| 摘要 |
A stern unit of marine craft that comprises a casing for housing a shaft, a propeller, and at least one rudder actuated by hydraulic pistons is described. The casing is open at the bottom, with its bottom surface having a parabolic shape in cross-section. The casing has an inlet section near to the hull that diverges rearwardly toward an outlet section. The casing provides a housing to the shaft, propeller, rudders, with a gap located above the trace line of the boat bottom where air is sucked above the water surface line such that an air film extends along the bottom surface of the casing towards the outlet section. The stem unit reduces frictional resistance and supplies additional thrust by providing cavitation between the propeller and the rudders.
|
