Cave Diving Survey

[DA Aquamaster]

I agree with the long hose configuration as long as there is a valid gas management process. So there are two questions arise:

1. Gas management rule and process of tank use.
2. Do you breath from the long hose and when (from what point).

I would like to hear opinion and solutions for these.

This is where I normally get beat up as I do not conform to the switch everry 300 psi crowd. I agree with Bobby in regard to it being more than is needed, but there is also little or no harm in it if you choose to do it that way.

After over a decade of independent doubles diving, my opinion is that it makes sense to breathe 1/3rd off the tank with the short hose (I put my short hose on the left tank in sidemount), then breathe 1/3rd out of the other tank, turn the dive while continuing to breathe out of that tank, then after breathing a total of 2/3rds from it, switch back to the first tank to breathe the second third from it.

At the point where it matters the most - the point of maximum penetration - both tanks will each have 2/3rds in them, and both tanks will each have an amount of gas in them that is equal to what you used from both tanks to get to the point of maximum penetration.

More importantly, for the purposes of this discussion, on the deeper half of the penetration, both on the way in and out, you will be on the long hose and the long hose is then instantly ready to donate.

You can switch every 200-300 psi but, provided trim is not an issue, it offers no advantage and is harder to manage as you end up with more than just 2 reg switches.

"Thirds" is also misleading as the size of the thirds can be easily varied. For example with tanks filled to 3600 psi, I could dive with full 1200 psi thirds, or in response to the need to gas match or leave a larger reserve at the end of the dive, I could utilize 1000 posi thirds, 800 psi thirds, etc and still only switch regs twice during the dive.

[Line Squirrel]

This is where I normally get beat up...

Ditto...I see no reason to switch regs more than once during a dive and this is how I do it as well.

Now that said, there are obvious exceptions like if I need to remove the tank happen to breathing from to push it ahead, I'll switch to the tank I have clipped off. If I have to unclip both...well then I flip a coin lol.

Another exception is if you push through a nasty restriction or bedding plane with a lot of debris I switch back and fourth once through the restriction to make sure both regs are working properly.

I damn near killed myself once because I pushed through (solo diving) a rather ugly restriction with a lot of leaves, twigs, pine needles. I had Jet-stream regs at the time and both managed to get crap stuck under the diaphragm, to the point where one would breath nothing but water and the other I had to really "sip" it to get any air. The front faces cannot be unscrewed to clear the diaphragm (like they can on Dive Rite, Scuba Pro, etc.) on these regs with out removing 4 little socket head cap screws using an allen wrench.

I sold the regs.

I don't get the trim argument...one tank having more gas than the other therefor making it more negative. True, it is more negative, but most of us have dove with a single stage bottle at one time or another and you don't swim around on your side until it becomes neutral do you?...or do you? The wing should compensate for it.

[SuPrBuGmAn]

I damn near killed myself once because I pushed through (solo diving) a rather ugly restriction with a lot of leaves, twigs, pine needles. I had Jet-stream regs at the time and both managed to get crap stuck under the diaphragm, to the point where one would breath nothing but water and the other I had to really "sip" it to get any air. The front faces cannot be unscrewed to clear the diaphragm (like they can on Dive Rite, Scuba Pro, etc.) on these regs with out removing 4 little socket head cap screws using an allen wrench.

I sold the regs.

Its stuff like this that will keep me swapping every 1/6th(whether that be 300/500/600). I'd likely find out about the issue sooner than later assuming I only jammed up one regulator. It ends up being one additional swap.

That... and depending on the tank, like an AL80 or LP72, I'd rather keep them near enough the same as far as their bouyancy characteristics. Being a 1/3rd off can make you feel catywhompous.

[Line Squirrel]

I'd likely find out about the issue sooner than later

Oh I knew right away!!!! lol

[argyris]

After over a decade of independent doubles diving, my opinion is that it makes sense to breathe 1/3rd off the tank with the short hose (I put my short hose on the left tank in sidemount), then breathe 1/3rd out of the other tank, turn the dive while continuing to breathe out of that tank, then after breathing a total of 2/3rds from it, switch back to the first tank to breathe the second third from it.

At the point where it matters the most - the point of maximum penetration - both tanks will each have 2/3rds in them, and both tanks will each have an amount of gas in them that is equal to what you used from both tanks to get to the point of maximum penetration.

More importantly, for the purposes of this discussion, on the deeper half of the penetration, both on the way in and out, you will be on the long hose and the long hose is then instantly ready to donate.

You can switch every 200-300 psi but, provided trim is not an issue, it offers no advantage and is harder to manage as you end up with more than just 2 reg switches.

