Arrangement and method in a ship

Abstract

A ship is disclosed which can include a hull, at least one propulsion unit having a propulsion engine, transmission, at least one propeller connected via the transmission to the propulsion engine, and an oscillation sensor situated in a vicinity of the at least one propeller in order to sense cavitation of the at least one propeller. A control unit can control the propulsion engine, the oscillation sensor being connected to the control unit, whereby the output signal of the oscillation sensor is analyzed in the control unit to detect and indicate that a worse degree cavitation is emerging on a display unit at the navigation bridge and/or regulate the rotation speed and/or the power of the propulsion engine.

1 . An arrangement in a ship comprising:
 a hull;   at least one propulsion unit having a propulsion engine, a transmission, and at least one propeller connected via the transmission to the propulsion engine;   an oscillation sensor situated in a vicinity of the at least one propeller in order to sense oscillations caused by cavitation of the at least one propeller; and   a control unit for controlling the at least one propulsion engine, said oscillation sensor being connected to the control unit, whereby an output signal of the oscillation sensor will be analyzed in the control unit in order to determine whether a worse degree cavitation is emerging, and indicate when a worse degree cavitation is emerging on a display unit at a navigation bridge and/or regulate rotation speed and/or power of the at least one propulsion engine when a worse degree cavitation is emerging.   
     
     
         2 . An arrangement according to  claim 1 , wherein said oscillation sensor is attached to a front edge of a support structure protruding downwards from the hull, said support structure being positioned after the propeller in a driving direction of the ship. 
     
     
         3 . An arrangement according to  claim 2 , wherein the oscillation sensor is situated on the front edge of the support structure at a base height position corresponding to a height of a tip of a blade of the at least one propeller when the tip of the blade is in an uppermost position, with a vertical deviation (V 1 ) which is equal to or less than ±25% of a diameter (D 1 ) of the propeller from the base height position. 
     
     
         4 . An arrangement according to  claim 1 , wherein said oscillation sensor is situated at a bottom of the hull in a position above the propeller. 
     
     
         5 . An arrangement according to  claim 4 , wherein the oscillation sensor is situated in a radial direction above the propeller a base longitudinal position exactly above a tip of a propeller blade when the tip of the blade is in an uppermost position, with a horizontal deviation (H 1 ) of the base longitudinal position which is equal to or less than 50% of a diameter (D 1 ) of the propeller from the base longitudinal position. 
     
     
         6 . An arrangement according to  claim 1 , comprising:
 a support structure pivotably supported at the hull around a turning axis and having a hollow body; and   a turning mechanism having at least one second electric motor for turning the support structure and thereby a chamber relation to the hull of the ship in order to steer the ship, wherein:   the at least one propulsion engine includes a first electric motor situated in the chamber having a front end and a rear end, said chamber being stationary attached to a lower portion of the support structure;   the transmission includes a shaft having a first end and a second end, said first end of the shaft being connected to the first electric motor and said second end of the shaft protruding from the front end of the chamber and being connected to the at least one propeller; and   said oscillation sensor is situated at a front edge of the support structure behind the at least one propeller in a driving direction of the ship.   
     
     
         7 . An arrangement according to  claim 1 , comprising:
 a support structure stationary attached to the hull and having a hollow body;   a rudder situated after the support structure and a chamber in a driving direction of the ship, said rudder being pivotably supported at the hull around a turning axis; wherein:   the propulsion engine includes a first electric motor situated in the chamber having a front end and a rear end, said chamber being stationary attached to a lower portion of the support structure;   the transmission includes a shaft having a first end and a second end, said first end of the shaft being connected to the first electric motor and said second end of the shaft protruding from the front end of the chamber and being connected to the propeller; and   said oscillation sensor is situated at the front edge of the support structure behind the at least one propeller in a driving direction of the ship.   
     
     
         8 . An arrangement according to  claim 1 , comprising:
 a rudder pivotably supported at the hull around a turning axis, said rudder being positioned after the propeller in a driving direction of the ship, wherein:   the propulsion engine includes a first electric motor or a diesel engine situated within the hull of the ship;   the transmission means includes a shaft having a first end and a second end, said first end of the shaft being connected to the propulsion engine and said second end of the shaft protruding from the rear end of the hull and being connected to the propeller; and   said oscillation sensor is situated at a front edge of the rudder behind the at least one propeller in a driving direction of the ship.   
     
     
         9 . An arrangement according to  claim 8 , wherein the oscillation sensor is situated on the front edge of the rudder at a base height position corresponding to a height of a tip of blade of the at least one propeller when the tip of the blade is in an uppermost position, with a vertical deviation (V 1 ) which is equal to or less than ±25% of a diameter (D 1 ) of the propeller from the base height position. 
     
     
         10 . An arrangement according to  claim 1 , wherein the ship is a cruiser, a tanker transporting oil or liquefied natural gas, a vehicle carrier, a container ship or a ferry. 
     
     
         11 . An arrangement according to  claim 1 , wherein a power of the at least one propulsion unit is at least 1 MW. 
     
     
         12 . A method for propulsion of a ship having a hull; at least one propulsion unit which includes a propulsion engine, a transmission and at least one propeller connected via the transmission to the propulsion engine; and an oscillation sensor situated in a vicinity of the at least one propeller in order to sense oscillations caused by cavitation of the at least one propeller,
 wherein the method comprises:   measuring cavitation of the at least one propeller with the oscillation sensor;   feeding an output signal of the oscillation sensor to a control unit;   analyzing the output signal of the oscillation sensor in the control unit to detect cavitation of the at least one propeller and to determine whether a worse degree cavitation is emerging; and   indicating when a worse degree cavitation is emerging on a display unit at a navigation bridge and/or regulating a rotation speed and/or power of the propulsion engine when a worse degree cavitation is emerging.   
     
     
         13 . An arrangement according to  claim 3 , wherein the ship is a cruiser, a tanker transporting oil or liquefied natural gas, a vehicle carrier, a container ship or a ferry. 
     
     
         14 . An arrangement according to  claim 5 , wherein the ship is a cruiser, a tanker transporting oil or liquefied natural gas, a vehicle carrier, a container ship or a ferry. 
     
     
         15 . An arrangement according to  claim 3 , wherein a power of the at least one propulsion unit is at least 1 MW. 
     
     
         16 . An arrangement according to  claim 5 , wherein a power of the at least one propulsion unit is at least 1 MW. 
     
     
         17 . The method according to  claim 12 , wherein a power of the at least one propulsion unit is at least 1 MW.