Breathing off the BC

[cat]

I pay a lot of attention to my SPG (newbie paranioa). That's how I noticed it was reading 300 psi low. (It's only a few months old and yes - about to be shipped back to DiveRite for repair or replacement, I'll be diving on another brand in the meantime). Whatever is wrong with it went wrong DURING a dive - I noticed the "missing" pressure while ascending. So - what happens if the next SPG reads too high, especially if it's something subtle like going off calibration at the lower end?

I have good equipment (with that possible exception). It's going to get regular servicing. I still don't trust it *that* much. Who does? Genesis is correct - if there's a probabiltity of failure, there's a probablity of multiple failure (can even calculate it out if you neglect the Murphy factor). OOAs happen. Sometime's it's going to be diver error (must be nice to never make mistakes - I make them all the time) and sometimes it's going to be the equipment, or the situation (hose puncture, for instance). Being told to prevent the OOA in the first place is NOT ANSWERING THE QUESTION OF HOW TO DEAL WITH ONE! (I know this has been said before - maybe having a frustrated newbie with no axe to grind - yet - shout it will get through). If my buddy swims off and I go OOA, I will yell at him later and have words with whoever did my last maintainence or manufactured my hoses but first I have to survive the OOA!

I've tried to distill this thread down and the conclusions I've come to are as follows (you're all welcome to check my logic here):
Problem: breathing the wing in an emergency is a heavy task load, especially for new divers.

Solution: practice the snot out of breathing the wing, same as any other emergency procedure. I orally inflate my wing at the surface all the time (it's inflated from the tank at other times and emptied after each dive, so there's no elevated CO2 in it if I have to breathe it). Why? So that when I have to orally inflate, it will be second nature and not much of a task load. Isn't that why we do all these ESA and S-drills in the first place - so we can be calm and competent in an emergency?

Problem: shouldn't practice breathing the wing because it has a lively microbial community.
Solution: regular cleaning and disinfection with Listerine (does this damage the wing bladder material at all?). Will make oral inflation more pleasant, too.

Problem: shouldn't re-breathe the wing because CO2 builds up and O2 drops.

Well, it's not going to be pleasant or ideal but - this is the absolute last resort we're talking about, correct? And its going to give me more volume to play with than just my lungs will (and I don't have the added stress of trying to keep slightly used but still life-supporting air in my lungs while letting an overpressure out on ascent).

Solution: find out in a controlled situation just how much it can be rebreathed. Blacknet 'cites' a YMCA study which suggests 13 times. (Maybe that's on a full wing - certainly the amount of air in the wing will affect the number of times it can be rebreathed.)
It's certainly at least once (the air I breathe out is good enough for the person I'm giving AR to).

I'm finding the "rebreathing the wing will mess up bouyancy" conclusion to be a little odd. If no air leaves the system of self and wing, how is this going to affect my bouyancy?

 

[Genesis]

Rebreathing the wing is exactly like breathing on a rebreather - it has ZERO effect on your buoyancy, because the gas volume carried does not change.

When you breathe off your OC scuba set your buoyancy changes - up and down a bit - with your breathing cycle. This is one of the reasons that nailing buoyancy control for neutrality is such a pain in the butt for new divers - until you get "in the zone" with it, and it becomes automatic, you can and WILL overshoot first in one direction than the other, not realizing that (1) it takes time you to start to move in the water column, and (2) its the AVERAGE of your lung volume, assuming you're breathing in and out regularly, that determines your buoyancy point.

New divers often have poor breath control, in that their breathing pattern is not regular - that is, they take a deep breath one time, a shallow one the next, etc. Their average lung volume over any given 10-20 second period is all over the place. This is what messes with their quest to become neutral, and until they get comfortable in the water and settle down with their breathing yelling at them about proper trim and buoyancy control is a waste of time, as it is IMPOSSIBLE to master until you're calm and consistent in your breathing patterns!

Now if you TAKE a breath from the BC and then exhale it into the WATER, your buoyancy will drop. Why? You just exhausted one tidal volume's worth of buoyancy.

I don't buy the "mess up your buoyancy" claim, except in relationship to the fact that it won't change as you would expect and perhaps are ingrained to compared to an OC breath.

People I know who have converted to rebreathers have said that one of the toughest things is regaining neutral buoyancy control since you cannot use breath control for "fine tuning"..... and the longer they dove OC scuba first, the worse it is.

 

[Davey Diverson]

NetDoc once bubbled...

You have asked "When are you screwed"? My answer predates the incident, but is still relevant.

Right. Who's on first. You're answering a question I didn't ask.

