Patent Publication Number: US-9889917-B1

Title: Curve and tilt passive cambering keel and steering fin mastless wingsail

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This continuation-in-part utility application claims the benefit of U.S. Provisional Application No. 62/158,647, filed on May 8, 2015; as well as U.S. Utility Application Ser. No. 15/149,037 filed May 6, 2016. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     N/A 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to sailing vessels, and more particularly to unique designs for flexible and resilient sailboat keels and steering control fins, a wingsail having no conventional mast, support members, hardware assemblies, as well as operation and control components. 
     2. Description of the Prior Art 
     Since their invention over thousands of years ago, sailboats have evolved in a multitude of fascinating ways. Many of the design advances made during that time were practical in nature, such as improving safety and simplifying operation, while others were made specifically to increase boat speed. Many different designs have also evolved for boat keels and steering mechanisms, in terms of both hardware components, functional operation and materials. 
     For example, U.S. Pat. No. 6,684,804 is entitled Rudder Construction, and discloses a rudder design having a blade attached to the hull with a thinned zone allowing a main rudder part to turn, as well as a flexible zone to create flexibility in a separate section of the rudder. 
     European Patent Application No. EP 2,213,569 A1 is entitled Dynamic Fin Comprising Coupled Fin Sections, and illustrates a fin having two parallel interfacing fin sections. One fin section is rotationally attached to the other, and the fin sections can provide a substantially cambered shape in certain positions. Coupling elements are also disclosed. 
     U.S. Pat. No. 3,670,685 is entitled Flexible rudder, and relates to a rudder consisting of a woven plastic water deflecting plate having a trapezoidal shape and supported with tension by a vertically slotted rod in the center plane of the vessels stern. A rudder stock and second slotted rod supporting the back of the woven plate are included. 
     U.S. Pat. No. 594,068 is entitled Rudder, which describes a rudder made of flexible material secured to the boat at its forward end, and an arm pivoted to the rear end of the rudder and extending forward. The arm is also secured to a pivoted cross-bar, and the rudder can be operated by hand. 
     However, none of the above-referenced patents or the prior art address the designs, components and/or operation of the instant flexible steering fin and passive cambering, tilting keel, which constitutes a substantial improvement over the art. Furthering previous concepts, the inventions described below provide simple, superior, and effective devices with enhanced performance, thereby creating a useful and beneficial advance in sailboat evolution. 
     In terms of wingsails, the art is generally devoid of a mastless wingsail having the structure and function of the instant inventions. 
     It is therefore an objective of the present invention to provide an improved flexible steering fin and passive cambering, tilting keel with custom designed components providing for superior hydrodynamic performance. 
     It is yet another objective of the present invention to provide an improved flexible steering fin and passive cambering, tilting keel which eliminates problems with prior designs and provides enhanced benefits for operation and control. 
     It is yet another objective of the present invention to provide an improved mastless wingsail which does not require a supporting mast or related conventional structure. 
     Finally, it is an objective of the present invention to provide to provide an improved flexible steering fin and passive cambering, tilting keel, as well as a mastless wingsail, both of which are cost effective and operationally efficient while incorporating the above mentioned objects and features. 
     SUMMARY OF THE INVENTION 
     Furthering previous sailboat concepts for keels and control fins, the instant inventions comprise a flexible steering fin and passive cambering keel having fundamental simplicity yet enhanced performance and superior operation in terms of design and components. The steering fin is a relatively short and elongated flexible blade with its leading edge fixed beneath the hull. A rod passing through the hull functions as a simple lever controlling the trailing edge of the blade, which provides both tilt and curvature for unique handling and ease of use. A separate flexible keel provides the function of tilting the keel as it is cambered, for greater lift. 
     A unique fundamental mastless wingsail is also disclosed having minimal components and simplicity of operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be better understood by reference to the drawings in which: 
         FIG. 1A  is a bottom plan view of an inventive sailboat incorporating the instant flexible steering fin and passive cambering keel. 
         FIG. 1B  is a side plan view of an inventive sailboat incorporating the instant flexible steering fin and passive cambering keel. 
         FIG. 1C  is a partial front plan view of the nesting hulls of the instant inventions. 
         FIG. 2A  is a rear transom view of the steering keel and lever actuator. 
         FIG. 2B  is a side view of the apparatus shown in  FIG. 2A . 
