0082]    The summation of the primary steering effect due to the turning of the steerable nozzle  20  and the secondary steering effect due to the tab drag produces steering superior to what could be attained with the nozzle alone. When the steerable nozzle  20  is returned towards its neutral, centered position, the starboard slider  46   a  stops exert a downward force on the starboard tab bracket  50   a  and the starboard tab  52   a , water pressure returns the starboard tab  52   a  to its neutral position with the help of the spring  58   a . A decelerator cable (not shown in FIG. 1) can be used to simultaneously actuate the tabs  52   a  and  52   b , creating a balanced drag force underneath the ride plate  60 .  
         [0083]    The techniques required for fabrication of the watercraft control mechanism  10  in accordance with the invention and as shown in FIG. 1 would be well-known to a man skilled in the art. Materials appropriate for the tabs and mechanical linkages would be aluminum, stainless steel titanium or any alloy that is non-corrosive in sea water. The steerable nozzle, due to its complex curvatures, would best be molded from a high-strength plastic fiber-reinforced polymer or equivalent.  
         [0084]    Referring to FIGS. 5 and 6, in a preferred embodiment, the watercraft control mechanism  10  further comprises stoppers  59  to limit the travel of the tabs  52 . Each tab bracket  50  further comprises a vertical extension  80  which houses a joint  82 . A decelerator linkage  84  links an L-Arm  88  via an upper joint  86  to the vertical extension  80  at a lower Joint  82 . The L-arm is fixed to the watercraft at a fixation  90 . A decelerator cable  94  is linked to the L-Arm  88  at a decelerator cable joint  92 . When the decelerator cable  94  is pulled, the L-Arm  88  pivots about the fixation  90 , causing the upper joint  86  to exert a downward force on the tab bracket  80  via the deflator linkage  84  and the lower joint  82 . The tab bracket  80  transfers the downward force to the tab  52  which then pivots about the hinge  54 . The tab  52  declines into the water until the tab bracket  50  collides with the stopper  59 . When the tension in the decelerator cable  94  is released, the spring  58  returns the tab  52  to its neutral position wherein the tab  52  is in contact with the stopper  59 .  
         [0085]    The angle of attack of the tabs is believed to be important in optimizing the sucking effect necessary to keep the stern of the watercraft well in the water during deceleration. For instance, while an angle of attack of 15 degrees may provide near-optimal down force at the stern, an increase of only ten degrees in the angle of attack of the tabs to 25 degrees could radically diminish the down force at the stem of the watercraft.  
         [0086]    A variant of the watercraft control mechanism  10 , illustrated in FIG. 10, comprises a steerable nozzle  20 , nozzle arms  30 , and spherical rod-end bearings  40 . Each spherical rod-end bearing is connected to one extremity of a telescopic link  41 , the other extremity of the telescopic link  41  being connected to a lower joint  82  fixed to a tab bracket  51 . Also connected to the tab bracket  51  at the lower joint  82  is telescopic decelerator linkage  85  which is connected to the L-arm  88  at the upper joint  86 . The L-Arm  88  is attached to the watercraft at the fixation  90 . The decelerator cable  94  is joined to the L-Arm  88  at the decelerator cable joint  92  When the decelerator cable  94  is pulled, the L-Arm  88  pivots about the fixation  90 , causing the telescopic decelerator or linkage to exerts a generally downward force of the tab bracket  51 . The downward force exerted on The tab bracket  51  causes the tab  52  to pivot downward about the hinge  54  until the tab bracket  51  collides with the stopper  59 . The declination of both tabs  52   a    52   b  decelerates the watercraft.  
         [0087]    When the steerable nozzle  20  is turned, the nozzle arm  30  exerts a force on the telescopic link  41  through the spherical rod-end bearing  40 . The force exerted on the telescopic link  41  causes the telescopic link  41  to compress until the telescopic link  41  runs out of travel at which point the telescopic link begins to transfer the force to the tab bracket  51  via the lower joint  82 . The force exerted on the tab bracket  51  causes the tab  52  to sweep downwards about the hinge  54  until the stopper  59  collides with the tab bracket  51 . Actuation of either starboard tab  52   a  or port tab  52   b  induces an offset drag force (i.e. offset with respect to the plane of symmetry of the watercraft) which creates a steering effect additional to that resulting from the steerable nozzle  20 .  
