Patent ID: 6851992

Claim:
A jet propulsion boat, comprising: a vessel body: a jet propulsion unit, said jet propulsion unit being provided at a rear portion of said vessel body; an engine, said jet propulsion unit being driven by the engine to emit a jet of water for propelling the boat; an engine cooling flow path, said engine being cooled by flowing a part of the jet of water in said engine-cooling flow path as cooling water, said engine-cooling flow path comprising: a flow regulating valve that opens a valve body thereof en a primary pressure exceeds a prescribed value; and, a constantly opened flow path provided in said engine-cooling flow path and having a constant cross sectional area from an upstream side to a downstream side of the flow regulating valve, wherein a cross sectional area of said engine-cooling flow path is varied by varying the opening of the valve body according to the primary pressure, wherein the constantly opened flow path is provided in parallel with the flow regulating valve, and said constantly opened flow path allows unobstructed flow therethrough from the upstream side to the downstream side of the flow regulating valve when the flow regulating valve is in an open position and a closed position.