Flettner vessels

A rotor ship is a type of ship designed to use the Magnus effect for propulsion. The ship is propelled, at least in part, by large vertical rotors, sometimes known as rotor sails. German engineer Anton Flettner was the first to build a ship which attempted to tap this force for propulsion, and the ships are sometimes known as Flettner ships.

The Magnus effect is a force acting on a spinning body in a moving airstream, which produces a force perpendicular to the direction of the airstream. This is used in backspin to increase range in ball sports, and also the bouncing bombs developed by Barnes Wallis. As described by Lloyd Bergeson (Naval Architect) who fitted a Rotor to the 42 Ft MV Tracker , Rotor ships take advantage of this same effect by spinning a large vertical cylinder, typically using an electric motor, and using the resulting force for propulsion. Due to the arrangement of forces, rotor ships are able to sail closer to the wind than conventional sails. Other advantages described by Bergeson are the ease of control from sheltered navigation stations and the lack of furling requirements in heavy weather.

The rotor ship should not be confused with the similar-looking turbosail. The turbosail also uses a solid vertical "sail", but uses airflow within the hollow interior to generate a force conventionally, instead of using the Magnus effect on the outside of the sail.

A rotor/Flettner ship is a type of ship designed to use the Magnus effect for propulsion. The Magnus effect is a force acting on a spinning body in a moving airstream, which acts largely perpendicularly to the direction of the airstream. Rotor ships typically use rotor sails — spinning bodies that are essentially vertical cylinders — powered by a motor to take create the effect when there is sufficient wind available. These types of propulsion cylinders are now commonly called Flettner rotors. Rotor ships have unique points of sail.

The German engineer Anton Flettner was the first to build a ship which attempted to use the Magnus effect for propulsion.

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