Sea witch

not without basis, that there may have been design, structural or metallic faults in one or more of the legs.

And then there is the third type of oil rig— the TLP—technically, the tension leg drilling/ production platform. At the time of this story there was only one of its type in the world. The platform, the working area, was about the size of a football field—if, that is, one can imagine a triangular football field, for the platform was, in fact, an equilateral triangle. The deck was not made of steel but of a uniquely designed ferroconcrete, specially developed by a Dutch shipbuilding company. The supports for this massive platform had been designed and built in England and consisted of three enormous steel legs, each at one corner of the structure, the three being joined together by a variety of horizontal and diagonal hollow cylinders, the total combination offering such tremendous buoyancy that the working platform they supported was out of reach of even the highest waves.

From each of the bases of the three legs, three massive steel cables extended to the base of the ocean floor, where each triple set was attached to large sea-floor anchors. Powerful motors could raise or lower these cables, so that the anchors could be lowered to a depth two or three times that of most modern fixed oil derricks, which meant that this rig could operate at depths far out on the continental shelf.

The TLP had other very considerable advantages.

Its great buoyancy put the anchor cables under constant tension, and this tension practically eliminated the heaving, pitching and rolling of the platform. Thus the rig could continue operating in very severe storms, storms that would automatically stop production on any other type of derrick.