Abstract
The single-propeller/twin-rudder system composed of a single propeller and two high-lift rudders of fish-tail type (VecTwin system) has been installed on many vessels in Japan. With this system, a ship can be maneuvered at any mode including going astern, hovering, dead slow forwarding and turning by means of various rudder angle combinations, with the propeller revolution kept in the forward direction. To improve propulsive efficiency of the single-propeller/twin-rudder system, a pair of reaction fins is attached between two rudders where the propeller slipstream passes. Performance of the reaction fin system is discussed. The design practice to determine fin size and form is presented.
