Water jet propulsion system

Abstract

A highly efficient watercraft propulsion system that relies on a positive displacement pump to generate a water jet. The pump is fully submerged at all times and its inlet is positioned so as to cause water to be forced into the pump as the watercraft moves through the water. The pump is preferably combined with a variable area pump opening which is configured, positioned and oriented so as to maximize the hydraulic reaction between the water jet stream and the surrounding body of water.

1 . A water jet propulsion system for a watercraft, comprising a non-pulsating positive displacement pump. 
   
   
       2 . The water jet propulsion system of  claim 1 , wherein said non-pulsating positive displacement pump comprises a counter-rotating helical lobe pump. 
   
   
       3 . The water jet propulsion system of  claim 1 , further comprising an inlet opening, a discharge opening and wherein said inlet opening, discharge opening and pump are arranged in a straight line. 
   
   
       4 . The water jet propulsion system of  claim 1 , further comprising an inlet opening, a discharge opening and wherein said inlet opening, discharge opening and pump are fully submerged at all times. 
   
   
       5 . The water jet propulsion system of  claim 4 , further comprising a variable area discharge opening. 
   
   
       6 . The water jet propulsion system of  claim 5 , wherein said watercraft includes a hull and wherein said discharge opening is positioned such that a discharged jet of water flows along a submerged portion of said hull. 
   
   
       7 . The water jet propulsion system of  claim 4 , wherein said inlet opening is positioned so as to cause water to be forced directly into said pump when said watercraft is moving through said water. 
   
   
       8 . A water jet propulsion system for a watercraft, comprising a counter-rotating lobe pump. 
   
   
       9 . The water jet propulsion system of  claim 8 , wherein said lobes have a helical shape extending along their axes of rotation. 
   
   
       10 . The water jet propulsion system of  claim 8 , further comprising an inlet opening, a discharge opening and wherein said inlet opening, discharge opening and pump are arranged along a common axis. 
   
   
       11 . The water jet propulsion system of  claim 8 , further comprising an inlet opening, a discharge opening and wherein said inlet opening, discharge opening and pump are fully submerged at all times. 
   
   
       12 . The water jet propulsion system of  claim 11 , further comprising a variable area discharge opening. 
   
   
       13 . The water jet propulsion system of  claim 11 , wherein said watercraft includes a hull and wherein said discharge opening is positioned such that a discharged jet of water flows along a submerged portion of said hull. 
   
   
       14 . The water jet propulsion system of  claim 8 , wherein said inlet opening is positioned so as to cause water to be forced directly into said pump when said watercraft is moving through said water. 
   
   
       15 . A water jet propulsion system for a watercraft having a hull, comprising:
 a counter-rotating helical lobe pump;   an inlet conduit for conducting water directly into said pump;   an outlet opening for conducting water discharged water from said pump;   a housing for said pump, inlet conduit and outlet orifice, wherein said housing is configured for attachment to said hull.   
   
   
       16 . The water jet propulsion system of  claim 15 , further comprising a power transfer box for transferring rotation from a prime mover to said pump, wherein said transfer box extends from said housing and through said hull. 
   
   
       17 . The water jet propulsion system of  claim 16 , further comprising a gear set for transferring rotation from said prime mover to said pump. 
   
   
       18 . The water jet propulsion system of  claim 15 , further comprising an inlet opening, a discharge opening and wherein said inlet opening, discharge opening and pump are arranged along a common longitudinal axis. 
   
   
       19 . The water jet propulsion system of  claim 15 , wherein said outlet orifice has a variable cross-sectional area. 
   
   
       20 . The water jet propulsion system of  claim 15 , wherein said lobe pump is reversible so as to enable water to be pumped from said outlet opening to said inlet opening and thereby enable a reversing of said watercraft.