"Thirds" is also misleading as the size of the thirds can be easily varied. For example with tanks filled to 3600 psi, I could dive with full 1200 psi thirds, or in response to the need to gas match or leave a larger reserve at the end of the dive, I could utilize 1000 posi thirds, 800 psi thirds, etc and still only switch regs twice during the dive.

I strongly agree with this gas switching & management. It can be used also with independent backmount twins, which in fact is a counter argument that people with independent twins can not use long hose to gas sharing.

Bobby the gas management you use is perfect for solo diving. It is interesting however to discuss a configuration perceived for soloers and try to implement team diving procedures.

Please not that although most divers are know the third gas rule this does not mean that are familiar to implement it effectively with independents cylinders.

[argyris]

I don't believe the agencies have a set rule for this even with doubles that have been around forever. I've still seen classes where students and instructors stuff the long hose. I wouldn't see this as something that would hold up adopting SM, since there's no standard for BM.

This is not true if you are a DIR/NTEC/Hogarthian diver.

[jj1987]

This is not rue if yoy are a DIR/NTEC/Hogarthian diver.

I think you misread my statement. I was stating that the agencies have not adopted written standards for breathing the long hose. Obviously NAUI/GUE are the two well known exceptions around NFL.

Myself, I prefer to follow well tested and debated setups that transition to a variety of diving and believe it's safest when the entire team is on the same page...but my personal opinion was somewhat unneeded for the statement I was making. Since breathing/stuffing the long hose isn't written firmly in standards for BM, I don't believe it would hold up a SM confirmation approval by the training directors.

[argyris]

I think you misread my statement. I was stating that the agencies have not adopted written standards for breathing the long hose. Obviously NAUI/GUE are the two well known exceptions around NFL.

Myself, I prefer to follow well tested and debated setups that transition to a variety of diving and believe it's safest when the entire team is on the same page...but my personal opinion was somewhat unneeded for the statement I was making. Since breathing/stuffing the long hose isn't written firmly in standards for BM, I don't believe it would hold up a SM confirmation approval by the training directors.

And not only, there are more like UTD, etc.

Hogarthian configuration is a well tested and debated setup for BM. I think it can be also for side mount also. What I asked is for us a community to establish a standard or protocol not the training directors.

I asked for the process because many fellow cave divers watch the topic without writing. An you will agree that some may be not expert to understand what the safest method is nor are on the same page with you and me.

I don't argue with you and do not want to hurt your feelings either. If I did it I apologize that was not my intention.

Argyris

[Bobby]

I strongly agree with this gas switching & management. It can be used also with independent backmount twins, which in fact is a counter argument that people with independent twins can not use long hose to gas sharing.

Bobby the gas management you use is perfect for solo diving. It is interesting however to discuss a configuration perceived for soloers and try to implement team diving procedures.

Please not that although most divers are know the third gas rule this does not mean that are familiar to implement it effectively with independents cylinders.

Argyris,
I do not understand why you say the configuration that I spoke of is perfect for solo diving but is not a good implementation for team diving?

When diving OC SM my long hose donation is exactly the same as a BM OC diver. If I am breathing the short hose I simply grab the long hose and donate it rather than the reg from my mouth. The regs feed from two different directions so it is impossible to mix the two of them up. My gas management of the independent cylinders is not a necessity but it does help insure that the donated reg, on the long hose, is in working order. Please clarify how this system does not work in team or mixed team diving.

Thanks,

Bobby

[jj1987]

And not only, there are more like UTD, etc.

I'd love to see more agencies adopt standards like GUE/UTD/NTEC, don't get me wrong.

I asked for the process because many fellow cave divers watch the topic without writing. An you will agree that some may be not expert to understand what the safest method is nor are on the same page with you and me.

I completely agree. SM seems to currently have no standardization. To be honest, if all SM rigs looked like aainslie's, I'd be a lot more likely to want to try and switch over, but most of what I see makes my head spin. If Steve Bogarts offered a SM class in Florida, I would take it, but I have zero interest in taking one now because you don't really know what you're going to get. It's very clear that standardization, if it ever happens, is a ways off.

Not to pick on SM, the same can be said for the agencies lack of policies (and this can be seen as god OR bad) on things such as stages (1/2+200 vs 1/3rds) and scooters (1/2 burn going in, 1/3 burn going in, 40% burn going in, as well as should you plan to tow a buddy, or each have enough to swim out, when do you add a tow scooter? etc). I guess these things just take time...

I don't argue with you and do not want to hurt your feelings either. If I did it I apologize that was not my intention.

Argyris

Sorry if I came off blunt. I was only being short to avoid personal opinions derailing the thread. I didn't take your post as argumentative, and hope mine didn't come off that way either.