SPIRAL-BAR-SHAPED SCREW AND BOW RUDDER FOR USE IN HALF-SUBMERGED CATAMARAN

摘要

PURPOSE: To enhance the propulsion efficiency of a ship pusher and the steering function of a half-submerged catamaran whose hulls are very small in width. ;CONSTITUTION: A screw which comprises a rotating shaft in the form of a spiral bar with an irregularly machined surface, and right, left and lower hull barrel front portions are all provided with variable angle portions and are operated simultaneously with a conventional stern rudder. Because the rates of generation of turbulent flow caused by stirring and a backward jet are very low, energy losses resulting from them are reduced and deflection of fluid pressure on the surface of the screw is prevented structurally. In addition, a dimple effect is available from the irregular machining of the surface of the rotating shaft, suppressing the peeling phenomenon of fluids. Application of this bow rudder significantly enhances steering functions as in a steep turn during navigation at high speeds.;COPYRIGHT: (C)1994,JPO&Japio