Variable marine jet propulsion

An improved water jet propulsion apparatus for a jet propelled watercraft, the water jet propulsion apparatus comprising:

• a) a variable-pitch propeller water pump structured for operating as a continuously variable power transmission for a motor external to the pump, the pump comprising a plurality of vanes and a mechanism structured for adjusting a pitch on the vanes in such manner that water flow and pump power demand vary as a function of the pitch of the vanes;
• b) a mechanism structured for coupling the pump to the external motor for driving the pump;
• and
• wherein an outlet of the pump is coupled to an inlet of a variable orifice discharge nozzle, and an orifice control mechanism is coupled for controlling an orifice of the variable orifice discharge nozzle.

An improved water jet propulsion system for a jet propelled watercraft, the water jet propulsion apparatus comprising:

• a) water pump having a variable pitch impeller and being structured for being coupled to an external driver;
• b) an inlet duct structured for receiving water from an external body of water and directing received water to the water pump, the inlet duct having a variable inlet orifice and an outlet orifice structured for being coupled to an inlet orifice of the water pump;
• and
• c) a discharge nozzle structured for receiving water from the water pump and discharging received water from a variable discharge orifice.

A method of water jet propulsion for propelling a watercraft, the method comprising:

• a) in a water pump, providing a variable pitch impeller;
• b) coupling an inlet duct to the water pump for receiving water into an inlet orifice thereof and directing received water to an inlet orifice of the water pump;
• c) coupling a discharge nozzle to the water pump for receiving water from the water pump and discharging the received water from a discharge orifice thereof;
• and
• d) varying at least one of the inlet orifice of the inlet duct and the discharge orifice of the discharge nozzle.

An improved water jet propulsion system for a jet propelled watercraft, the water jet propulsion apparatus comprising:

• a) water pump being structured for being coupled to an external driver;
• b) a inlet duct structured for receiving water from an external body of water and directing received water to the water pump, the inlet duct having an elongated inlet tunnel between a variable inlet orifice and an outlet orifice structured for being coupled to an inlet orifice of the water pump;
• c) a grate structure internal of the inlet duct and positioned within the elongated inlet tunnel;
• and
• d) a discharge nozzle structured for receiving water from the water pump and discharging received water from a variable discharge orifice.

A jet propelled watercraft, comprising:

• a watercraft;
• a water pump having a variable pitch impeller;
• a power supply coupled for driving the water pump;
• an inlet duct having a variable inlet orifice coupled to a first surface of the watercraft in a position for receiving water and directing received water to an inlet orifice of the water pump;
• a discharge nozzle coupled to the water pump for receiving water from the water pump, and coupled to a second surface of the watercraft in a position for discharging the received water from a discharge orifice thereof.