Abstract:
This apparatus provides an automatic release of a resilient buoyant tether from a water-skimming board device. In use, a tether ( 100 ) is attached to a waterboard ( 50 ) at one end and secured to an anchor ( 30 ) at the other. By maneuvering the board, a rider ( 20 ) first stretches the tether and then releases the force stored in the stretched tether to propel the board ( 50 ) with rider over the water at high speed. As the board approaches the anchor point ( 30 ), the tether ( 100 ) automatically releases to reduce drag for an unencumbered ride. When used on a river, the described hook ( 140 ) and loop ( 120 ) apparatus is easily retrieved by the rider and reconnected to the board ( 50 ) in preparation for the next ride. Safety features ensure protection of the rider and of observers. The coupling mechanism may be built in to new water boards or retrofitted to others.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application claims benefit of U.S. Provisional Application No. 60/807,334, filed Jul. 13, 2006, entitled “Automatic Disconnect for Riverboard Propulsion System”, which is incorporated here by reference in its entirety. 
   This application is related to U.S. Pat. No. 7,025,644 filed May 24, 2004 and issued Apr. 11, 2006, titled “High-performance riverboard system,” which is commonly assigned, the entire contents of which are incorporated herein by reference. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   FIELD OF THE INVENTION 
   The present invention relates generally to a towing mechanism for a personal watercraft. More particularly, the described device provides a means for automatically releasing from a riverboard the cable of a propulsion system after its purpose has been achieved, and further enables quick reattachment of the cable to the riverboard. 
   BACKGROUND OF THE INVENTION 
   In U.S. Pat. No. 7,025,644 titled “High-performance riverboard system” inventors Geier and Veon described enhancements to what had previously been an informal sport, bringing it to levels of performance previously unachievable. In the targeted water sport system the user is enabled to maneuver a riverboard on the surface of flowing water. A special propulsion subsystem in the form of a resilient tether selected for its extreme elongation is used to secure the riverboard to an anchor. 
   To use the riverboard system, a rider moves the attached riverboard downstream from the anchor until all slack is removed from the tethering subsystem and then mounts the riverboard assuming a choice of standing, kneeling or prone positions. The weight of the rider keeps the riverboard in the water as the resistance of the riverboard against the water flow causes the tethering subsystem to become taut. As the rider shifts weight toward the rear of the riverboard, its front is uplifted, dropping its rear deeper into the water so as to present a greater drag that causes the elastic tether of the propulsion subsystem to stretch. When the rider then shifts weight by leaning forward, the drag of the riverboard against the water is reduced and the resilience of the propulsion subsystem attempts to restore the tether to its static, unstretched condition. This propels the riverboard toward the anchor. To assist a rider to remain in contact with the riverboard during a high-speed upstream ride, previous embodiments provided for a handle, similar to a ski tow rope, attached to a point in the front portion of the riverboard. Alternate embodiments of the riverboard allowed for various bindings to assist the rider to maintain a foothold. 
   With experience, riders of a high-performance riverboard system often choose not to use any form of handle or binding in order that they may be free to execute the freestyle maneuvers more commonly associated with surfing, snowboarding or skateboarding. To such experienced riders the attachment of the tether to their riverboard becomes an additional inconvenient and undesirable limitation. A first consideration is that as the riverboard approaches the upstream anchor point, that tether becomes slack and introduces some drag in the water that reduces performance resulting in a shortening of the duration of the ride. A second consideration is that the performance of the propulsion system is such that the rider and riverboard may be propelled upstream to a distance beyond the anchor that is greater than the length of the unstretched tether. For at least these two reasons, it would be advantageous for a rider to be able to disconnect the tether from the riverboard at that time during a particular ride when it is no longer desired for propulsion. Furthermore, it is preferred that the tether automatically disconnect itself from the riverboard after it has served its purpose. Additionally, a convenient method of reattachment is desirable, as are safety precautions associated with an unconnected tether that is lying at or just below the surface of the water. 
