Introducing an effective new ship rudder type, Telescopic Rudder

Rudder is the most important controlling device in ship maneuvering. Usually, it is a passive equipment of a ship, which generates the control forces and moments by inflow velocity and loses its performance when the ship speed reduces. Many parameters are involved in rudder design such as rudder's shape, area and span. By increasing rudder span, the aspect ratio, rudder area and rudder forces are increased. In addition, research shows that the increasing of rudder aspect ratio is the best option to receive highest performance of rudder than any other change of rudder parameters. Having known that the rudder dimensions limited by ship stern form, rudder span is limited to the ship overall geometry and the stem geometry. In this research, a new and innovative ship rudder type (Telescopic Rudder) is suggested that allows enlarging the rudder height hence increasing the rudder aspect ratio. This improves the controllability (maneuverability) of vessel by increasing the hydrodynamic coefficients of rudder. The telescopic rudder made by two pieces, which secondary part slides into the main part. A hydraulic system is used to facilitate sliding thus increasing the rudder height, increasing the aspect ratio and area of rudder producing larger forces. A computer code is also developed to investigate the hydrodynamic characteristics of telescopic rudder by boundary element method (3D-panel). The effectiveness of the new rudder type is studied by the said code in comparison with the conventional type.