A Voith Schneider propeller is a very efficient boat propeller comprised of rotating hydrofoil-shaped blades that extend downward from a circular plate beneath a boat. The blades of the Voith Schneider propeller are able to be controlled by the captain of the boat to drive the boat both forward and in reverse as well as to the left and right without any delay or hesitation. So effective is the Voith Schneider propeller in propelling and directing the boat that vessels equipped with this type of propeller use no rudder to steer the boat. Boats commonly using this propeller are tug boats, fire boats and even some types of aircraft carriers among others worldwide.
By changing the angle of the hydrofoil-shaped blades on the rotating plate, a Voith Schneider propeller is able to change the direction of the thrust created by the blades. This allows a vessel equipped with the Voith Schneider propeller to operate without the need for a rudder. Many vessels, such as ferries, that require extreme control rely on this type of propulsion system to maneuver in and away from docking positions. In a tug boat application, the maneuverability allowed by the propeller enables the tug captain to make minute adjustments on the direction of push or pull without hindering the movement of the vessel, maintaining a smooth flow of movement.
Commonly arranged in pairs, the Voith Schneider propeller commonly uses six vertical rotating blades per propeller to direct thrust in all directions as the captain deems necessary. The low acoustic output of the Voith Schneider propeller made it a favorite on World War II minesweeper boats used by both Germany and Japan. The German navy also fitted the Voith Schneider propeller in pairs to the bow of some aircraft carriers to aid in maneuverability while in harbor or while docking. More recently, the propulsion system is being used on offshore platforms as well as the various platform supply vessels, enabling the ships to be easily controlled as they unload their supplies in rough water.
The tremendous thrust capability of the Voith Schneider propeller allows one unit to maintain control of a boat in the event that one engine fails. One disadvantage of the propulsion system is that the hydrofoil-like blades protrude down from the bottom of the vessel. This can create problems if the ship enters shallow water and the blades encounter the bottom, rocks or other underwater objects.