US 6,439,940 B1Granted

Fin and watercraft system

OwnerAlexander Pouchkarevinventor

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Abstract

A fin and watercraft system includes at least one pair of fins mounted to the underside of a watercraft adjacent the side edges. The fins rotate freely from a position substantially parallel to the centerline of the watercraft through an arc of up to 90 degrees to alternate positions angled from the nearest side edge toward the centerline of the watercraft. The fins include a front portion extending from a leading edge to a vertical axis and a rear portion extending from the vertical axis to a trailing edge. The rear portion is larger than the front portion causing the fin to rotate in the direction of an oncoming water flow. The fins have symmetrical lateral surfaces and include a bearing plate mounted in a recess in the lower surface of the watercraft. A pin extends from a top surface of the fin engages an arcurate slot in the bearing plate to limit rotation of the fin. In a variant of the invention, a setscrew fitted to a threaded opening in the side edge of the watercraft is positioned to bear against the pin, varying the initial angle of the fin to the centerline of the watercraft. An opening fitted with a sealing plug penetrates the upper surface of the watercraft and permits a water stream to be introduced into the recess so that dirt and debris may be flushed from the bearing plates and out through a flexible seal at the lower surface of the watercraft surrounding the fin.

A fin and watercraft system, comprising:

a watercraft, said watercraft having a front end, a rear end, a midpoint between said front end and said rear end, a lower surface, an upper surface, first and second sides and a centerline between said first and second sides;
at least one pair of fins, said pair of fins comprising a first side fin and a second side fin, said pair of fins being disposed between the midpoint and the rear end, equidistant from said centerline and equidistant from said rear end;
said first side fin being disposed adjacent said first side and said second side fin being disposed adjacent said second side;
each of said first and second side fins having a top end, a bottom end, a leading edge, a trailing edge, a vertical axis, a horizontal axis extending from said leading edge to said trailing edge, a front portion extending from said leading edge to said vertical axis, a rear portion extending from said vertical axis to said trailing edge, and first and second lateral surfaces;
each of said first and second side fins being rotatably mounted about said vertical axis to the lower surface of the watercraft;
said first side fin being rotatable from a first position to a second position;
said second side fin being rotatable from a third position to a fourth position;
and
whereby, when the watercraft is forced to move parallel to its centerline, an oncoming flow of water beneath the watercraft will cause the first side fin and the second side fin to rotate to the first and third positions, respectively, and when the watercraft is forced to move in a direction from the centerline toward its first side the oncoming water flow will cause the first side fin to rotate to the second position and the second side fin to remain in the third position, and when the watercraft is forced to move in a direction from the centerline toward its second side the oncoming water flow will cause the second side fin to rotate to the fourth position and the first side fin to remain in the first position.

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Abstract

Claims18