Abstract: A water jet propulsion watercraft that allows accurate speed detection of a speed detection unit to be achieved. A water jet propulsion watercraft includes a hull bottom plate with left and right guide grooves for guiding water rearwardly of the hull. The left and right guide grooves are disposed in a fore-and-aft direction at an area excluding at least a front portion of the hull bottom plate. Further, the hull bottom plate includes a flat surface formed at the front portion of the left and right guide grooves and on a surface facing the water. The flat surface is provided with an opening for guiding water to a speed detection unit.

Abstract: A drive shaft supporting structure for a small boat is provided which permits simplification of a hull and for which manufacturing productivity is increased. The drive shaft supporting structure includes a shaft-supporting member for rotatably supporting a drive shaft inside of a hull, and an elongate cylindrical sleeve. The cylindrical sleeve is arranged between the shaft-supporting member and a hull opening which permits penetration of the drive shaft through the hull. The drive shaft supporting structure is configured in such a manner that a front end portion of the cylindrical sleeve is connected to the shaft-supporting member and a rear end portion of the cylindrical sleeve is connected to the hull opening.

Abstract: A trim adjusting device for a surface boat is provided that includes a nozzle for projecting jet water rearward arranged rearwardly of a jet propeller arranged in a boat body; a nozzle drive mechanism connected to the nozzle for operating the nozzle upward or downward; and an operating means arranged on a handle being connected to the nozzle drive mechanism. The nozzle drive mechanism includes a lever member connected to a trim operation lever of the operating means, a cam member provided with an engaging portion that engages the lever member arranged so as to be capable of rotating freely, a reverse rotation preventing claw member that engages the engaging portion, a link member that comes into abutment with the cam member at one end thereof, and the nozzle connected to the other end of the link member.

Abstract: A propulsion unit for a boat has a cooling water intake structure through which entry of cooling water is obstructed when the boat is towed while the impeller is not turned, and through which sufficient cooling water enters when the impeller is turned. The propulsion unit includes an impeller, plural stationary blades provided on the downstream side of the impeller, and a cooling water intake structure. The intake structure is disposed between adjacent first and second stationary blades, on the side of the first stationary blade relative to a bisecting line between the two stationary blades. Hydraulic pressure on the side of the first stationary blade, relative to the bisecting line, is lowered by guide action of the impeller, and hydraulic pressure on the side of the second stationary blade relative to the bisecting line is raised, respectively, when the boat is towed while the impeller is stopped.

Abstract: Jet pump mounting structure of a small-sized boat including a front face of a thrust plate attached to a rear face of a front wall of a pump case, and a jet pump attached to a rear face of the thrust plate. The jet pump is arranged in the pump case. The front wall is formed at an up grade toward the rear of the hull, the front face of the thrust plate is formed at an up grade so that the front face is parallel to the front wall, and the rear face of the thrust plate is formed in parallel with a plane perpendicular to the axis of the jet pump.

Abstract: A water jet propulsion boat includes a pump chamber provided at a rear portion of a boat body of the boat. Further, a water jet pump is disposed in the pump chamber and a ride plate closes a bottom of the pump chamber. The ride plate includes a base fixable to the boat body. A setting plate detachably fixed to the base, and forms part of a bottom surface of the rear portion of the boat body.

Abstract: A trim operating wire is disclosed wherein the length of the pull wire connecting between the push-pull converter and the trim operating lever can be made short, and the push wire can be made long. As a result, even where the pull wire, which is thin and highly flexible, is disposed in the state of being bent at several portions thereof, the sliding resistance of an inner wire of the pull wire is small, and operability is enhanced.

Abstract: A water jet propulsion watercraft that allows accurate speed detection of a speed detection unit to be achieved. A water jet propulsion watercraft includes a hull bottom plate with left and right guide grooves for guiding water rearwardly of the hull. The left and right guide grooves are disposed in a fore-and-aft direction at an area excluding at least a front portion of the hull bottom plate. Further, the hull bottom plate includes a flat surface formed at the front portion of the left and right guide grooves and on a surface facing the water. The flat surface is provided with an opening for guiding water to a speed detection unit.

Abstract: A water jet pump is provided which reduces cavitation and thereby allows an improvement in pump efficiency. In a water jet pump in which an impeller driven for rotation and is provided in a cylindrical housing, an edge portion of the outer circumferential surface of the impeller that opposes the inner surface of the housing is formed with a radius of curvature. This structure reduces a variation in the pressure of a water stream passing between the outer circumferential surface of the impeller and the inner surface of the housing toward the impeller front surface side, thereby reducing the occurrence of cavitation and improving the pump efficiency.

Abstract: A water jet propulsion boat includes a pump chamber provided at a rear portion of a boat body of the boat. Further, a water jet pump is disposed in the pump chamber and a ride plate closes a bottom of the pump chamber. The ride plate includes a base fixable to the boat body. A setting plate detachably fixed to the base, and forms part of a bottom surface of the rear portion of the boat body.

Abstract: A trim operating lever device is disclosed which can downwardly or vertically swing a nozzle capable of adjusting the jet direction of jet water. When the trim operating lever is gripped with a finger of the hand which is gripping the steering handle, a lever of the lever lock means can be substantially simultaneously operated with the finger, to effect locking. Therefore, the number of operations by the left hand necessary for swinging the nozzle is reduced. Also, because the trim operating lever makes it possible to enlarge the operating force, the nozzle can be swung quickly.

Abstract: A water jet pump is provided which reduces cavitation and thereby allows an improvement in pump efficiency. In a water jet pump in which an impeller driven for rotation and is provided in a cylindrical housing, an edge portion of the outer circumferential surface of the impeller that opposes the inner surface of the housing is formed with a radius of curvature. This structure reduces a variation in the pressure of a water stream passing between the outer circumferential surface of the impeller and the inner surface of the housing toward the impeller front surface side, thereby reducing the occurrence of cavitation and improving the pump efficiency.

Abstract: A trim operating wire is disclosed wherein the length of the pull wire connecting between the push-pull converter and the trim operating lever can be made short, and the push wire can be made long. As a result, even where the pull wire, which is thin and highly flexible, is disposed in the state of being bent at several portions thereof, the sliding resistance of an inner wire of the pull wire is small, and operability is enhanced.

Abstract: A trim operating lever device is disclosed which can downwardly or vertically swing a nozzle capable of adjusting the jet direction of jet water. When the trim operating lever is gripped with a finger of the hand which is gripping the steering handle, a lever of the lever lock means can be substantially simultaneously operated with the finger, to effect locking. Therefore, the number of operations by the left hand necessary for swinging the nozzle is reduced. Also, because the trim operating lever makes it possible to enlarge the operating force, the nozzle can be swung quickly.