About 17 per cent of the world's present day oil supplies comes from wells drilled in the continental shelf of some 28 countries. The demand for oil is increasing each year and is expected to quintuple in the next decade. In the same period, the demand for gas will climb to at least 20 times its present rate.In the next decade, the percentage of oil and gas obtained from, offshore is expected to rise to nearly half the world's consumption.The offshore oil industry is currently striving to achieve new technological advances in the field of deep ocean operations, especially in face of adverse seas. While the emphasis was put on drilling vessels for exploration, the industry was slow in developing effective offshore construction vessels. Until a year ago, construction vessels were but large barges with construction equipment mounted on their decks. These vessels all shared the same severe limitation: when the sea exceeds a 5 ft wave height (and in some cases as little as 3 ft) the conventional construction barge is forced to suspend operations. In face of an oncoming storm they must run for shelter.Their utilization, therefore, is limited and in rough weather areas, such as the North Sea or the Bass Strait, is lower than 50 per cent.In July, 1969, the world's first column stabilized construction vessel was christened the derrick pipe-laying barge Choctaw. In October of the same year, Choctaw was working in the Bass Strait in the East Gippsland area, defying 10ft swells and high winds.This paper describes the economic and technical background to the development of Choctaw, as well as the pIiifosophy of design and design procedure including tank tests and results. Finally, the paper discusses how the design expectations were realized in actual operations in the Bass Strait.