Watercraft having low cavitation drive

Abstract

A watercraft comprises a hull which is bouyant in water, and a propulsion system coupled to the hull for for propelling the hull in the water. The propulsion system comprises a propulsion disc and at least one drive input coupled to the propulsion disc. The propulsion disc is rotatable by the drive input about an axis of rotation and comprises a cavitation-reducing ring and a plurality of paddles extending radially outwards from the cavitation-reducing ring, The cavitation-reducing ring is configured to reduce cavitation in the water during rotation of the propulsion disc.

1 . A watercraft comprising:
 a hull bouyant in water; and   a propulsion system coupled to the hull for propelling the hull in the water, the propulsion system comprising a propulsion disc and at least one drive input coupled to the propulsion disc, the propulsion disc being rotatable by the drive input about an axis of rotation and comprises a cavitation-reducing ring and a plurality of paddles extending radially outwards from the cavitation-reducing ring, the cavitation-reducing ring being configured to reduce cavitation in the water during rotation of the propulsion disc.   
     
     
         2 . The watercraft according to  claim 1 , wherein the paddles are substantially resilient. 
     
     
         3 . The watercraft according to  claim 1 , wherein the propulsion disc has a pair of opposing sides, and comprises at least one aperture disposed radially outwards from the axis of rotation and extending axially between the opposing sides, and the cavitation-reducing ring is disposed radially outwards from the at least one aperture. 
     
     
         4 . The watercraft according to  claim 3 , wherein the cavitation-reducing ring comprises a pair of cylindrical walls each extending axially outwards from a respective one of the opposing sides. 
     
     
         5 . The watercraft according to  claim 4 , wherein the drive input comprises comprises a pedal provided on a crankshaft, and the propulsion disc comprises a keyed centre configured for receiving the crankshaft therein, the keyed centre being concident with the axis of rotation. 
     
     
         6 . The watercraft according to  claim 4 , wherein the propulsion disc further comprises a support ring disposed around a circumference of the disc. 
     
     
         7 . The watercraft according to  claim 6 , wherein each said paddle includes an outer end and extends radially outwards from the cavitation-reducing ring and terminates at the respective outer end, and the support ring is coupled to the paddles at the outer ends thereof. 
     
     
         8 . A propulsion system for watercraft, the propulsion system comprising:
 a propulsion disc having a central axis and comprising a cavitation-reducing ring; and   a plurality of paddles extending radially outwards from the cavitation-reducing ring, the cavitation-reducing ring being configured to reduce cavitation in water during rotation of the propulsion disc about the central axis.   
     
     
         9 . The propulsion system according to  claim 8 , wherein the paddles are substantially resilient. 
     
     
         10 . The propulsion system according to  claim 8 , wherein the propulsion disc has a pair of opposing sides, and comprises at least one aperture disposed radially outwards from the central axis and extending axially between the opposing sides, and the cavitation-reducing ring is disposed radially outwards from the at least one aperture. 
     
     
         11 . The propulsion system according to  claim 10 , wherein the cavitation-reducing ring comprises a pair of cylindrical walls each extending axially outwards from a respective one of the opposing sides. 
     
     
         12 . The propulsion system according to  claim 11 , wherein the propulsion disc comprises a keyed centre configured for receiving a crankshaft therein, the keyed centre being concident with the central axis. 
     
     
         13 . The propulsion system according to  claim 11 , wherein the propulsion disc further comprises a support ring disposed around a circumference of the disc. 
     
     
         14 . The propulsion system according to  claim 13 , wherein each said paddle includes an outer end and extends radially outwards from the cavitation-reducing ring and terminates at the respective outer end, and the support ring is coupled to the paddles at the outer ends thereof.