Application possibilities of electric driven propulsion of multi-mode ships

The ship propulsion solution based on unconventional thrusters driven by electric motors is most often applied for the multi-mode ships. These ships ought to have dynamic positioning system. It forces an application of a few thrusters (most often four, seldom more up to eight). Records from a number of multi-mode ships show amean load of less than 40% of maximum load on the propulsion system. In other side the demand for electric energy of ship industrial part is large, more often than for the propulsion part. In that case the diesel-electric propulsion system application may be economical, because the electric energy generation for all ship's purposes makes possible the main engines work on the optimum loads on lowest specific fuel consumption and allows them a long-term work on heavy fuels. For multi-mode ships like cable ships, suppliers, drilling vessels are convenient an application of unconventional thrusters with direct electric propulsion as well, especially for dynamic positioning systems. The efficiency of the thrusters is a predominant factor for the successful and economical operation. Forecasted development and rise of quantity of diesel-electric propulsion (it means with electrical transmission) would cause increased interest of unconventional thrusters. Ultimately they may revolutionize ship propulsion systems.