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both main engines and the fresh water is continually circulated 

 at 120° F. 



(c) When the standby engines are put on 30 minutes' notice they 

 are started once each 12 hours and brought up to temperature. 



(d) With the insulation and construction of this class of vessel, it 

 was found that a cold engine could be started and warmed up to oper- 

 ating temperature in approximately 20 minutes. 



(e) There were several periods during the operation when the ship 

 lay to in the ice. either due to poor visibility or during operations 

 ashore. At such times the ship was either wedged between the ice 

 floes or had her bow jammed into the bay ice. The main plant was 

 secured, but put on short notice, the main motor control boards and 

 exciter sets being completely secured. The latter was feasible because 

 the main motor set-ups could be made much faster than the main 

 engines could be made ready. 



(/) The pitometer log and sound gear are kept secured at all times 

 while working \yAck or making passage through brash ice. Speed 

 under such conditions may be ascertained by use of radar on bergs 

 lying near the course line. 



The U. S. S. Edisto offers the following suggestions : 



{a) Main engines and lubricating oil are kept warmed up during 

 standby operation by the water jacket heaters. 



(6) All holding down bolts on engine base, shaft bearings, fittings, 

 and attachments are frequently checked for tightness against the heavy 

 shocks and vibration constantly encountered in ice breaking operations. 



((?) When the maximum 10.000 horsepower is not needed during 

 opei'ations, an engine combination should be selected whereby the 

 engines will be operated at or close to 80 percent of designed horse- 

 power rating. Failure to do this results in inefficient engine-fuel com- 

 bustion, high-carbon deposits on pistons, stuck piston rings, carbon 

 deposits on exhaust ports, unburned-fuel deposits in exhaust stacks 

 and mufflers, sometimes a serious stack fire, or increased maintenance 

 cost and renewal of engine parts. 



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