Can't reliably reach doubles valves....Help!

[Akimbo]

Following up on Sat Diver and Bob/Grateful Diver's comments: Aside from protection, the second reason for valve-down is the way I use the isolation valve on doubles, which seems to be different than just about everyone in the US.

For me, isolation valve access must be quick, comfortable, and covenant because I open and close it 3-6 times per dive. An ex-British Navy diver first turned me on to progressive equalization. To me it makes perfect sense. You start the dive with the isolation valve shut. Once you breathe down the primary cylinder you reach back, equalize the two cylinders, and close the isolation valve again. The reserve aspect is a hallmark of most triple and quad cylinder rigs used by Cousteau and is far more effective than the early J/Reserve valves.

Each equalization can correspond with a pre-determined event based on the dive plan. For example:

1. Start meandering back toward the boat
2. Look more aggressively for the anchor
3. Stop fooling around and find the anchor
4. Forget the anchor and leave bottom right now

IMHO, the entire failure mode analysis behind the isolation manifold would be better served by leaving the isolation valve shut. If an O-ring, hose, or burst disk fails, gas is only lost from the one cylinder. You can still shut the regulator stop valve if the failure is upstream and potentially safe more gas -- especially when you can't react immediately or misdiagnose the problem on the first try.

 

[Tom Winters]

OMS made this: OMS 24" Detachable Remote Valve Knob Assembly. The idea of this would really set off the tech community - they'd line up for hours stuffing themselves with their egos and bean burritos so they could light their farts for hours flaming this thing.
I always liked the tanks mounted upside down with a really good valve protector. You can see this in Europe a whole lot more than over here. Not so many Taco Bells over there.

 

[DevonDiver]

We call those 'Slob Knobs' in the UK.

They're a poor substitute for a skills-based inability to accomplish a shutdown.

If a diver legitimately (that's rare) cannot reach their valves due to a physical mobility problem, then they should consider inverting the tanks. The "Slob Knobs" are notorious for sheering off and failing.

For some decent solutions: Technical Diving Skills - Reaching Your Valves

 

[Akimbo]

For whatever reason, the 24" Detachable Remote Valve Knob Assembly, AKA Slob Knob, is no longer offered by OMS. A lot of people complain that it was a poorly executed design, though I suspect that most are driven more by blind ideology. Either way, it was a Band-Aid for a fundamentally flawed concept -- unprotected valve up doubles.

I applaud the introduction of the double post DIN regulator valves with an isolation valve. It is just a shame they didn't carry it further and develop a truly elegant solution. It amazes me how so many people are willing to put up with simple-minded mediocre designs simply because that is how things started. At least fire fighters, mine safety, and most rebreathers have figured it out. I guess we should be thankful that double hose regulators were replaced before the sports become dominated by Luddites.

OK, it is safe for small children to come out again. Rant over.

 

[Centrals]

You roll off your left post. It closes, and you don't even know it. No problem at all ... unless for some reason you need to pass your primary reg to a buddy. You pop your backup reg in your mouth, take a breath ... take another breath and halfway thru that second breath you're suddenly OOA. Now what? Your buddy has the other one. You can (if you're not in a restriction) get his attention and buddy breathe while he turns your left post back on. But if you're in a tight spot ... one of you is gonna be pretty well hosed, depending on who wins the battle for the working reg.

As a small child.....
I was taught to attach the long hose to the left post for the IANTD technical wreck course back in 1998. The book is still lying somehwere. If there is roll off on the left post, I would be the first to notice and act accordingly. I am not sure if they still teaching this way.
I had attached the long hose to the right post for several yrs but will take a few breath from the redundancy regularly to make sure everything is working in overhead environment.

 

[mikecotrone]

Ok, so I am a fairly inexperienced diver with only about 130 dives (although most have been in cold water and poor visibility or in relatively rough open ocean conditions.) I am experimenting with doubles (about a dozen dives so far) because I want to be able to do longer and or deeper dives that will require some decompression, and think that I should have proper instruction for such activities. I have “signed up” for some IANTD instruction which should occur in the near future.

However, I although I am trim, athletic, and have a low BMI, (and a low SAC rate) and have been a competitive athelete for most of my life I reach the point now in the year 2010 where I am 57 years old, have had rotator cuff surgery on my left shoulder, and simply no longer have the physical strength and flexibility that I once had. The net result is that I can sometimes reach the valves on my new doubles set, and sometimes not. I've read everything there is, including TS&M's reference to a complete instruction posting on reaching doubles.

