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THE MAIN ENGINE 



a. Direct Reversible Diesel: 



The direct reversible diesel engine offers much promise for the 

 small ship. It requires a minimum of engine space, is easily tended 

 by a minimum crew, and is quite reliable and economical. On the 

 other hand, it offers two distinct disadvantages: its speed cannot be 

 reduced beyond a certain point and it subjects the ship to considerable 

 vibration. 



b. Diesel-Electric: 



This type of machinery overcomes the objections of the direct diesel 

 in regard to flexibility, but the vibration considerations remain; and 

 it is therefore not suitable for the present design. 



c. Reciprocating Steam: 



Reciprocating steam engines offer great advantages in flexibility and 

 in simplicity. Steam engineers acquainted with this kind of machin- 

 ery are available all over the world and repairs may be effected in 

 almost any seaport. It does offer the disadvantage of having two 

 separate machinery spaces and it is generally noisy and dirty. 



d. Steam Turbine: 



The steam turbine is a comparatively efficient engine, especially 

 when using very high temperatures and pressures. It is not as flexi- 

 ble as the 'knee-action' steam just described but it is much cleaner 

 and smoother in operation. As in the case of any steam propulsion , 

 two engine spaces are required. This type cannot be considered be- 

 of its inflexible nature. 



e. Turbo-Electric: 



The efficiency of the steam turbine combined with the great flexibility 

 of electric engines points to a Turbo-electric system as the most 

 preferable. It may be made quiet, powerful, light and relatively 

 small. It suffers some from the higher frequency vibrations but 

 these may be fairly well dampened. It also requires a separate fire- 

 room but the tremendous advantages of the combination of steam and 

 electricity outweight the disadvantages. 



Steam is a necessity. It means drinking water and showers for the 

 crew, lightweight power for auxiliary machinery and great flexibility with con- 

 stant-tension features for deck machinery. 



AUXILIARY MACHINERY 



The research ship requires auxiliary power comparable to that required 

 for a warship of about the same size. Generators are needed to furnish approxi- 

 mately 120 KW of auxiliary electrical power and this power must be distributed 

 among several voltages both A.C. and D,C. The distribution is dependent upon 

 the design of the motors for the several winches, radios, air-conditioners, 

 reefers, etc. 



It is suggested that the auxiliary generators be driven by small high- 

 pressure steam turbines which are fed from steam from the main boilers. At 

 least one small generator should be diesel-driven and backed by a bank of bat- 

 teries. 



Low-pressure steam should be used to operate some of the deck machin- 

 ery, for the whistle and siren, general heating systems and for the steering en- 

 gine. 



