This 1984 cover depicts the world’s first full-scale tension leg platform. Positioned in the North Sea, 260 miles off the Scottish coast, above the Hutton oil field, it was anchored to the seabed in 485-ft-deep water by 16 steel tethers. The floating structure could swing to either side of its foundations like an inverted pendulum by up to 68 ft, eliminating vertical movement and revolutionizing deepwater oil and gas extraction. Its 300-ft-by-300-ft base featured pontoons which supported six, 200-ft-tall columns built in a dry dock, with a 26,000-ton hull and a 19,000-ton 250-ft-by-243-ft steel deck. Developer Conoco UK Ltd. employed Bechtel Great Britain Ltd.; Brown & Root (UK) Ltd., and British naval architect Vickers Offshore Ltd. to design the floating vessel and foundations. Each of the tethers (also known as tendons) consisted of a 106-ton string of 17 specially designed 10-in.-dia steel pipes threaded together.…