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.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS[0001]The following non-provisional application follows provisional application 60 / 894,782, filed Mar. 14, 2007, Attorney Docket No. 350932-0106, which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention relates to a marine apparatus. Specifically, the present invention relates to a towed personal watercraft apparatus.BACKGROUND OF THE INVENTION[0003]Standard rigid towed personal watercraft, designed for standing or kneeling, such as waters skis, water toboggans, ski boards, and wake boards, ride on the surface of the water, and as a result, are subjected to high drag forces and surface roughness. Towed personal watercraft drag forces can be reduced and surface roughness issues mitigated by reducing or eliminating contact with the water's surface. To this end, a variety of towed personal watercraft have been fitted with lift elements, commonly called hydrofoils, to allow the body of the t...

AI Technical Summary

Benefits of technology

[0007]The present invention fulfills needs present in the art by providing a towed personal watercraft apparatus where drag forces are reduced, surface roughness issues are mitigated, and pitch instabilities found in the present art are practically eliminated. To accomplish each of these objectives simultaneously, a torsion spring-mounted forward hydrofoil assembly, herein referred to as a canard assembly, in an embodiment of the present invention provides a restoring lift force and torque to counteract pitch deflections in the body of the towed personal watercraft.

[0013]Pitch stability is a critical design issue. Rigidly mounting one or more hydrofoils forward of the platform center of mass results in pitch instability. That is, pitching a front end of the platform up urges the hydrofoil to a greater angle of attack, increasing the forward lift, further increasing the pitch. Similarly, pitching down a front end of the platform urges the hydrofoil to a reduced angle of attack, reducing lift and increasing drag, further reducing pitch. Pitch attitude transients can be introduced by weight shifts of an operator or water turbulence.

[0017]Pitch transients in the platform of the towed personal watercraft do not rotate the canard assembly with respect to a fluid flow vector. Thus, the hydraulic force dampens canard assembly rotation for any appreciable towed velocity. A vertical velocity component associated with a pitch rate momentarily changes the rotatable hydrofoils effective angle of attack, providing a short lift force pulse that resists the pitch transient just before the rotatable hydrofoils is able to realign with the new fluid flow vector. When the vertical velocity component is removed, the torsion spring remains deflected by the angular difference in the pitch of the platform of the towed personal watercraft and the fluid flow vector. The torsion spring provides a restoring torque to counteract the pitch transient in the platform of the towed personal watercraft. As a result, the towed personal watercraft in the present invention can ride above the water's surface, reducing drag and the effects of surface roughness, without suffering the pitch instabilities of similar towed personal watercraft in the present art.

[0020]In some embodiments, each of the one or more hydrofoils comprises a lateral termination features. The lateral termination feature can be approximately cylindrical with a radius greater than approximately two times a distance between the vertical stabilizer side planes. The lateral termination feature reduces 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.

[0021]The one or more vertical stabilizers minimize a resistance to fluid flow and stabilizes the platform about a pitch axis substantially parallel to the platform major axis.

Problems solved by technology

Standard rigid towed personal watercraft, designed for standing or kneeling, such as waters skis, water toboggans, ski boards, and wake boards, ride on the surface of the water, and as a result, are subjected to high drag forces and surface roughness.

Computer controlled towed personal watercraft are obviously not a practical option for towed personal watercraft.

Typically, these watercraft require tremendous skill and balance.

None are stable; that is, none have a restoring force to counteract pitch deflections in the body of the towed personal watercraft.

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