Watercraft having a jet propulsion system that generates improved thrust

Abstract

A watercraft is equipped with a jet propulsion system that has improved output propulsion and energy efficiency. Vanes are disposed within the water passage that extends through the jet propulsion system. The vanes are disposed upstream of an impeller. The vanes substantially correct the rotational motion of the water, which is created by the drive shaft. This assists in minimizing swirl created when the watercraft is turned. This also helps to improve the operational efficiency of the jet propulsion unit.

What is claimed is:  
     
         1 . A watercraft comprising: 
 a hull having a tunnel formed therein that forms a water passage with an inlet and an outlet;    a pump support mounted in the tunnel and defining a portion of the water passage;    an engine supported by the hull and having a drive shaft;    a jet propulsion unit operatively connected to the drive shaft of the engine and supported in the tunnel within the water passage adjacent to the pump support, wherein the jet propulsion unit comprises a pump housing and an impeller; and    a plurality of vanes extending into the water passage upstream of the impeller.    
     
     
         2 . The watercraft according to  claim 1 , wherein the jet propulsion unit further comprises a stator disposed adjacent to the impeller.  
     
     
         3 . The watercraft according to  claim 1 , wherein: 
 the jet propulsion unit further comprises an inlet grate disposed proximate to the inlet to the water passage; and    the plurality of vanes extend into the water passage downstream of the inlet grate.    
     
     
         4 . The watercraft according to  claim 3 , wherein the plurality of vanes are disposed at a closer proximity to the impeller than to the water passage inlet.  
     
     
         5 . The watercraft according to  claim 1 , wherein the pump support is disposed upstream of the pump housing and forms a water intake ramp.  
     
     
         6 . The watercraft according to  claim 5 , wherein the plurality of vanes are secured within the pump support.  
     
     
         7 . The watercraft according to  claim 1 , wherein the plurality of vanes extend inwardly from a passage in the pump support.  
     
     
         8 . The watercraft according to  claim 1 , wherein the plurality of vanes surround the drive shaft.  
     
     
         9 . The watercraft according to  claim 8 , wherein the plurality of vanes are disposed in the water passage such that a plane perpendicular to the drive shaft intersects each vane.  
     
     
         10 . The watercraft according to  claim 1 , wherein: 
 the drive shaft includes a generally circular cross-section; and    the vanes are concentrically disposed about the drive shaft.    
     
     
         11 . The watercraft according to  claim 1 , wherein the vanes are fixed with respect to the hull.  
     
     
         12 . The watercraft according to  claim 1 , wherein the plurality of vanes are disposed proximate to an inlet of the pump housing.  
     
     
         13 . The watercraft according to  claim 1 , wherein: 
 the impeller comprises at least one rotating blade; and    the plurality of vanes are disposed upstream of the at least one blade.    
     
     
         14 . The watercraft according to  claim 1 , wherein the plurality of vanes comprises at least six vanes.  
     
     
         15 . The watercraft according to  claim 14 , wherein the plurality of vanes comprises eight vanes.  
     
     
         16 . The watercraft according to  claim 1 , wherein each of the vanes have a substantially equal length.  
     
     
         17 . The watercraft according to  claim 1 , wherein each of the vanes is separated from the drive shaft by a substantially equal distance.  
     
     
         18 . The watercraft according to  claim 1 , wherein each of the vanes have a tapered leading edge and a trailing edge downstream of the tapered leading edge.  
     
     
         19 . The watercraft according to  claim 18 , wherein the leading edge is angled rearwardly with respect to the pump housing such that the leading edge is disposed at an acute angle relative to a plane perpendicular to a longitudinal axis of the drive shaft.  
     
     
         20 . The watercraft according to  claim 19 , wherein the trailing edge is substantially perpendicular to a longitudinal axis of the drive shaft.  
     
     
         21 . The watercraft according to  claim 20 , wherein the leading edge, the trailing edge and the longitudinal axis of the drive shaft are disposed in the same plane.  
     
     
         22 . The watercraft according to  claim 19 , wherein the vanes have a curvature such that the leading edge, the trailing edge and the longitudinal axis of the drive shaft are not disposed in the same plane.  
     
     
         23 . The watercraft according to  claim 1 , wherein the vanes are disposed around the inner periphery of an insert disposed within the water passage.  
     
     
         24 . The watercraft according to  claim 23 , wherein the insert is a ring and the plurality of vanes are evenly spaced around the inner periphery of the ring.  
     
     
         25 . The watercraft according to  claim 23 , wherein the insert includes an outer wall secured within the tunnel.  
     
     
         26 . The watercraft according to  claim 23 , wherein an inner periphery of the insert is generally annular.  
     
     
         27 . The watercraft according to  claim 23 , wherein the insert is secured within the pump support disposed within the water passage proximate to the pump housing.  
     
     
         28 . The watercraft according to  claim 27 , wherein the pump support is coupled to the pump housing.  
     
     
         29 . The watercraft according to  claim 23 , wherein the insert is secured within the pump housing.  
     
     
         30 . The watercraft according to  claim 1 , wherein the pump support comprises: 
 a generally ring shaped body, the ring shaped body having an inner peripheral wall defining a passage extending therethrough, the plurality of vanes being disposed on the inner peripheral wall; and    a pump housing attachment surface.    
     
     
         31 . The watercraft according to  claim 1 , wherein the plurality of vanes are disposed within the pump housing.  
     
     
         32 . The watercraft according to  claim 1 , wherein the jet propulsion unit further comprises a stator and a venturi disposed downstream of the stator.  
     
     
         33 . A jet propulsion unit pump support, comprising: 
 a generally ring shaped body including an inner peripheral wall defining a passage extending therethrough, a plurality of vanes supported by the inner peripheral wall, and a pump housing attachment surface, the pump housing attachment surface being configured for attachment to a pump housing.    
     
     
         34 . The jet propulsion unit pump support of  claim 33 , further comprising a ring shaped insert secured within the inner peripheral wall, wherein the vanes extend from the insert.  
     
     
         35 . The jet propulsion unit pump support of  claim 33 , further comprising a ramp extending from the ring shaped body that forms a portion of a water inlet.  
     
     
         36 . The jet propulsion unit pump support of  claim 35 , wherein the plurality of vanes are disposed between the ramp and the pump housing attachment surface.  
     
     
         37 . A jet propulsion unit vane insert, comprising: 
 a generally ring shaped body including an inner peripheral wall defining a passage extending therethrough, a plurality of vanes disposed on the inner peripheral wall, and an outer peripheral wall configured for attachment to a jet propulsion unit.