Gas Sharing in Deco

[cadet diver]

For those who are doing deco diving what is your procedure for an out of gas situation in deco? If your buddy for whatever reason found that they did not have enough deco gas, would you share yours with them? In my trimix class we had 5' hoses on all our deco bottles to be able to share with, or we could just pass a bottle. The problem is then you blow your own deco too. :(

[Rick Murchison]

The short answer is that you always have a backup deco plan - usually enough reserve back gas to complete a deco on that gas. But specifics vary from dive to dive. Anyway, it isn't a big deal if you've planned and equipped yourself correctly. (other than a looooong hang)
Rick

[Northeastwrecks]

Agreed. I always carry a "no deco gas" plan on my slate. In most cases, my dive plan will handle this (albeit with very little margin).

I'd rather share deco gas and shoot a bag asking for another bottle of whatever's on board than leave a buddy.

[cadet diver]

Since problems tend to snowball, if one did not have enough gas for both divers to do full deco. For instance the situation in the Last Dive, would you share your gas and blow your deco as well? What will buddy breathing do to your deco. Or am I making this into something its not.

[Spectre]

cadet diver once bubbled...
Since problems tend to snowball, if one did not have enough gas for both divers to do full deco. For instance the situation in the Last Dive, would you share your gas and blow your deco as well? What will buddy breathing do to your deco. Or am I making this into something its not.

It's tough to use "the last dive" as examples, since there was planning and gas management problems to begin with in those situations. e.g. you carry all your gas with you... you don't leave it somewhere to loose.

I'm not doing deco diving yet; but: What Rick and Dan are saying is that you have more than one plan. You have your plan with your deco gas, and then you have a backup plan in case you loose your deco gas. When planning your bottom time, you plan it in such a way that if you loose your deco gas, you still have enough back-gas to do the 'no deco gas' plan.

In other words, if your EAN50 stops are 1 @ 40, 1 @ 30, 8 @ 20, and your 'no deco gas' stops are: 1 @ 40, 3 @ 30 and 13 @ 20; you need to make sure you hit your 40' stop with enough back gas to do those extended stops.

[Bottomfeeder]

Rick Murchison once bubbled...
The short answer is that you always have a backup deco plan - usually enough reserve back gas to complete a deco on that gas.

That might work for something like 100 ft for 70 minutes on EAN32, but you will never have enough backgas to deco out of a deeper dive according to a software generated plan.

Since we carry our gas in the ocean, we are not going to lose all of it. You just do the best you can with what you have. If you do the lower stops right, your chance of getting out unscathed is pretty good even if you completely lose one deco bottle (not likely). I had a buddy lose a first stage seat once, and he just did his deco by turning the bottle on and off. There are also other divers around, and you can get their bottles as they complete their decos. In the ocean, we always limit our exposure because of the number of variables. We don't incur 2 hour deco obligations unless we have extensive support.

I find that understanding decompression so that you can make intelligent decisions when it goes wrong is more effective than carrying a slate with 6 different plans on it. If you carry 6 plans, you will encounter the 7th situation.

As you might have guessed, deco diving is something that needs to be done gradually if it is to be done safely.Taking a trimix class is only a first step, you need to build experience with progressively deeper and longer dives.

Dive smart
bot

[Doppler]

cadet diver once bubbled...
For those who are doing deco diving what is your procedure for an out of gas situation in deco? If your buddy for whatever reason found that they did not have enough deco gas, would you share yours with them? In my trimix class we had 5' hoses on all our deco bottles to be able to share with, or we could just pass a bottle. The problem is then you blow your own deco too. :(

One 'correct' procedure and one that has been taught and practiced successfully for many years is to buddy breathe the deco gas. This is also useful if someone stages the incorrect gas at, let's say the 140 foot stage! (Are you out there Ralph?) :)

But what facinates me is what on earth do you mean when you say by sharing gas you blow your own deco?

DD

[WreckWriter]

Doppler once bubbled...
One 'correct' procedure and one that has been taught and practiced successfully for many years is to buddy breathe the deco gas.

The scary thing is that we had multiple posts on this topic and you're the first one to mention this!

