Abstract: A marine jet propulsion system has a jet pump, a venturi connected to the jet pump, a first steering nozzle rotationally mounted relative to the venturi about a first steering axis, and a second steering nozzle rotationally mounted relative to the first steering nozzle about a second steering axis. The second steering axis is disposed rearwardly of the first steering axis. Rotation of the first steering nozzle relative to the venturi about the first steering axis in a steering direction causes the second steering axis to rotate about the first steering axis in the steering direction and the second steering nozzle to rotate relative to the first steering nozzle about the second steering axis in the steering direction. A watercraft having the jet propulsion system and a nozzle assembly for a marine jet propulsion system are also disclosed.

Abstract: A watercraft includes a watercraft control mechanism that is capable of steering, decelerating, and/or trimming a watercraft without causing the stern to elevate and the bow to dive; steers or assists steering in off-power situations; steers, trims and/or decelerates a watercraft, or assists in steering, trimming, and/or decelerating a watercraft that can be stowed or retracted to minimize hydrodynamic drag at high speeds; steers, trims and/or decelerates a watercraft, or assists in steering, trimming, and/or decelerating a watercraft that does not become clogged or jammed by seaweed or flotsam or foreign objects floating in the water; and decelerates or assists in decelerating a watercraft in a smooth and stable manner when the watercraft is travelling at high speeds.

Abstract: The present invention provides a jet pump assembly that includes a rotatable shaft adapted to be operationally coupled to a power source. An impeller is operationally connected to the rotatable shaft. A housing surrounds at least a portion of the rotatable shaft operationally coupled to the impeller. In addition, a single bearing is disposed between the housing and the rotatable shaft, permitting rotation of the rotatable shaft therein. The bearing has at least an inner race operationally coupled to the rotatable shaft and an outer race operationally coupled to the housing. The bearing also includes at least two sets of rolling components disposed, side-by-side between the inner and outer races, permitting rotation of the inner and outer races with respect to one another.

Abstract: A watercraft, equipped with a jet propulsion system with improved efficiency of operation is disclosed. Structures are disposed within a water passage of the jet propulsion system at a position upstream of the jet propulsion unit that modulate the amount of water that is allowed to pass through the water passage. The structures can be a flexible fluid filled bag, an adjustable ride plate, and an additional water passage. Each of the structures allow a greater amount of water into the water passage during acceleration than during constant speed travel of the watercraft.

Abstract: Variable venturi for use in jet propulsion systems of watercraft include discharge openings with selectively variable discharge areas that enable a venturi controller to selectively maximize top speed, acceleration, and/or fuel efficiency. The variable venturi may include a plurality of circumferentially-spaced, squeezable, flexible sections that selectively move radially inwardly to alter the discharge area. Alternatively, the variable venturi may include a flexible venturi with a variably-shaped flexible discharge opening. Alternatively, the variable venturi may include a main rear discharge opening and a plurality of additional discharge openings with selectively openable valves, whereby selective opening of the valves effectively increases the discharge area. Alternatively, the variable venturi may have a movable end flap that selectively varies the discharge area.

Abstract: The invention is directed to a thick stator vane that effects continuous acceleration of the water stream within the jet pump, a non-uniform spacing of stator vanes or impeller blades to reduce noise output of the jet pump during operation, and a coupling structure positioned between the impeller and engine that prevents transfer of axial thrust to the engine caused by jet pump failure.

Abstract: Variable venturis for use in jet propulsion systems of watercraft include discharge openings with selectively variable discharge areas that enable a venturi controller to selectively maximize top speed, acceleration, and/or fuel efficiency. The variable venturi may include a plurality of circumferentially-spaced, squeezable, flexible sections that selectively move radially inwardly to alter the discharge area. Alternatively, the variable venturi may include a flexible venturi with a variably-shaped flexible discharge opening. Alternatively, the variable venturi may include a main rear discharge opening and a plurality of additional discharge openings with selectively openable valves, whereby selective opening of the valves effectively increases the discharge area. Alternatively, the variable venturi may have a movable end flap that selectively varies the discharge area.

Abstract: A watercraft, equipped with a jet propulsion system with improved efficiency of operation is disclosed. Structures are disposed within a water passage of the jet propulsion system at a position upstream of the jet propulsion unit that modulate the amount of water that is allowed to pass through the water passage. The structures can be a flexible fluid filled bag, an adjustable ride plate, and an additional water passage. Each of the structures allow a greater amount of water into the water passage during acceleration than during constant speed travel of the watercraft.

Abstract: The invention is directed to a thick stator vane that effects continuous acceleration of the water stream within the jet pump, a non-uniform spacing of stator vanes or impeller blades to reduce noise output of the jet pump during operation, and a coupling structure positioned between the impeller and engine that prevents transfer of axial thrust to the engine caused by jet pump failure.

Abstract: A watercraft includes a watercraft control mechanism that is capable of steering, decelerating, and/or trimming a watercraft without causing the stern to elevate and the bow to dive; steers or assists steering in off-power situations; steers, trims and/or decelerates a watercraft, or assists in steering, trimming, and/or decelerating a watercraft that can be stowed or retracted to minimize hydrodynamic drag at high speeds; steers, trims and/or decelerates a watercraft, or assists in steering, trimming, and/or decelerating a watercraft that does not become clogged or jammed by seaweed or flotsam or foreign objects floating in the water; and decelerates or assists in decelerating a watercraft in a smooth and stable manner when the watercraft is travelling at high speeds.

Abstract: The present invention provides a jet pump assembly that includes a rotatable shaft adapted to be operationally coupled to a power source. An impeller is operationally connected to the rotatable shaft. A housing surrounds at least a portion of the rotatable shaft operationally coupled to the impeller. In addition, a single bearing is disposed between the housing and the rotatable shaft, permitting rotation of the rotatable shaft therein. The bearing has at least an inner race operationally coupled to the rotatable shaft and an outer race operationally coupled to the housing. The bearing also includes at least two sets of rolling components disposed, side-by-side between the inner and outer races, permitting rotation of the inner and outer races with respect to one another.

Abstract: This invention relates to an improved snowmobile drive train configuration arrangement that incorporates a fixed ratio speed reduction mechanism directly coupled to the engine crankshaft. This mechanism is in turn coupled to the driving pulley of a variable ratio belt drive system, the driven pulley of which is mounted on the axle of the sprocket wheels that drive the snowmobile track. Interposing the reduction drive between the engine and the belt drive system reduces the operational speed of both the pulleys and the belt, which proves beneficial from several aspects: the mechanical efficiency of the global system is increased, the dynamic response of the transmission to throttle modulation is improved; aerodynamic losses are reduced; the bending vibrations of the crankshaft are no longer transmitted to the drive clutch; and the engine can be run at higher RPM without decreasing the efficiency of the belt drive system.

Abstract: In a snowmobile drive train the variable ratio belt drive is not directly coupled to the engine crankshaft as in the prior art, but rather the driving pulley of the variable ratio belt drive is carried on one end of a jackshaft and the engine power is applied to the opposite end of the jackshaft. The jackshaft is supported in a fixed bearing in the vehicle frame, this bearing being immediately adjacent to the driving pulley so that the influence on the belt drive of vibrations generated by the engine is vastly diminished. Therefore the engine mounts can be arranged to fully absorb vibrations of the engine. Previously, when the driving pulley was directly coupled to the engine crankshaft it was necessary to include a tie restraint to limit movements of the engine housing in the direction of separation between the axes of the driving and driven pulleys.