As for drowning victims, please don't put words in my mouth or try to divine my feelings about them.

I don't have to put words in your mouth. Or are you saying a gremlin broke into your house and typed:

Divers drown because they choose to.

I will give you the same courtesy.

Well then answer the question.

In other news: I was asked by Hamburger if I could think of any reasons for an OOA… and I gave my answer. Sorry if it doesn’t make you feel all warm and fuzzy inside or vindicate your sense of injustice here.

You live in complete fantasy land where OOAs don't happen, and I'm warm and fuzzy? Back in reality, where folks do go OOA, I have a question I'd like you to answer. At what point are you going to die? What steps have you taken to prevent it, even if they were futile?

OK, that's two questions.

Somehow I feel that you won't accept any of my answers until such time that I completely agree with you. That will not happen with this issue.

I'll be happy with whatever answer you give. As soon as you give one.

 

[MikeFerrara]

Reading this thread got me thinking. I've never really tried breathing from the bc either from the bc or using the bc as a third reg. I never thought it was very important since I have redundancy on dives where I think I might need it and other times I figure the old standard methods will get me by. I had some time to kill in the pool the other night so I thought I would try some things.

First I tried breathing from the wing. It wasn't really a valid excersize since I was only at 10 ft and didn't have enough air in the wing to get even a small fraction of a breath. It was just a tease. Certainly if I had further to ascend the air would expand enough to provide a breath.

I also tried depressing the inflate button and the deflate button at the same time. The idea was to breath it like a free flowing reg without filling the bc. I was unable to do it with out filling the bc. If I stayed vertical (so as much air escaped as possible) and breathed quick and then dumped the extra air from the bc quickly I could do a half assed job of controlling my depth. It was a lot of work though. If I was in a cave restriction or entangled (a place where buoyancy control didn't matter) and couldn't get to a reg I could get enough air to keep me going for a while.

I'll play around with it a little more in the next couple of days and see what happens. In the mean time I'm open to suggestions in the way of technique to make it work better. As of right now I'm thinking that if you get in a spot where this is the only way you have to get air, you might be in big trouble. If you are at all thinking that you might ever resort to this you had best give it a try ahead of time. I sure don't think I could traverse a bunch of cave passage this way.

I'll let you know.

 

[fins wake]

I've tried to stay out of this thread, I really have. But then the classic and dangerous diver board menace turns up: The newbie diver, believing that the loudmouth - it's almost invariably a him - who shouts the loudest (and usually with the silliest metaphors and filthiest language) in the thread will win the argument.

Dear newbie ladies and gentlemen: This is simply not so. One of the joys of being a certified diver is being allowed the luxury of checking and re-checking opinion - sometimes stupidly dangerous opinion - for factual content. Your tools are
1) your own brain
2) your possible scientific background (yes, open up those old school physics, chemistry and biochemistry/physiology books if you have them, and do some basic ground work).
3) standard reference works of dive medicine (Edmonds et al, Bennett & Elliott).
4) your standard reference text on diving (U.S. Navy Diving Manual, PADI OW manual, NAUI or SSI equivalent or whatever)

Now use these tools to go through the wildly disparate points expressed in this overlong thread, not forgetting to go through all the links provided. There's more info there. It all builds up the knowledge base.

Enough said. Now for the nitty-gritty, provided by Cat. Actually Cat is to be commended for reading the threads thourougly, distilling out the rubbish and ending up with problems and solutions. Well done! Seriously!

Now, let's examine the conclusions therein:

Problem: breathing the wing in an emergency is a heavy task load, especially for new divers.

Correct.

Solution: practice the snot out of breathing the wing, same as any other emergency procedure.

Remember: No agency condones this, nor has any standards in place for it. Even the GUE blokes are doing this ad hoc (which says it all, really). If you do this you are on your own. And read on below ...

Problem: shouldn't practice breathing the wing because it has a lively microbial community.

... which can be a bit nasty. SARS, anyone? TBC?

Solution: regular cleaning and disinfection with Listerine

Well, most of us don't know how to clean things to surgical standards. But fair enough, if you're going to practice breathing your BCD, use Listerine, iodine or similar. It's better than not using disinfectants.

Problem: shouldn't re-breathe the wing because CO2 builds up and O2 drops.

Yes. And the risks inherent have been so downplayed by some on this thread that it is genuinely scary. I mean that. Real scary!

Well, it's not going to be pleasant or ideal but - this is the absolute last resort we're talking about, correct?

