ROUTE SELECTION AND CABLE LAYING 315 



purposes included precise determination of repeater crystal frequencies 

 on the bottom, gain frequency runs to show up any fine grained structure 

 which might exist in the band, and values of line current and driving 

 voltages. 



Copper resistance and capacitance measurements proved to be of 

 dubious value; in the first case because of the temperature/resistance 

 characteristic of the vacuum tube heaters; in the case of capacitance, 

 probably because of polarization effects in the castor oil capacitors used 

 in the repeaters. 



Shipboard Test Equipment — A new test room had been equipped for 

 making the above measurements with transmitting and receiving trans- 

 mission measuring sets^ including the crystal test panels. These sets were 

 provided in duplicate to forestall difficulty should one set develop trouble 

 during the laying. The transmitting consoles were recjuired only for 

 use in calibrating the receiving sets, and for some measurements which 

 were made on individual ocean blocks in the ship's tanks. 



Additional gear in the test room included a cable current power sup- 

 ply,-* and a "Lookator" which is a pulse echo type of fault locator useful 

 from a point in the cable to the adjacent repeater on either side. 



Laying Sequence 



H.M.T.S. Monarch is the largest cable ship afloat, \\ith capacity for 

 about 2,000 miles of the Type D deep sea cable in her tanks. However, 

 because of the inherent limitation on their bending radius, the presence 

 of flexible repeaters in the cable puts a restriction on the height to 

 which the coil can be permitted to rise in the tanks. For repeatered Type 

 D cable, therefore. Monarch's capacity is cut back to about 1,600 nauti- 

 cal miles. 



Types A and B cable, used in shallower waters, are considerably larger 

 and heavier than Type D and consequently, less of these can be car- 

 ried. 



The ideal laying program would have involved one continuous pas- 

 sage across the North Atlantic from cable station to cable station. How- 

 ever, this would have required carrying over 1,900 miles of cable in- 

 cluding about 300 miles of Type A and something less than 50 miles of 

 Type B. Such an amount of cable would greatly exceed the ship's 

 capacity. 



Each cable was, therefore, laid in 3 sections. The No. 1 cable (southern- 

 most), which transmits from west to east, was laid in the following se- 

 quence: Clarenville to just beyond the mouth of Trinity Bay, a distance 

 of 200 miles; thence about 1,250 miles to Rockall Bank (a submerged 