         [0088]    A variant of the tab  52 , illustrated in FIGS. 8 and 9, comprises three ramps  53  moused on the underside of the tab  52 . The three ramps  53  exert an upward force on the tab  52  at high speeds to ensure that the tab  52  remains flush and that no accidental or infected opening of the tabs occurs at high speeds.  
         [0089]    Another embodiment of the watered control mechanism  10 , illustrated in FIG. 7, comprises a pivot lock  55  and a lock stopper  57  to achieve the same objective as the tab  52  illustrated in FIGS. 8 and 9 but without augmenting the drag on the underside of the watercraft. The spring  58  exerts an upward force on the pivot lock  55 . During either deceleration or steering, the pivot lock  55  rotates about a pivot  55   a , urging an arm  55   b  of the pivot lock  55  to sweep upwards into contact with the lock stopper  57 . This causes a lower extension  55   c  of the pivot lock  55  to unlock the stopper  59 , thereby enabling the tab  52  to pivot freely about the hinge  54 . When deceleration or steer ceases, the spring  58 , which is under tension, urges the tab  52  back to its neutral position (i.e. flush with the ride plate  60 ). The spring  58  may also be assisted by reversing the load on the deceleration cable  94  or on the push-pull steering cable  70 . As the tab  52  reins to its position flush with the ride plate  60 , the lower extension contacts the stopper  59  and the lock stopper  57  contact the pivot lock  55  as shown in FIG. 10, thereby locking the tab  52  and preventing the tab  52  from opening accidentally.  
         [0090]    Referring to FIGS. 11 and 12, an alternative embodiment of a watercraft control mechanism  100  comprises a steerable nozzle  20 , a steering arm  75 , a steering joint  72  and a push-pull steering cable  70 . The steerable nozzle is connected to a pair of spherical rod-end bearings  102 . Each spherical rod-end beam is joined to a transverse damper  104  and a transverse linkage  106  each of which is angled substantially perpendicularly to the thrust vector  20   a  of the steerable nozzle  20 . Joints  108  link the transverse linkages to tabs  110  which, when actuated by the turning of the steerable nozzle  20 , swing into the water to create a drag-steering effect. Springs  112 , vertical dampers  1   14  and vertical linkages  116  connect the tabs  110  to a transom bar  118  mounted transversely along on the stern  120  of the waters.  
         [0091]    [0091]FIG. 13 illustrates a variant of the embodiment shown in FIGS. 11 and 12. In the variant of FIG. 13, the transverse linkages  106  are mounted to the steerable nozzle  20  near the nozzle&#39;s inlet while, in FIGS. 11 and 12, the transverse linkages  106  are mounted to the steerable nozzle  20  near the nozzle&#39;s outlet. When the verse linkages  106  are attached to the steerable  16  nozzle  20  near the nozzle inlet (as in FIGS. 11 and 12), a given angular displacement of the steerable nozzle  20  results in a small displacement of the tabs  110 . When the transverse linkages  106  are attached to the steerable nozzle  20  near the nozzle outlet, a given angular displacement of the steerable note  20  results in a comparatively larger displacement of the tabs  110 .  
