What is the deepest you can do an OOA?

[mikerault]

I can easily hold my breath for about 1 min, maybe 2 if my life depended on it, and even if I blacked out, maybe I could still get a minute or two in of unconscious ascent with an inflated BC (but then I might drown on the surface). So swimming as fast as 60' per minute (faster if necessary) I could easily do an OOA ascent from 100'. However, I might end up bent on the surface.

The other question is about how much gas I had in my lungs to start with. The 1-2 min breath-hold is at home when I'm sitting here relaxed and just took a full breath. OTOH, the gas in my lungs would be expanding as I ascended so maybe I could use that to my advantage to make it last a little longer. Also, if there was gas in my BC then I could take a hit of that from the power inflator/deflator. My strategy (assuming I could remain calm and collected) would be to start off at a fairly fast pace, but then stop for a mini-safety stop IF I had enough gas in my lungs or BC around 20' or 10' or at least slow down closer to the surface and of course I'd breathe out to avoid over-expansion injuries.

NEVER, NEVER, NEVER hold your breath on a CESA, even a depth change of 10-15 feet could result in serious damage to your lungs holding your breath with presurized air at depth. The length of time you can hold your breath has no meaning in SCUBA or CESA and continued thinking along these lines will kill you from a LOI (Lung overexpansion injury) think ruptured lungs, bloody froth form the mouth, death.

Mike

 

[mikerault]

Recent???the British did 600 in the early 70's... Michelin man suits have been used since the 50's

However, the US SUbmarine service used Steinke hoods through at least 1979 (when I left the service) and only recently started using the suits.

In Government terms 1970's is recent...

Mike

 

[TSandM]

When you take a breath, the air you inhale is effectively devoid of CO2. Therefore, there is a large gradient from the blood to the alveoli (air sacs) to drive diffusion of CO2 into the breath you are beginning to exhale. As time goes on, that gradient decreases, and therefore, so does the rate of CO2 diffusion into the gas. The next inhale increases the gradient again, and this is how CO2 elimination is done. As you can imagine, since the alveoli do NOT collapse with each exhalation, they have a finite volume at all times, and therefore the inhaled gas is diluted to some extent by what remains in the alveoli, and therefore always has a higher CO2 content than what you are breathing.

Therefore, as you are exhaling a single inhalation, NO MATTER HOW LONG IT TAKES YOU TO DO IT, your rate of CO2 elimination is rapidly decreasing, and at some point, you are no longer taking CO2 out of the blood at all. CO2 levels are the determinant of the drive to breathe, and although this drive is capable of voluntary inhibition, and that degree of voluntary inhibition can be increased with training, it's a very strong drive.

I don't know from how deep it is possible to do a CESA. I did mine in OW from 45 feet, and it was surprisingly easy. I believe the submariners used to do them for practice from 100 feet -- at least, an old submariner I talked to at Cove 2 one day told me that. It may well be POSSIBLE to do it from any recreational depth. Whether you get bent or not is another story, but a non-lethal case of the bends beats drowning any day.

I don't ever want to find out how deep I can do a CESA, which is why I only dive with attentive, disciplined buddies, and these days, most of the time I'm diving doubles.

 

[mikerault]

Got my first set of doubles finally! Now I have to drill, drill, drill to get th skills for their use...

Mike

 

[O2BBubbleFree]

I asked this same question a couple of years ago, and was directed to the story of a scientist who did early research on submarine escape. He basically did a CESA from some unbelievable depth, like 600'. I'll keep trying to find it. In the mean time:

Here's an interesting read. Scroll down to p. 321 (Free Escape). It seems that 'in practice,' feeling a need to inhale is not a problem.

 

[Soggy]

So a complete exhale is impossible?

Yes

http://en.wikipedia.org/wiki/Tidal_volume

 

[*Floater*]

NEVER, NEVER, NEVER hold your breath on a CESA, even a depth change of 10-15 feet could result in serious damage to your lungs holding your breath with presurized air at depth. The length of time you can hold your breath has no meaning in SCUBA or CESA and continued thinking along these lines will kill you from a LOI (Lung overexpansion injury) think ruptured lungs, bloody froth form the mouth, death.

Mike

Yes, that's why I wrote "I'd breathe out to avoid over-expansion injuries."

