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Tom, How many people have to die in deep water, in the ocean, with steel tanks on their backs and convoluted buoyancy control systems to make you change this message? For openers there is more than adequate gas in double 80cf aluminum cylinders to dive to the rule of thirds and perform all but the deepest of ocean dives and still return with more than 1500 psi in your back tanks. For reasons too numerous to mention most people would agree that it is very wise to limit deep exposures in the ocean (300 < x < 200 fsw) to less than 30 minutes. A cave is there when you return from a dive 99.99% of the time. Everyone who has dived offshore knows that the variables of the weather, currents, anchor lines, deco lines, shipping traffic, dive boat integrity, diver emergency etc. etc. etc. are subject to change at a moments notice. It is simply unwise, hazardous and fraught with actionable risk to extend ocean dive bottom times beyond this range unless the surface support system is especially robust. When exposures are kept below these times the survivability of aborted or shortened decompressions is far greater. Exposures beyond these times require more complex decompressions with more gas changes ( to insure asymptomatic surfacing) than is possible with diver carried decompression gas. The caveat here is diving without a drysuit and in relatively warm water. If a diver cannot complete a less than 30 minute dive within the parameters I have described that diver has absolutely no business diving in this range. In my opinion, if a diver requires more than 1/3 of the contents of dual 80 cf aluminums, than the individual is either physically unfit, emotionally unfit, inadequately experienced, excessively task loaded or trying to prove something which is likely to get them killed in the end. In the WKPP if you are overweight, out of shape a known deco hazard or otherwise unfit you don't do the dive. Nobody argues with this because the intent of this policy is reasonable with respect to risk management. Too many of these gear convolutions are a result of trying to be "nice" and accommodating to people who should not be engaging in this activity for the aforementioned reasons. Chances are you will be rescuing somebody who does not meet the basic criteria. This is precisely why it can be argued that allowing such an unfit person to dive in the first place or leading them to believe that they can safely do this might be construed as a fraudulent or deceptive act. We have witnessed all too many times the problem of "Deep". Introductory socalled "technical divers" want to prove that they can accomplish the deep and return to tell about it. This, as you well know, was major contributing factor in the recent Pompano Beach death. It was also a major factor in the West Palm Beach fatality last January. For this reason we have taken a very strong stand against exceeding anything other than the accepted 130fsw sport diving limits for any kind of technical training. Insurance carriers who underwrite training activities beyond this range are incurring huge contingent liabilities. It is my bet that these activities will be proscribed in the near future when losses become intolerable. After training then it is up to the boat captain to throw down the red flag to prevent people from killing themselves. Let me further say that there is absolutely no reason to carry anything greater than 40cf aluminum stage bottles. If a diver is fit and keeping exposure times to less than 30 minutes than there is more than enough gas to perform all of the necessary decompression. If a diver cannot complete the decompression with this gas then either they should shorten their bottom time to accommodate the available gas or not do the dive. Period. Stage bottles must be carried under the left arm and never placed on the right side where they will invariably get in the way and lead to additional task loading and discomfort. Using the relative side to determine the high oxygen mix, rather than a clearly marked MOD, does not work. In the most recent fatality the instructor watched the victim for at least a half hour, breath the 80/20 from 130ft on up and failed to recognize the problem until it was way too late. Arguments in favor of multiple BCs and bungee wings range from the absurd to the sublime. Multiple BCs merely add failure points, complicate the gear configuration and are an erroneous band aid for a condition which should call the dive before it starts. This harkens back to the well worn analogy of carrying a gas can in the front seat of your car because the gas tank is too small. To make this safe you have to carry a fire extinguisher and drive with an asbestos suit. Too many incorrect things in socalled "technical diving" are in response to situations which should not be tolerated in the first place. Best regards, Bill -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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