Doubles?

[ucfdiver]

As I am just moving up to doubles this thread has been particularly timely.
My tech instructor is a world class diver, published author, big dives... Doria, cave exploration, etc.
While advocating flexibility in choosing various configurations under different circumstances, I was surprised to learn his personal preference. He dives manifolded doubles but with the isolator CLOSED, diving them as independent doubles.

His vast experience notwithstanding, this sounded kind of nuts to me, simply because I had never heard of the practice in my fairly extensive reading. After following this discussion, it actually now seems like a way to reap the benefits of both systems.
Half the gas is saved as the default, no action required. But all the gas can be accessed in the event of the far more probable regulator failure.

Has anyone else heard of this? What do you think about it?

Avra

So what hose does he donate?

 

[rjack321]

So what hose does he donate?

Yeah and where's his gauge?

 

[avra cohen]

You are confusing using doubles with techncial diving and the two are separate and distinct skills... Don't make it into more than it is.

Point taken. I must confess you make what appeared to me to border on reckless, to seem almost reasonable. Almost

I will still stand by my more conservative advice and the OP will undoubtedly do as he
sees fit. I did not suggest that it would be impossible to put together a balanced rig. I only wondered whether the concept was familiar to our young aquanaut. Perhaps he will tell us. Under the watchful eye of someone qualified I would have far fewer reservations. But a 15 year old diver with all of a dozen dives under his belt, buying vintage gear on-line and slapping together a rig on his own? I still think caution is well advised. Patience and prudence are not notable traits of adolescence. This I know, I used to be one.

Just my opinion... that's what makes horse racing!

 

[avra cohen]

So what hose does he donate?

Ah. Exactly what I asked. So far we have been doing the classwork. In a couple of weeks I will see this in practice.

As I said, this is this instructor's personal choice, not a method that he is necessarily advocating to his students. That is, he is NOT telling us: 'This is the best way', or any such.

For him, diving in many remote locations, manifolded doubles were rarely available. Consequently he became adept at diving independents. If I understood him correctly, he does not use each tank in thirds as another poster suggested. Rather he switches regs every 5 to 7 minutes. He is obviously not DIR, and while he pays them great respect, he advocates greater flexibility and adaptability depending on circumstances and available equipment. With manifolded doubles he stated he used to use two SPGs, but now uses only one and finds that at the end of a dive, when he opens the isolator, he rarely sees the needle swing more than 50-100psi.

I am looking forward to seeing how he rigs himself. What I gather is that the long hose is bungeed on one tank, and the other necklaced. Obviously only the long hose can be donated no matter which he happens to be breathing. Like I said, he is not DIR. This is what works for him. We have another class this week and I will probe further. None of this is part of our course per se, just a sidebar.

Sorry if this is an aside to the question of the OP. But thanks to him (!) and everyone else for a provocative discussion!

Cheers... Avra

 

[DA Aquamaster]

I will still stand by my more conservative advice and the OP will undoubtedly do as he sees fit. I did not suggest that it would be impossible to put together a balanced rig. I only wondered whether the concept was familiar to our young aquanaut. Perhaps he will tell us. Under the watchful eye of someone qualified I would have far fewer reservations. But a 15 year old diver with all of a dozen dives under his belt, buying vintage gear on-line and slapping together a rig on his own? I still think caution is well advised. Patience and prudence are not notable traits of adolescence. This I know, I used to be one.

I agree - a good mentor or instructor can make learning anything new a lot less painless and save you money and time in the long run.

I learned to fly at age 16 and some of the incredibly stupid things I did (16-18 year old in a rag wing airplane with way too much power = opportunity to do really scary edge of the envelope things smarter and wiser people would avoid) didn't phase me then but makes my knees shake now 25 years later when I think about them from the perspective and wisdom gained since then.

 

[avra cohen]

We have another class this week and I will probe further.

We won't be in the water till next week, but in class tonight I did seek clarification.

Both regs are necklaced, but in a breakaway fashion. Long hose from the left (!) with the hose stowed horizontally behind the neck, under the first stages. He allowed that this makes S-drills impractical. If I recall their was a bit of a dither in the DIR community a couple of years back about the best way to attach the reg to the necklace, ie removable or with a tie. The upshot was that the value of secure placement outweighed the utility of being able to yank it off in the very unlikely event of a double failure (your primary off and buddy needing to share). But in this instance, the long hose reg, being necklaced, must be available for donation, and so it is. Different type 2nd stages allow the diver unambiguous clarity about which he is breathing at any given moment. An OOG diver blindsiding and ripping the reg from your mouth has a 50/50 shot at getting the long hose, but a 100% shot at a working reg!

An approaching OOG diver whose need is evident, will be presented with the long hose reg freed from the necklace.

I am as yet unpersuaded by the superiority of this method over standard DIR configuration and procedure. But it does seem like a way to have your cake and eat it too with respect to independent vs manifolded doubles. I look forward to seeing the rig in the water.

Any thoughts welcome. Avra

 

[PerroneFord]

Any thoughts welcome. Avra

Honestly, sounds like a bit of a mess to me. When I clip on a stage, it's a completely independent source of gas and is very tidy. Not sure what going with the convolution of two long hoses, or bungied hoses, or all that really brings to the game.

If you REALLY want independents, just sidemount. Much cleaner and with the advantage of being able to adjust the tanks any way you like. Why bother manifolding them if you aren't going to use the manifold?

Just my thoughts.

 

[avra cohen]

Honestly, sounds like a bit of a mess to me... Not sure what going with the convolution of two long hoses... Why bother manifolding them if you aren't going to use the manifold?

I tend to agree, but just to clarify: just one long hose, stowed behind neck under first stages, and fed to the left. Don't know what reg would accommodate this but maybe some Poseidons? I know my AGA FFM is left feed. Anyway I imagine this facilitates regular reg switching and awareness of which is which.

Purpose is all gas is still available even after failure of a burst disc or first or second stage regulator. Here you have time to shut down the failure but at least half your gas is isolated as a default. All gas is available when you open the isolator.

Downside is the task loading of switching regs and maintaining balanced gas reserves. When I actually see this fish swim, I'll relay my impression Avra