Tunnel thruster

Abstract

A tunnel thruster of a pleasure boat includes a propeller and a tunnel. The tunnel is installed through and across the at least one hull, from a first aperture at a first side of the hull to a second aperture at a second side of the hull. The propeller rotates about a propeller principal axis within the tunnel so that, when the pleasure boat is level, the propeller principal axis is substantially horizontal and substantially perpendicular to a disc swept by the propeller. The tunnel thruster is operable to drive water between the first and second apertures to provide lateral thrust to the hull. Each of the first and second apertures has a respective highest point, and the top of the disc swept by the propeller is located at a position higher than the respective highest points of the first and second apertures when the pleasure boat is level.

1 . A pleasure boat having at least one hull and a tunnel thruster, wherein: 
 the tunnel thruster includes a motor, a propeller and a tunnel;   the tunnel is installed through and across the at least one hull, from a first aperture at a first side of the hull to a second aperture at a second side of the hull;   the propeller is mounted for rotation about a propeller principal axis within the tunnel so that, when the pleasure boat is level, the propeller principal axis is substantially horizontal and substantially perpendicular to a disc swept by the propeller;   the tunnel thruster is operable to drive water between the first and second apertures to provide lateral thrust to the hull; and   each of the first and second apertures has a respective highest point, and the top of the disc swept by the propeller is located at a position higher than the respective highest points of the first and second apertures when the pleasure boat is level.   
     
     
         2 . The pleasure boat according to  claim 1  being a pontoon boat with two or three hulls.  
     
     
         3 . The pleasure boat according to  claim 1  wherein the at least one hull has a bow region and a stern region, the thruster being installed in the bow region or in the stern region, or respective thrusters being installed in the bow region and in the stern region. 
     
     
         4 . The pleasure boat according to  claim 1  wherein the tunnel of the thruster is installed through and across the hull from the first aperture located at a first side of the hull to the second aperture at a second side of the hull. 
     
     
         5 . The pleasure boat according to  claim 4  wherein the tunnel has a central region formed as a generally horizontal tube which accommodates the propeller and the tunnel additionally has lateral regions which are oriented downwardly towards the respective apertures in the hull. 
     
     
         6 . The pleasure boat according to  claim 5  wherein an angle formed between a downward slope of each lateral region and the horizontal is at least 3°. 
     
     
         7 . The pleasure boat according to  claim 1  wherein a vertical distance between the top of the disc swept by the propeller and the respective highest point for each aperture is at least 2cm.  
     
     
         8 . The pleasure boat according to  claim 1  wherein the motor is attached to the tunnel and is located above the tunnel, a drive shaft extending substantially vertically from the motor to a gearbox held within the tunnel, the gearbox being located on one side of a central point of the tunnel and the propeller being located on the opposite side of the central point of the tunnel. 
     
     
         9 . A tunnel thruster for installation in a hull of a pleasure boat, wherein: 
 the tunnel thruster includes a motor, a propeller and a tunnel;   the tunnel is suitable for installation through and across the hull of the pleasure boat, from a first aperture at a first side of the tunnel thruster to a second aperture at a second side of the tunnel thruster;   the propeller is mounted for rotation about a propeller principal axis within the tunnel so that, when the tunnel thruster is level, the propeller principal axis is substantially horizontal and substantially perpendicular to a disc swept by the propeller;   the tunnel thruster is operable to drive water between the first and second apertures to provide lateral thrust; and   each of the first and second apertures has a respective highest point, and the top of the disc swept by the propeller is located at a position higher than the respective highest points of the first and second apertures when the tunnel thruster is level.   
     
     
         10 . A pleasure boat having at least one hull and a tunnel thruster, wherein: 
 the tunnel thruster includes a motor, a propeller and a tunnel;   the tunnel is installed in the at least one hull, from a first aperture at a first position through the hull to a second aperture at a second position through the hull;   the propeller is mounted for rotation about a propeller principal axis within the tunnel so that, when the pleasure boat is level, the propeller principal axis is substantially horizontal and substantially perpendicular to a disc swept by the propeller;   the tunnel thruster is operable to drive water between the first and second apertures to provide thrust to the hull; and   each of the first and second apertures has a respective highest point, and the top of the disc swept by the propeller is located at a position higher than the respective highest points of the first and second apertures when the pleasure boat is level.   
     
     
         11 . A tunnel thruster for installation in a hull of a pleasure boat, wherein: 
 the tunnel thruster includes a motor, a propeller and a tunnel;   the tunnel is suitable for installation in the hull of the pleasure boat, from a first aperture at a first side of the tunnel thruster to a second aperture at a second side of the tunnel thruster;   the propeller is mounted for rotation about a propeller principal axis within the tunnel so that, when the tunnel thruster is level, the propeller principal axis is substantially horizontal and substantially perpendicular to a disc swept by the propeller;   the tunnel thruster is operable to drive water between the first and second apertures to provide thrust; and   each of the first and second apertures has a respective highest point, and the top of the disc swept by the propeller is located at a position higher than the respective highest points of the first and second apertures when the tunnel thruster is level.