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December, 1925 MARINE REVIEW 19 At Left—Totally enclosed waterproof direct current motor for deck auxiliaries--Brake to commutator end—At right—Drip proof fully protected marine type motor (Ball Bearing for chinery at reduced powers, the aux- iliary fuel consumption does not drop in the same proportion, and under such conditions, the percentage fuel used for auxiliaries may be as high as 75 per cent of that used by the main unit. Another item of great importance to steam vessels is the securing of a proper heat balance. An excess of auxiliary exhaust steam above that which may be absorbed by the feed heating system, shows a tremendous loss. In steam plants, losses invari- ably pyramid. Where excess auxiliary exhaust steam is piped to the con- denser, through a relief valve, the vacuum is affected or increased power is required on the circulating pump; this, in turn, requires more steam, therefore, a larger amount of feed to the boilers, which increases the duty of the feed pump. Fuel oil pumps and forced draft blowers are also speeded up slightly, and we find ourselves in a vicious circle. Econ- omy in steam practice depends pri- marily in breaking up these pyramid- al losses. The great economic benefits to be derived through partial or total elec- trification of the engine room auxil- iaries is, therefore, due not only to the higher thermal efficiency of the individual ‘pieces of apparatus, but also to the realization of a proper heat balance and the elimination of unnecessary losses. In the average steam installation on ships, the maximum quantity of under-deck auxiliaries auxiliary exhaust steam that may be absorbed by the feed water heating system is from 12 to 15 per cent of the total quantity generated. The main propelling machinery has been highly developed the past few years, steam conditions have been im- proved and water rates have been re- duced. The percentage of steam used for auxiliaries has, therefore, become higher rather than lower, which fur- ther complicates the problem. In or- der to keep a well balanced plant, es- pecially where highly efficient main propelling units are installed and where high pressure and temperature steam is used, electric auxiliaries be- come almost a necessity. The application problems involved (Continued on Page 40) MOTOR DRIVEN COMPRESSOR ON THE DIESEL ELECTRIC TUG VAN DYKE III OWNED BY THE ATLANTIC REFINING CO.— 25 HORSEPOWER, 310 REVOLUTIONS PER MINUTE, 230 VOLT ELECTRIC CARGO WINCH WITH WATERTIGHT SOLENOID TYPE BRAKE ON THE M. S. EAST INDIAN OWNED BY THE FORD MOTOR CO.