 

[Gary D.]

Some of these replies are right on and some are off the charts. One thing to remember is that when you start up, the very second you start up, any air in your lungs is going to start expanding. That expanding air needs to be vented off and you will have NO urge to breathe.

I have done a lot of these both totally free and some with a variety of submarine escape devices. Not once did I ever want to take a breath and I have had solid exhales for over three minutes.

We normally did these from 100-119’ but I have done some from over 150’ with no ill effects.

If basic OW training still included the gas laws people may better understand what is going on. Don’t worry about what MIGHT happen. It would be a real stupid act to hang onto a rock and die because there might be the possibility of getting bent, bypassing a safety stop or coming up a little bit to fast.

Redundant gear is fine but when you have a failure of your main gear you now have NO redundant gear and have to rely on something else. And yes, redundant gear can fail just like the main gear can. Safety valves do not always work.
Never dive solo and rely on a buddy is fine. But guess what, when that buddy is not there you are now a solo diver.

They have eliminated some very important things from sport training. If you practice it or not you need to have the information to know that it can be done and done with ease. The theory can be practiced in very shallow depths with GOOD supervision. The only difference between 10’ to 200’ is the length of time you will be exhaling.

I don’t know what it says now but the US Navy dive manual used to have a very good section on this. My suggestion is to down load it and read it.

Tens of thousands of people have done them and tens of thousands are still here to tell about it.

Relax a little, they work.

Nothing beats good gas management.

Gary D.

 

[airsix]

Telling divers they shouldn't use CESA is like telling fighter pilots that they shouldn't use parachutes because they are dangerous. They should just not get shot down instead because not getting shot down is safer.

There is only one situation in which you would use a CESA, and coincidentally in that situation there is no other option for survival. Every year we read about diver OOA drowning deaths. At least some of these could possibly have been prevented by proper use of CESA. The reality is that divers drown and CESA training could reduce the number of deaths. Why is it not being taught? Is this some sort of weakest link policy that since some people are morons nobody gets to learn this skill because someone might do it wrong? If someone screws up a CESA and dies, guess what. They were going to be dead anyway or they wouldn't have tried it.

My first instructor was a former Navy diver. He provided instruction in proper CESA execution. I've practiced it, and by doing so if I'm ever so stupid as to get into a situation where it is needed I know that I will be less likely to panic because I won't be asking myself "Does it really work? Will I do it wrong? What if..." I already know the answers because I've experienced it. I've done it and I know it works. If I ever HAVE to do it, hopefully I'll keep my head... and my life.

The furor this topic generates has always puzzled me.

1. It works. It's proven. There is NO debating this fact.
2. If you know how to do it, it could save your life.
3. If you are trained to do it, you will be better prepared to handle an emergency. You will be less likely to panic because you won't have to ask yourself if you are capable of it - you'll already know you are. Panic is caused by a cascading failure of self confidence. Training gives you skills and just as importantly it gives you a knowledge of both your limitations and abilities. An emergency situation is not the time to "get to know your limitations and abilities" because you will doubt and doubt can lead to panic.

Telling someone to 'not get into that situation' is not a suitable substitute for training them to deal with the emergency.

-Ben

ps - Regarding the comments questioning whether a person can really do a CESA from depth without the urge to inhale, or ascend to rapidly, etc. etc. I'll just say this: With proper training a CESA is not difficult. You are not uncomfortable, you don't ascend too quickly, you don't black out, you don't run out of air, and you don't embolize. The last training CESA I did was from 65ft with an ascent rate of less than 60ft/min with steady exhalation and when my head broke the surface I had to exhale 1/2 a breath. It works. As you ascend you can regulate your exhalation rate to maintain a comfortable 'not too full, not too empty' lung volume (assuming you had some to start with). And if a diver gets bend doing a CESA it means he/she made a multitude of mistakes long before air ran out.

 

[Soggy]

The reality is that divers drown and CESA training could reduce the number of deaths.

No, the "reality is" that fundamental skills like team diving and gear redundancy is not being taught to an acceptable level and thus those drowning divers made mistakes that should never have happened in the first place.

Even then, can you please cite some documentation that shows that CESA training reduces deaths? I'd rather see that time put into training skills that will prevent the situation from occurring in the first place.