Deep CESA Practice Okay?

[Mike Boswell]

On another thread here (How deep w/80 cuft tank?) some posters felt sure that they could do a CESA from 100 feet if necessary. But I don't recall anyone saying that they actually had done it. I DO seem to recall that we did a 30' CESA as part of our PADI training (OW or AOW).

I actually don't know whether I could do a 100-foot CESA under realistic diving conditions and I would like to give it a try one of these days. Let's call it a kind of practice drill.

My question: Is this a good idea or a bad one, and what is the best way to do this?

 

[UCFKnightDiver]

On another thread here (How deep w/80 cuft tank?) some posters felt sure that they could do a CESA from 100 feet if necessary. But I don't recall anyone saying that they actually had done it. I DO seem to recall that we did a 30' CESA as part of our PADI training (OW or AOW).

I actually don't know whether I could do a 100-foot CESA under realistic diving conditions and I would like to give it a try one of these days. Let's call it a kind of practice drill.

My question: Is this a good idea or a bad one, and what is the best way to do this?

I don't think it's a great idea, and also keep in mind, a practice cesa taking a deep breath of gas and an actual cesa could be two totally different things.

 

[TMHeimer]

I've heard that people have done it from 80-100'. One has to wonder though...You're coming up a long way on one exhale. How fast would you have to ascend (even though the air in your lungs is expanding to give you "more") to make it on one exhale. Would it be too fast to allow sufficient offgassing from that deep? I would guess you'd try the CESA immediately after reaching your depth so you'd have much less N in your system to begin with.

 

[Indian Valley Scuba]

Neat idea, but here is the basic flaw in any simulated CESA practice. How much of a breath did you get before you started? Of course, the answer is a full one! Well gosh, wouldn't it be nice on a dive, whether it be to 30 ft or 100 ft, to draw in that last full inhalation, and just when your lung capacity was reached, to somehow sense, or be told, that a CESA was needed, and now!

You know that in reality, when the proverbial feces hits the fan, you won't be getting a full final breath, in fact you'll probably be sucking on that regulator like a madman, unconvinced that it really, truly just quit on you!

So, take that into consideration when pondering how deep you can effectively complete a CESA from!`

 

[dumpsterDiver]

I think it is a bad idea. It is likely that in a real emergency, you will not know you have zero remaining breathable air until after you have fully exhaled. So to be realistic, i would think that you would need to simulate this empty lung condition.

However, it is also my understanding that if is possible, maybe even more likely, to get a lung over-pressurization injury if you have fully exhaled because this can shut off, or isolate portions of the lungs and allow these small areas to experience barotrama even though the theoretical lung volume is no where near capacity. I recall that this was the explanation for divers that expereinced air embolisms, even though their instructors accompanied them and saw them exhale the entire ascent.

I myself used to drop my tank on the bottom in 60 feet and slowly swim up exhaling all the way and then rest a little and snorkel down and recover the tank and put it back on. I don't think this actually simulates a true emergency and it was not from 100 feet. I considered it playing around. Based on this expereince, I am reasonably sure I can make it up from around 60 feet in an emergency and anything deeper, I wear some redundancy when scuba diving.

 

[Scott L]

Neat idea, but here is the basic flaw in any simulated CESA practice. How much of a breath did you get before you started? Of course, the answer is a full one! Well gosh, wouldn't it be nice on a dive, whether it be to 30 ft or 100 ft, to draw in that last full inhalation, and just when your lung capacity was reached, to somehow sense, or be told, that a CESA was needed, and now!

You know that in reality, when the proverbial feces hits the fan, you won't be getting a full final breath, in fact you'll probably be sucking on that regulator like a madman, unconvinced that it really, truly just quit on you!

So, take that into consideration when pondering how deep you can effectively complete a CESA from!`

Aren't you supposed to get a near full breath during such an ascent from a reg system? It would also be a bad moment in a diver's career to discover the deficiencies of split fins..:shocked2:.

 

[Indian Valley Scuba]

Oh my goodness, that is at least a 15 yard penalty for "piling on"!

 

[Mike Boswell]

Okay, points all noted. Suppose I descend from the surface to 100 feet, then exhale, then begin my ascent while blowing bubbles at 60 feet per minute, with the reg held in my hand for just-in-case? Any problems?

 

[Indian Valley Scuba]

Don't forget to do your deep stops!

 

[a22shady]

Best emergency situation is the one you can avoid. Carry a Back-up Sling Bottle (30-40) so if your primary shoud fail you have reserve on seperate system. But for the argument sake I don't think I could make it from 100. Thats a long way I did the 30 and Didn't feel as if i was going to die or struggled with it. But from 100 not sure. If I was Kicking like all hell and I would exceed the limit to surface. I could see 60-70 Max