         FIG. 3A  is a rear transom view of the steering keel and bent rod actuator. 
         FIG. 3B  is a side view of the apparatus shown in  FIG. 3A . 
         FIG. 4A  is a side plan view of the inventive flexible tilt steering fin mounted within a hull. 
         FIG. 4B  is a bottom plan view, and end view thereof, of the apparatus shown in  FIG. 4A . 
         FIG. 4C  is a bottom plan view, and end view thereof, of the apparatus shown in  FIG. 4B  in a starboard biased configuration. 
         FIG. 4D  is a bottom plan view, and end view thereof, of the apparatus shown in  FIG. 4B  in a port biased configuration. 
         FIG. 4E  is a perspective view of the flexible steering blade of the instant invention. 
         FIG. 5A  is a side plan view of and alternative inventive flexible tilt steering fin mounted within a hull. 
         FIG. 5B  is a bottom plan view, and end view thereof, of the apparatus shown in  FIG. 5A . 
         FIG. 5C  is a bottom plan view, and end view thereof, of the apparatus shown in  FIG. 5B  in a starboard biased configuration. 
         FIG. 5D  is a bottom plan view, and end view thereof, of the apparatus shown in  FIG. 5B  in a port biased configuration. 
         FIG. 5E  is a bottom plan view of the apparatus shown in  FIG. 5B  illustrating the movement of the instant undulating steering blade. 
         FIG. 6A  is a side plan view of the inventive flexible curve and tilt passive cambering keel mounted within a hull. 
         FIG. 6B  is a bottom plan view, and end view thereof, of the apparatus shown in  FIG. 6A . 
         FIG. 6C  is a bottom plan view, and end view thereof, of the apparatus shown in  FIG. 6B  in a starboard biased configuration. 
         FIG. 6D  is a bottom plan view, and end view thereof, of the apparatus shown in  FIG. 6B  in a port biased configuration. 
         FIG. 6E  is a perspective view of the inventive keel in a tilted and curved configuration resulting from encountering hydrodynamic forces. 
         FIG. 7A  is a side plan view of the mastless wingsail of the instant inventions. 
         FIG. 7B  is an end plan view of the apparatus shown in  FIG. 7A . 
         FIG. 7C  is a top plan view of the apparatus shown in  FIG. 7A . 
         FIG. 8A  is a top plan view of the inventive mastless wingsail and a complementary mini sail. 
         FIG. 8B  is a side plan view of the apparatus shown in  FIG. 8A . 
         FIG. 9A  is a side plan view of the inventive mastless wingsail depicting the moon structure. 
         FIG. 9B  is a top plan view of that shown in  FIG. 9A . 
         FIG. 9C  is an end view of that shown in  FIG. 9A . 
         FIG. 10A  is a top plan view of an alternative embodiment for the flexible steering fin and passive cambering keel. 
         FIG. 10B  is a side plan view of the apparatus shown in  FIG. 10A . 
         FIG. 10C  is an alternative top plan view of the flexible steering fin and passive cambering keel shown in  FIG. 10A  under forces of water flow and turning actions. 
         FIG. 10D  is a side plan view of alternative embodiment for controlling the steering assembly of  FIG. 10A  through a pivoting bar mechanism. 
         FIG. 10E  is a top plan view of the apparatus shown in  FIG. 10D . 
         FIG. 10F  is an alternative plan view of the apparatus shown in  FIG. 10F  while manipulating the pivoting bar mechanism. 
         FIG. 11A  is a top plan view of an alternative embodiment for the flexible steering fin and passive cambering keel incorporating a rotational circular hull section, frame and cam mechanism. 
         FIG. 11B  is a side plan view of the apparatus shown in  FIG. 11A . 
         FIG. 11C  is an alternative view of the apparatus shown in  FIG. 11A  while manipulating the steering assembly. 
         FIG. 11D  is another alternative view of the apparatus shown in  FIG. 11A  while manipulating the steering assembly. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Curve and Tilt Flexible Steering Fin 
     The modern rudder designs considered to be highly efficient have long blades that extend deep in the water. That depth requirement often creates limitations of where a boat can sail due to shallow water, shoals sand bars, reefs and the like. Therefore, a short and efficient replacement for long blade rudders would be most valuable to sailors. Although the prior art includes numerous steering devices for shallow water, none are as simple and effective as the novel device disclosed and illustrated herein. 
