Who here has done a real life CESA and what was your experience?

[InTheDrink]

Hi,

Just wondering about people's real life experiences of CESA's is. I've never had to do one and hopefully never will but would be interested to hear how the theory translated into reality for those who have had to do it.

1. Why did it happen?
2. What depth?
3. What was your reaction?
4. What was your ascent rate?
5. Did you have to go to the chamber?
6. General experience/thoughts/advice/anything else relevant

TIA,
John

 

[Doc Intrepid]

More than two decades ago, on an island in the South Pacific, a class of new open water scuba instructors graduated. (Things were different then, each had first been apprenticed as a Dive Master for a year, then had spent the better part of nine months going through instructor training. This particular class had spent a great deal of time in the water.....) As a 'graduation celebration', or a final exercise - take your pick, the class stood on the sandy bottom in about 105' of warm, clear ocean to receive small tokens of graduation and shake hands all around. Then following our instructor trainer, we removed our BC's/tanks/regulators and watched as the rigs drifted up to the surface above us. Looking around at us, our trainer smiled at us and gave the thumbs up, and we all began swimming to the surface. No one was particularly concerned, of course, it was by no means an 'emergency', and we began swimming upwards at a leisurely pace. After about a minute and a half, however, our pace no doubt increased in direct correlation to the inclination to inhale we all felt, and upon popping to the surface all of us were relieved to recover our rigs and get back into them. Still, in the warm aftermath of graduation, no one particularly thought much of it at the time; this had been a routine exercise performed by each graduating class of instructors for quite a few years.

In terms of general thoughts, here are a few:
* 105' or so is not the deepest CESA. (Navy submariners train from deeper depths, for example.) But its a long way to swim up, and longer if you are not relaxed and in excellent physical condition.
* None of us dropped our weightbelts. (!) In an emergency it might not be a bad idea. Still, either way its going to take the better part of two minutes to execute the ascent.
* It would be good not to panic. We simply swam up. No one was kicking furiously or anything, an even, controlled pace will work fine.
* The things you are told about gas expanding in your OW class are true - we each exhaled continuously the entire way up, and only near the surface did I ever experience any sensation that I had little remaining to exhale. (of course, the rate of exhalation is something you want to watch! You don't 'blow out' so much as allow a small stream of bubbles to escape continuously...)
* On the other hand, just because you are 'exhaling' all the way to the surface it does not follow that you feel no impulse to inhale! After about a minute and a half or so, the desire to inhale becomes profound! (You're swimming, remember? Hold your breath as long as you can. Then do the same thing while performing jumping jacks. You will experience a variance.....)
* Physical conditioning is a factor. Blacking out underwater is a higher risk for those who may not be in good physical condition. (Other factors of your dive may also be contributory, for various reasons.)

Therefore, while I'm absolutely sure that CESAs are an option from depths up to around 105' or so, my inclination is to believe that they would be increasingly risky from greater depths. This is because, given that the rate of upward swimming is relatively constant, for most scuba divers I suspect that carbon dioxide build-up over time and related black out would likely begin to increase risks above survivable limits from much greater depths. But this is just my hypothesis from an N of 8. I have no other data to suggest any proof, either way.

Hope this helps,

Doc

 

[Rick Inman]

Nice post, DI.

When I used to do a lot of solo diving, I would intentionally do a couple 3 or 4 of them per year, usually form only about 30'. I found that doing a few is the only way to really get the timing on the exhaling, as doc mentioned. There in a place where the amount of exhale in relation to the gas expansion is just right - so you don't run out or so your lungs don't embolize. And I believed that, without practicing it, I would be hard pressed to do it well in a real-life emergency.

That being said, I never recommend that anyone practice this. IMHO, a much better mind-set is to always solve your problems underwater. As I have moved into overhead (obligated) diving, escaping to the surface is not an option. If I can't start the dive in a manner that allows me to solve my issues underwater (good dive partners, proper equipment, etc), then I am apt not to do the dive. Just having it in my mind that I can always escape to the surface might preclude me from taking the time to more safely take care of things underwater, or to properly plan before the dive.

