Propeller

A rotating set of blades that produces thrust by accelerating water astern or ahead.

Marine propellers are mounted on a shaft, saildrive, stern drive, pod or outboard gearbox. Diameter, pitch, blade area, number of blades and rotation direction are matched to the vessel, engine, gearing and intended operating conditions.

Poor selection or damage can cause loss of performance, vibration, cavitation or engine overload. A turning propeller presents a severe hazard, so machinery must be isolated before anyone enters the water or works near it.