Compact water jet propulsion system for a marine vehicle

An integrated hull and water jet propulsion system for a marine vessel, comprising:

• a hull means;
• and
• at least one water jet propulsion system, said at least one water jet propulsion system being positioned at an aft portion of said hull means, said at least one water jet propulsion system, comprising:
• an integrated inlet duct for redirecting water flowing along said hull means into said system, said inlet duct adapted for mounting to a surface of said hull means and extending internally thereof, said inlet duct extending between an initial end and a terminal end, said initial end circumscribing an inlet opening and defining an inlet plane, said terminal end circumscribing an inlet exit and defining a terminal plane, said duct having a centrally located reference axis extending from said inlet plane to said terminal plane wherein said reference axis defines an inclination angle relative to said inlet plane, said inclination angle being between about 45.degree. and about 75.degree.;
• a pump for accelerating the flow redirected into said system, said pump including a casing having at least one side wall and an end wall forming an impeller chamber, an axial inlet opposite said end wall, at least one outlet, and an impeller rotationally mounted in said impeller chamber, a rotation axis of said impeller aligned with said reference axis of said inlet duct, said impeller having a back face located adjacent said end wall and a front face having a plurality of radially extending impeller blades projecting axially therefrom toward said axial inlet, said at least one side wall and said impeller defining a flow passage, said pump being attached at said axial inlet to said terminal end of said inlet duct;
• a length of said inlet duct from said inlet opening to said inlet exit being less than or equal to a diameter of said impeller;
• power means for rotating said impeller;
• a drive shaft connected at a first end with said power means and at a second end to said back face of said impeller wherein said drive shaft is situated entirely outside said flow passage so as not to interfere with the flow, said drive shaft being substantially aligned with said reference axis of said inlet duct;
• and
• a downstream flow duct arranged substantially longitudinally in said hull means, said flow duct connected at a first end to said at least one outlet of said pump and having an outlet nozzle at a second end thereof, said second end being mounted to said aft portion of said hull means for discharging accelerated flow in a generally rearward direction.