Deep CESA Practice Okay?

[boulderjohn]

There have been many, many threads on this topic in the past, and many people have reported doing CESAs from 100 feet and beyond. It is not at all unreasonable to expect to do it successfully.

A couple of points:

Yes, the expanding air will provide you with air throughout the ascent, even if you are not rushing it too much.

You should have a full breath to start because you will know you are running out of air. The regulator will get harder and harder to breathe from on those last breaths, so you should have ample warning that you are on the edge.

Your tank is not out of air. Your regulator must be able to provide you with air at a pressure above the ambient pressure of the water around you or you cannot breathe it. When that pressure falls too low, you cannot get the air. Ascend to a shallower depth and (thus) a lower ambient pressure, and you will get air from the tank. That is why you do not discard your regulator or hold it in your hand. Keep it in your mouth where it can do some good if needed.

Put the last two points together. If you realize through labored breathing that you are almost out of air and start our ascent, you might be able to use a normal breathing pattern all the way to the surface.

Finally, watch your gauge and stay with your buddy and this whole thing will remain nothing more than an internet debate.

 

[highdesert]

It would also be a bad moment in a diver's career to discover the deficiencies of split fins..:shocked2:.

This comment is, IMHO ...

1) absolute rubbish

and ...

2) has no place, and, is in no way related, to the OP's question

 

[KevinG58]

What sinking was this? Just need the subs name to research. I think I vaguely recall but would like to research. Big submarine fan Sorry for the hijack.

Well, of course there are better ways of doing things. But my point on the original post and again on this post is this: If you are out of air and buddy is not available, do you sit down and accept your fate? No, and I'll say it again... It's a no brainer. You head for the surface. 99 out of 100 times, you'll make it. Is it something you want to get in the habit of? Of course not. But, if everything else fails you, like your brain, dive buddy, or bail-out, what choice do you have?

Depending on the direction of this topic, I had a link prepared of a sunken sub in 74m. 72 People ascended from the sunken sub. 29 of which were not submarinemen but rather dock workers hitching a ride. All 72 Men survived the ascent, 29 of which who had 0 training.

Unfortunately, I'm not on that computer today, so I don't have the link from this laptop. But I will find it later for you guys to read the article.

 

[Superlyte27]

What sinking was this? Just need the subs name to research. I think I vaguely recall but would like to research. Big submarine fan Sorry for the hijack.

Bah, that was a week ago. I'll see if I can find it, sorry

 

[LeadTurn_SD]

The advantage to "practicing" is less in the familiarity that practice creates and more in the confidence that it breed.

1+

Confidence in your ability to "make it" is the key. Knowing that it can be done will hopefully push back the boundaries of panic just a little bit, and allow you to try and save yourself.

We did fairly deep CESA's as part of my basic OW class in the 70's... from about 60'. I do not know if this was typical, or if our ex-Navy instructor was teaching beyond the standards at the time. I've been led to believe that he was "enhancing" our instruction a bit

I'm glad we practiced from that depth. It was a "long" minute to reach the surface, but not as hard as you'd think.... easier than swimming a "lateral" 60' simulated CESA it seemed.

CESA from 60' depth is well within reach for most reasonably fit people, at an ascent rate of about 60'/min.

I think it is important to know you have a good chance of survival right up to the edge of recreational depth limits if you stay calm.

I think that knowledge is the true value of CESA training / practice.

I'm not a dive pro of any kind, so I won't advise for or against practicing CESA outside of a class setting... there are obviously risks.

Best wishes.

 

[MauiScubaSteve]

I'm fairly certain that "back in the day" more than one agency had printed standards "at least" twice as deep as today. One of my classmates at zero-to-hero school claimed to have done a 60' CESA in his 2000 Caribbean OW course (the classmate that washed out).

I have breathold dived to 102', twice, so I am comfortable with the 80-100' no pony solo.

 

[LeadTurn_SD]

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?

Mike,

I've actually thought about your question for a long time; but was hesitant to fully answer in my first post. So, this is not a recommendation, just "thinking out loud".

If I were to practice deep CESA's today, and wanted to be as safe as possible doing them, I'd look at where the greatest danger is:

Losing control of your ascent rate, especially as you hit shallower water (the last 20' or so).

You risk air embolism and/or DCS.

If your ascent rate is "pretty much" in control (in the 60'/min ballpark), and you are exhaling, and you do it at the very beginning of the dive (and do not dive any more that day) I do believe the risks are small.

But a risk still exists.

If Basic OW classes practice CESA from 30' you know that from this depth a practice CESA can be accomplished "safely" with caution.

But how about deeper CESA practice?

The rate of expansion of the air in your lungs (and BC) is not as rapid at depth as it is in the final 30'. One possible "safer" way would be to CESA from 90' to 30', at 60'/min.... then full stop at 30', and hover for a few minutes for sort of a "safety stop" (breath on the regulator! ) , then do the final 30' CESA at a "slow" 30'/min rate.

You'd experience the entire 90' CESA, and you did a total of 2 minutes of "exhaling ascent" (which would actually simulate the time to perform a 120' CESA); but with a "safety stop" of sorts at 30' to make sure your ascent rate was under control, allow you to off-gas a little, etc., before proceeding.

Again, this is not a recommendation!!

I'm just thinking about how I might approach practicing this while keeping the risk as "under control" as possible.

Best wishes.

 

[KevinG58]

Bah, that was a week ago. I'll see if I can find it, sorry

I found this.

HyperWar: War Damage Report 58: Submarine Report [Section 22]

Tang (SS306) was sunk off the coast of China in 180 feet of water on 26 October 1944 by the malfunctioning of one of her own torpedoes. Six men made successful individual escapes from underwater, one from the conning tower and five from the forward torpedo room escape trunk. The conning tower escape and one of the forward torpedo room escapes were "free". The remaining four were "lung" escapes. At least eight other men are known to have left the escape trunk but either died shortly after reaching the surface or were not seen again after leaving the trunk.

 

[DCBC]

...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?

Good question Mike. I teach all OW students to do a 50' CESA and Advanced do a 100' CESA. In dive school with the Navy, we had to do an actual doff and don in 100' of water, which given the 10' visibility scared the bejesus out of me (we had a strobe on the valve, but it couldn't be seen until you got within 25 ft). Since then, I quite often practice CESA between my deepest depth and the first decompression stop.

If you are practising them, I'd start at 50' and if successful go deeper in progressive steps. Keep your regulator in the mouth and be careful not to ascend too swiftly. I know this is obvious, but sometimes people forget they can in-fact breathe at any time and go too fast towards the surface. In a real emergency, I'd rather reach the surface with DCS rather than not reach it at all, but there's no use hurting yourself for the sake of practice. It's also good in practice to start deeper and end at a safety stop before surfacing. Good luck.

 

[jonathon50]

heres a tried out theory(Done in the pool i hasten to add!) A DM said to me when i was doing my rescue course, "where else do you have air if you run out"? threw me, BCD he says! as you ascend the air expands, it might taste like the proverbial but its air, so we tried it, got neutrally buoyant in the pool (3 mtres) and sucked off the BCD! we got about 3 good lung fulls before it gave up. would this be poss do to in a emergency?