         [0092]    Referring, to FIGS. 14, 15,  16  and  17 , a variant of a tab  152  comprises a control linkage  150  activated by the driver, a pivot  154  fixed to the watercraft and about which tab  152  is free to rotate, and a stopper  159 , also attached to the watercraft. The tab  152  further comprises a spring-loaded flap  198  and rotational springs  199 . When the control linkage  150  is actuated for deceleration, a downward force is exerted on the leading edge  152   a  of the tab  152 , causing the tab  152  to rotate about the pivot  154  until the rear of the tab collides with the stopper  159 . With the leading edge is inclined into the water, deceleration of the watercraft occurs. At high speeds, the momentum of the water colliding with the tab  152  can induce large tensile stresses in the control linkage and may also provide deceleration that is too severe. In order to alleviate the substantial drag of the tab  152  at high speeds, the tab  152  comprises a spring-loaded flap  198  which opens at high speeds as illustrated in FIGS. 14 and 16. The sprig-loaded flap  198  is pinned to the tab  152  and preferably restrained by two rotational springs s. When the momentum of the water colliding with the exposed portion of the tab  152  is decreased as the watercraft slows, the rotational spun  199  urge the spring-loaded flap back to its neutral position, flush with the bottom surface of the tab  152 . When the tab  152  is returned to its neutral position as shown in FIG. 15, the control linkage exerts on upward force on the tab  152  near the leading edge  152   a , thereby causing the tab  152  to rotate about the Divot  154  until the tab  152  reaches its neutral position. For trimming,, the control linkage  150  exerts an upward force on the tab  152  near the leading edge  152   a  thereby causing the tab  152  to rotate about the pivot  154  such that the trailing edge  152   b  declines into the water. To return the tab  152  to the neutral position of FIG. 15, a downward force is exerted on the tab  152  until it reaches the neutral position.  
         [0093]    [0093]FIGS. 18 and 19 illustrate another embodiment of a waters control mechanism  200  comprising a tab  252  flush-fitted with the hull of the watercraft. This is especially advantageous for personal waters which are of-ten beached or travel in very shallow water. The watercraft control mechanism  200  includes an actuation linkage  294  which is generally parallel to the tab  252  in its neuter (flush) position. The watercraft control mechanism further includes a vertical link  210  capable of exerting a generally vertical force on the tab  252  near its leading edge. The watercrafts control mechanism further includes an L-Arm  288  capable of pivoting about a point fixed to the watercraft hull and capable of converting the generally horizontal force exerted by the actuation linkage  294  to a generally vertical force onto the tab  252 . In addition, the watercraft control mechanism includes a stopper  259  to limit the declination of the tab  252 . In operation, generally horizontal forces exerted upon the L-arm  288  by the actuation line  294  cause either the leading edge or the trailing edge of the tab  252  to contact the water, thereby creating drag for steering, deceleration or trying.  
         [0094]    [0094]FIGS. 20 and 21 illustrate another embodiment of a tab  352  for use in a watercraft control mechanist as disclosed herein. The tab  352  is shown mounted integrally with the ride plate  60 . The tab  352  pivots about a hinge  354 . At high speeds, if the momentum of the water impinging on the exposed portion of the tab  352  exceeds the torque exerted by the rotational springs  199  on the spring-loaded flap  198 , then the spring-loaded flap  198  opens and alleviates the pressure ac, on the tab  352 , thereby attenuating the tensile stresses in the actuation linkage (not shown).  
         [0095]    [0095]FIGS. 22 and 23 illustrate tab  452  which is a variant of tab  352 . Tab  452  comprises a pair of stoppers  459  that limit the range of declination of the tab  452  as it pivots about the hinge  454 . FIGS. 24 and 25 show the tab  452  in its open configuration and in its closed configuration ion, respectively.  
         [0096]    [0096]FIG. 26 illustrates a hooked tab  552 , a variant of tab  52 , that rotates about a pivot  554 . Unlike the flat prior art tabs that sweep downward from the stern of the watercraft and cause the stern to lift, the hooked tab  552  catches the water and sucks the watercraft downward. The hooked tab  552  would be actuated by an actuation linkage similar to the actuation linkages shown in FIGS.  14 - 17 .  