     With reference to  FIGS. 1A and 1B , the steering fin  12  and passive keel  18  are shown as mounted within a sailboat hull  10 , the boat having a sail  11  and mast  9 . As will be further detailed hereinafter, the passive cambering keel includes a mounting member  20  and internal pivoting rod  22  which tilts the blade  18  as it bends as represented in motion lines  19 . As water pressure bends the middle inward, curving and tilting of the blade  18  creates maximum lift. Steering fin  12  is mounted beneath hull  10  with vertical mounting member  14  passing through the hull. 
     The steering fin  12  consists of a flexible blade with its leading end fixed beneath the hull  10 . The entire blade, including connection points can be a single molded plastic part. In a preferred embodiment, the blade is made of low density polyethylene, but other plastics, composites and even resilient metals can be used. Rod  16  passing through a hole in the hull functions as simple lever controlling the trailing edge of the fin  12 , producing both tilt and curvature as it is moved and pulled from the center to either side. Appropriate materials for the rod  16  include fiberglass, carbon fiber and bamboo. This unique combination of tilt and curvature does not exist in the prior art for boat steering devices. The fin when curved provides a high lift coefficient and the tilt improves the uniformity of pressure distribution across the surface of the blade. Furthermore, the diagonal trailing edge  11  also improves efficiency by reducing vortex drag. 
     The simple lever version  16  as depicted is most useful on low flat hulls, while a rotating shaft version, and vertical pivoting version are better suited to taller hulls. 
     The prior art of shallow water keels includes several designs that vary camber in response to side pressure from the flow of water. By adjusting camber automatically, those devices provide useful increases in lift. The instant invention improves over the art with the additional function of tilting the keel as it is cambered. Tilting this curved flexible keel improves flow pressure uniformity, thereby providing even greater lift for improved sailing efficiency. Without the tilt, the flow pressure would decrease with distance from the hull bottom. An additional advantage of this design is that it fits into a standard dagger board opening in the hull, so that either type of device may be used. 
     As control lever  16  pivots, as illustrated in motion lines  15 , it imparts both tilt and curvature to flexible steering fin/plate  12 , as illustrated in motion lines  13 . 
     With reference to  FIG. 1C , an embodiment of the hull stacking and car roof carrying features are shown. Hulls  26  are illustrated in a nested configuration secured to the roof  24  of a vehicle. The hull is typically made of polyethylene molded over EPS foam, providing high durability, light weight and low cost. The top surface of the hull is both concave and padded. The lateral curvature of that concave surface has a depth of about one inch (25 mm) over the width of forty inches (1 m). That curvature was selected to provide a wide stable contact area when mated to the top of most cars. The longitudinal concavity of the top surface also increases car top mounting stability. Slots  30  in the wing like undersides  27  of the hull provide a stable path for straps  28  that can secure the boat directly to the car roof or a rack. The hull wings also increase buoyancy along the sides of the hull to improve lateral stability in the water. The concave top, convex bottom and wing portions of the hull are also designed to mate securely, so multiple boats can be stacked together securely for storage and transport. 
     With reference to  FIG. 2A , a transom view of the steering keel and lever actuator are illustrated. The lever action of control arm  33  maximizes turning force by angling the flexible steering keel  37  to pressurize the flow between keel and hull  31 . Increased pressure allows the surface area to be smaller than a rudder blade, so the frictional drag will be lower for the equivalent turning force. Top plate  39  reduces vortex drag and pitching motion, while its angle can be made adjustable to control hull trim. Cross bar  32  is attached to the second hull, and control arm  33  is positioned within guide slot  34  to pivot point  36 . The pivot arc  38  follows the curvature of the hull. The pressurized water flow and resultant forces acting on keel  37  are illustrated with a port turn  40 , starboard turn  42 , and straight heading  44 . 
       FIG. 2B  is a side view of the structure and components illustrated in  FIG. 2A . As shown, there is a minimal gap  48  between the fixed keel  46  and the steering keel  37 , which can also include an anti-vortex curved tip  49 . 
     Unlike rudders, the curved keel  37  is inherently immune to turbulent drag and cavitation at high speed. Fewer parts save cost and weight. Eliminating appendages improves safety, reliability and ease of use. Lower drag increases speed. Kick up rudders will become unnecessary as high speed shallow water sailing will finally be possible. 