   These and various other novel features and advantages of the present invention will be readily understood by those skilled in the related arts with reference to the following detailed description taken in conjunction with the accompanying drawings. 
   BRIEF SUMMARY OF THE INVENTION 
   The disclosed invention is primarily intended as part of a water sport system as it relates to a device that enables automatic disconnection and easy reconnection of a riverboard to its tether line. In one configuration a loop is formed at the end of the tether where it may be connected to a hook on the underside of a riverboard. In an alternate configuration the tether terminates in a hook that may be captured into a tapered hole on the underside of a riverboard. In either situation the shape of the hook and/or hole is critical in order to achieve proper connect and disconnect operations. 
   The angle presented by the hook to its mating counterpart is such that the connection between them is maintained when the riverboard is in a nearly vertical, nose in the air, orientation. At the other extreme the hook is sufficiently open to facilitate disconnection of the coupling without rider intervention when the tether goes slack. For reconnection, the unconnected end of the tether floats and is easily discovered in the water. The mating portion of the connector accommodates reconnection by a rider who is operating blindly from the opposite surface of the riverboard while floating in the water. All hooks are appropriately recessed or shrouded so as to avoid injury to the rider and to observers. 
   The portion of the connector at the riverboard, whether it be a hook or a hole, may be built into the board at the time of its manufacture. If so, it will be located in a reinforced block in order to avoid pullout under the extreme loads presented by the stretched tether. Aftermarket retrofit of other riverboards is accommodated by a block that may be inserted into an owner-bored hole and installed with reinforcement plates to avoid tearout under load. Alternately, riverboards with sufficient structural integrity may be adapted to receive a special hook into an owner-drilled and tapered hole. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The particular features and advantages of the invention briefly described above as well as other objects will become apparent from the following description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  shows a rider on a riverboard that is connected at its underside by the present invention to a tether; 
       FIG. 2  shows the present invention with the riverboard in a near vertical orientation as the tether is being stretched against flowing water; 
       FIG. 3  shows the tether connected to the riverboard in the riding position; 
       FIG. 4  is a close-up of an embodiment of the present invention showing the components of the connector system; 
       FIG. 5  is an enlarged view detailing the preferred embodiment of a loop portion of the connection subsystem at the end of a tether; 
       FIG. 6  shows a top view of the preferred embodiment of a hook portion of the connection subsystem built into a riverboard; 
       FIG. 7  is a cross-section of the hook portion of the connection subsystem of the preferred embodiment; 
       FIG. 8  identifies in a bottom view the components of the hook portion of the connection subsystem of the preferred embodiment; 
       FIG. 9  is a cross-section of the hook of the preferred embodiment; 
       FIG. 10  depicts an alternate embodiment oriented similar to that of  FIG. 2 ; 
       FIG. 11  shows the alternate embodiment of  FIG. 10  in the riding orientation as that of  FIG. 3 ; 
       FIG. 12  is a side view of an alternate embodiment suitable for retrofitting in an aftermarket installation; and 
       FIG. 13  shows side views of an alternate embodiment having a hook at the end of the tether, where  FIG. 13A  shows the hooked end prior to engagement with a hole in the riverboard,  FIG. 13B  is a view with the riverboard in the vertical orientation to stretch the tether, and  FIG. 13C  shows the hook fully engaged in the hole in the riverboard as it would be during a ride. 
