When a semi-submersible drilling platform reaches position it requires dynamic positioning to remain stationary, but if the rig needs to remain in the same position for an extended amount of time then a mooring pattern will be laid. Due to the size of the platforms and the depths in which they operate, it is essential that the mooring pattern is spread - often over an area spanning 6km - using a series of winches and brakes to control the cable payout.rnBrakes supplied by Altra Group subsidiary, Wichita Clutch, are currently being used on semi-submersible rigs for the dynamic tensioning and static holding of anchor cables that maintain rig position during drilling operations. At times, when these cables are run out to several kilometres, the winches bear torsional loads of up to several hundred tonnes. But thanks to their copper alloy heat transfer surfaces, which provide optimum heat dissipation, these dual-action brakes are perfectly capable of taking the peak loads.
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