     With reference to  FIG. 3A , turning tiller/actuator rod  50  maximizes turning force by angling the flexible steering keel  58  to pressurize the flow between keel and hull  51 . Increased pressure allows the surface area to be smaller than a rudder blade, so the frictional drag will be lower for the equivalent turning force. Top plate  56  and curved end tip  57  reduce vortex drag and pitching motion, while the angle of the plate can be made adjustable to control hull trim. Unlike rudders, the curved keel  58  is inherently resistant to turbulent drag and cavitation at high speed. Fewer parts save cost and weight. Eliminating appendages improves safety, reliability and ease of use. Lower drag increases speed. As mentioned, deep draft rudders will become unnecessary for high performance and high speed shallow water sailing. 
     In this embodiment, the actuator rod is positioned within two pivot sockets  52 , and the actuator includes bent rod section  53 . The pivot arc  54  follows the curvature of hull  51 , and the pressurized flow forces acting on the flexible steering keel  58  and resulting curvature is illustrated for port turn  60 , starboard turn  62  and a straight heading  64 . 
       FIG. 3B  is a side view of the structure and components shown in  FIG. 3A . 
     Appropriate materials for the flexible steering keel include the popular hull materials, polyethylene and fiberglass, so it can be molded as an integral part of the hull. The standard material for the actuator rod is fiberglass and alternate materials include epoxy composites of carbon fiber or stainless steel. 
     With reference to  FIG. 4A , a side plan view of the inventive flexible curve and tilt steering fin  12  is shown mounted within a hull  10  with associated control rod/lever  16 , connection at angled end  11 , and mounting member  14  having a capped retaining end as an overhang which locks the blade into the hull, all the foregoing described and illustrated with respect to  FIGS. 1A and 1B .  FIG. 4B  depicts the steering fin components in straight heading configuration, and  FIGS. 4C and 4D  illustrate the undulating curved and tilt fin  12  in starboard and port steering maneuvers by control lever  16  and the resulting action of fin  12  with both tilt and curvature in three dimensions.  FIG. 4E  is a perspective view of steering fin  12  illustrating the simultaneous three dimensional curved and tilt configurations of the blade. 
       FIGS. 5A through 5E  depict an alternative embodiment of the undulating fin  66 , which provides enhanced and efficient thrust in undulation action similar to that of a fish tail. The thrust is produced as it moves from side to side. This embodiment of the steering fin  66  utilizes two resilient rods  68  and  70  to produce an undulating motion that creates forward thrust in addition to providing steering force. The leading edge of this fin is fastened to a resilient rod  68  that extends upward through an opening in the hull. The internal surfaces of the opening form an hourglass shape that provides the leading edge rod with a pivot point inside the hull. A second rod  70  passes through a pivot hole in the transom and is fastened to the trailing edge of the fin. The trailing edge rod is substantially longer than the leading edge rod. The two rods are joined above the hull. Moving the top ends of the rods from the center to either side causes the fin to undulate, because the spring action of the longer rod delays the lateral movement of the trailing edge. Continuous side-to-side movement of the rods produces an undulation pattern with the trailing edge following the lateral movements of the leading edge. This function can be described as biomimetic, because it mimics the thrust producing movement of fish tails.  FIGS. 5B through 5E  illustrate the undulating motion of the blade  66  when the actuator arm is moved from side-to-side. 
     Curve and Tilt Passive Cambering Keel 
     With reference to  FIG. 6A , a side plan view of the inventive flexible curve and tilt passive keel  18  is shown mounted within a hull  10  with associated mounting member  20  having a capped retaining end as an overhang which locks the keel into the hull, all the foregoing described and illustrated with respect to  FIGS. 1A and 1B .  FIG. 6B  depicts the keel components in straight heading configuration, and  FIGS. 6C and 6D  illustrate the undulating passive curved and tilt keel  18  in starboard and port maneuvers and the resulting action of keel  18  with both tilt and curvature.  FIG. 6E  is a perspective view of keel  18  illustrating the simultaneous curved and tilt configurations of the keel and pivot rod  22 . 
