A thermal drill for making large holes in sea ice

A drill has been developed that utilizes thermal energy in the form of heated water to melt a groove by convective heat transfer in thick sea ice. The system components are described, as well as the techniques involved in cold-starting the system at ambient temperatures down to -35°C. The five operational units that have been constructed are also described and some of the field operations are discussed, including the drilling of a hydrohole 1.2 m by 3.7 m through sea ice about 8.5 m thick at Ice Island T-3. Comparable holes of various sizes and shapes can be made with suitably-designed cutting heads and multiple melts.