Rotation of and Tortion in the Unbiliacl Cable for the Chikyu “Under Water TV”

Offshore industry often uses underwater devices and most of those devices need umbilical cables for power feeding and communication. Although such umbilical cables are vital for the underwater devices, sometimes unfortunate failures can be happen on the cables. Excessive torsion of cables would be a significant cause of failures and generally, so-called free fall operations are conducted to release torsion. In this paper, some failures caused by torsion of a Chikyu “Under Water TV” umbilical cable are shown. Then cable data obtained in free fall operations and related experiments are shown and discussed. We believe that these failure examples and cable data are of general interest and are valuable to be published. Countermeasures we employed to prevent failures are introduced briefly as well.