A model having a capacity of 16, 000 ps was jointly developed by Japan Ships' Machinery Development Association and Kawasaki Heavy Industries Co. Ltd., during the term between April of 1972 and March of 1975. It was already described in several technical papers that sufficiently satisfied results which could make us believe that the device could be used practically on a ship was obtained by the tests. Owing to an emphasis of oil saving after the Oil Crisis of 1973, diesel engines have become the main current of propulsion engines of vessels. Particularly, a ship propulsion system of a propeller of low speed such as 36-65 rpm driven by a long stroke two cycle diesel engine of about 90 rpm having high reliability and high efficiency is holding the public eye. An electromagnetic gear can be thought most suitable for a power transmission of such a ship propulsion system.
Various technical characteristics of electromagnetic gears such as high efficiency, availability of clutch mechanism and reversibility of rotating direction could be confirmed by the tests. However, the first reason why electromagnetic gears can be considered to be widely used on board is that it was found that an electromagnetic gear can be manufactured by almost the same cost as that of a mechanical gear of the same capacity. We have been planning to use electromagnetic gears on several ships for these three years although fitting such electromagnetic gear on board has not been realized.
This paper introduces problems on applications of electromagnetic gears, reconsidering the results of manufacturing for trial and the tests.

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The shaft driven AC generator system (FPP-SGS) uses a part of the power to drive a fixed-pitch propeller in order to generate sufficient electric power for the ship's requirement during normal sea going.
The FPP-SGS can substantially reduce fuel and operation costs, and its major advantages are as follows:
: Substantial reductions in fuel costs during normal sea going due to the fact that the electric power is generated by bunker oil through the main engine rather than by diesel oil through an independent generator engine,
: Great reduction in the need for maintenance and service on generator engine,
: Simplified operation in the engine room.
The FPP-SGS needs to be equipped with at least one auxiliary generator which can be engaged and disengaged with a diesel engine by a clutch.
During normal sea going, the FPP-SGS alone can provide sufficient power to meet the ship's electrical demands, and auxiliary diesel generator acts as a synchronous condenser to supply reactive power.
The auxiliary generator engine is kept in stand-by condition by disengaging the clutch.
The FPP-SGS operates in conjunction with a thyristor inverter, jointly developed by MITSUBISHI HEAVY IND. LTD. and MITSUBISHI ELECTRIC CO., LTD.

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