Analysis of Asymmetrical Shaft Power Increase During Tight Manoeuvres

In the present work the phenomenon of asymmetrical shaft power increase during tight manoeuvres is investigated by means of the analysis of turning circle manoeuvres at different speeds and rudder angles performed during sea trials for a series of twin screw naval ships; a common trend for shaft power increase has been found, and possible reasons for it have been examined. It is believed that, for unconventional propulsion plant arrangements, in which for instance two shaft axes are powered by the same prime mover via a unique reduction gear, automation plant will need to monitor carefully these effects, in order to avoid possible problems.