Abstract: A novel water craft, which may include a hull with a keel, having propulsion means extending below the water line. The propulsion means comprises a pair of flappers each adapted to oscillate through an arcuate path in a generally transverse direction with respect to the central longitudinal dimension of the watercraft. Means are operatively associated with the propulsion means for applying input force to the propulsion means. The flappers 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 arcuate path.

Abstract: A catamaran having two spaced apart elongated hulls joined by front and rear cross members holding the hulls in alignment, and having a trampoline extending between the cross members. Cables or wires are carried within enclosures forming side loops in the trampoline and running from the front to the rear of the trampoline between cross members. A plurality of restraining hooks are affixed to the sides of each of the hulls. The cables are detachably held by the hooks to maintain lateral tension in the trampoline.A rudder blade assembly at the rear end of each hull includes a tiller arm connected at its upper end to a tiller crossbar, the connection between the upper ends of the tillers and the ends of the crossbar being live flexible rubber elbows with a snap connect and disconnect between tiller crossbar and the upper ends of the tillers.Pre-formed cylinders are laterally molded into the sides of each of the hulls and positioned to snugly receive the front and rear cross members.