| 摘要 |
PROBLEM TO BE SOLVED: To provide a jet propulsion planing boat capable of maintaining the cooling ability in an exhaust piping even if one of the cooling passages is blocked by a foreign material. SOLUTION: This jet propulsion planing boat is provided with an engine, an exhaust piping extended from the engine and having the double-pipe structure formed of the exhaust piping and a cooling passage at least at a part, and a water jet pump to be driven by the engine. A first cooling passage 9 is provided to supply cooling water to a double-pipe structure part of the exhaust piping Ep, and a bypass piping 2 is provided to supply the cooling water after cooling the engine E to the double-pipe structure part of the exhaust piping. With this structure, the cooling water can be supplied to the double-pipe structure part of the exhaust piping Ep from any of the first cooling passage 9 and the bypass passage 2.
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