Another scary thing is that buddy breathing is an optional skill in at least one agency, has been for a long time. I wonder what percentage of divers don't even know how to do it?

WW

[Rick Murchison]

Bottomfeeder once bubbled...
but you will never have enough backgas to deco out of a deeper dive according to a software generated plan.
Perhaps you may not. But I will. Whatever it takes. That may mean a "cave" protocol with a continuous guideline back to prestaged hang tanks, but I will *always* be able to complete deco with the loss of any single bottle, be it stage, deco or back gas. (that may mean gas sharing with a buddy at some point, but not "buddy breathing a deco bottle") If the plan does not accomodate a lost gas scenario safely it is a bad plan and I won't dive it.
Any GUE trained divers out there handy with the "DIR" solution? I'm curious...
Rick

[Rick Murchison]

cadet diver once bubbled...
Since problems tend to snowball, if one did not have enough gas for both divers to do full deco. For instance the situation in the Last Dive, would you share your gas and blow your deco as well? What will buddy breathing do to your deco. Or am I making this into something its not.
This question presupposes diving a bad plan in the first place. Don't dive a bad plan and you won't have to answer it.
Rick

[WYDT]

Great Post Bottomfeeder! I totally agree!!


Bottomfeeder once bubbled...
That might work for something like 100 ft for 70 minutes on EAN32, but you will never have enough backgas to deco out of a deeper dive according to a software generated plan.

Since we carry our gas in the ocean, we are not going to lose all of it. You just do the best you can with what you have. If you do the lower stops right, your chance of getting out unscathed is pretty good even if you completely lose one deco bottle (not likely). I had a buddy lose a first stage seat once, and he just did his deco by turning the bottle on and off. There are also other divers around, and you can get their bottles as they complete their decos. In the ocean, we always limit our exposure because of the number of variables. We don't incur 2 hour deco obligations unless we have extensive support.

I find that understanding decompression so that you can make intelligent decisions when it goes wrong is more effective than carrying a slate with 6 different plans on it. If you carry 6 plans, you will encounter the 7th situation.

[Doppler]

WreckWriter once bubbled...


The scary thing is that we had multiple posts on this topic and you're the first one to mention this!

Another scary thing is that buddy breathing is an optional skill in at least one agency, has been for a long time. I wonder what percentage of divers don't even know how to do it?

WW

I sometimes run into technical program candidates who have not been taught buddy breathing in their open water class, and so need a bit of 'remedial' work. And my guess is the number of people who are not familiar with the skill will increase... scary is right! However, that said, the actual percentage who've never done it is quite small... now the percentage of people who have not practiced it since open water is very high... that's scary too!

Take care and dive safe

[Epinephelus]

It seems to me that there are two issues here...
(1) Buddy breathing training - I agree that buddy breathing should be a skill that is in the "back pocket" of any competent diver.
(2) Having a plan that requires buddy breathing in the event of the loss of a single decompression tank. Now that's not smart! If you're going to dive a plan where you'll have to share a decompression bottle should you lose one, then, by golly, put two second stages on your decompression bottles!
E. itajara

[cadet diver]

Doppler what I meant was that if you had to buddy breath off the same deco bottle and there was not enough gas to finish your own deco now that you are splitting your supply between you and your buddy.

[Genesis]

buddy-breathing a deco bottle?

I guess you can, if there is no other option.

But is there really never any other option?

Let's say you are deco diving and have a 30 minute (total) deco obligation between three or four stops.

You lose a deco bottle for whatever reason.

Ok, you and your buddy now have one deco bottle (instead of two) BUT you also have two sets of BACKGAS!

So why not hand off the long hose from the person who DOES NOT have the problem (the guy WITH the deco bottle) and let him deco on the EXTRA backgas (the guy with the deco bottle doesn't need it!) He can deco on his primary tanks until they get down low enough where he needs the remainder for surface swimming, then use the guy's backgas WITH the deco bottle (he's not using it - he's breathing off the deco bottle.) This keeps the brown stuff factor as low as you can reasonably manage.

The buddy with the deco bottle does the deco on the bottle; the other guy has TWO sources of gas.

