Power boat propulsion system

Abstract

A power boat propulsion system installed in a power boat having a waterway in the stern, an engine on the inside, and a shaft coupled to the engine and inserted through the waterway, includes a barrel-like impeller duct fixedly fastened to the rear outlet of the waterway, an impeller pivoted to the inside of the impeller duct and connected to the shaft for synchronous rotation with the shaft, a stator mounted inside the impeller duct and adapted for supporting a rear end of the shaft, and a rudder mounted inside the impeller duct near a rear outlet of the impeller duct. The rudder has top and bottom sides thereof pivoted to the impeller duct for deflection leftwards and rightwards.

What is claimed is:  
     
         1 . A power boat propulsion system installed in a power boat, said power boat comprising a waterway extended from the foot to the stern thereof, an engine mounted in the inside of the boat, and a shaft coupled to said engine and inserted through said waterway to a rear outlet of said waterway, the propulsion system comprising: 
 a barrel-like impeller duct having a front inlet fixedly coupled to the rear outlet of said waterway and a rear outlet for output of water from said waterway;    an impeller pivoted to the inside of said impeller duct and connectable to said shaft for synchronous rotation with said shaft;    a stator mounted inside said impeller duct and spaced from said impeller at a rear side and adapted for supporting a rear end of said shaft; and    a rudder mounted inside said impeller duct near the rear outlet of said impeller duct, said rudder having top and bottom sides thereof pivoted to said impeller duct for deflection leftwards and rightwards.    
     
     
         2 . The power boat propulsion system as claimed in  claim 1 , wherein said power boat comprises a recessed portion in the stern below the waterline; said waterway is disposed in the foot of said power boat and smoothly upwardly extended from the foot of said power boat to a front sidewall of said recessed portion; said impeller duct has a front side fixedly fastened to the front sidewall of said recessed portion, and at least one connecting arm disposed at a top side and respectively fixedly fastened to a top sidewall of said recessed portion.  
     
     
         3 . The power boat propulsion system as claimed in  claim 1 , wherein said impeller duct defines substantially a cylindrical internal space, and has a flat bottom sidewall.  
     
     
         4 . The power boat propulsion system as claimed in  claim 1 , wherein said rubber is deflectable leftwards and rightwards within 50° in each direction.