   

   The following Reference Numbers will be used in conjunction with the accompanying figures:
       20 . rider     30 . anchor     50 . riverboard     56 . nose of riverboard  50       100 . tether     120 . loop at end of tether  100       122 . wire loop     124 . connective device that is releasable, such as a carabiner     130 . handle     132 . connector end of handle  130       134 . tether end of handle  130       136 . outer surface of handle  130       140 . hook at underside of riverboard  50       142 . hook, alternate embodiment, formed into underside of riverboard  50       144 . hook, shaped steel     146 . slotted nut     148 . hook, alternate embodiment     150 . reinforcing block     152 . ramp     154 . rod     156 . recess in underside of riverboard  50       180 . hole, tapered   

   DETAILED DESCRIPTION OF THE INVENTION 
   Riders of a high-performance riverboard system such as that described in U.S. Pat. No. 7,025,644 are able to achieve greater performance with an automatically disconnectable propulsion system. Referring to  FIG. 1 , it will be seen that in the previously described riverboard system a resilient tether  100  capable of extreme elongation serves both to secure the riverboard  50  to an anchor  30  and to act as a special propulsion subsystem. After securing one end of the tether to an anchor point and the other end to the underside of the riverboard, a user  20  jumps into flowing water such as that of a river and drifts downstream until the slack is removed from the tether  100 . By shifting weight to the rear of the riverboard, the nose  56  or front of the board tilts upward toward a near vertical orientation (as shown in  FIG. 2 ) presenting greater drag against the water which causes the tether to stretch. After stretching the tether to a suitable elongation, the rider then shifts weight toward the front of the riverboard dropping the nose  56  of the board into a position that allows it to plane on the water. With the decreased resistance in this orientation the tether contracts propelling the riverboard and its rider upstream. 
   Up to this point in the ride cycle there is no reason that the riverboard should not be permanently connected to the tether. However, as the riverboard and rider progress upstream to the point where the tether returns to its unstretched length and then becomes slack, the tether, having served its purpose for propulsion, is no longer needed. As the riverboard ride progresses beyond this point an attached tether becomes a drag which decreases performance. Furthermore, an extended ride on such a high-performance system may easily send the board and rider some distance upstream of the anchor point in excess of the length of an unstretched tether. It is therefore an advantage to release the tether from the riverboard at some point prior to this so as not to degrade the performance of the system from its potential. Due to the considerable speed, 20 to 30 mph, that is achievable in the high-performance riverboard system, it is desirable not only for convenience but also for safety purposes that disconnection of the tether from the riverboard be automatic, requiring no user intervention. 
   In  FIG. 1  a rider  20  is depicted in a riding stance on a riverboard  50  with the present invention connecting a tether  100  to the underside of the riverboard  50 . The close-up view in  FIG. 2  shows the connection of a loop  120  at the end of the tether  100  to a hook  140  at the underside of the board  50 . In this figure the riverboard is in a near vertical orientation as if the rider was located at the rear in order to stretch the tether, charging the propulsion system against the flowing water. It is important that the hook has sufficient extent that the loop does not become disconnected when in this orientation. Each of the components of the connection system must have sufficient strength to hold up against the considerable forces encountered while stretching the tether. 
   After the tether  100  has been suitably stretched, the rider  20  shifts weight toward the front of the riverboard dropping it into a relatively horizontal orientation as shown in  FIG. 3 , with a close-up view in  FIG. 4 . In this orientation the riverboard planes upon the surface of the water during the upstream portion of the ride. This orientation places a few restrictions upon the connection. It must be located near the front of the board so as to avoid instability as the board is drawn over the water. The connection must also be sufficiently flexible in order to allow relatively unrestricted motion with regard to pitch, roll, and yaw. Since the connection point between the riverboard  50  and the tether  100  is near the nose  56  of the board, and the planing phase of the ride is relatively frictionless, the board will generally travel upstream toward the anchor point as long as there is tension in the tether  100 . An exception, of course, will occur for a rider who is executing extreme maneuvers, in which case there need be no guarantee that the connection will remain intact. 
   The connection between the tether  100  and the riverboard  50  that is provided by the present invention will automatically release as the attached riverboard  50  proceeds toward the anchor  30  beyond the point at which the tether  100  goes slack. With reduced load on the connection, the loop  120  easily falls away from the hook  140  as the riverboard  50  with attached hook  140  continues to fly upstream. If for some reason the loop  120  does not fall freely from the hook  140 , its release will be assisted by continued upstream travel of the riverboard  50  which will carry the hook  140  to such point that the loop  120  will be flipped by the drag of its tether  100  in the water pulling the loop  120  from the hook  140 . 
