ROUTE SELECTION AND CABLE LAYING 307 



Monarch is driven by two steam engines. The maximum propeller 

 revolutions are estimated at 110 per minute, giving a ship's speed of 

 about 14 knots. 



Two cable engines are fitted forward, both capable of being used for 

 picking up or paying out. These are driven by electric motors having a 

 maximum rating of 160 hp, which will permit picking up at a rate of 

 0.9 nautical miles per hour with a stress of 20 tons, or at 3.5 knots with 

 a stress of 5.3 tons. The drive system is constant current, so designed 

 that a uniform torque may be held at the drum for any setting of the 

 speed control. When paying out, these motors operate as generators to 

 provide electrical braking, and auxiliary mechanical brakes are also 

 provided. 



A single cable engine is fitted aft and this is the main paying out gear. 

 In addition to the electrical brake, the aft engine is provided with 

 a multiple drum externally contracting band brake, manually adjustable 

 and water cooled, and with a further auxiliary fan brake. The fan shaft 

 is driven in such a manner that when cable is being paid out at approxi- 

 mately 8f knots the fan will revolve at 1,000 rpm and absorb 120 

 bhp. Adjustments in this are effected by varying the amount of opening 

 in the fan shroud so that as little as 27 bhp may be absorbed. 



Dynamometers, both fore and aft, provide for measurement of the 

 cable tension. 



Taut wire gear is furnished on the starboard quarter to provide an 

 effective means for calculating the amount of slack paid out. With this 

 gear, steel piano wire, anchored to the bottom, is paid out at constant 

 tension and provides a rough measure of distance steamed over the 

 ground. 



A test room with trunks to each cable tank is provided on the shelter 

 deck and fitted with instruments for measuring and locating faults. 



Modifications for Flexible Repeaters 



In the normal cable-paying-out process, the cable is drawn from the 

 tank, carried along fairleads to the holdback gear (a mechanism for ap- 

 plying slight tension to the cable so that it will snub tightly around the 

 drum), and then wrapped around the drum of the cable engine from two 

 to four turns depending upon the weight of the cable and the depth of 

 the water. At the drum, a fleeting knife is fitted which pushes over the 

 turns already present to make way for the oncoming turn. From the 

 drum the cable passes through the dynamometer and thence to the 

 overboarding sheave. 



The Bell System repeaters, manufactured by the Western Electric 



