71394 ⎘
Propulsive elements directly acting on water of rotary type with rotation axis substantially in propulsive direction; Single or multiple threaded helicoidal screws, or the like, comprising foils extending over a substantial angle; Archimedean screws with helicoidal foils projecting from inside surfaces of rotating shrouds; Archimedean screws
Spiral drive mechanism, particularly for mechanical vehicles, land and marine machines
#2Marine propulsion unit having a rotating cylinder driving an impeller
#3Peripheral tunnels propeller with alternative balance
#4Open core continuous helical fin marine drive system