160 ELECTRIC AUXILIARIES ON MERCHANT SHIPS. 



Of all the electric apparatus aboard a ship the winch is subject to the most abuse. 

 Everything about it, therefore, should be designed, manufactured and installed in the most 

 substantial and workmanlike manner. 



Specifications for electric deck machinery should cover the following : 



1. Insulation should be as highly moisture-resisting as it is possible to get by the use 

 and treatment of the best materials. This applies not only to windings but to all bushings, 

 brush holder collars, etc., which, if hygroscopic, are liable to result in grounds. 



2. Motor frames should be thoroughly cleaned and painted on the inside to prevent, as 

 far as possible, scale forming by corrosion. 



3. Covers for inspection openings should preferably be hinged and arranged so as to 

 clamp tightly. On all apparatus, motors, resistor boxes, controllers, etc., if impracticable to 

 hinge the covers they should be attached by swinging bolts. Cap screws or cap bolts should 

 not be used, as they are liable to be dropped into the motor or left on deck and lost. 



4. Bearings should be designed to prevent, as far as possible, ingress of water and 

 egress of oil due to rolling of the ship. 



5. All apparatus should be provided with some form of drain. It must be recognized 

 that, while machinery may be built in the factory so watertight that it can be submerged, 

 there is no assurance that this condition will exist after it has been once opened on deck. 

 Further, any totally enclosed electrical apparatus is liable to breathe under varying temper- 

 atures which may result in an accumulation of moisture by condensation. 



The cost of good electrically fitted machinery installed should be little, if any, more than 

 that of high-grade steam machinery. Of course, until apparatus reaches a stage of standard- 

 ized production the costs cannot be materially reduced. It must be remembered that, while in 

 steam machinery all kinds of economies may be practiced at the cost of quality, in electrical 

 apparatus built to withstand marine conditions and severe service a departure from the high- 

 est grade is most certain to be followed by failure and consequent cost to the operator. The 

 making and insulating of electrical machinery cannot be materially hastened, as the succes- 

 sive dryings or bakings of the insulation must be given proper time; otherwise, it may be 

 imperfect. The insulation in a marine motor must be moisture resisting to the maximum 

 practical extent ; otherwise, it should not be deemed proper for the service. 



Plate 29 shows a deck winch developed in this country, several of which type will shortly 

 be installed on ships. This winch is a radical departure from the generally recognized de- 

 signs using either spur or worm gearing. 



Electric steering gears have been developed for mechanical control of the rudder. For 

 these the service is extremely intermittent, operating from two to ten times per minute, which 

 means that the motor would be started, stopped and reversed thousands of times during one 

 voyage. Such gears require the installation of a motor of sufficient torque to swing the 

 rudder to the extreme angle, whereas during most of the time a very small amount of 

 power is required. This means loss in efficiency as the motor is operating nearly all the 

 time very much underloaded. 



For controlling the steering gear from the pilot house two electrical means are avail- 

 able — follow-up and nonfollow-up. The first entails considerably more wiring, a multiple 

 switch in the wheel house, a more complicated control in the steering engine compartment, 

 and has the disadvantage of moving the rudder step by step a definite number of degrees. 

 By the nonfollow-up means the rudder can be moved by fractions of degrees in either di- 

 rection; its use, however, calls for the installation of a rudder indicator in the wheel house. 

 A device has been worked out to show positively the position of the rudder at any instant, 

 using simple means already developed. 



