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. (Wikipedia) In the port of Emden (Germany) you can see the E-Ship 1 lying. It is a cargo ship with 12.968 gt, which in addition to diesel engines additionally has Flettner rotors. It was completed in 2010 at the Cassens shipyard in Emden. It is designed for the transport of wind turbines. The fuel savings through the Flettner rotors should be up to 25 percent.