The Assistant Driller was operating the winch to lift the kelly hose to be installed on the drill string. Although it was being guided by the roustabout the hose became snagged on a bolt securing the hand tools board hanging on the rig floor handrail. The assistant driller stopped the winch and then reversed it to lower the kelly hose but at the same time the roustabout went to release the hose manually and his right hand middle finger trapped between tool board and hand rail causing crush injury.