Design. It is apparent that loads weighing in excess of 1 00 tons will 

 require more than one cable for support if they are to be safely lowered to 

 6,000 feet. The need for more than one suspending medium is peculiar to 

 the cable systems. For a 600-ton load, for example, six cables controlled by 

 six coordinated winches will be required for the system. Of primary concern 

 in this or any other multiline system is the problem of cable entanglement. 

 The tendency of wire ropes to rotate under strain and spinning of the load in 

 underwater currents can cause the lines to wrap around each other. Another 

 very serious source of line entanglement is the kinking which results from 

 relieving line tension. There will be a large amount of energy stored in the 

 cables when they are stretched their full lengths under high-load conditions. 

 The release of this energy, initiated by disconnecting the load, will lead to 

 very serious entanglement unless thwarted by some device such as a large 

 strongback. Research on the cable tangling problem is being conducted at 

 the Naval Civil Engineering Laboratory. At present, it should be considered 

 an area of great uncertainty. 



A dynamic load analysis analogous to that for the pipe string system 

 was conducted. Heave motion spectra for the T-2 tanker, C1-M-AV1 ship, 

 and FORDS platform, combined with dynamic load curves for the cable in 

 question, indicate that no serious dynamic forces will be encountered with 

 large vessels in a sea state 4 or less. 



It was found that the lighter loads suspended on cable can be 

 displaced considerable distances under heavy currents. However, no 

 unusually high stresses will occur in the cable because of the current 

 loading. 



Cable Handling Equipment. The equipment needed to handle the 

 amount and size of cable necessary for this project is within the state-of-the- 

 art. The FORDS study^ of J. Ray McDermott and Company, Inc., contains 

 a description of some winching equipment capable of raising and lowering a 

 450-ton payload to 6,000 feet. Each of the four winches supported one-fourth 

 of the load, and was equipped with 6,600 feet of 3-1/8-inch diameter wire 

 rope. As with the pipe handling systems discussed earlier, the winches, sheaves, 

 and other associated items of equipment for the cable systems would be 

 enlarged and strengthened versions of smaller units. The fact they are not 

 off-the-shelf items can be attributed to lack of demand. 



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