Pneumatic Underwater Coral-Coring Drill

Abstract To extract meter-length, large-diameter cores from live massive corals on shallow reefs we developed a versatile underwater pneumatic drill driven by a portable gasoline-powered air compressor carried onboard a small boat. This drill was used to obtain intact cores 8.0 cm in diameter and 0.5‐1.5 m long from Guam's coastal waters. Advantages of this pneumatic drill over standard hydraulic drills include (1) lower cost; (2) easier portability; (3) more stable, safer, and faster drilling; and (4) elimination of the need to carry and use hydraulic fluid on the coral reef. The pivotal innovation in the application of pneumatic technology was use of an air motor rather than a conventional handheld pneumatic drill. Another significant innovation was employment of a pneumatic water pump to provide a continuous flow that purges debris from the borehole and the cutting edge of the diamond drill bit. This drill can provide paleo-climate researchers and others interested in retrieving high-quality coral core samples with a reliable, economical, easy to operate, safe, and environmentally friendly alternative to more expensive and cumbersome hydraulic drills.