Abstract: Some shipyard employees were working in the aluminum hull of a Navy patrol boat (Job No. PCT-G216). One of the employees was working alone in a 6-foot by 6-foot by 3-foot fuel tank hold inside the hull. He was welding a sounder tube into place. He had a grounded drop light and an Arrow welding gun (Model No. AH20-E). The welding gun was plugged into an Airco welding machine (Model No. 25 DTR-24A, Serial No. HE753734) at ground level. The welding machine output was rated at 460 volts and 250 amperes and was connected in three-phase mode. He was only fitting and tacking the tube in place. Another worker was to finish welding the tube. Sometime between 1:45 and 2:00 PM, he apparently received an electric shock. He was discovered unconscious in the hold at about 2:00 PM. He had been electrocuted. The autopsy found current entry and exit wounds on a forearm and on a cheek. The source of the electric shock was not determined.