THE CABLE SHIP ON REPAIRS. 235 



distances between positions, lengths of cable paid out, percen- 

 tage slack, &c. The positions of the various splices and types 

 of cable at the splices at the time of laying are all recorded in 

 the splice list, and this is kept up to date by the entry of all 

 new splices and lengths of cable added during subsequent repairs. 

 By referring to these records it is often possible to avoid the 

 making of a new splice close to an old one, and so adding 

 unnecessarily to the joints in the cable. For instance, while 

 picking up towards a fault, say that the tests make it about 

 three miles further on. This estimate may or may not be 

 correct, and the fault may still be seaward when the cable is cut 

 at this distance. At any rate, if the chart indicates a previous 

 splice existing one mile beyond the estimated distance, it will be 

 better to pick up the four miles and cut at the splice, so saving 

 an extra joint in the cable. 



Capacity of Tanks. — While cable is being coiled on board 

 during the operation of picking up, we may for a moment con- 

 sider the approximate lengths of cable that can be stored in the 

 tanks. Three or four tanks are provided, so that the total weight 

 of cable may be distributed to properly trim the ship, and these 

 are not usually more than two-thirds full. Repairing-ships 

 carry a good deal of spare cable of different types for splicing in 

 and have to stow this as most convenient for the work in hand, 

 while space must be provided for cable as picked up in the 

 course of repairs. This is arranged as far as possible to suit the 

 work and trim the ship, but sometimes both these conditions 

 cannot be met and the ship is too much down by the stern. In 

 that case water is pumped into the forward ballast-tank until 

 the ship is on an even keel. 



The length in nauts of any given type of cable that can be 

 coiled in a tank of known dimensions may be found roughly by 

 dividlno; the net coiling space by the volume of the cable per 

 naut, both being expressed in the same units, say, in cubic 

 feet. By the net coiling space is meant the volume of the 

 tank less that of the cone ; that is, the actual space available 

 for taking cable. 



To fix ideas, take a tank of 30ft. diameter, in which is a 

 central cone of 6ft. mean diameter. The net coiling space is : — 



[(30)-2-(6)2] -7854 = 679 cubic feet per foot height. 



