Ferranti Subsea Systems, Inc.

James L Mank

Bryson Riddler

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.

Communication arrangement between a sub-sea structure and floating vessel

A lifting system (FIG. 3) for lifting a hanging flexible elongate member such as an umbilical 10 without disconnecting its ends comprises a foundation member 21 permanently clamped to the umbilical at a lifting point and a removable lifting member 22 suspended from winch 63 of lifting mechanism 23. The foundation member has a rigid body portion 25, including a downwardly facing shoulder 29, and a bend restrictor 26 at its upper end and the lifting member comprises a pair of hinged semicylindrical segments 40, 41 which can be joined about an upper part of the umbilical to form an annular carrier of support members 45 movable radially by hydraulic actuators 50. The lifting member is initially applied with support members withdrawn, to slide down the umbilical and past the foundation member, the support members then being brought together and the lifting member raised, engagement of the support members with shoulder 29 lifting also the foundation member and umbilical. Loading forces between umbilical and lifting means are spread over the contacting length of the foundation member and flexing of the umbilical is kept within to safe radius of curvature by the bend restrictor. The removable lifting member prevents fouling with equipment at other times and can be caused to lift from an inaccessible lifting point while being applied to the umbilical at a higher more accessible point.

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High Wycombe, United Kingdom

James L Mank