GLOMAR CHALLENGER

oceanographic drilling and coring vessel, constructed in the late 1960s by Global Marine, Inc. The only ship of its kind in the world, it is capable of drilling in water depths up to 6,000 m (20,000 feet) and of bringing back core samples from depths as much as 750 m (2,500 feet) below the seafloor. To maintain the extreme stability required for this operation under differing current, wind, and wave conditions, the vessel is equipped with a computer-controlled roll-neutralizing system. An automatic pipe-racking device helps handle the numerous lengths of drill pipe needed. A drilling derrick 43 m (140 feet) high, mounted in the centre of the vessel, lowers the drill through an opening 6 by 6 m (20 by 20 feet) that extends through the bottom of the ship, which is 120 m (400 feet) long and 20 m (65 feet) wide. To prevent the roll and pitch of the ship from bending the string of the drill pipe too sharply, a flared structure on the ship surrounds the pipe. Living facilities are provided on board for 70 persons. Core samples gathered by the Glomar Challenger from 1968 to 1983 added much weight to the hypothesis of seafloor spreading, which played a pivotal role in the development of the theory of plate tectonics.