Abstract: An exhaust system for a small watercraft for effectively reducing exhaust noise and allowing a high output of an engine to be easily obtained at the time of high speed operation. An exhaust outlet of an exhaust pipe extending from an engine provided in a watercraft body is disposed at a position that allows it to sink in the water at the time when a travel speed of the watercraft body is a predetermined speed or less. The exhaust outlet is raised above the water at the time when the travel speed of the watercraft body exceeds the predetermined speed. An open surface of the exhaust outlet is offset toward a side wall surface of a pump chamber from a center of a jet pump in the pump chamber and is made oblique toward the side wall surface toward which the open surface of the exhaust outlet is offset.

Abstract: An exhaust system for a small watercraft for effectively reducing exhaust noise and allowing a high output of an engine to be easily obtained at the time of high speed operation. An exhaust outlet of an exhaust pipe extending from an engine provided in a watercraft body is disposed at a position that allows it to sink in the water at the time when a travel speed of the watercraft body is a predetermined speed or less. The exhaust outlet is raised above the water at the time when the travel speed of the watercraft body exceeds the predetermined speed. An open surface of the exhaust outlet is offset toward a side wall surface of a pump chamber from a center of a jet pump in the pump chamber and is made oblique toward the side wall surface toward which the open surface of the exhaust outlet is offset.

Abstract: A small boat has left and right sponsons extending in a longitudinal direction and respectively attached to left and right side walls forming a boat body. The sponsons are provided with an attachment section contacting a left side wall, a gliding section extending substantially horizontally from a lower edge of the attachment section, an inclined section connecting to a side edge of the gliding section, an upper edge of the attachment section, and projecting sections extending from an upper edge to a lower edge of the inclined section. Water flowing along the inclined section is guided by the projection sections and removed or separated from the inclined section. Accordingly, a small boat that turns through a small arc turning locus is provided, e.g., a small boat that is capable of relatively tight turning.

Abstract: A control unit is provided for increasing the number of engine revolutions per minute to a predetermined number of revolutions per minute when the throttle is closed and when the engine has been rotated for more than a prescribed time period at more than a prescribed number of revolutions per minute, and the throttle has been opened for more than a prescribed time period at more than a prescribed opening. The control unit increases the number of engine revolutions per minute to a predetermined number of revolutions per minute irrespective of the throttle and maintains the same for a predetermined retention time when the steering handle is turned to the left or the right by more than a prescribed angle. The time to start controlling the number of engine revolutions per minute may be delayed by providing a delay time for delaying the time to start controlling the engine revolutions. The number of engine revolutions per minute may be controlled after the hull is underwater.

Abstract: A small boat has left and right sponsons extending in a longitudinal direction and respectively attached to left and right side walls forming a boat body. The sponsons are provided with an attachment section contacting a left side wall, a gliding section extending substantially horizontally from a lower edge of the attachment section, an inclined section connecting to a side edge of the gliding section, an upper edge of the attachment section, and projecting sections extending from an upper edge to a lower edge of the inclined section. Water flowing along the inclined section is guided by the projection sections and removed or separated from the inclined section. Accordingly, a small boat that turns through a small arc turning locus is provided, e.g., a small boat that is capable of relatively tight turning.

Abstract: A piping joint includes a male member or joint fastened to a female member or socket by locking pawls of a retainer sleeve onto pawl engaging portions. By pressing a flange by the tip ends of the pawls, the male member (joint) can be disengaged from the female member (socket) by reducing the diameter of the retainer sleeve and disengaging the pawls from the pawl engaging portions. A ring member is formed of an elastic material and is inserted between the retainer sleeve and a cylinder portion in a locked condition. A reduction of the diameter of the retainer sleeve is prevented by the presence of the ring member. Therefore, the connecting or detaching of the piping joint can be carried out in a condition where a holding force of the piping joint is maintained.

