The Diver whilst underwater has a restricted ability to move as easily as he does in air. For example using a hammer underwater the drag is over 800 times greater than the drag in air. The added restriction provided by hoses, communication cables etc further reduce the divers ability to perform with efficiency.  Other restrictions such as the visibility, the light concentration and the optical properties of water further hamper the diver's ability. Cold water and limits on the bottom time make some of the simpler operations difficult to perform. When designing tools considerations are size , weight and shape.  Switches and controls must be large enough to be operated with gloved hands. The use of buoyancy aids and suction cups and springs can help to overcome some of the restrictions. The weightlessness which so eases the movement of the diver underwater now act against the diver when he tries to exert pressure against the work piece..
Free swimming divers find small reaction forces even harder when applying pressure.

Copyright by Diving Heritage 2006