   With the riverboard  50  now disconnected from the tether  100 , the rider  20  is free to maneuver without impediment to the extremes allowed by speed and skill, even to the extent of executing flips if desired. Eventually all good things must end, the riverboard  50  and rider  20  will return to the water and drag will carry them both downstream. Generally, the rider  20  will lie prone on the riverboard  50  as it drifts downstream allowing it to be maneuvered by paddling with the arms and kicking the feet. In this final phase of the ride it is important that the connector at the end of the tether  100  be retrievable as the would-be rider  20  seeks to locate it and to reattach it to the hook  140  on the underside of the board  50 . Various safety features are incorporated into the present invention to assist the rider in this process while minimizing the dangers of entanglement in the tether and snagging on the connector system. 
   The components of the loop  120  in the preferred embodiment of the present invention are shown in  FIG. 5 . Here it can be seen how the wire loop  122  is preferably attached to the end of the tether  100 . The wire loop  122  is stainless steel so as to avoid corrosion and is preferably coated with a plastic sheath to reduce friction in its connection to the hook  140 . Wire sized at about 8-gauge (roughly ⅛-inch diameter) is used to provide a sufficient load-rating. To facilitate repair as well as manufacture, the wire loop  122  is connected to the end of the tether  100  by a connective device that is releasable, such as a carabiner  124 . A tubular handle  130  having a length of approximately 8 inches covers a portion of the stainless steel wire loop  122 , the connective device  124 , and a portion of the end of the tether  100 . Approximately a 2 inch length of the wire loop  122  protrudes from the connector end  132  of the handle  130  in a rigid mount, whereas the tether at the other end  134  of the handle  130  may be relatively flexible or stiffened. The outer surface  136  of the handle  130  is embossed or textured to provide a good handgrip especially when it is wet. The tubular handle  130  is constructed to provide flotation, whether by use of an air pocket, a plastic foam fill or other means, so that it will remain close to the surface of the water when drifting unattended. The tubular handle  130  is brightly colored (preferably yellow) so as to be easily visible to those in the water as well as to shoreline observers. 
   As the riverboard floats downstream, its rider finds the brightly colored handle floating near the surface of the water at the end of the tether and maneuvers into position to retrieve it. With a secure grip on the handle, the board and rider are prevented from drifting further downstream than what is allowed by a small stretch of the tether system. The rider is easily able to reach around the riverboard and to twist the rigid end of the handle to reconnect the wire loop to the hook at the underside of the riverboard. With the connection thus easily made, the board and its user are ready to begin the next ride. 
   The embodiment shown in  FIGS. 2-4  comprises a hook  140  mounted into the body of the riverboard  50  and a loop  120  constructed as an integral part of the tether  100  at the end of the propulsion system. The close-up views of  FIGS. 6-9  show the construction of the preferred embodiment of the hook  140  assembly. A block of rigid ABS plastic  150  is molded into the nose  56  of the riverboard  50  to provide support for the hook  140 . A recess  156  is cut into the underside of the riverboard  50  aft of the ABS reinforcing block  150  to facilitate the location of the hook  140  and connection to it of the loop  120  by a rider who will be operating blindly from the opposite side of the riverboard  50  when in the water. 
   The connective portion of the hook  140  is a straight stainless steel rod  154  that has had most of its length inserted into the reinforcing block  150 . The rod  154  has a diameter of about ¼″ and protrudes approximately ½″ out of the ABS block  150  into the recessed area  156  of the riverboard  50 . A ramp  152  is cut into the reinforcing block  150  near the protruding steel rod  154  to provide relief for the loop  120  when it is connected to the hook  140  when the riverboard  50  is oriented in the planing position. Not only does this ramp  152  eliminate some of the wear that would otherwise occur through use of the connector system, it also facilitates the automatic release of the loop  120  from the hook  140 . 
   One alternate embodiment of a hook  142  in the present invention is shown in  FIGS. 10-11 . This embodiment is adequate for waterboards that will not be subjected to the severe loads of a high performance riverboard system. Here the hook  142  is formed directly into the underside of the waterboard. This requires that the board have extra thickness to accommodate the necessary relief while leaving sufficient material to shape the tongue of the wider hook  142 . It is to be noted that this format presents considerably more friction than that of the preferred embodiment and will result in a slower automatic release. 
