The single-armor type is frequently employed as undersea 

 transmission cable. The double-armor cable is used extensively 

 in oil-drilling operations and in naval systems such as the 

 variable-depth sonar. There is a significant advantage in 

 using a cable with the electrical leads in the outer jacket 

 as this simplifies the problem of connecting measuring 

 instruments along the cable. This advantage is offset, 

 however, by handling problems, as the electrical leads are 

 susceptible to crushing and wear. In some applications, a 

 wire rope and a separately attached electrical cable have 

 been employed. Here, the handling problem is still serious, 

 as the electrical leads may be crushed under the wire rope 

 in passing over sheaves and drums; it is not practicable to 

 prevent twisting of the two cables in handling. Furthermore, 

 under tow, the electrical cable tends to billow out between 

 points of attachment and thus to increase the drag and vibra- 

 tion of the system. This can cause early fatigue failure of the 

 electrical leads, and breakdown of the insulation. 



Another design employs the strength member as an electri- 

 cal conductor. This principle is used in the cable used in 

 the deep oceanographic instrumentation probes being developed 

 by Scripps Institute of Oceanography, That cable, manufactured 

 by Columbia-Geneva Steel, is a steel strand composed of 19 wires, 

 0.031-inch O.D., and 18 wires, 0„028-inch 0,0., covered with a 

 polyethylene jacket to 0.32-inch OoD« This cable has an 



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