Importance

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Abstract

A communication arrangement between a sub-sea structure and a surface vessel is by a flexible control umbilical deployed from the vessel in such a way as to accommodate relative movement between the structure and vessel. Unpredictably excessive movements can risk breakage of the umbilical, causing damage to equipment controlled by it and `down-time` while the equipment is repaired and the umbilical replaced. In the present invention (FIG. 2) the umbilical 13 is suspended from a reel 20 of deployment means 14, which is braked to resist motion below a predetermined level of umbilical tension but above that level the braking is overcome enabling the deployed umbilical to draw off, and deploy, a further length 13' while the communication channels of the umbilical are shut-down, including powering-down any sub-sea equipment in controlled manner. If, subsequently, the further length of umbilical is all deployed, or optionally, the umbilical tension exceeds a second predetermined tension, umbilical coupling means 28, at which the umbilical is coupled to the vessel system, is released at the coupling point to fall into the sea to be recovered and re-coupled when conditions permit.

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First Claim