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IMHO, if you are not diving doubles then you should not be getting in virtual or real overhead conditions (i.e. caves, wrecks or deco) so you might as well be a rec diver. Being a rec diver means being able to head to the surface under any emergency condition. Your failure mode for most if not all issues is a controlled ascent to the surface. Other than that you are fooling yourself using H, Y or whatever systems. If anything it could make matter worse by introducing CF factors into a simple rec rig. My reasoning on this is to have enough gas to deal with a problem on the bottom even after isolating the valve with the problem, impossible to do with a H or Y valve. Doubles vs. Singles is more an issue of convenience and logistics. You can't make a silk purse out of a sows ear so if your gonna do it, do it right. Don't overhead dive without doubles. Jim ------------------------------------------------------------------- Learn About Trimix at http://www.cisatlantic.com/trimix/ > From: Simon L Hartley <shartley@sc*.ed*.au*> > Date: Fri, 06 Jul 2001 16:46:52 +1000 > To: techdiver@aquanaut.com > Subject: RE: Y - valve > > I'm still not entirely committed to the Y or H valve thing, however I do > use a Scubapro H valve. I don't dive doubles (so no excuse there) but have > found that hose routing is much cleaner with a H valve than with a single > first stage. Also means I use a basic DIR doubles layout (with two Apeks > US4's) saves mucking around with odd hose lengths and different hose > layouts. > > Not really sure how effective a H or Y valve would be in practice, dealing > with a burst hose or o-ring. Guess it would come down to how quickly you > diagnosed the problem, which hose or o-ring you blew and how much air you > had in your tank at the time. The only time I've isolated one of my first > stages (apart from in practice) was for a fairly minor leak (I fixed the > problem by cleaning crud out of the second stage during the dive). > > As far as Y vs H valves. I haven't used a Y valve so I'm probably talking > through my arse. However, couple of things come to mind. With the H valve > there is the potential for the left valve to rotate or be damaged WHEN it > hits the roof of an overhang or swim through (I've done this numerous times > but sofar with no damage or movement that I can detect (having a single > tank adapter doesn't help)). On the Scubapro H valve though (with the hose > layout I use, see... > > http://www.scu.edu.au/schools/rsm/staff/pages/shartley/projects/gear/first_a > ...jpg > > .....) both valves are easy to reach and turn. Two Apeks US4's also fit side > by side easily (enough space). With the Y valves I've seen I'd want to > find out first if I could fit the two first stages side by side as I have > them now and second if the hoses would interfere with access to the valve > knobs (which angle down so would sit in closer to the first stages and > hoses). I think you'd definately be screwed if you used a tank with one of > those carry handles on like on the Beuchat site > (http://www.beuchatdiving.com/frame3.htm). Tanks with those are hard > enough to turn on and off on the boat before a dive let alone behind your > back during a dive (seems like that would defeat the purpose of having a > redundant valve in the first place). > > At 16:41 5/07/2001 -0700, "James Endicott" <webbie721@ea*.ne*> wrote: >> Some people like the idea of a y valve so they don't have to have a set of >> gear for single and doubles. They can dive a double tank configuration with >> a single tank. I have found that my regs fit much better on my tanks with Y >> valves as opposed to the H valve. The y valves are extremely hard to come >> by right now. Good Luck >> >> James >> >> -----Original Message----- >> From: Steve Schultz [mailto:se2schul@st*.ma*.uw*.ca*] >> Sent: Thursday, July 05, 2001 2:51 PM >> To: Porter, Greg; techdiver@aquanaut.com >> Subject: Re: Y - valve >> >> >> Greg, >> >> Y-valves only come in yoke, not DIN as far as I know. You can get DIN H >> valves or yoke y-valves. There are other valves available as well that >> offer first stage redundancy, but they aren't very popular and I don't know >> them off hand. >> >> I think www.northeastscubasupply.com has H valves for sale. >> >> Let me give you a suggestion that may save you some money. If your dive >> really warrants first stage redundancy, you are likely safer to buy doubles. >> If your dive doesn't require first stage redundancy, why not just use an 80 >> with a K valve? If you are planning on using a Y valve as training wheels >> for doubles, I'd suggest just going right to doubles. If you're planning on >> using it for recreational dives, you don't need the redundancy, so just use >> an 80 with a k valve. >> >> Just a suggestion, >> ss > > Simon > > Simon L Hartley > RSM Website Coordinator\First Year Course Coordinator > Associate Lecturer > School of Environmental Science and Management > Southern Cross University > P.O. Box 157 > Lismore NSW, Australia 2480 > Ph: (02) 66203251 or (61 66) 203 251 > Fax:(02) 66212669 > E-mail: shartley@sc*.ed*.au* > > http://www.scu.edu.au/schools/esm/staff/pages/shartley/ > > http://www.scu.edu.au/schools/esm/ > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. > -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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