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Hi Keith, I was particularly interested in your posting in that I have been playing with the same idea of wearing dual tanks with the valves downward. Mind you I have never done it, but I've been doing a lot of thinking about it. BTW this is a classic case of where you can get more information from this list in less time than it would have been humanly possible to do previously without the experience and cooperation of the people who are willing to take the time to share their knowledge. First I must say that I am uncomfortable with the concept of too much "Personal Preference" in any potentially dangerous activity in that a great deal of information and experience can be ignored and eventually lost if we must keep making the same mistakes over and over again. There is a great deal to be said for listening to and learning from the people who have done the deeds, so to speak, that we are attempting to emulate. Second I have to guess that wearing tanks in the manner you suggest is probably not in the DIR configuration. I imagine this because I do not see or hear of GUE trained divers wearing their tanks in this way. So be prepared for a great deal of emotional objections to the method. However along with the emotional outcries will also come the well thought out reasons why it will or will not work from one of the most prestigious group of cave divers in the world. It's up to you to separate out the two kinds of responses. On the other hand, sometimes alternate approaches (SPG's Vs J valves, HID lights, electronic Vs mechanical timers and depth gauges, etc.) may be worthy of further consideration. And I would like to hear some more discussion, particularly about possible negative consequences, on this concept of wearing tanks with the valves down. At first the idea seems silly because it is not what we were taught or have been using. It can't work. Nobody does it that way. It's ridiculous. But after the initial reactions, some serious evaluation can then take place. Your comments that the inverted configuration is used by almost all emergency services personnel are well taken. I agree that it would seem to be more logical for the weakest portion of the cylinders (or the portion most prone to damage or failure) to be placed in the most protected position. And at first glance that position would seem to be at the bottom of the cylinders or to the rear if the cylinders were moving. I mean here the most protected position while the tanks are being used in the water, not necessarily when being handled on land. However there are other considerations that must also be taken into account. And in this case, the comments sent by Steve (se2schul@uw*.ca*) and Brock (Bfrede1615@em*.ms*.co* (Sidney Brock Frederickson)) need to be evaluated. The fact that the hose lengths and routings will be affected is obvious. This immediately causes a potential problem in that I have no experience with this configuration. Therefore I must rely on theory and related experience and this gives rise to concern. Even though I hold a Ph.D. in engineering, deep in a cave I trust experience a hellofa lot more than untested theory. The fact that the tanks cannot simply be stood on the ground in a position convenient to donning the tanks is also obvious. In this case the tanks might be put on "over the head" (never in my wildest dreams would I even try doing this with dual tanks) but I have to admit that over my protestations I have seen divers do this even in a swaying boat. I could stop my students from doing this in class but of course have no control over other divers. Each time I thought they were completely nuts but they did get away with it the times I was watching. I still think they were nuts. Another option, that as an aside I personally almost always use, is to put the tanks on in the water. I have a 3 1/4 inch (80 mm) stainless steel screw pinning my right ankle together, so I try not to carry full dual tanks unless I am wearing some form of ankle support, usually a pair of sturdy hiking boots. Wetsuit boots do not lend much support and if I twist my ankle going down to a cenote, it would get real messy real quick. So I make sure my rig is in the water (with the wings inflated of course) before I get into my wetsuit. And I simply slip into the equipment in the water. Brock mentioned another possibility of wearing some form of "cage" around the valves to protect them and permit the tanks to rest on the cage. I believe OMS makes something like this but I have no experience with it. It would seem to me that such a cage if designed correctly, might potentially reduce (rather than increase as was my first thought) the entanglement hazard as opposed to an "uncaged" valve. And I can envision (at least in theory) that such a cage could reduce significantly the possibility of rolling off a valve. Another consideration is the accessibility of the valves to the diver should a problem occur. If I get in trouble in a restriction, I need to consider whether my hands are above my head or at my sides. I also need to consider whether my buddy is in front of me or behind me while I am in the restriction. Each case must be evaluated. A final consideration is simply the one of doing something different. There just might be something calmly waiting out there to jump up and bite me in the ass. I simply don't know. I have no experience with it. And when it comes to anything unfamiliar in cave diving, I am a devout coward. Remember the early bird may catch the worm but only the second mouse to arrive gets to eat the cheese. Be reeeeaal careful. So where are we. You have presented an idea which on its surface appears to possess some advantages. A few drawbacks have been identified. Is the idea still worth following? In my personal opinion, I'd like to study the concept further to see if the concerns can be answered and the idea actually used in our world. I will review the archives of this list to try to locate any pertinent data as Steve suggested. Along with you I am soliciting from this list and am sure we will hear, facts and opinions both pro and con on which to base our future actions. This knowledge will determine whether or not I follow the idea further. To the members of this list thanks, in advance, for the info. Take care and safe diving, Scott
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