No, not really. You've just talked about "practising the snot out of breathing the wing". (It's not your fault, you're merely concluding what some people in this thread have been shouting about, back and to.) That is to say, you are advocating practising a reasonably difficult exercise which carries REAL RISK of DEBILITATING INJURY or DEATH! Now, thing about this. How many lives per year will be saved by hordes of newbie divers practising this technique ad nauseam? Two? Five? Fifteen? Well, how many of those would have been saved by proper diving techniques, paying proper attention to your gear and to your buddy? Most of them? All of them? Now for the flip side: How many newbie divers will risk hypoxia or hypercapnia whilst running the drills? How many will risk uncontrolled ascents (lung barotrauma, AGE, possible DCS) or drowning due to, say, inhalation of water through the inflator? Fifty? A hundred? More?

Think about it! The way some people would have it, there's a giant conspiracy going on between the training agencies, who for some murky reason won't let newbie divers practice BCD breathing ...

Well, there's another point of view. Maybe all the agencies are wary because they know the cure will be more dangerous than the supposed affliction. Hey, y'know, it could really be that simple ...

Solution: find out in a controlled situation just how much it can be rebreathed.

What is a 'controlled situation' when no standards are in place? Anywhere! Remember, you can go hypoxic without any warning and die of drowning in a meager 10 centimetres (4 inches) of water ... this is the more likely if one decides to practice this while solo diving.

Blacknet 'cites' a YMCA study which suggests 13 times.

I'd be surprised if there is a figure. This will be dependant on the
a) BCD volume
b) lung volume of the diver
c) rate of exertion
d) other physiological factors, possible asthma or similar etc.

It's certainly at least once

Correct. Maybe even a bit more, and don't forget to breathe out into the water. (This is basically as far as I've agreed myself earlier in the thread, if the **** really hits the fan and it's the very last option before drowning. )

I'm finding the "rebreathing the wing will mess up bouyancy" conclusion to be a little odd. If no air leaves the system of self and wing, how is this going to affect my bouyancy?

This, incidentally, is one reason why newbie divers shouldn't practice rebreathing the BCD and why agencies won't condone it. Again, think about it. If you breathe back and to into you own BCD, you will have free gas which will expand as you ascend (to the surface and to pure, free air). You will have to vent this gas as you otherwise will have an uncontrolled, fast ascent. This is no different to ascending with gas in your BCD as usual. You went it out through the inflator (or other dump valve). When rebreathing the BCD you are still subject to the same laws of diving physics.

To be honest, I know most newbie divers don't fully understand these principles and others. Which is why, again, you must use the four tools outlined at the top of this post. Because - you see - a lot of the self-professed "experts" on this board don't understand these principles either. And their suggestions could get you killed ...

 

[The Chairman]

managed to accomplish in my lifetime since the advent of the SPG and certification, I have truly been blessed. I have escaped having an OOA situation completely (obviously by sheer dumb luck according to some) have never had a student have an OOA (more sheer dumb luck) and I have never had a buddy have an OOA (what an amount of sheer dumb luck I am having). I have had a few buddies do a LOA and so we shared air, did our safety stops and lived to dive another day. I have had a ton of "issues" that have cropped up, but none that have led to an ESA or any serious injury.

I like my version of "fanatsy land" just fine and will continue on my Quixotic quest to prevent the preventable.

Davey you can play this game if you like, I will not. I have given you my answers in the most sincere way possible and yet you seem determined to brow beat me into some sort of submission. You don't accept my answers now and no amount of logic will change that. I can live with that just fine. That is YOUR decision.

For the other readers with open minds, let me implore you to examine the way you are diving. As a nation we are revolted by the concept of taking responsibility for our actions. As a dive instructor, I can't stress enough that YOU ARE RESPONSIBLE FOR YOUR OWN LIFE!!! If you die because you were too distracted, or pre-occupied or lazy to check your SPG then I will weep at your grave. But I will point out to the living how your decisions ended your life. I will not let you die in vain... others will live by learning from your mistakes. This is not callous, but merciful to those who are still alive. I wish no harm on ANYONE, especially any member of our board. So, I hope that you too will choose life... and not death. It's your decision so make a wise one!!!

 

[Davey Diverson]

fins wake once bubbled...
Now, let's examine the conclusions therein: Correct. Remember: No agency condones this, nor has any standards in place for it. Even the GUE blokes are doing this ad hoc (which says it all, really). If you do this you are on your own.

When you are in the water, you are on your own. You can't breath standards no matter which agency generates them.

And read on below ... ... which can be a bit nasty. SARS, anyone? TBC?

There are many cures for respitory infection. There are none for drowning.

And the risks inherent have been so downplayed by some on this thread that it is genuinely scary. I mean that. Real scary!

As opposed to what, drowning? The "experts" seem to downplay that risk quite a bit. I find that scary.

