Patent ID: 8684777

Claim:
A propulsion device for propelling a floating watercraft, said propulsion device being adapted for connection to an output drive shaft that transmits a rotary motion, the propulsion device comprising a flexible fluke that is pivotable about a horizontal axis, and a fluke oscillation drive including a gear reducer for gear reduction of the rotary motion transmitted by the output drive shaft, and a rotary-to-oscillator motion conversion mechanism for converting the rotary motion transmitted by the output drive shaft to oscillatory motion of the fluke; wherein the fluke oscillation drive comprises an impeller for propelling the watercraft in a substantially reverse direction with respect to a propulsion direction resulting from operation of the fluke; and wherein the fluke oscillation drive comprises a disengagement mechanism for disengaging the fluke from the output drive shaft; and an engagement mechanism for engaging the impeller with the output drive shaft for propelling the watercraft in a substantially reverse direction with respect to a propulsion direction resulting from operation of the fluke.