Now this means that the guy WITH the gas stays in longer, but that's infinitely preferrable to buddy breathing off a bottle that would otherwise have to be twice the size as really required.

The "oh s$#%" plan is just that - its for those situations. If you add another complication (buddy breathing) to a deco situation, IMHO you're asking for it to get out of control.

You should have enough backgas between the TWO of you to complete the hang on the longer intervals; remember, you do still have ONE good deco bottle between the two of you, and one of you can consume it. The longer hangs won't hurt that guy (assuming we're not talking dangerous PO2s - if we are, then he needs backgas breaks, etc.) If not, then your dive plan is no good; if you can't do the longer hang with two backgas supplies for one diver (the other guy on the deco bottle) then you probably couldn't successfully buddy breathe off the deco gas either and not run out of that.

Is not one of the first credos of rescuing someone in trouble "do not kill/bend yourself in the process"?

What am I missing here?

[MikeFerrara]

I don't know about anyone else but when we do a dive with only one decompression gas it isn't a real long dive and we could deco on back gas. I suppose if you wanted to shorten it up a little when the one with deco gas finishes with it he could hand it off. It's nicer to breath it all the way to the surface but oh well.

When our dives require multiple decompression gases the ascent time on back gas alone (all decompression gas lost) would be undoable. It would be hours and hours and even if you had the gas you would likely die of the cold. However, finishing the dive with either of the two decompression gasses would be very doable. What's all this buddy breathing silliness. Remember all the other options. We can swap regs or fix them. We can turn a tank on and off to breath if a reg is free flowing. We can depress the purge to breath if a diaphram is damaged and leaking. If your really worried stage extra tanks.

[Rick Murchison]

MikeFerrara once bubbled...
What's all this buddy breathing silliness.
Bingo.
Rick

[WreckWriter]

MikeFerrara once bubbled...
What's all this buddy breathing silliness. Remember all the other options.

Its just another option, one that it appears many people don't know how to do. Its not a first choice but, assuming you know how, it is an option.

Of course you can deco out on backgas or on backgas plus one gas when 2 were planned. Figure half-again your time in the water or so, more if on backgas with 2 gases lost.

Buddy breath the gas one guy has lost, figure original scheduled time at stop.

Why is that "silliness"?

WW

[MikeFerrara]

WreckWriter once bubbled...




Why is that "silliness"?

WW

I guess I called it silliness for a couple of reasons. First, I don't think it should come to that given that we plan for lost gas and will most likely have better options. Second, The fact that not all OW divers are tought buddy breathing shouldn't account for someone doing a "technical dive" not being able to do it should they decide it's needed. IMO, Anyone doing a dive requireing a significant decompression obligation (or any other overhead) should be prepared to use any one of a number emergency procedures most or all of which IMO, would be better than buddy breathing. I do agree though that if the dive gets real bad you do whatever it takes.

[WreckWriter]

MikeFerrara once bubbled...
I guess I called it silliness for a couple of reasons. First, I don't think it should come to that given that we plan for lost gas and will most likely have better options. Second, The fact that not all OW divers are tought buddy breathing shouldn't account for someone doing a "technical dive" not being able to do it should they decide it's needed.

You're right, it obviously shouldn't come to that but as you know when things get sideways they have a way of getting extremely sideways in a big hurry.

I think with the relative ease that divers can become "technical" today there are probably a large number of certified tech divers who have never done it, after all its been optional in o/w for a good number of years (what percentage of instructors do you think teach it?). It wasn't covered in a my of my higher level classes.

I think most consciencious instructors still teach it, I think most lazy instructors don't.

Personally I feel that its an excellent skill, a last resort yes but one that can remove one's bacon from the fire! It saved mine once about 20 years ago.....

