Steering and propulsion arrangement for ship

Abstract

A large ship having a hull about 100 meters or more in length, so that the ship is suited for transoceanic traffic, with a narrow wedge-like bow and the broadest part of the underwater hull being located amidships, includes at least one steerable rudder propeller device at the forebody of the ship. The steerable rudder propeller device(s) at the forebody of the ship substantially provide(s) the steering and control of the ship and produce(s) a part of the propulsive force pushing the ship forward at least substantially within all speed ranges. In harbour manoeuvering, the steerable rudder propeller device(s) at the forebody of the ship provide(s), as needed, at least about 20% of the ship's total propulsive power. When steering ahead in sea traffic, the steerable rudder propeller device(s) at the forebody of the ship provide(s) at most about 10% of the ship's total propulsive power.

1 - 5 . (canceled)  
   
   
       6 . A method of operating a large ship having a hull about 100 meters or more in length, so that the ship is suited for transoceanic traffic, with a narrow wedge-like bow and the broadest part of the underwater hull being located amidships, said ship comprising at least one propulsion device at the rear of the ship and at least one steerable rudder propeller device at the forebody of the ship and arranged so that it does not extend significantly below the base line of the ship, said method comprising: 
 employing said at least one steerable rudder propeller device at the forebody of the ship to substantially provide the steering and control of the ship and to produce a part of the propulsive force pushing the ship forward at least substantially within all speed ranges,    in harbour manoeuvering, employing said at least one steerable rudder propeller device at the forebody of the ship to provide, as needed, at least about 20% of the ship's total propulsive power, and    when steering ahead in sea traffic, employing said at least one steerable rudder propeller device at the forebody of the ship to provide at most about 10% of the ship's total propulsive power.    
   
   
       7 . A method according to  claim 6 , wherein at the forebody of the ship in the underwater section of the hull at a distance from the base line of the ship, there is an area, which is designed sufficiently flat so that it enables the mounting and free turning of said at least one steerable rudder propeller device, and that the bottom of the ship hull from said area towards the stern is smoothly shaped so that said at least one steerable rudder propeller device, while the ship is moving ahead, can be directed according to the shape of the ship hull, whereby the flow behind said at least one steerable rudder propeller device towards the hull surface can be minimized accordingly.  
   
   
       8 . A method according to  claim 7 , wherein the ship is provided with a bulb and said area is situated behind the bulb.  
   
   
       9 . A method according to  claim 6 , wherein there are at least two steerable rudder propeller devices at the forebody of the ship.  
   
   
       10 . A method according to  claim 6 , wherein all the propulsion devices of the ship are permanently situated outside the ship hull.  
   
   
       11 . A method according to  claim 6 , wherein said at least one steerable rudder propeller device is mounted to the forebody of the ship in a region of the hull that is above the base line of the ship, and the lowest point of the hull in a transverse section through said region of the hull is in said region of the hull.