I stretch my shoulders with weights while lying on the couch (to the hysteria of others in the vicinity). Nevertheless, it takes me an eternity to shut down a valve - if I can - (although interestingly the isolator is easier than the tank valves.) Common sense and a mechanical engineering background says to me that a set of valve shut downs that rest on my shoulder straps seems to be the “Only Common Sense” response. I am experienced in epoxy / carbon fibre / composite construction and can manufacture (or can buy if I know where-money, no object) some “valve extenders” that are extremely unlikely to fail. (Yes, at this point, I would rather stake my life on an extra layer of technology rather than the more uncertain and slower possibility of reaching the valves in a situation of regulator failure.)

However, before I move in that direction I have decided to seek out the feedback that ScubaBoard can offer, as I have found your input to be invaluable in the past. I am reluctant to rely too heavily on the redundancy of doubles until I solve this problem.

Thank you in advance for any input you might offer in regards to this issue.

By now you have gotten sound advice from many very experienced SB'ers on this topic. I just wanted to share with you that I had the same problem and kind of times 2. When I first started diving doubles I couldn't reach any of my valves in my wet suit nor my dry suit. I spoke to an employee of mine on the topic since she is also a yoga instructor. She showed me two basic stretches and told me to try it once a day 4-5 times a week for 4 weeks. Then try twice a day for 2 weeks after that. Within the first 3 weeks I was able to reach my valves to my actual surprise After two months of stretching I was then able to reach my left/right and isolator valves in my Dry suit I stretch while in the shower (com'mon be adults here ) since it only takes a few minutes. It made all the difference for me.

 

[mikecotrone]

Following up on Sat Diver and Bob/Grateful Diver's comments: Aside from protection, the second reason for valve-down is the way I use the isolation valve on doubles, which seems to be different than just about everyone in the US.

For me, isolation valve access must be quick, comfortable, and covenant because I open and close it 3-6 times per dive. An ex-British Navy diver first turned me on to progressive equalization. To me it makes perfect sense. You start the dive with the isolation valve shut. Once you breathe down the primary cylinder you reach back, equalize the two cylinders, and close the isolation valve again. The reserve aspect is a hallmark of most triple and quad cylinder rigs used by Cousteau and is far more effective than the early J/Reserve valves.

Each equalization can correspond with a pre-determined event based on the dive plan. For example:

1. Start meandering back toward the boat
2. Look more aggressively for the anchor
3. Stop fooling around and find the anchor
4. Forget the anchor and leave bottom right now

IMHO, the entire failure mode analysis behind the isolation manifold would be better served by leaving the isolation valve shut. If an O-ring, hose, or burst disk fails, gas is only lost from the one cylinder. You can still shut the regulator stop valve if the failure is upstream and potentially safe more gas — especially when you can’t react immediately or misdiagnose the problem on the first try.

Thank you Akimbo. That is surely a technique I didn't know about and will research. That does make sense.

 

[TSandM]

One could always consider sidemount . . . one of my dearest friends converted to that primarily because of severe difficulties reaching valves.

 

[Akimbo]

...That is surely a technique I didn't know about and will research...

The only reference I have seen on the Web to the technique is mentioned here: Nigel's twinset rig

One thing I forgot in my earlier post is you can also plan to equalize at a pressure range, say 1400-1600 PSI rather than suck down the online bottle until you feel resistance. That would make it easier to follow a profile based on an odd-number percentage reserve rather than an even percentage.

The way it was explained to me, the British Navy developed the technique because they often worked in black water and could not see an SPG. They liked it so much they started using it in clear water. That in turn carried over to recreational and the rare commercial Scuba dives.

I understand that Cousteau used equalizing a third or fourth cylinder for reserve-only/dive-over, not for progressive equalization. Remember this was in the days of lower pressures and predates SPGs. I suppose you could say that was the origin of the “rule of thirds”.

 

[turnerjd]

Thank you Akimbo. That is surely a technique I didn't know about and will research. That does make sense.

also described here:
http://rubicon-foundation.org/dspace/bitstream/123456789/7763/1/SPUMS_V33N1_10.pdf

Jon T