     Molded into the LDPE blade  18  is a bent stainless steel rod  22  that rotates inside a socket in the hull as the flow pressure curves the blade. The pivoting action tilts the blade to improve flow pressure uniformity thereby improving efficiency. 
     Mastless Wingsail 
     The inventive wingsail design presented herein is extremely simple, efficient and robust. Since it does not depend on a mast for support, it is ideally suited as a collapsible sail for small boats or as a tail for controlling the rotational movement of a wingsail. The use of tails to control the rotation of wingsails is documented in prior art. 
     The inventive mastless wingsail  72  is depicted as a propulsion device in  FIGS. 7A through 7C , and as wingsail tail  80  in  FIGS. 8A and 8B . This novel structure utilizes a tensioned rod to replace the previous methods of supporting and tensioning sails. The fundamental device consists of a cloth sail  74  and a resilient rod  75 . The semi-circular sailcloth surface has an internal sleeve  76  along the curved edge which accommodates rod  75 . The preferred rod materials are fiberglass and carbon fiber, but bamboo and hardwoods are viable alternatives. The wingsail surface is tensioned by the insertion of the rod into the sleeve. With the rod inserted and secured in place, a stable and efficient aerodynamic structure is formed. For propulsion, the wingsail may be mounted to a base  77  with a bearing or pivot that allows it to rotate freely. The rod may be secured along a curved path in the base or at several connection points with various combinations of rigid struts and tensioned cords. In the alternative function as a wingsail tail  80  as shown in  FIGS. 8A and 8B , the device is supported by a clamping bracket  81  at or near the mid-point of the internal rod. 
     With reference to  FIGS. 9A through 9C , an alternative embodiment of the instant invention replaces the straight rod of the fundamental device with a curved vertical mast  90  that is tensioned inward by the sailcloth surface  91 . The preferred cross-sectional profile of the mast is generally elliptical, but can also be round. In this embodiment, base  92  is integrated into the structure of the vertical wing. These parts may be made of aluminum, wood or composites. The base encompasses a robust rotational bearing system anchored to the hull. In this embodiment, the sailcloth surface  91  is raised and lowered by a rope running within the vertical wing structure. 
     The rotation of the wingsail is controlled by a rope or ropes fastened to the trailing edge. The wingsail rotates freely in response to the wind unless there is tension on the rotation rope. Left free to rotate, it continually turns in the direction of the wind while creating minimal thrust from drag. Thrust is created as aerodynamic lift when the operator uses the rotation rope to pull the wingsail toward the wind. Releasing the rotation rope stops the thrust immediately. This simple on-off function is extremely intuitive and risk free, providing greater safety than previous sailing systems. Moreover, the inherently low drag and high flexibility of the structure eliminates the danger of being overpowered by high winds. Folding the wingsail is also a simple operation, because sliding the rod out of the sleeve makes the wing collapse. The wingsail can also be raised by sliding the rod into the sleeve. 
     In addition to the novel safety advantages, this inventive wingsail is also substantially more efficient than conventional sails. The semi-circular shape creates the efficiency advantage of elliptical area distribution, which increases the lift to drag ratio by providing uniform pressure distribution without the need for specific contouring of the surface. 
     Unlike sails, these inventive wingsails can always be aligned to the wind for maximum thrust, even when sailing downwind. With conventional sailing rigs, the mast support wires prevent the sail from rotating toward the front of the boat and therefore limit downwind sailing to the inefficient regime of simply being pushed by the wind. To overcome that limitation, many sailboats raise additional sails when sailing downwind, while this invention provides comparable thrust from a single easily controlled wingsail. Furthermore, the increased lift to drag ratio of this design also minimizes the side pressure that causes sailboats to lean over. 
     Like other sailing rigs, the alignment of the wingsail to the wind is controlled by a rope or ropes connected to the trailing edge. Unlike most conventional sails, which are located completely behind their connection to the mast, the surface of this wingsail may be balanced by moving a portion of the surface forward of the pivot axis. This balancing effect can be used to cancel most of the turning force produced by wind, creating a ‘semi-balanced’ condition that greatly reduces the controlling force required to keep the wingsail optimally aligned with the wind. Therefore, the wingsail may be controlled by simply holding the rotation rope directly, providing a more tactile feeling of the wind pressure than when pulleys are used. Nonetheless, rotation control pulleys or other devices may be necessary or preferred depending upon the specific application and individual preferences. 
