<=i 



^ 



us NAVY TYPE 



CONICAL HOLE 



Fig 7 25 Typical hull inserts for electrical penetrators 



tions, and thus a tapered hole is favored, al- 

 though individual matching of each penet- 

 rator may be required to fit each insert. The 

 hull insert material must be the same as the 

 hull material and full penetration welds at 

 the insert-hull interface are desired. 



Electrical Connectors 



Cables (harnesses) and connectors for elec- 

 trical components have been the most failure 

 prone items on submersibles, and, while such 

 failures may not jeopardize the occupant's 

 safety, they can result in the loss of time, 

 money and good diving weather in the form 

 of aborted dives and subsequent down-time 

 for repairs. 



Any attempt to lay the blame for connector 

 and cable failures reduces to the dilemma of 

 "Who struck John?" Earlier, Rynewicz (2), a 

 user of connectors, cautioned submersible 

 designers that cables, connectors and circuit 

 breakers constituted the major areas for im- 

 provement in deep submergence. Another 

 user, a senior engineer for Perry Submarine 

 Builders, recently replied to a query regard- 

 ing the connectors they found most reliable: 

 "We use one until we get disgusted with it 

 and then replace it with another until we've 



had enough of it!" International Hydrody- 

 namics, as noted above, finally gave up and 

 makes its own connectors and penetrators. 



Conversely, J. D. Tuttle, a manufacturer 

 and vendor of connectors (Electric Oceanics, 

 Inc.), states (34) that much of the fault re- 

 sides with the user for not establishing speci- 

 fications which completely encompass the 

 boundary conditions within which the con- 

 nector must function. Furthermore, Tuttle 

 suggests that the user may not understand, 

 among other things, the maintenance proce- 

 dures and limitations of a perfectly well de- 

 signed and manufactured connector. D. K. 

 Walsh (35), a manufacturer (Vector Cable 

 Co.), also lays the blame on the user and 

 states that the principal area of abuse has 

 been in misapplication, mishandling and 

 careless installation. 



A revealing insight into the problem is 

 provided by the DOT Handbook in the form 

 of a Failure Mode and Effects Analysis, for 

 connectors, penetrators and junction boxes. 

 The investigators identified 142 modes by 

 which failures of these components could 

 occur. The failures are grouped under Inher- 

 ent (manufacturing design deficiency and 

 material fatigue) and Induced (installation/ 

 assembly deficiency, maintenance deficiency, 

 excessive operational demands and rough 

 handling). If it is assumed that inherent 

 deficiencies are laid to the manufacturer and 

 induced to the user, then the user appears to 

 be the chief potential culprit, for in 181 out of 

 297 causes of failure the user is to blame. To 

 clarify these figures it should be noted that 

 both user and manufacturer may be found 

 guilty in the case of one failure, for example, 

 where insulation material breaks down due 

 to use of contaminated materials, the cause 

 could be inherent in the original design, or 

 induced through installation/assembly, im- 

 proper use or deficient maintenance. 



It would appear, then, that both manufac- 

 turer and user share somewhat equally in 

 the problem, the former by ignoring various 

 ramifications; the latter through ignorance 

 or inattention to details. 



Connector Design: 



There are dozens of companies in the U.S. 

 which produce connectors both for commer- 

 cial application and for which the military 

 has supplied specifications. Military specifi- 



345 



