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Kevin-Neil Klop <kevink@ap*.co*> wrote: >Umm... I DON'T dive independents anymore, actually, unless you consider a >pony bottle as an independent... ::grin:: I find manifolds much better. The reason I haven't been using a manifold is primarily due to a perceived lack of redundancy; even with two regulators, even with an isolation valve, there are still failure modes in which the manifolded supply could fail. I've been a big fan of having two independent supplies, each of which can take me back to the surface, and especially considering how how far into decompression doubles could carry me, I didn't really want to stage a really big pony along with the doubles. Even if a good manifold offers full redundancy 99% of the time, that 1% would still add too much to my stress level. Anyway, I've meanwhile been listening to the folks who advise against long decompressions on air and I've started carrying a stage of nitrox for decompression. (Theory: the added oxygen envigorates a person sufficiently that carrying three tanks back up the ladder into the boat isn't as daunting as would otherwise be the case.) With the nitrox, my backup supply on the bottom now would only need to bring me up to my first stop, and my 13 cf pony would therefore suffice. This would keep me in the situation of having an alternative for the failure of any one supply (go pony if the main manifolded supply fails, or have enough air left to decompress on if the nitrox goes). I've meanwhile acquired a manifold, and as soon as I can add a fourth regulator that'll be my configuration. >>This is based on a philosophy of always having at least enough air in >>each tank for a diver to safely end the dive, so if my buddy has a >>problem I could hand off either reg to him and we start upwards, ... > >I agree with this philosophy _in_theory_. The problem here is knowing >how much air your buddy will need. Are you monitoring THEIR air supply >so that you know what their consumption rate is, add in some fudge factor >(how big of one) to deal with the increased air consumption of a stressed >diver, plus the slower movement of two people trying to swim in >formation? ... Hmmm. I'd been switching a couple of times during the dive to keep the two supplies reasonably close to each other. Since one would turn to one's own backup supply first, I had based sizing of my air reserve on my own consumption rate allowing for stress. My usual buddies have consumption rates fairly close to my own. There's the danger of turning to a backup supply and finding it nonfunctional, but other than that you'd already be on the way back up at the first failure before anything else bad happens. (Also, two people in openwater (I'm not a caver) don't have to swim too close using a 7' hose.) Anyway, getting that manifold set up will greatly simplify things. -- Anthony DeBoer adb@he*.re*.or* (here) adb@ge*.co* (work)
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