     Alternative Embodiments for Curve and Tilt Flexible Steering Fin and Passive Cambering Keel 
     With reference to  FIGS. 10A, 10B, and 10C  are top plan and side views of an alternative embodiment for the flexible steering fin assembly  96  and passive cambering keel  98 . The steering assembly utilizes a rotating pivot mechanism in place of the fixed pivots utilized in embodiments previously illustrated and described. The pivot consists of a section of plastic (or other material) pipe  100  that fits into an angled socket  102  located in the transom of the boat. The portion of the pipe that extends above the hull socket  102  contains two cross holes through which the two tensile rods  104  are inserted. The trailing ends of the rods extend substantially beyond the transom of the boat, supporting a flexible plastic blade  106 . The flexibility and multi-axis rotation inherent to this system make it extremely resistant to damage. Moreover, the spring action of the rods  104  functions as a transmission, smoothing the application of force and limiting the peak strain felt by the operator. 
     A handle  108  is fixed to the leading ends of the rods. Moving handle  108  from the center to either side steers the boat in the same manner as a conventional rudder. However, the longer length of this structure adds leverage that improves efficiency because it provides more turning force for a given blade size. Moving handle  108  from side to side produces thrust from the undulating motion of the flexible rods  104  and blade  106 . 
     Also illustrated are enhancements to the function of the passive keel  98 . A circular section  110  of the hull containing the daggerboard slot is provided with bearings  112  that permit the section to rotate freely within the greater hull. As the boat moves forward, any sideways drift will push against one side of the blade, causing the circular hull section  110  to rotate toward the opposite side of the boat. That rotation increases the blade angle automatically, adding efficiency to the inventive curve and tilt blade structure. In conventional sailing terminology, the automatic turning of this keel is described as self-tacking. 
       FIG. 10C  illustrates the flexible steering fin and passive cambering keel under hydrodynamic forces of water flow, as well as rotating and turning actions of rotational bearing assembly  110 ,  112 . 
       FIGS. 10D, 10E and 10F  depict an alternative embodiment for controlling the steering assembly of  FIG. 10A  through a pivoting bar mechanism  114 , which is pivotally attached to the vessel about center point  115 . Steering fin  106  is controlled by pivoting bar  114 , which can be controlled by foot movement of the vessel operator. Movement of bar  114  is communicated to rods  104  by a control line (or rope, etc.) that connects the ends of bar  114  to rods  104  as the line passes through a pulley  118  located on each side of the transom. The use of a foot bar provides additional thrust and range, while freeing the operator&#39;s hands for other tasks.  FIG. 10F  illustrates manipulating the pivoting bar  114  mechanism for steering rods  104  and blade  106 . 
       FIGS. 11A through 11D  depict an alternative embodiment for the flexible steering fin and passive cambering keel incorporating a rotational circular hull section  110 ,  112 , along with a frame  120  and cam  122  mechanisms. This assembly provides additional controls on the keel. The rotation of the circular hull section  110  is regulated by the interaction of the generally U shaped frame  120  and cam  122 , as the rotation of the circular hull section and keel is limited when the inner edges of the frame  120  make contact with the foot bar pivot and cam. This function may be utilized to set the optimal blade angle for maintaining straight line tracking under varying conditions. In addition to resisting the side force produced by sailing, this rotating keel also resists the side to side motion of the hull caused by the oscillation of the steering fin as it drives the boat forward.  FIGS. 11C and 11D  illustrate the steering and turning action of assemblies. 
     The stabilizing action of this rotating keel mimics the way fish use their body movements to resist the turning force of their tails when swimming in a straight line. To change from straight line swimming to turning, fish change their body position to augment the turning force of their tails. The instant invention utilizes a cam lobe  122  located on the central pivot  115  to switch between the two functions of resisting turns and augmenting turns. When used for propulsion, the foot bar  114  normally turns between 5 and 20 degrees and cam lobe  122  does not make contact with the frame. To turn the boat, the operator simply pushes the bar beyond 20 degrees, where cam  122  engages the frame to steer the keel. That function completes the natural swimming action of the system. 
     The above inventions have been described and illustrated with the reference structure, components and functions. Modifications and variations thereof will occur to those of ordinary skill in the art, and it is intended such modifications and variations will be within the scope of the inventive subject matter.