112 



In 1976 the National Research Council published an analysis of potential 

 electrical shock hazards related to the U.S. Navy's ROV SNOOPY. Two situations 

 were developed to illustrate under what conditions a hazard may exist: 

 1) cable handling by shipboard personnel, and 2) submerged diver operations 

 with the vehicle. 



The results of these analyses are tabulated in Figure 4.1; following are the 

 conclusions: 



"Under normal operating conditions, the NAVFAC SNOOPY Vehicle 

 System poses no electrical shock hazard to shipboard personnel or 

 divers. However, in the rare occurrence of the current monopole 

 produced by widely separated immersion of both cable conductors 

 a possible hazard will exist within 0.5m (1.6 ft) of such cable, 

 the potentially hazardous region is limited to approximately 0.25m 

 (0.8 ft) from the break. Some additional margin exists in these 

 estimates in that the fields will continue to fall off with 

 distances comparable to diver dimensions in a region free of other 

 conductors. Such additional conductors would tend to distort the 

 external fields resulting in larger and smaller field intensities 

 at given distances from faults, but these are very difficult to 

 model. Unfortunately, in problems of this complexity, carefully 

 instrumented testing is frequently prescribed to justify or replace 

 the estimates obtained by modelling." 



Although the ROV community has reportedly only one incident where electrical 

 shocks did occur, the results of the National Research Council's analysis 

 have a potentially wider application. The use of ROVs as diver assist vehicles 

 does bring the diver and the vehicle in close proximity underwater. It is 

 in this circumstance that consideration should be given to electrical shock 

 considerations. Since the above analysis was conducted only on the SNOOPY, 

 the results do not necessarily apply to other vehicles, analyses must be 

 conducted on a case-by-case basis. 



4.18 MANEUVERABILITY 



Problems related to lack of vehicle maneuverability fall into two areas: vehicle 

 bulk and power/thrust distribution. In the first area the operator reported 

 that the bulk of the vehicle prohibited it from operating within the close 

 confines of a structure (e.g., the junctions between "K" joints and other 

 multi-nodal configurations) . This restriction applies, however, only to a 

 specific class of vehicles since some can work in areas where even the diver 

 cannot fit. 



The second area, power/thrust distribution, also applies only to two specific 

 vehicles, not to the field at large. In one instance the problem was outlined 



-"-Underwater Electrical Safe Practices, 1976, Panel on Underwater Electrical 

 Safe Practices, Marine Board, Assembly of Engineering, National Research 

 Council, National Academy of Sciences, Washington, D.C., 66p. with Appendices. 



