Incident: Searching for the remains of 

 the submarine THRESHER at 8,200 feet, a 

 severe short circuit occurred in the bathy- 

 scaph's main propulsion motors. The over- 

 load relays in the battery circuit failed to 

 open and they arced over to each other caus- 

 ing the batteries to discharge to zero and 

 melt the battery cables. Emergency batter- 

 ies in the sphere allowed control of shot 

 dropping and continuation of the life support 

 system. The author points out that if the fire 

 had been elsewhere than underwater, the 

 arcing, which occurred only 4 feet from the 

 gasoline reservoir, could have ignited the 

 46,000 gallons of high octane gasoline in the 

 buoyancy tanks. 



Submersible: UZUSHIO Date: June 1974 



Reference (20) 



Incident: Diving in 33 feet of water the 

 tethered diving bell VZUSHIO experienced 

 an electrical short circuit in the interior vi- 

 nyl wiring insulation. An alarm on the sup- 

 port ship WAKASHIO sounded and the bell 

 was brought to the surface within moments. 

 Less than 2 hours after the alarm sounded 

 the two occupants were dead, the cause 

 being either toxic fumes or rapid consump- 

 tion of oxygen by the fire. It has been re- 

 ported that the vehicle's designer subse- 

 quently committed suicide. 



Separation From Support Craft 



Submersible: DEEPSTAR 4000 Date: 



1968 Reference (1) 



Incident: The vehicle was diving at 

 night in the vicinity of the Gulf Stream. The 

 subsurface current profile did not follow the 

 surface current profile. This resulted in sepa- 

 ration of DS-4000 from its support ship and 

 loss of communications. Using established 

 "loss of communications" procedures, the ve- 

 hicle surfaced. An electrical storm affected 

 the small "CB" radio and surface communi- 

 cations could not be established. Six hours 

 after surfacing the pilot fired a small flare 

 that was seen by the support ship. Because 

 of this incident, the submersible's "CB" radio 

 was replaced with a higher powered FM sys- 

 tem and an FM direction finding capability 



was added to the support ship. The submers- 

 ible flare system was upgraded to a 20-mm 

 size with a parachute flare capability. 



Submersible: DEEPSTAR 2000 Date: 5, 

 6 July 1972 Reference (9) 



Incident: The submersible was diving in 

 Wilmington Canyon, 125 nm southeast of 

 Cape May, New Jersey. Tracking was con- 

 ducted with a range and bearing device from 

 a small (16-ft) boat with three people aboard; 

 the small boat was visually kept in sight by 

 the support ship. Weather predictions were 

 obtained from a New Jersey commercial ra- 

 dio station which predicted occasional show- 

 ers and 10- to 15-knot winds. At 1405 hours 

 (LCT) DS-2000 routinely surfaced out of vis- 

 ual range of both the small boat and the 

 support craft. Radio contact was established 

 with the submersible and its flashing xenon 

 light was on to assist recovery. By 1515 

 hours squalls and low clouds came into the 

 area which reduced visibility to several 

 hundred yards. The support craft and small 

 boat proceeded in a direction they believed 

 would take them to the submersible. Though 

 separated by only 200 yards, the small boat 

 lost visual contact with the support craft but 

 maintained radio contact. The weather was 

 deteriorating rapidly and winds increased to 

 35-50 knots with seas of 12 to 15 feet in 

 height. One hour and 25 minutes after DS- 

 2000 surfaced, the support craft, not able to 

 locate either the submersible or the small 

 boat, radioed the Coast Guard for help. At 

 1900 hours a Coast Guard aircraft sighted 

 DS-2000''s light and vectored the support 

 craft to it. The weather was now so inclem- 

 ent that retrieval was unacceptable and 

 the support craft maintained visual contact 

 with the submersible until 1350 hours the 

 following day when it retrieved the submers- 

 ible under extremely trying conditions. The 

 small boat, on the preceding evening, re- 

 ported that it had found a buoy and would tie 

 up to it. At this point its radio went dead. 

 The description of the buoy as received from 

 the small boat matched nothing on the 

 charts of the area. In spite of a 10-foot-high 

 radar reflector in the small boat, the sea 

 return was sufficient to mask out any radar 



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