| 摘要 |
PURPOSE:To enhance the propulsion efficiency of a propeller by a structure wherein fin stiffners are provided only in the locations, in which the fin stiffners do not intersect the water plane passing through a propeller shaft in order to reduce the resistance due to fin stiffner. CONSTITUTION:Rotating currents, the rotating direction of which is opposite to that of the currents caused by the blades of the propeller, are generated in order to enhance the propulsion efficiency of the propeller by providing fins 12a-12e in such a manner that the trailing edge of the fin located at the side, at which the blade of the propeller moves downward, is higher than the leading edge and the trailing edge of the fin located at the side, at which the blade of the propeller moves upward, is lower than the leading edge. The fin stiffners 15 are provided between the fins and a stern frame 11 and not provided between the fins or at the locations which the water plane passing through the propeller shaft 9 intersect. Owing to the structure as described above, the total resistance applied to the device is reduced, resulting in enhancing the propulsion efficiency of the propeller. |
