| 摘要 |
PROBLEM TO BE SOLVED: To provide a jet propulsion boat which can keep a propulsion force for turning performed at the same time as the operation of closing a throttle by simple structure. SOLUTION: The jet propulsion boat 1 jets a jet water stream by using the torque of an engine 4 and to acquire the propulsion force from the jet water stream, and changes the jetting direction of the jet water stream to perform its turning. The jet propulsion boat 1 has an auxiliary intake valve 25 disposed to an intake pipe 21 to open and close an auxiliary intake passage 24 bypassing a throttle valve 23, and a control unit (ECU) 29. The ECU 29 controls the opening of the auxiliary intake valve 25 when a speed of an engine 4 is a predetermined threshold or higher to be larger than the opening of the auxiliary intake valve 25 in idle speed, controls the opening of the throttle valve 23 to be zero when the engine speed is threshold or higher, and controls to keep the opening of the present auxiliary intake valve 25 when a steering mechanism 12 is steered at a predetermined angle or larger. COPYRIGHT: (C)2007,JPO&INPIT
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