ELECTRIC AUXILIARIES ON MERCHANT SHIPS. 187 



Particular attention should be called to Mr. Pierce's remarks, "in many ships the steam 

 steering gear could be replaced by a hydro-electric gear with considerable saving and with- 

 out increasing the size of the generating sets." Mr. Pierce is a man of experience; the hydro- 

 electric steering gear is one of the most expensive single pieces of equipment on a ship; his 

 recommendation therefore to a great measure vindicates the author's contention as to the 

 desirability of entire electrification. 



Referring to Mr. Pierce's recommendation that enclosed motors be used below deck 

 except where the size prohibits, it would seem that if it be granted that enclosed motors 

 must be used in order to assure reliability, this rule would apply with the greatest force to 

 the larger motors, and in the higher ratings the size would be found to be impracticable. The 

 author would point out that motors which are designed to run continuously become tremen- 

 dously heavy and expensive when enclosed; further, if they are to be located in a damp place, 

 they will become wet inside and are just as liable, or perhaps even more liable, to deteri- 

 orate when not running than are ventilated motors. Experience has shown that ventilated 

 motors are entirely reliable on shipboard if designed for the conditions and built of suit- 

 able materials. 



Referring to Mr. Pierce's remark that this practice (referring to the use of enclosed 

 motors below deck) has been followed on foreign ships with success, the author would refer to 

 an article in the Electrician (London) of July 29, 1921, on page 131, in which it is stated "but 

 for all ordinary purposes a semi-enclosed and preferably drip-proof design is best." This 

 article refers to British practice. 



In making a general recommendation in favor of enclosed ventilated motors for below 

 deck installation, the following points were given consideration: 



Open motors would have to be protected from dripping water by shields which would 

 cost the shipbuilder something to install. 



In the smaller sizes the cost of such shields would be high in proportion to the first cost 

 of the motor. i 



In many instances such shields would occupy valuable space and would interfere with 

 accessibility of the motor and other apparatus located nearby. 



The cost of the enclosed ventilated motor is slightly more than the open motor and very 

 much less than the enclosed motor for continuous operation. 



Motors suitable for marine service can be built with open frames. They would cost but 

 little less than ventilated motors designed to keep out dripping water. 



Referring to Mr. Pierce's criticism of alternating current for tankers, while it is true 

 that troubles have been experienced, I believe the particular tankers referred to were a war 

 product, and many details of application were responsible for the troubles. There are cer- 

 tain very definite reasons in favor of alternating current for particular applications on ships, 

 and the fact that some installations have not been successful is due to improper application 

 rather than to the fact that alternating current was used. The author is of the opinion 

 that in most cases direct current will be found to be more suitable for auxiliary power on 

 ships ; he believes, however, that very careful consideration should be given to special appli- 

 cations where alternating current might be preferable. 



Regarding Mr. Pierce's remark that the author was making insinuations relative to the 

 wireman's discretion, it would seem that the author had been somewhat unfortunate in the 

 way he expressed himself on the subject and that Mr. Pierce had been unfortunate in the ex- 

 perience he had had with generators, motors, controllers, and starting panels. What the 



