Abstract: A watercraft having propulsion means extending below the water line comprising a pair of flexible fins each adapted to oscillate through an arcuate path in a generally transverse direction across the central longitudinal dimension of the watercraft. As input force is applied, the fins twist to form an angle of attack for providing forward thrust while moving in both directions along the arcurate path. Each of the fine have a generally squared off top and preferably an outer area of harder rubber than the inner area. Each of the fins can be adjusted at the trailing edge to provide adjustable tensioning of the trailing edge.

Abstract: A remote powered propulsive device having a rudder which carries a propeller or oscillating fins which are powered by pedals alone or with hydraulic assist or by an electric motor.

Abstract: An air inflatable watercraft, having a cockpit with a bottom area forming part of the cockpit having a through opening therein adapted to receive a human operated propulsion mechanism which can be operated from the cockpit to propel the watercraft.

Abstract: A remote powered propulsive device having a rudder which carries a propeller or oscillating fins which are powered by pedals alone or with hydraulic assist or by an electric motor.

Abstract: A human propelled watercraft having a pair of flexible fins extending into the water each adapted to oscillate through an arcurate path in a generally transverse direction with respect to the central longitudinal dimension of said watercraft. Pedals are provided for applying input force whereby as input force is applied, the flexible fins can twist to form an angle of attack for providing forward thrust with respect to the longitudinal dimension of the watercraft while moving in both directions along the arcurate path. Each of the fins preferably have a generally squared off top and an outer area of harder rubber than the inner area. Preferably, each of the fins is provided with adjustable tensioning at the trailing edge.

Abstract: A watercraft having propulsion means extending below the water line comprising a pair of flexible fins each adapted to oscillate through an arcuate path in a generally transverse direction with respect to the central longitudinal dimension of said watercraft, and means operatively associated with said propulsion means for applying input force to said propulsion means whereby as input force is applied said flexible fins can twist to form an angle of attack for providing forward thrust with respect to the longitudinal dimension of the watercraft while moving in both directions along said arcuate path; the improvement wherein each of the fins preferably have a generally squared off top and an outer area of harder rubber than the inner area. Preferably, each of the fins is provided with means at the trailing edge to provide adjustable tensioning of the trailing edge, preferably by threaded means at the clew of the trailing edge.

Abstract: An air inflatable watercraft, preferably having a bow and stern, and having a cockpit, a bottom area forming part of said cockpit having a through opening therein adapted to receive a human operated propulsion mechanism which can be operated from the cockpit to propel the watercraft. An air inflatable watercraft having an inflatable, airtight bow and stern, and having a bottom area between two side inflatable, airtight compartments which run essentially the length of the watercraft, upon inflation the two side compartments at least partially extend above the bottom to provide a cockpit therebetween, and the inflated bow and stern form a configuration which is adapted to be efficiently propelled, viz., adapted to cut through the water. This embodiment can be hand rowed or provided with a pedaled propulsion mechanism provided a through opening is built into the bottom.

Abstract: A retraction system for rudders for small boats having a deck comprising a rudder means connecting said rudder to the rear of a boat enabling said rudder to pivot on an axis such that when the rudder is retracted, it rotates upwardly through about 270° from the normal operating position in the water while twisting about 90° so as to lay essentially flat on said deck.

Abstract: A retraction system for rudders for small boats having a deck comprising a rudder means connecting said rudder to the rear of a boat enabling said rudder to pivot on an axis such that when the rudder is retracted, it rotates upwardly through about 270° from the normal operating position in the water while twisting about 90° so as to lay essentially flat on said deck.