Abstract: A controller that executes engine output control that a throttle is closed when a boat is navigated at a predetermined speed or higher and the output of an engine is gradually increased up to predetermined output when a steering system is steered right or left at a predetermined angle or more is provided. Thus, an overshoot phenomenon that the engine speed is held at a predetermined engine speed after the engine speed once increases up to the predetermined engine speed or higher when the engine speed is increased in deceleration can be avoided. As a result, the body of the boat can be prevented from sliding laterally to a great extent at the beginning of turning and the turning performance of the body can be enhanced.

Abstract: When a large load is exerted during restraint control of an engine of a jet propulsion boat, the drop of the engine revolution frequency causes a feeling of harsh braking. An engine revolution frequency control apparatus provided to prevent this problem includes a engine revolution frequency detector for detecting an engine revolution frequency, and threshold value setting units for setting first and second engine revolution frequency threshold values. The second threshold value is set to be higher than the first threshold value. An engine control unit includes an overspeed governing capability that starts restraint control for restraining rotation when the engine revolution frequency detected by the engine revolution frequency detector is more than said first threshold value when the engine is accelerating, and terminates restraint control when the engine revolution frequency is less than a second thresholds value during deceleration.

Abstract: A controller that executes engine output control that a throttle is closed when a boat is navigated at a predetermined speed or higher and the output of an engine is gradually increased up to predetermined output when a steering system is steered right or left at a predetermined angle or more is provided. Thus, an overshoot phenomenon that the engine speed is held at a predetermined engine speed after the engine speed once increases up to the predetermined engine speed or higher when the engine speed is increased in deceleration can be avoided. As a result, the body of the boat can be prevented from sliding laterally to a great extent at the beginning of turning and the turning performance of the body can be enhanced.

Abstract: A piping joint includes a male member or joint fastened to a female member or socket by locking pawls of a retainer sleeve onto pawl engaging portions. By pressing a flange by the tip ends of the pawls, the male member (joint) can be disengaged from the female member (socket) by reducing the diameter of the retainer sleeve and disengaging the pawls from the pawl engaging portions. A ring member is formed of an elastic material and is inserted between the retainer sleeve and a cylinder portion in a locked condition. A reduction of the diameter of the retainer sleeve is prevented by the presence of the ring member. Therefore, the connecting or detaching of the piping joint can be carried out in a condition where a holding force of the piping joint is maintained.

Abstract: When a large load is exerted during restraint control of an engine of a jet propulsion boat, the drop of the engine revolution frequency causes a feeling of harsh braking. An engine revolution frequency control apparatus provided to prevent this problem includes a engine revolution frequency detector for detecting an engine revolution frequency, and threshold value setting units for setting first and second engine revolution frequency threshold values. The second threshold value is set to be higher than the first threshold value. An engine control unit includes an overspeed governing capability that starts restraint control for restraining rotation when the engine revolution frequency detected by the engine revolution frequency detector is more than said first threshold value when the engine is accelerating, and terminates restraint control when the engine revolution frequency is less than a second thresholds value during deceleration.

Abstract: a control unit is provided for closing the throttle when the engine has been rotated for more than a prescribed time period at more than a prescribed number of revolutions, and the throttle has been opened for more than a prescribed time period at more than a prescribed opening. The control unit increases the number of engine revolutions to a predetermined number of revolutions irrespective of the throttle and maintains the same for a predetermined retention time when the steering handle is turned to the left or the right by more than a prescribed angle. The time to start controlling the number of engine revolutions may be delayed by providing a delay time for delaying the time to start controlling the engine revolutions. The number of engine revolutions may be controlled after the hull is underwater. As a consequence, the amount of sideslip of the jet propulsion boat can be improved.

Abstract: A vehicle has a connecting tube for air intake disposed on the same side of the vehicle as an exhaust pipe. The connecting tube and the exhaust pipe are disposed on opposite sides of one of right and left side pivot plates, the pivot plates supporting a swing arm.