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Half duct propeller

 Sometimes refered to as half kort

One or two nozzles may be fitted just ford of the propeller. There purpose is to steer the flow of water to enter the propeller with minimum shock. Efficiemcy claims are up to 3%. The advantage of this system over the full duct or kort nozzle is that it does not suffer from the same cavitation damage on the inner surface. A simplified version of this is two fins welded to the hull at a slight angle to the shaft centre line




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