 

[The Chairman]

It was the summer of 1976 or 1977 and there was a "bottomless" lake here in Orlando where a diver had recently died. There was talk of closing it to diving, so my friend and I decided to go for a look see. Neither of our regs had seconds on them, we had no BC and no gauges either. I had a ScubaPro J valve, on a salvages tank off of some air vehicle, and I believe it was a healthways regulator. The lake was black water, but we hit the spring water (maybe 30-40 feet) and though it was dark, we could see easily. We found the hole and started to descend. Lots of sand a few lime rocks sticking out. It was cold and had no thermal protection. I felt the constriction in my breathing that signaled the end of my air. Usually I had two or three breaths here, and I kicked down to get my buddy, when my breathing stopped. I reached behind my back for the j-rod and pulled. Crap, it was already down, and he was too far below me. I turned and ascended at ICBM speed. I didn't want to be the second fatality in this lake. I blew past the entrance and soon hit the black water where I was immediately hit with panic and disorientation. I had no idea which way was "up" now, so I just kept kicking. The hot humid air at the surface was the sweetest I had ever breathed.

How deep? I have no idea. I would suspect below 100'. After thoughts? I gave up diving for 20 years after that. The addition of depth/pressure gauges and the BC are WONDROUS additions. Getting certified was a plus too. I don't believe I have had an OOA since. I learned my lesson.

 

[Underwater Ogre]

OOA...
You don't always really know when you inhale if there is another breath left in the tank. I have exhaled and tried to inhale with a "no go". Of course this was an exercise on a safety stop. And swam to the surface with no air in my lungs.

Doing a CESA from 100' with absolutely no air in your lungs and the urge to inhale must be hell. I think it would turn into a "Hunt for Red October" ascent. No dumping air out a of BC, no flaring...just give me air!!

 

[Web Monkey]

Just wondering about people's real life experiences of CESA's is. I've never had to do one and hopefully never will but would be interested to hear how the theory translated into reality for those who have had to do it.

1. Why did it happen?
Because I ignored my training on something small that turned out to be important.

2. What depth?
Around 30' - 40'

3. What was your reaction?
I though f--- me. I was really stupid for doing this.

4. What was your ascent rate?
Not too bad. Less than 60'/minute.

5. Did you have to go to the chamber?
No.

6. General experience/thoughts/advice/anything else relevant
If you don't ignore your training, you probably won't have to do one.

I went diving with my regular buddy, who had disconnected his Air-2 because it was leaking. I had assumed that because it was a shallow dive, that there was no way I'd run out of air since it shouldn't have used much more than 1/3 of a tank for the entire dive, so needing to share air wasn't very likely.

The water was very cold (very low 30's) and the dive was uneventful until I tried to send up my SMB by inflating it with my second stage.

Although I have a cold water regulator with a sealed first stage, I was unaware that the second stage could still ice up and freeflow if it was flooded and then purged for a significant amount of time. Anyway, the second stage freeflowed while I was filling the bag, and then got worse with each breath until it was a huge continuous column of bubbles and my tank pressure was dropping like a stone.

Ordinarily I would have just shared air with my buddy, however his Air-2 was disconnected and it was faster and easier (and safer) to just do a direct ascent than to spend time trying to re-attach his inflator while wearing big blue drygloves.

The "take-away" is that little things from SCUBA class can become very important under the right circumstances.

Terry

 

[knotical]

In the early seventies I was a pretty experienced diver, but not certified. My gear included the then common j-valve with pull-rod. My buddy had wandered off. Toward the end of the dive at about 30 feet I first had difficulty breathing, then ran out entirely. So I pulled the pull-rod but it was already in the down position. Not sure why I wasn’t stressed, but I swam leisurely to the surface, and got a few more breaths because of the reduction in ambient pressure. The key was keeping my regulator in my mouth and continuing to try to breathe. I didn’t start with a slow exhalation because I’d already exhaled.

 

[DA Aquamaster]

A CESA was part of OW training (mid 80's) and I believe we did them from about 40'. They followed a "blow and go" model where you started exhaling, then started swimming up.

