1) Why cut metal underwater

There are many reasons why we might wish to cut metal below water; to remove damaged or corroded parts for repair or replacement, for salvage operations, decommissioning of redundant structures or modifications to structures, whilst they effectively remain in service. In each case the ability to cut metal in the wet environment obviates the need for drydocking or the construction of a dry habitat, with considerable savings in time and cost. The important factors are diver safety, speed of cut, and the process cost. In the case of repair or modification, quality of cut is significant.