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>>I do not know. From what I found in related documentation about accident >>analysis rules, the actual accidents described were deeper than 180 feet >>(most of the time between 250 and more than 300 feet - on air). The 130 >>feet rule seems to be established just to be compliant with the recreational >>diving depth limit. > > Michel, your facts are a "little" off here. Stop > and think: do you believe we are using 130 aed in > our cave exploration dives because we are concerned > about recreational limits, or do you think maybe > we are just not "good" any deeper? Why do you think > we do it the way we do? > = George Sorry if I took a little bit of time before answering, but I wanted to refer to some basic documents about Accident Analysis. Since this discussion is about a safety rule for cave diving, I decided not to look at other information (DCIEM diving standards, commercial diving standards, all the deep diving manuals and books, etc...). In "Basic Cave Diving - A blueprint for survival" by Sheck Exley, the sample case reports a dive planned to 270 feet. Following, the paragraph "How Deep is Deep?" relates: "The sport diving community advocates limiting dives to 130 ft. or shallower and it would appear that there is very good reason for it. An analysis by the author of cave diving accidents in Florida has shown that the small percentage of accidents where a continuous guideline and the third rule were used all involved dives to depth of 155 feet or greater. ..." Exley also wrote an article "Accident Analysis Revisited" (available in the October 1, 1989 edition of the NSS Student Cave Diver Workbook). In this article, we can read: "One of two rules (or) violations (often both) were found to be present in nearly all the accidents for which we have data. These were not using a guideline from the entrance, and not reserving (at least) a third of the starting air supply for emergencies. The few accidents where we did not have data suggesting that either or both of these rules had been violated all occurred at depths of 155 feet or deeper (Exley 1976)." "One of the best diver in the world in 1972 was Randy Hilton. In February of that year he died at Eagle's Nest, Florida, at a depth of 155 feet. While he did perish while violating the depth rule, it is highly unlikely that Randy was unduly influenced by narcosis. He routinely dived in caves below 250 feet and three months earlier had become the seventh of only eight people known to have survived a dive to 400 feet on air." The statements in the previous texts make me think that YES, the 130 feet rule was set to follow standards already put in place in the sport diving industry. As well, I do not think that deep diving to 140 feet was recognized as a high risk dives considering that all accidents occurred in dives deeper than 155 feet. I also think that if the only accident to occur at 155 feet is Hilton's one, the depth itself was probably not the factor (because of his previous experience). I agree that training cave dives should not be deeper than 130 feet (I do not like to combine specialties during training), but I think that saying that diving on a EAD of more than 130 feet is dangerous is a little bit exagerated. There are other reasons to not dive deeper than 130 feet in recreational diving. We could think about the lack of training, of redundancy, of support, of knowledge, etc. But I do not understand why, in technical diving, we could not become able to dive deeper with an acceptable safety level. Exley was telling me that in caves, because of loss of visual references, we are probably more "narked" by a factor of 4/3 compare to open water situations. If this is true, this would imply that a properly trained and equiped technical diver could be able to dive deeper than 155 feet with an acceptable safety level. >> >>All very excellent advice learned by many people, some who survived >> >>close-calls, others who did not. If you made the "D" standard 100 feet, >> >>would fewer people die? If you made it 150 feet, would more people die? >> >> YES > >Well then, if fewer people would die if the max EAD was 100 feet, let's >make it 100 feet. It's an easier number to remember anyway. > >Aloha, >Rich I have another question. If you made the "D" standard to 0 feet, would fewer people die? If the answer is yes, I think this is even more easy to remember than a 100 feet standard maximum depth. Have a nice day! Michel Therrien m.therrien@ne*.qc*.ca* PS: I do not advocates deep diving on air. I do not advocates diving on air or any other gas either.
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