Development of Flap Rudder Systems for Large Container Vessels

Abstract

Feedback from the large container ships operators repeatedly suggest that these vessel tends to have maneuvering problems where typical shipyard supplied full spade rudders are fitted. This problem especially evident during Suez Canal transits where shallow water effects are also likely to be present. Problems reported included extreme difficulty in checking vessel yaw if it start to drift off course. The fitting of a flap rudder of suitable area will improve the slow speed yaw checking ability of such vessel however the standard flap arrangement used may result in excessive flap loading for very large flap rudders. Main idea of the theses to develop the existing standard design to be more suitable for installation in these type ships. Investigate more optimal flap angle with respect to rudder angles. The existing flap actuation mechanism result in very aggressive flap angles at relatively low rudder angles. From previous CFD work it is known that this result in rudder stall starting at the flap trailing edge which spreads rapidly forwards as the rudder angle increases. More increase of flap angle as the rudder angle rotates would alleviate this situation. This work would be performed for varying operating conditions such as slow and cruise speed maneuvering. Initial calculation to be done in two dimesional CFD Solver, so would be relatively quick to implement. Final calculation would have to be made with 3D model and propeller present. The project aim to improve the performance of the standard Becker flap rudder redesigning its flap angle and rudder angle combinations.