Watercraft having a jet propulsion system with improved efficiency

A watercraft comprising:

• a hull having a bow and a stem;
• an engine supported by the hull;
• a water passage having an inlet at a position forward of the stem of the hull and an outlet at a position proximate to the stern of the hull;
• a jet propulsion unit disposed in a portion of the water passage, the jet propulsion unit being operatively connected to the engine;
• and
• a ride plate supported by the hull proximate to the inlet, at least a portion of the ride plate being operatively moveable through a predetermined range from at least a first position where the ride plate portion is disposed behind the inlet and a second position where the ride plate portion partially covers the inlet, such that the position of the ride plate portion determines the size of the inlet.

A watercraft comprising:

• a hull having a bow and a stem;
• an engine supported by the hull;
• a primary water passage having an inlet at a position forward of the stem of the hull and an outlet at a position proximate to the stem of the hull;
• a jet propulsion unit disposed in a portion of the primary water passage, the jet propulsion unit being operatively connected to the engine;
• a secondary water passage longitudinally aligned with the primary water passage, the secondary water passage including a secondary inlet and a secondary outlet through which water may flow from the secondary water passage into the primary water passage;
• a valve disposed adjacent to the secondary water passage that modulates the flow of water from the secondary water passage into the primary water passage, the valve being movable between at least a first position and a second position;
• and
• an actuator operatively connected to the valve to move the valve between the first and second positions based on sensed conditions of the watercraft.

A watercraft comprising:

• a hull having a bow and a stem;
• an engine supported by the hull;
• a primary water passage having an inlet at a position forward of the stem of the hull and an outlet at a position proximate to the stern of the hull;
• a jet propulsion unit disposed in a portion of the primary water passage, the jet propulsion unit being operatively connected to the engine;
• a secondary water passage and a tertiary water passage each disposed laterally adjacent to the primary water passage, the secondary water passage including a secondary inlet and a secondary outlet through which water may flow from the secondary water passage into the primary water passage, and the tertiary water passage including a tertiary inlet and a tertiary outlet through which water may flow from the tertiary water passage into the primary water passage;
• a valve disposed adjacent to each of the secondary water passage and the tertiary water passage that modulates the flow of water from the secondary water passage and the tertiary water passage into the primary water passage, each valve being movable between at least an open position and a closed position;
• an actuator connected to the valves to move the valves between the open position and the closed position based on sensed conditions of the watercraft;
• and
• a controller operatively connected to the actuator that controls movement of the valves to progressively open when the watercraft accelerates and to progressively close when the watercraft is operated at a high speed.