Abstract: A boat drive of the type in which a housing outside the hull of the board and below the water level receives a hollow propeller shaft driven by a drive shaft connected to the propeller shaft by a transmission. The hub of a variable pitch propeller is mounted on the propeller shaft and the axially extending stems which adjust the pitch on this hub are engaged by a push rod extending through the prop shaft and connected to a double acting cylinder at the opposite end from that at which the rod is connected to the stems.

Abstract: A variable-speed propeller in a ship drive has the hydraulic valves feeding the working chambers of the hydraulic drive for the variable-speed propeller formed as electromagnetic valves controlled by timing relays which can be switched by a rocker switch or push-button switches to adjust the propeller pitch by an angular increment controlled by the "on" time of the relays. The engine speed is detected and, when the engine speed exceeds the maximum speed of the engine, the relay associated with increased pitch is triggered to obtain an increment of engine-speed reduction, thereby preventing the system from inadvertently having the blade pitch reduced when the engine is at maximum speed.