CESA from 100 feet?

[Scuby Dooby]

I have a friend who used to be a spearfisher in the 80s, separated from his buddy (by intent) and at just under 100' suddenly couldn't get a breath in (corrosion inside the Al tanks clogged his first stage) . . . he immediately ascended without dropping weights and made it to the surface to talk about later. I'll bet it wasn't the prettiest CESA though . Joking aside, this was a harrowing experience for him - he stayed out of the water for quite a while afterwards and truly feels lucky to be alive.

 

[StSomewhere]

IIRC, the CESA is pretty far down on your list of options.

 

[Charlie99]

I did a practice CESA from about 90' in Cozumel. It was amazingly easy. One of the oft-repeated myths in scuba is that one must continuously breathe out. The real requirement is that one keep the airway open.

The difference is, that with an open airway, the excess air from ascending just bubbles out naturally.

If you actively force air out, you aren't going to make a 100' CESA. Just let it bubble out, and it becomes easy. My ascent rate was about 40fpm, and I didn't feel out of breathe at all -- had more air in my lungs when stopping at 15' than when I started.

Don't try this unless you have good voluntary control of your epiglottis, glottis, or whatever that doohickey at the back of your throat is called.

Report of very slow 100' submarine escape traing tower ascent

 

[Grajan]

The CMAS Deuxieme Echelon (DM equiv) training I did many years ago required a CESA from 130' (40m). We practiced from 130' to 90' then from 130' to 60' then to 30' then to the surface. My recollection was, that with a lot of training, it was pretty easy. You could ascend at a reasonable rate and stop and do a 360deg rotation at ten feet to clear the surface (this was required to demonstrate control although I'm not sure what the options were if you found a threat....).

One thing I have noticed is that they teach this now with the mouthpiece in. This makes it much harder to control the outflow of air and there is a tendency to breath out too much early on. It is much easier (although possibly not safer) to trickle air out through pursed lips. I don't think the commercialized training systems we have now would be willing to spend the time needed to teach this effectively.

Regardless of the above this is DEFINITELY the last resort in my dive planning.

 

[Doc Intrepid]

I did a practice CESA from 100' in 1984, warm clear tropical ocean. It was pretty relaxed, there were 8 of us all together. Then I did another one in 1986 that was, um, unplanned, from somewhere between 110' and 104' in Lake Michigan. It was not pretty relaxed. While I don't recommend getting into that situation, a CESA from 100' or so certainly a viable option. (Remember Boyle's Law, the air in your lungs expands as you ascend - you don't feel 'out of breath' except for the last couple feet, and thats cause it comes out much faster automatically as you ascend the last 15'.) (I must say that having done it previously and knowing what to expect took away much of the anxiety when the time came to do it for real.) Oh yeah, the gas in your hose DOES expand on the way up. I kept my reg in mouth and got another breath off it somewhere around 40' or so on the way up. Do like you've been taught, and you won't have any problems. But, ...do like you've been taught and avoid getting into that situation in the first place. Like Grajan says, its definitely the court of last resort...

 

[phylo]

One other thing to consider is the fact that the air in your hoses will also expand as you rise, one of the reasons that your instructor had you keep that reg in your mouth when you did your CESA durring your checkout dives. So what that means is that at 100' when you try to draw a breath and you cant, its highly likely that you will be able to at say 60', especialy if you have lots of hoses comming off of your reg as they will all trap air. Granted its not going to be much air, but if I ever get to the point where Im in an ooa situation Ill take what I can get! And if you get desperate enough, Im sure there is air in your bc so as you ascend that air is going to expand and you are going to need to vent it so you might as well vent it into your mouth!

Phil

Ooops, Just noticed Doc's post above stating almost the same thing

 

[pete340]

Oh yeah, the gas in your hose DOES expand on the way up. I kept my reg in mouth and got another breath off it somewhere around 40' or so on the way up.

Also, the first stage maintains a pressure of about 150 psi (if I remember the number right) above ambient pressure in the hose. In order to do that, the tank has to be providing at least that much pressure. When you're out of air it's because the tank pressure is too low at that depth. When you ascend the ambient pressure goes down, so the remaining pressure in the tank is now high enough for the regulator to deliver some air into the hose.

 

[Hank49]

I did a practice CESA from about 90' in Cozumel. It was amazingly easy. One of the oft-repeated myths in scuba is that one must continuously breathe out. The real requirement is that one keep the airway open.

The difference is, that with an open airway, the excess air from ascending just bubbles out naturally.

Report of very slow 100' submarine escape traing tower ascent

That's an excellent point Charlie. In the OW class it's hard to reach the surface on a shallow CESA if you continually blow air out. I've also heard that unless you try to pinch your trachia that it's hard to hold the air in as it expands on your ascent. (do NOT try to hold it in, please) PLus I think we can amaze ourselves when it comes to surviving.

 

[Epinephelus]

I've practiced the CESA from 100'. It was surprisingly easy if started with a full breath.
I have not tried it beginning at the "bottom" of a breath (fully exhaled) but imagine that wouldn't be much fun.
E.

 

[pasley]

If successfully making a CESA from 100 feet is you ONLY option then you will just have to do it,...or die. Personally I would rather have other options as in: Not having the problem in the first place, or having a buddy close to hand, and/or a pony bottle.

Can you do it? Possibly. Should you do it? No.