Towed personal watercraft

Abstract

A towed personal watercraft apparatus includes a submergible unit and a platform. The submergible unit comprises at least two independent vertical stabilizers and one or more hydrofoil units mounted to at least one of the vertical stabilizers. One or more of the hydrofoil units is pivotally attached to the vertical stabilizers. Pivotal attachment can include a torsion spring or roller bearing to allow the hydrofoil units to pivot or rotate about the pitch axis of the platform, thereby improving stability of the towed personal watercraft. Rotation of the hydrofoil units can be limited for functional concerns and performance. For example, rotation of the hydrofoils about the pivot can be allowed in a first direction to prevent a nose dive, while being restricted in a second direction to facilitate a launch of the watercraft out of the water. The platform includes a user mount, such as foot holds or equivalents.

1 . A towed personal watercraft apparatus, comprising:
 (a) an elongated platform having a top surface, a bottom surface and a platform major axis, wherein the top surface and the bottom surface are substantially parallel, and the platform major axis lies in a plane substantially parallel to the platform top surface and the platform bottom surface, and substantially aligned with the largest platform dimension;   (b) one or more vertical stabilizers rigidly attached to the elongated platform at least one of the one or more vertical stabilizers having a set of two substantially parallel vertical stabilizer side planes, wherein:
 (i) the platform major axis lies approximately in each set of the two vertical stabilizer side planes associated with the one or more vertical stabilizers, and 
 (ii) each set of the two vertical stabilizer side planes associated with the one or more vertical stabilizers is substantially perpendicular to the platform top plane and the platform bottom plane; 
   (c) one or more hydrofoils pivotally attached to at one of the one or more vertical stabilizers; and   (d) one or more hydrofoils rigidly attached to at least one of the one or more vertical stabilizers.   
   
   
       2 . The apparatus of  claim 1 , further comprising one of a resilient member and a bearing providing for rotation of the first subset of the one or more hydrofoils about a pitch axis substantially perpendicular to each set of the two vertical stabilizer side planes associated with the one or more vertical stabilizers. 
   
   
       3 . The apparatus of  claim 1 , wherein the resilient member is selected from the group consisting of: a resilient material; a torsion spring, a coil spring, a leaf spring; and combinations thereof. 
   
   
       4 . The apparatus of  claim 2 , wherein the rotation of the first subset of the one or more hydrofoils is limited by one or more of an upper stop and a lower stop. 
   
   
       5 . The apparatus of  claim 4 , wherein the one or more of the upper stop and the lower stop are rigidly affixed to the one or more vertical stabilizers. 
   
   
       6 . The apparatus of  claim 4 , wherein the rotation of the first subset of the one or more hydrofoils is limited by an upper stop of the one more of the upper stop and lower stop such that an angle between the first subset of the one or more hydrofoils and the platform major axis is greater than approximately −5 degrees. 
   
   
       7 . The apparatus of  claim 4 , wherein the rotation of the first subset of the one or more hydrofoils is limited by a lower stop of the one or more of the upper stop and the lower stop such that the angle between the first subset of the one or more hydrofoils and the platform major axis is less than approximately +90 degrees. 
   
   
       8 . The apparatus of  claim 2 , wherein the provided for rotation of the first subset of the one or more hydrofoils approximately aligns the first subset of the one or more hydrofoils to a fluid flow vector in a reference frame centered at the pivot. 
   
   
       9 . The apparatus of  claim 2 , wherein the providing for rotation of the first subset of the one or more hydrofoils stabilizes the platform about the pitch axis. 
   
   
       10 . The apparatus of  claim 1 , wherein the one or more hydrofoils provide a lift force for the platform. 
   
   
       11 . The apparatus of  claim 10 , wherein the lift force is greater for a third subset of one or more aft hydrofoils than for a fourth subset of one or more forward hydrofoils. are rigidly attached to the one or more vertical stabilizers. 
   
   
       12 . The apparatus of  claim 2 , wherein each of the one or more hydrofoils comprises a pair of hydrofoils substantially symmetric about a plane parallel to the vertical stabilizer side planes. 
   
   
       13 . The apparatus of  claim 1 , wherein each of the one or more hydrofoils comprises a respective lateral termination feature. 
   
   
       14 . The apparatus of  claim 13 , wherein the lateral termination feature is approximately cylindrical with a radius greater than approximately two times a distance between the vertical stabilizer side planes. 
   
   
       15 . The apparatus of  claim 13 , wherein the lateral termination feature is configured to reduce a formation of air bubbles on or near the one or more hydrofoils and reduces a turbulence at or near the one or more hydrofoils. 
   
   
       16 . The apparatus of  claim 12 , wherein one or more of the pair of hydrofoils rotate independently about the pivot. 
   
   
       17 . The apparatus of  claim 1 , wherein the one or more vertical stabilizers minimize a resistance to fluid flow. 
   
   
       18 . The apparatus of  claim 1 , wherein the one or more vertical stabilizers stabilizes the platform about a pitch axis substantially parallel to the platform major axis. 
   
   
       19 . The apparatus of  claim 1 , wherein the platform further comprises an operator interface. 
   
   
       20 . The apparatus of  claim 19 , wherein the operator interface is selected from a group consisting of a foot hold, a toe hold, a hand hold, a seat, and combinations thereof.