the appropriate reference given. Where no 

 reference is provided, it is from the author's 

 personal experience. 



One or two submersibles appear more fre- 

 quently than others in the following inci- 

 dents; this is not because they are less safe, 

 but reflects the fact that they either dived 

 more often or their incidents were recorded 

 and published. DEEPSTAR 4000, for exam- 

 ple, appears quite frequently. This can be 

 attributed to its frequency of diving between 

 1966 and 1969 (approximately 500 working 

 dives) and the fact that Mr. Pritzlaff is an 

 employee of DS-4000''s owners (Westing- 

 house Corp.) and has access to its diving 

 history. 



INCIDENTS 



As far as is known, the only instrument 

 used to avoid exceeding operational depth 

 which has performed satisfactorily is the 

 depth gage. Automatic deballasting or re- 

 straining (surface buoys) devices seem, in- 

 stead, to have worked as the following inci- 

 dents demonstrate. 



Buoys 



Submersible: PC-3B (TECHDIVER) Date: 



5 June 1965 



Incident: Trailing a 0.25-inch-diameter 

 nylon line and surface buoy, PC-3B found 

 forward movement impossible at a depth of 

 400 feet along a vertical escarpment in the 

 Tongue of the Ocean, Bahamas. After back- 

 ing down, it was found that the line was 

 hung on an outcrop. The line's breaking 

 strength was believed beyond the ability of 

 the submersible to break by deballasting; 

 hence, it was removed and not used on subse- 

 quent dives in this operation. 



Submersible: SP-350 (DIVING SAUCER) 



Date: 1959 Reference (2) 



Incident: Trailing a 330-foot nylon line 

 attached to a surface buoy, SP-350 experi- 

 enced difficulty in steering. Turning the ve- 

 hicle around, the operator found that the 

 line was snagged on a coral head at the 100- 

 foot depth and, by maneuvering, freed the 

 line. 



Submersible: PC5C Date: NA Reference (1) 



Incident: On shallow missions Perry op- 

 erated vehicles (PC5C, SHELF DIVER and 



others) periodically towed surface buoys for 

 tracking purposes. These buoys have occa- 

 sionally become entangled in surface struc- 

 tures or the tracking ship. In one case, the 

 ship caught the buoy line and actually 

 dragged the submersible off course. Because 

 the buoy and buoy line were firmly attached 

 to the submersible and there was no method 

 available for the submersible to release the 

 line if it became entangled, a line release/ 

 cutter assembly was added to the submers- 

 ibles to jettison the line. 



Submersible: DEEP JEEP Date: ca. 1966 



Reference (3) 



Incident: While submerged, DEEP 

 JEEP^s "fail-safe" electromagnetically se- 

 cured ballast plates accidentally dropped 

 and, without the operator's knowledge, the 

 submersible began to ascend with five or six 

 ships overhead. The operator was able to 

 bring the vehicle to a halt 30 feet below the 

 surface where he remained until located by 

 his support craft and cleared to surface. 



Underwater Obstacles 



Submersible: ASHERAH Date: 1964 Refer- 

 ence (1) 



Incident: ASHERAH was operating in a 

 depth region where wave action was a factor. 

 There were no guards on the viewports and 

 no structures in front of the pressure hull. 

 The submersible struck an underwater ob- 

 ject and the viewport cracked, but did not 

 flood. External guards were later installed in 

 front of the viewports (Fig. 15.1). 



Loss of Normal Surfacing 



Submersible: SP-350 Date: 



1959 Refer- 

 ence (2) 



Incident: At 360 feet deep SP-350's 

 nickel-cadmium batteries short-circuited. 

 The ascent weight was dropped and the vehi- 

 cle began to ascend until gas generated in 



686 



