Efficiency Rudder

 
 
 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 

 

 

 

 

 

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Efficiency Rudder

marine

A patented semi-balanced 
rudder
 developed by Wärtsilä Corporation. The Efficiency Rudder is characterised by a streamlined “torpedo”-shaped bulb on the 
rudder horn
 immediately abaft and coaxial with the 
propeller hub
. The bulb ensures a more homogeneous water 
flow
 both in front of the 
propeller
 and in the propeller slipstream. The bulb increases propulsion efficiency by the “wake gain” effect, which means that it reduces the water speed into the propeller so that less power is needed to produce the same propeller thrust. The bulb also reduces propeller-induced hull noise and vibration by eliminating hub vortices and separation, and 
cavitation
 behind the propeller hub collapsing on the propeller. Single-screw vessels equipped with the Efficiency Rudder have 5-7% improved propulsive efficiency, pressure impulses are reduced by 30-45%. See also 
Energopac
.

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Wärtsilä is a global leader in innovative technologies and lifecycle solutions for the marine and energy industries. We emphasise innovation in sustainable technology and services to help our customers continuously improve their environmental and
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