ELECTRIC AUXILIARIES ON MERCHANT SHIPS. 165 



It would seem that for cargo ships direct current can be used to the greatest advantage. 

 On tankers this is not so apparent. 



Except in the smaller ships, it is desirable to use not less than 230 volts. The lower 

 voltage necessitates large or more expensive control; also the cost of wiring and switches 

 is greater. 



For lighting, the arguments seem to be in favor of 115 volts. This necessitates the instal- 

 lation of a small 115/230-volt motor-generator set. The use of incandescent lamps for 230 

 volts is not recommended. They are of necessity built with a very fine filament and are, 

 therefore, less substantial and, further, are not easily procured in seaports. 



WIRING AND INSTALLATION. 



It is impossible to speak too forcibly on this subject. A great deal of the criticism of 

 electrical apparatus when thoroughly investigated has been found to be directly due to faulty, 

 careless, slipshod methods of wiring and installation. Care and attention have been given to 

 choosing apparatus, but the method of installation, the kind of wire, and many details of 

 vital importance have been left to the wiremen's discretion with the inevitable result. 



It is not the intention here to suggest that definite rules be laid down. Each engineer 

 must work out his own particular problems. Certain underlying fundamentals, however, can 

 generally be applied. The following are recommended: 



That the vi^iring and distribution in the engine room be made as simple as possible, with 

 relatively few circuits. 



The switchboard should be largely a distribution panel designed with the idea of attain- 

 ing maximum simplicity and occupying the least amount of engine-room space. 



Circuits may be led from this distribution panel to different parts of the ship where they 

 may be further subdivided, as, e. g., five circuits for deck machinery, No. 1 to the steering 

 engine, No. 2 to the after hatches, No. 3 to the forward hatches, No. 4 to anchor windlasses 

 and forward capstans, No. 5 to after capstans. This will permit opening all the winch cir- 

 cuits when at sea and also allow for thorough inspection and try-out of the capstans, an- 

 chor windlass or steering engine when in port, even if cargo is being handled. 



In the engine room a similar method may be applied, one circuit to the engine-room 

 auxiliaries, port side, and another to the starboard side. By such simplification it will be 

 possible to obtain low cost with maximum reliability. 



Cables should not be run in conduits except, perhaps, for very short lengths where 

 necessary for mechanical protection. Cables in the engine room should be run overhead. 

 All cables should be thoroughly anchored so that the covering will not be chafed, due to 

 vibration. 



OPERATION. 



To study the relative merits of ships' auxiliaries, it is necessary to consider the part 

 which they play in the economic operation of the ship. 



For certain special types of ships designed and built to operate for some particular 

 service, such as tankers and lake ore carriers, it is not difficult to show definitely why a cer- 

 tain installation will give the best return on the investment. 



In the cargo ship, however, the problem is not so clearly cut. While it is true that a 

 certain number of ships may be designed with the intention of traveling particular trade 

 routes and handling a special cargo, it is often found that their schedule must be modified. 



