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At 07:46 PM 4/21/99 +0100, Stuart Morrison wrote: >> With the possible exception of being in a very tight restriction, >> yes, I can always reach all my valves every single time. > >As you say, there are possible exceptions, and you can guarantee that when >things go wrong it happens in exceptional circumstances. Well, I said there was *one* possible exception, that of being in a very tight restriction. The likelihood that I'd need to get at my valves at the exact moment when I'm in the restriction is exceedingly small. Cave diving is risky; I play the odds as much in my favor as possible. The odds that I get into a restriction and have a need to access my valves is far, far smaller than the odds I forget to periodically open my isolator. >past. In the past I've reached my valves just about every time I've tried. >But not each time. Sometimes I have to reach that little bit further, my >shoulders are a little stiffer than I realised, I'm more tired than I >expected... it happens, let's all be honest. No, it doesn't happen. Stuart, I love cave diving; it's one of the best and most important things in my life. Yet, if I ever had a problem reaching my valves and couldn't immediately find and correct the reason upon surfacing, I would give up cave diving. I'm rather appalled that you are willing to dive at all while unsure about reaching your valves. To me, it's equivalent to diving with a single tank and single regulator. I would no more dive with a single regulator than I would if I couldn't reach my valves. >> There are probably other reasons, but some that immediately come >> to mind are that to use the isolator as you described requires: >> >> 1. Your long hose be on the left. > >Point 1, a fair point, but my view is below. If you have a roll-off while donating your long hose off the left post, it will be a *very* bad scene. You all but agreed in your last sentence. Disregarding the other reasons, isn't this alone reason enough to put the long hose on the right? >I agree and you can argue either way -- and people have been for a long, >long time. In the end you have to make a personal decision as to which you >think is the more likely event to occur and rig accordingly. Ultimately, >it is a moot point because if the cave is restricted you should be kind to >the environment (and yourself) and use sidemounts. Sidemounts have their place, but the fact remains that a roll-off is most likely while sharing air regardless of the size of the cave. [SNIP] >Actually point 2 is wrong. As I proposed, the gauge goes on the side being >breathed, so it is reading the used cylinder, not the unused one. I still see a problem either way. If the gauge is on the unbreathed tank, it's useless most of the time. You have no idea how much air you really have in your breathed tank, and you can't monitor your RMV which is an important clue to judge how soon you'll have to turn the dive and is useful information when you need to decide if you really want to go into that tight tunnel off to the left even though you haven't yet reached thirds yet. If the gauge is on the breathed tank, you can't monitor the unbreathed tank which might be free-flowing or have a leaking hose. It's not always possible to hear a leak or free-flow in a noisy, high-flow cave or when scootering. If your gauge is showing pressure dropping faster than it should be, you know something is wrong. Closing the isolator denies you this information. >It is >reading more conservative rather than more liberal. But it's reading wrong. The only thing worse than no information is wrong information. This goes double in a cave! >With the gauge on the used cylinder, forgetting to equalise simply means >you hit thirds in half the time you would expect to. You have actually only >used a sixth of your gas in the event that you fail to crack open the >valve. Stuart, imagine you're flying in an airliner. The airplane has two fuel tanks, but only one fuel gauge on the right tank and the engines can only draw fuel from the right tank. The flight engineer has to periodically start a pump to refill the right tank from the unused left tank, but most of the time has no clue how much fuel is really in the left tank. I don't know about you, but this scenario would make me VERY nervous! I wouldn't fly on that airline if I knew this is how they managed fuel. Your gas-management proposal is analogous to this example. >Leaving >> the isolator open allows it to 'take care of itself'. You >> don't even have to think about it the vast majority of the >> time. > >Maybe that's part of the problem. I do think about it. It doesn't make >sense not to. For some, a passive way of diving can slip easily into >unawareness during the dive. My method requires the diver to actively >monitor his situation. One of Sheck Exley's most famous quotes was: > >"...you cannot allow your concentration to slip for a second...you must be >thinking what do I do next?..." He also said: "[something] to check on before the dive is to make sure that you can reach both tank valves and turn them off quickly." Had isolation valve manifolds been in common use at the time, I'm sure he would have suggested you make sure you could reach all *three* valves. In any case, I think you're taking Sheck's comment out of context. Of course you have to maintain concentration on what you're doing in a cave, but that doesn't mean you have to invent busy-work to keep yourself concentrating. You only have so much mental horsepower available to you during a dive. If you have to spend 5% of that available mental energy to constantly fiddle with your isolator, that's 5% less that's available to deal with the dive. Why give yourself that handicap? You can remain aware of the status of your isolator without constantly opening and closing it. >> Take a step back and carefully analyze what you propose. Try >> to think of everything that can go wrong in a cave and how >> each of those events would affect you when diving using your >> methods vs Hogarthian. I think you'll find that your methods >> are not optimal. >> > >For the cold, turbid and remote environments that I dive in, I think they >are. Once again, European cave divers are so prolific in exploration yet >only a handful use the orthodox DIR concept, and even then only in a >handful of springs with Florida-like conditions. These are few and far >between. Stuart, I'm very concerned that my argument isn't winning you over. I truly think you're diving a very dangerous method and I am concerned for your safety. I can only hope you don't don't get yourself hurt. I'm feeling very frustrated here, so I think this will be my last post on the subject. Good luck. -Mike Rodriguez <mikey@ma*.co*> -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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