   Another alternate embodiment suitable for retrofit in the aftermarket to previously manufactured riverboards is shown in  FIG. 12 . Here, an appropriately shaped steel hook  144  is inserted through the board  50  and threadably captured to be held in place by a retainer  160  attached from the upper side of the board  50 . One possible combination of hardware for use in this configuration includes a slotted nut ( 146 ) serving as a suitable retainer for a spurred-flange hook ( 144 ), where the spurred flanges act to prevent rotation of the hook. This system accommodates installation with relatively few tools. In its simplest form a small diameter hole is drilled through the board  50  for insertion of the hook  144 . The threaded end of the hook  144  is pressed through the hole from the underside of the board  50  and the retainer  146  is threaded onto it at the top side of the board  50 . For a flush mount, the threaded retainer  146  may be inset into the upper side of the board  50  by boring a sufficiently larger diameter relief. Depending upon the board material and the loads that will be encountered, various other hardware may be used. Those skilled in the art will recognize that the hook itself may be shaped or various flanges and locking mechanisms other than those mentioned here may be included so as to avoid pullout, tilting or rotation of the hook  144  that could cause a premature disconnect from the loop  120 . 
   Yet another alternate embodiment, shown in  FIG. 13 , includes a tether  100  that terminates in a hook  148  to be captured into a tapered hole  180  on the underside of a riverboard  50 . In this case the shape of the hole  180  becomes critical in order to achieve a sufficiently strong connection over the range of angles needed to stretch the tether  100  and then plane along the surface of the water until the hook  148  disconnects. Depending upon the thickness of the board and the material from which is constructed, this embodiment will generally require reinforcement around the hole  180 . This is easily achieved by forming a properly shaped hole in a plug made of a metal or ABS plastic. The board  50  is then bored to receive the plug which will be held securely in place by some combination of adhesives, flanges, pins, reinforcement plates, etc. 
   The hook  148  itself cannot be very aggressive, being limited to angles in the range of 75 to 90°, in order that it not become too firmly attached to the hole  180  in the board  50 . The hole  180  must be shaped to allow rotation of the hook  148  through the various orientations of the riverboard  50 , and sufficiently large that the hook  148  will simply drop out when tension is relieved from the tether  100 . When the hook  148  in this embodiment is not connected to the riverboard  50 , it will be floating freely in the water at the end of the tether  100 . This requires that the hook  148  be suitably shrouded so as to avoid injury to the rider  20  and to observers; for instance the rider  20  must be able to locate the end of the freely floating tether  100  in the water, grasp it and properly orient it to fit into the hole  180  in the board  50 . A brightly colored handle  130  (not shown here but similar to that described above with a loop at the end of the tether) made of a material that will float keeps the hook  148  and tether  100  near the surface of the water. A handle shaped as a pistol grip, for instance, provides the user with sufficient tactile information to properly orient the hook  148  without actually being able to see it. A compressible foam sleeve between the handle  130  and the end of the hook  148  provides protection against inadvertently being snagged by the hook  148 . 
   The disclosed invention has been described for use with a high performance riverboard system for use on flowing water. It will be recognized that the same form of connective system can be used with devices other than riverboards to provide for automatic disconnects. Also, the techniques taught here may be applied to assist a user to make connections to other devices where visibility is limited. 
   The description here of alternate embodiments of an automatically disconnectable tether for a riverboard sport system is in no way intended to suggest that these are the only embodiments available. Now that the invention has been described, it will be apparent to those of ordinary skill in the many related arts that various combinations of the methods and configurations described here can be implemented in keeping with the intent of the disclosed invention and may have particular utility in other applications without departing from the spirit and scope of the invention as will be represented in the claims. Furthermore, the individual subsystems described for use in this particular form of water sport are not meant to limit in any manner the application of those subsystems to other fields of art.