Abstract
The British Antarctic Survey has developed a hot-water drilling system used chiefly for installing temperature sensors through ice shelves and for retrieving oceanographic equipment tethered through thick fast ice. The specification, design and operation of the drill for these two activities will be discussed and practical field problems will be highlighted.A novel aspect of the design is the use of reaming nozzles to enlarge a pilot hole. These nozzles eject water upwards along the surface of the nozzle cone, and drill most efficiently when they hang free and unsupported by the sides of the pilot hole. The nozzles incorporate a nozzle-mounted valve, activated when the nozzle cone contacts the ice, thus increasing the back pressure of the water flow. The pressure increase is monitored at the surface and the winch speed is reduced accordingly in order to ensure an efficient drilling operation.
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