submersibles have been built throughout the 

 world and have conducted thousands of dives 

 carrying over 30,000 people. In this 25-year 

 period there have been four fatalities in sub- 

 mersibles themselves and one submersible- 

 related fatality. It would seem that irrespon- 

 sibility is not a characteristic of this ungov- 

 erned industry. 



POTENTIAL HAZARDS 



"// everything has been done in ad- 

 vance, and no one makes a fool of hint- 

 self, or forgets, a submarine is the safest 

 kind of boat to be in.^^ 



— Simon Lake 



Albeit a submarine is a safe boat to be in, but 

 Mr. Lake did not envision that it would be 

 lifted out of the water after each dive and 

 carry an agglomeration of equipment while 

 it poked its way into narrow canyons or 

 amongst a tangle of debris. Because it is a 

 component of a system, the submersible's 

 occupants are as dependent upon a safe 

 launch/retrieval system as they are upon a 

 safe vehicle. 



There are two general areas wherein po- 

 tential hazards exist; 1) the submersible sys- 

 tem, and 2) the environment in which it 

 operates. These two areas are grouped under 

 System Hazards and Environmental Haz- 

 ards, and the potentials for failure are dis- 

 cussed below. 



System Hazards 



Within this category fall Materials and 

 Sub-Systems, Instruments, Operators and 

 Launch/Retrieval Systems. Many of the po- 

 tential hazards which may befall the sub- 

 mersibles' occupants are obvious; some are 

 not, and the possibility of more than one 

 occurring during the same dive is always 

 present and has occurred. The groupings be- 

 low are not presented in order of priority, 

 because, at the risk of being repetitious, the 

 submersible is part of a system and that 

 system, like the proverbial chain, is only as 

 strong as its weakest link. 



Material and Sub-System Failures 



Pressure Hull: Failure of the pressure hull 

 may occur within the vehicle's operating 



depth due to a design fault, incorrect mate- 

 rial selection or errors during fabrication 

 procedures. 



Penetrations: Thru-hull penetrations are ad- 

 ditional areas where failure may occur. Elec- 

 trical penetrations are liable to overload con- 

 ditions which may completely burn away the 

 thru-hull conductor and open a conduit 

 through which water may enter the hull 

 (Fig. 13.1). Conversely, in a lock-out vehicle, 

 the sudden pressure drop created by the loss 

 of the conductor may be detrimental to the 

 occupants if they are decompressing at 

 higher-than-ambient pressures. 



Emergency Deballasting: All Submersibles have 



some means of reducing weight in order to 

 surface when the normal procedures mal- 

 function and the possibility exists that these 

 emergency systems may also malfunction. 



Entanglement: Various Vehicle appurte- 

 nances, e.g., skids, motors, ballast tanks, may 

 protrude or be designed in such a fashion 

 that they are liable to entanglement in ca- 

 bles or ropes (Fig. 13.2). 



Life Support Systems: Failure of a life support 

 system and its emergency backup system 

 can occur during a dive leaving insufficient 

 time to surface or, if unable to ascend, to 



Fig. 13,1 A short circuit produced these burned penetrator housings on ALUMI- 

 NAUT (NAVOCEANO) 



626 



