316 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1957 



plateau) ; and finally the remaining 500 miles from Rockall Bank to Oban. 

 The No. 2 cable followed the opposite sequence, starting at Oban and 

 proceeding in 3 sections of 500 miles, 1,250 miles, and 200 miles to the 

 terminal at Clarenville. Shore ends, about f mile long at Clarenville and 

 2 miles at Oban, were prepared and put in place in advance of the time 

 when they would be needed. At each intermediate point, the cable was 

 "buoyed off" with a mushroom anchor, connecting lines, and a surface 

 buoy of size appropriate for the water depth. 



The mileages indicated are actual cable lengths. They exceed the 

 geographical distances between the points involved because of the slack 

 allowance which experience has shown to be necessary to assure reason- 

 able conformance of the cable with the contour of the ocean bed. Nor- 

 mally, about 5 per cent slack is considered desirable in deep water, with 

 the allowance decreasing in steps to zero in shallow water. 



All available information indicated that the most favorable weather 

 conditions in the North Atlantic could be anticipated in the period ^lay 

 through August. Prior to May, ice could be expected along the western 

 sections of the route and after August, hurricanes were likely, and later 

 the winter storms. 



The laying of the No. 1 cable was started June 28, 1955, and com- 

 pleted September 26. The actual laying period took in but 24 days in 

 this interval, the remainder of the time being spent in transit and in re- 

 loading. The No. 2 cable was started June 4, 1956, and completed August 

 14. About 16 of laying days were involved. 



The routine aboard ship during laying consisted in passing out cable 

 at the rate of 6 to 7 knots for a repeater section length of a little over 

 37 nautical miles, then slowing down to about 3 knots as the repeater 

 passed through the cable machinery and overboard, then back to speed 

 again. During all of this period the testing crews, both on shipboard 

 and at the transmitting cable station, were busy measuring, recording 

 data and planning the equalization trimming. At a point shortly after 

 the passage of the next-to-last repeater in an ocean block, special meas- 

 ures were required for the equalization program. From that point until 

 the joints associated with the connection to the following ocean block 

 had been completed, the speed was reduced to 5 knots. The need for 

 this arose from the following considerations. 



Stopping of the ship in deep water introduces serious possibility of 

 formation of kinks in the cable, and is to be avoided at all costs. To per- 

 mit continuous laying, it was necessary to determine the amount of 

 cable needed for equalization, measure out this cable, and complete 

 the splices before reaching the end of the block being laid. 