         [0097]    [0097]FIG. 27 illustrates yet another embodiment of the 1818 watercraft control mechanism  600  comprising a first arm  610  and a second arm  620  which are generally parallel to one another. Arms  610  and  620  are pivotally mounted preferably to the stern of the watercraft and are also pivotally corrected to a transverse link  630 . A tab  652  is pivotally connected to one end of the transverse Link  630  near the leading edge  652   a  of the tab  652 . Linear or rotational actuators can be used to displace the arms  610  and  620  and then to vary the angle of attack of the tab  652 . In its stowed position (shown in stippled lines), the tab  652  is well above the waterline. When deployed, the arms  610  and  620  swing downward. The leading edge of the tab  652   a  can be inclined into the water (by an actuator not shown in FIG. 27) thereby creating a drag force to either steer or decelerate the watercraft.  
         [0098]    Alternatively, the trailing edge  652   b  of the tab  652  can be dipped into the water to trim the watercraft. One of the main advantages of the embodiment illustrated in FIG. 27 is its capacity to stow the tab and its associated mechanism safely above the bottom of the hull so that a watercraft featuring such a watercraft control mechanism could be beached or used in extremely shallow water without risk of damaging the exposed parts of the watercraft control mechanism.  
         [0099]    Illustrated in FIG. 28 is a watercraft control mechanism whose tab or tabs are fixed at an angle of inclination of approximately 15 degrees. Such a watercraft control mechanism could be used only for steering or decelerating, and not for trimming. The tab or tabs are translated from a retracted or stowed position (as shown in dotted lines) to an operative or submerged position (as shown in solid lines) by one or more linear actuators. Although FIG. 28 presents a simple vertically-oriented actuator, it should be known to those skilled in the art that there are many equivalent mechanisms that could be just as easily implemented for raising and lowering the tab or tabs. It should also be noted that the determination of the optimal angle of inclination of the tabs as well as a hydrodynamically optimal tab profile are merely matters of routine experimentation.  
         [0100]    [0100]FIGS. 29, 30,  31  and  32  illustrate how it is possible to achieve a non-proportional ion of the tabs  52 . FIGS. 29 and 30 show an actuating linkage fixed to a nozzle arm such that it is offset from the axis of rotation of the nozzle. FIGS. 31 and 32 show an actuating linkage fixed to a tab such that it is offset from the pivot axis of the tab. In FIGS. 29 and 30, an angular displacement of the port nozzle arm results in the actuator linkage traveling twice as far when the port nozzle arm is turned to port than when it is turned to starboard. In FIGS. 31 and 32, the actuating linkage fixed to the port nozzle arm travels equal distances but, due to the offset fixation of the actuating linkage on the tab, the angular displacement of the tab is twice as large in declination as it is in inclination.  
         [0101]    Each of the foregoing embodiments of the watercraft control mechanism preferentially employs two tabs (as illustrated in FIGS. 1, 3 and  19 ) in order to steer the watercraft. It should be obvious to one skilled in the art that in lieu of two tabs, the watercraft control mechanism could equivalently have four or six or any even number of tabs. Activating three smaller tabs on the starboard side, for instance, would therefore be essentially equivalent to activating, a single Large tab on the starboard side. Furthermore, the watercraft control mechanism could be equipped with an odd number of tabs with one central tab straddling the plane of symmetry of the boat so that the cent tab would perform strictly a decelerating role, contributing nothing to the steering Another possible variant of the embodiments presented above would be to employ but a single, central tab for deceleration purposes only.  
         [0102]    Another embodiment of the watercraft control mechanism not shown in the drawing would entail an electronic feedback control system capable of sensing the angle of the steerable nozzle, degree of decelerator cable actuation as well as watercraft speed, pitch, roll and wave conditions. Such an electronic control system would be able to activate solenoids or electric motors to make rapid and precise adjustments to the angle of the tabs in relation to the input parameters. Furthermore, in the foregoing description of preferred embodiments, it would be obvious to one skilled in the art that many of the mechanical components and sub-systems, chosen for their mechanical simplicity and reliability could be replaced by more complex albeit functionally equivalent component and subsystems involving solenoids or electric motors. Therefore, the above description of preferred embodiments should not be interpreted in a limiting manner since other variations, modifications and refinements are possible within the spirit and scope of the present invention The scope of the invention is defined in the appended claims and their equivalents.