A series of drills has been developed at the Bedford Institute of Oceanography for collecting cores of hard rock from the ocean floor. Early deep-sea drills were hydrostatically powered and were principally employed on the Mid-Atlantic Ridge. However, these drills have been replaced by a deep-water version of an electric rock-core drill originally designed for continental shelf work. Part of the design philosophy behind these drills is operability from any research ship. To that end, the cable is mounted on a portable winch, and the workshops and controls are built into standard 20-foot containers.
The drill is driven by a 2,400-V electric motor powered and controlled from the ship through a contrahelically armored triaxial cable. Information from the drill, such as tilt angle, extension rate, down load, and flushing pressure, is multiplexed and transmitted up the cable. A television camera and light mounted on a pan and tilt unit have been added to the drill to aid site selection. Problems with interference and lighting have not been completely solved. The drill has been proved at depths of 3,500 m and on slopes of up to 30°. The drill was used in May 1986 to recover a short core of massive pyrite and pyrrhotite from the Middle Valley of the northern Juan de Fuca Ridge.
KeywordsMotor Current Short Core Fuca Ridge Empty Chamber Electric Drill
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