WW

[Rick Murchison]

Buddy breathing in and of itself is a necessary skill for any technical diver. One that a team should be able to do while maintaining a deco stop. But it's among the *last* solutions, not the first.
My point is that to have buddy breathing a deco bottle as a necessity after a single bottle failure is *not* good planning. As Epinephelus says, if your gas plan has you sharing a deco bottle in the event of a single bottle failure, then put two seconds on your deco bottles.
Buddy breathing is what you do after the whole world turns to worms.
Rick

[cadet diver]

First I would like to say that I teach buddy breathing for my OW classes. Second I would like to say I do not propose buddy breathing as the next option, but in the case of some huge catastrophic loss of gas; something unforseeable. In a cold water ocean and wreck enviorment, things go wrong.

[faye]

Don't stage your nessessary deco-gas if you can possibly lose it.
If you can't finish your deco on back gas then put a 2nd reg on your mandatory bottles.
Buddys stay together through deco and do the same deco.
If you can't finish the dive without certain bottles then have surface suport and a means to communicate.
If you poorly planned a dive, (ie can't finish the dive with the loss of one bottle), buddy breathing is a skill to have when the reapers on your shoulder.

[Doppler]

Guys: this is not complicated... And who really wants to put two second stages on a deco bottle... that's an unnecessary complication to your gear configuration. After all is said and done, sharing deco gas is an unlikely contingency situation.

Dear Genisis: Your post about doing deco on back gas is not relevant here. We are talking about losing deco gas not back gas, so the person who lost their deco gas still has their own back gas and plenty of it... the point is that by decoing on back gas, the hang may be inordinatly long and it will inevitably split the buddy team... one able to follow the schedule the other unable to keep pace.

Both divers start the dive with sufficient gas for both her and her buddy to complee a full deco and the point of that is that it's there if you want to share.

As for the post about sharing deco gas is too difficult, well that's nonsense. If it's too difficult then practice it until it's easy. Buddy breathing deco gas is a straightforward and effective contingency plan. It involves on extra complications, and not special gear... just competancy.

Graduates from a decompression class should be able to share deco gas while hovering in mid-water... simple rule, simple technique, simple solution to an Oh **** situation.

Someone stated that you shouldn't stage deco gas if there is a chance you'll lose it. Excellent point; however, there are times when deco gas has to be staged. In these situations, it is generally prudent to employ support divers. However, there may still be a time when buddy breathing allow a team to stay on a schedule while help is on its way.

The message here... learn to buddy breathe and forget the complicated apparatus and dive schedules using back gas... deco on 16/50 is not pretty!

Dive safe

DD

[Rick Murchison]

Doppler once bubbled...
deco on 16/50 is not pretty!
HHHhhhaaaarrrrr!
You definitely have a point there!
I would, however, as a practical matter, either hang an extra deco bottle or put two seconds on the deco bottles we're carrying. I want buddy breathing to be after at least two, not one, failure.
Rick

[Doppler]

Rick Murchison once bubbled...

HHHhhhaaaarrrrr!
You definitely have a point there!
I would, however, as a practical matter, either hang an extra deco bottle or put two seconds on the deco bottles we're carrying. I want buddy breathing to be after at least two, not one, failure.
Rick

An extra cylinder waiting somewhere on the way up or hanging from a support diver is a nice, comfortable solution... not always doable though.

Must admit I have a problem with two second stages on a deco bottle. Sharing gas is a contingency and therefore is not an everyday episode... whereas one must configure and carry that extra reg on all your dives. Makes for an overly complex rigging issue... IMHO. And if complete regulator failure is the issue, then swap the whole regulator from one bottle to another... but of course this a a different topic... swapping regs on an empty bottle doesn't bring back lost gas.

Incidently, to get a handle on how unlikely a deco gas sharing episode is, how many times has anyone been in a situation where deco gas has dissappeared... either bottle emptied mysteriously or bottle lost in some way (Running out of deco gas doesn't count that's simply poor planning).

My peer group execute something like 400 person mix dives in the Great Lakes annually and I think in the past four years we've had two, maybe three, instances of people having to share deco gas... 1600 to 3 are long odds. :)

Thanks

DD

[Epinephelus]

Doppler once bubbled...
Incidently, to get a handle on how unlikely a deco gas sharing episode is, how many times has anyone been in a situation where deco gas has dissappeared... either bottle emptied mysteriously or bottle lost in some way
Never seen it yet. Don't plan to see it. PPPPPPP.
E. itajara