A CAPSTAN WINCH WAS USED TO POSITION AND TIE-OFF BARGES UNDER A FIXED LOADING SPOUT. THE INJURES EE COULD NOT UNTIE THE MOORING ROPE FROM THE D3E-ENERGIZED CAPSTAN WHEN HE NEEDED TO REPOSITION A BARGE BECAUSE OF HIGH ROPE TENSION. THE EE USED AN UNAUTHORIZED PROCEDURE: HE STARTED THE CAPSTAN & KICKED ROPE WITH RIGHT FOOT. IT BECAME CAUGHT. ENTIRE LEG INJURED, AMPUTATED LOWER LEG.