| 摘要 |
PROBLEM TO BE SOLVED: To improve drainage efficiency from a scoop drainage opening and reduce propulsion resistance of a hull by standingly providing a wall-shaped lip at the front edge and the rear edge of a scoop drainage opening, or in their periphery. SOLUTION: A scoop drainage opening 2 is formed on the surface of a hull1 such as the bottom or a side of a ship, substantially semi-cylindrical wall-shaped front edge lip 3 and rear edge lip 4 are respectively standingly provided at the front edge and the rear edge of the opening. When this drainage system has such front edge and rear edge lips 3, 4 or a lip formed by integrating them, water flow following propulsion of the hull, when passes through the front edge lip 3 and the rear edge lip 4, generates negative pressure regions respectively after the front edge lip 3 and before the rear edge lip 4. In other words, negative pressure regions are generated at two places between the front edge lip 3 and the rear edge lip 4, and negative pressure is provided in a wide region of the opening of the scoop drainage opening 2. Thus, since the negative pressure regions are generated at two places, lip height can be reduced.
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