maintain a controlled tension in cables during deployment. These 

 features also reduce greatly the dynamic tensions in the cable. 



Electrical Ingress Devices . If the electrical circuit is required 

 to be monitored during the cable deployment, slip rings are generally 

 used on the cable spool. For multi-conductor and coaxial cable, the 

 complexity of such slip rings increases and reliability decreases. A 

 "transfer drum" design in the cable spool eliminates the use of slip 

 rings. The design consists of two parallel drums revolving about each 

 other inside the cable spool. One end of a drum connects to one spool 

 shaft while one end of the other drum connects to the cable spool. Elec- 

 trical cable comes in through the shaft, wraps on one drum in one direc- 

 tion and on the other drum in the other direction and, finally, connects 

 to the electrical-mechanical cable on the cable spool. As the cable is 

 being payed out, the internal transfer drums transfer the electrical 

 cable from one drum to another allowing electrical continuity without 

 the use of a slip ring. 



The disadvantages of such a design are additional resistance due to 

 the increase in cable length and the fatigue strain induced to the cable 

 conductors during the transferring from one drum to another. 



Surface Platform . Towed barges have been used in relatively shallow 

 water by the offshore industry for laying power and communication cables. 

 In high seas, it becomes difficult to maintain a course. Huge cable 

 ships are used in transocean telephone cable laying. The C/S LONG LINE 

 is 550 feet long and was built to lay armorless SD cable onlv. No parti- 

 cular difficulties have been reported. A dynamically positioned ship 

 NAUBFC was used in cable laying operations and provided automatic control 

 of the course. The system worked successfully in maintaining course but 

 the lateral thrusters caused severe rolling of the ship. 



Flotation Packages . For deep ocean deployments it is generally re- 

 quired that a suspended cable be neutrally buoyant. Spherical buoys have 

 been attached manually to the cable during the paying out phase. Fast 

 snap-on slamps and preformed wires have been used to fasten the buoys. 

 Even so, the process is time-consuming and as the cable rotates in the 

 water the buoys may be worked loose. The problem may be eliminated bv 

 the development of neutrally buoyant cables or auickly attached buoyant 

 jackets. Development work is currently being conducted by the Navy on 

 "buoyant" working and structural cables. 



Inspection and Protection 



After cable is laid on the seafloor in shallow water the general 

 practice is to check the electrical characteristics. If the cable does 

 not perform properly divers are sent down to inspect the cable. Usually 

 the damaged location is found, retrieved and repaired. In deep water the 

 inspection of cables either laid on the seafloor or suspended in the 

 water column becomes a difficult task. Small working submersibles are 

 usually limited to depths less than 10,000 feet. Also, to locate and 

 follow the cable throughout its length is time-consuming and difficult. 



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