As posted above the big part is timing the exhalation correctly - the "ahhhh" sound we were taught to make on the way up vents too much gas on a long CESA. The worst part of a "blow and go" approach is that you vent too much at depth where you don't really need to vent much at all and you vent much of the gas when it still contains usable O2. It also does nto refelct the fact that unlike in training, you normally don't initate a CESA with a full lungs anyway as the "Hmm...my reg just gave me less than a full breath of air" clue is what prompts you to think about a CESA anyway. In the real world, just make little bubbles and ensure your airway is open all the time.

I did a couple of real world CESA's back when I was young, dumb and too poor to buy an SPG. Both were from about 40' and both were the result of the J-valve getting accidently pulled/snagged earlier in the dive. That said it was really no big deal. With the reg in your mouth you get another partial breath anyway on the way up.

My last CESA was from about 90' in 120' of water and the events leading to it rank right up there with the stupidest things I have ever done. I did a nice long dive, then decided to use the dregs of the tank to dive under the boat, inspect a few things, check the annodes, etc. After doing this for 15 minutes or so, I dropped my wrench (it was on a lanyard but of course I was not using the lanyard.) It turns out a 3/8" wrench on a lanyard falls through the water column exactly as fast as I can swim down after it as it led me by 10' all the way down to about 90' where I exhaled and then inhaled about 1/4th of a lung full of air before the reg stopped giving me anything.

The first major difference between this and my previous CESA's was the reg I was using. When a tank goes dry with an unbalanced reg, it just gets progressively harder to breathe but there is some warning and you are never left with a partial lungful of air or no air at all. That is not the case with a balanced reg that will let you breathe the tank down to what is essentially ambient pressure with no warning at all.

Difference number 2 is that with an unbalanced reg, the inflator will usually still work even after the second stage stops delivering air. This is again not the case with an unbalanced reg.

This left me in O2 debt at 90' with only a partial lung full of air and very negatively buoyant. It got my attention and I did an immediate 180 for the surface trying for a balance between speed and swimming efficency to maximize the O2 I had in my lungs - probably about 60 fpm. This was the only time in my life I ever saw the potential need for ditchable weights underwater but unfortunately I did not have any. I was however very motivated to get to the surface and on the plus side of the balance sheet I was a very good swimmer with extensive freediving experience.

As I swam up, I got more buyoyant and, as the ambient pressure fell I eventually got another full breath air from the tank and another partial one on top of that before reaching the surface. So even starting out in the hole so to speak the CESA itself was not a major problem. In retrospect, messing around near the bottom dumping weights would have speeded the ascent a bit (not always a good thing anyway)but would have also delayed the start of the ascent so if I had had them they probably would have been a wash. As long as you are diving a balanced rig and can swim it up, I am still of the opinion that ditchable weights are not an essential item nor even desireable in many cases.

As posted above, having air in your lungs is not enough, it is the presence of CO2 that provides the urge to breathe and that urge will be present on the way up even if your lungs are full.

What I learned:

1. If you do a real world CESA, keep the reg in your mouth as the odds are that you will be able to inhale another breath or two from the tank on the way up.

2. If not, just the effort of trying to inhale helps open up lung passages that may otherwise trap air and cause a lung expansion injury.

3. In addition, the inhalation effort itself seems to help fight the CO2 induced urge to breathe.

4. Use a redundant air supply.

5. If you drop a $3 wrench in 120' of water, just let it go and get it on the next dive or just buy a new wrench.

 

[garyfotodiver]

And I also did one CESA from about 50fsw. It WAS a result of my own stupidity; I ascended slower than my bubbles; I did not panic - my training kicked in. And yes, there was one or two breaths available from my cylinder as I ascended.

Of course, I did not tell my wife or children about it for several days.

 

[LeadTurn_SD]

This is a really good topic, with some great posts by those who have done deep CESA's. Thanks for sharing!

We trained for CESA in the mid-70's at somewhat deeper depths than what is taught today. I'm remembering 60' for my class, but with the ravages of time on my memory, this could be wrong

I've never done an "emergency" CESA. I would occasionally practice them in the 70's from 60'. My most recent "practice" CESA's were last year with my kids when they did their OW class CESA's from 30' (I was along on OW class dives as an unofficial DM). 30' CESAs were easy for everyone in the class, including the kids in the class. I've never done a practice CESA from deeper than 60', so it was great to hear about the experiences of those who have.

Anyway, great topic.