That is to say, you are advocating practising a reasonably difficult exercise which carries REAL RISK of DEBILITATING INJURY or DEATH!

Weren't you just whining about who shouts the loudest? DIVING CARRIES A REAL RISK OF DEBLITATING INJURY OR DEATH!!!

How many lives per year will be saved by hordes of newbie divers practising this technique ad nauseam? Two? Five? Fifteen? Well, how many of those would have been saved by proper diving techniques, paying proper attention to your gear and to your buddy?

Who's on second? Here is another question that I'm sure won't get answered.

Why bother with ESA at all?

Think about it! The way some people would have it, there's a giant conspiracy going on between the training agencies, who for some murky reason won't let newbie divers practice BCD breathing ...

No one is saying that. In fact, we've gone out of our way to ecludiate the fact that no training agency prohibits anything once you're certified.

To be honest, I know most newbie divers don't fully understand these principles and others.

Translate: You're <deleted> to figure it out.

Which is why, again, you must use the four tools outlined at the top of this post. Because - you see - a lot of the self-professed "experts" on this board don't understand these principles either.

Irony! Woot!

 

[Davey Diverson]

NetDoc once bubbled...
I have had a ton of "issues" that have cropped up, but none that have led to an ESA or any serious injury.

Oh. I see. Since it hasn't happened to you, it doesn't happen? Brilliant!

I like my version of "fanatsy land" just fine

Clearly.

Davey you can play this game if you like, I will not. I have given you my answers in the most sincere way possible and yet you seem determined to brow beat me into some sort of submission.

I'm just looking for answers, Doc. It would be simpler for you to just say "I won't answer your question" which would be the truth.

You don't accept my answers now and no amount of logic will change that.

Quite wrong. Even a little bit of logic would change that. But there is no logic in answering questions that havn't been asked, and even less in insisting that they have.

So, I hope that you too will choose life... and not death. It's your decision so make a wise one!!!

Ten Bears says Divers drown because they choose to.

 

[Windwalker]

As far as this discussion goes.. Re-breathing from a BC in the even of an OOA.

I agree with NetDoc, He is correct that 99.5% of all OOA situations can be avoided through proper training, proper maintenance of gear, good buddy proceedures, and awareness of the diving environment.

I also agree with Genesis, You can't tell Murphy that he will not be diving today. Properly maintained gear DOES fail, no matter how many precautions are taken (just ask the columbia crew)

I have never suffered an OOA personally, my instructor beat that into my head (check my gauges often, more often the deeper I go) Yes, I am a Newbie, but I am not an Idiot. (despite popular opinion)

Based on my interpretation of what Popeye was saying.. if that .5% happens and the the dive boat hits you on the way down, Do what you have to too survive. Knowing every option - no matter how remote, is better then having to come up with options when Murphy decides to visit. A good militarism is, "a good plan never survives implementation intact." I don't really believe that breathing from the BC should be taught in BOW. However the subject should not be kept from curious eyes.

I ride motorcycles - sportbikes. I think of all the things that can go wrong.. some things are out of my control and I know it. Sportbiking is a heck of a lot more dangerous then SCUBA, at least you can try out the whole "Breath from a BC" in a pool under supervision. If I try a "Rear wheel break at 60MPH in a parking lot" even if supervised I might not survive my dismount. Its essentially the same thing. The diver is taking their lives into their own hands by attempting this. As is being stupid enough to take a canyon curve at 60mph. On the other hand, Knowing that I can climb up on my bike is something that might save me some skin when my riding leathers wear. While Breathing off a BC might save my skin when all else fails and my buddy just got hit by a sea wasp and accidently grabbed my LP hose and ripped it out of my first stage in panic and pain.

All options for survival should be discussed, Pro's and Con's should be weighed, Knowlege is power! Common sense is the key. Newbies should not be exempt. Darwin was right!

 

[The Chairman]

I agree with NetDoc, He is correct that 99.5% of all OOA situations can be avoided through proper training, proper maintenance of gear, good buddy proceedures, and awareness of the diving environment.

Doncha think??? :tease:

And so I will continue to address the 99.5% (or should that be 99.999%???) of all of the incidents, with prevent, prevent, prevent!

For that last 0.5% (0.001%???) and ALL those who choose to ignore those skills...

Kick like your life depended on it. It does. There is air, sweet air on the surface! All you would care to breathe. Don't waste time or the last bit of air in your tank which still has more than your BC and is far more reliable (and cleaner). Just keep your reg in your mouth and you will find more air as you ascend. You have got to love Boyle's law. Stick to your training... and it will get you through.