Patent ID: 7635252

Claim:
A shock absorbing device for a watercraft propeller, comprising: an outer tube that is unitary with a blade of a propeller; an inner tube positioned in the outer tube and coupled with a propeller shaft; an intermediate tube positioned between the outer tube and the inner tube; a first damping device located between the intermediate tube and the outer tube; and second damping device located between the intermediate tube and the inner tube; wherein one of the first damping device and the second damping device includes: an elastic member having a spring constant with which elastic deformation of the elastic member begins at a moment that the propeller shaft initiates rotation thereof, the elastic member being interposed between one of the tubes and another one of the tubes, and an engaging device arranged to limit an angle range in which the one of the tubes and the another one of the tubes are rotatable relative to each other to a predetermined angle range, each of the one of the tubes and the another one of the tubes being rotatable; and the other of the first and the second damping devices includes a torque limiter having a circumferential surface that slips against frictional resistance when transmission torque exceeds a predetermined amount of torque.