Abstract: A pedal-operated nautical propulsion device for small craft, such as a pneumatic raft. The device comprises a pedal crank system producing circular motion which is transmitted by a frame-supported mechanism to a holder carrying a paddle to cause the paddle to undergo translation in a vertical plane, whereby the paddle is plunged in the water to propel the craft and then raised thereabove. The mechanism which makes it possible for the paddle to extend well forward of the pedal crank system includes a bar coupled to the system to transmit the motion thereof, the end of the bar being hingedly connected to the end of the paddle holder. Further included are first and second interhinged connecting rods, the end of the first rod being hinged to the bar and the end of the second rod being hinged to the paddle holder to define a deformable quadrilateral structure.