I had trouble with the CESA

[jcxd45]

Couple of questions, I've been reading quite a bit about troubles that people had during open water.
I experienced many of the same....weight belt removal, and had no problem with others that give people fits.....mask removal, taking regs out.
My biggest problem by far was the CESA, took me two tries and both caused a huge amount of stress.
Part of the problem was my BCD being too tight.
My question is how safe is this to practice from a shallow depth (20')?
Also, is there a much deeper CESA in AOW?

 

[Linedog]

For me the easiest way to perform the CESA was to hum. Yes just by humming I was able to relaxe and exhale just enough and not over do it.

 

[boulderjohn]

You are not required to do a CESA again in your instruction, which is probably too bad.

Done properly, the CESA is extremely safe. It has been done from depths beyond 100 feet. Back when divers usually used J-valves without pressure gauges, it was fairly common for them to pull their lever expecting to get their air reserve, only to find that the lever had been accidentally pulled or the tank had been filled improperly, giving them no reserve. CESAs were fairly common then, and divers were more used to it. The problem with CESAs today is that it is barely taught, and usually not well. This leaves the diver with the notion that you have: it is really hard, and I can't do it. As a consequence, if you are ever in a situation in which you need to do it, you are likely to hold your breath instead of doing a proper exhale. Research shows that this is the number one reason for preventable dive accidents by far.

 

[boulderjohn]

The main problem with the way we teach CESA is that artificial need to minimize the exhalation in order to cover the required distance with one breath. That is because we teach it horizontally in a pool and at very shallow depths in open water. In a real situation, the vertical ascent gives a much greater expansion of air. Although that is the danger, it is also the blessing. You do not have to be so very limiting when you exhale in a real situation.

 

[TMHeimer]

20 feet is safe. Probably deeper is OK too as you always have the reg in mouth if you need air. Try without taking a big breath first--it's quite possible that in a real OOA situation you won't have full lungs to start off.

 

[DukeAMO]

If you're doing the PADI OW certification, you'll do one CESA for your checkout dives, and it'll have to be from around 30-35 feet deep, I think.
I found it slightly easier to do the CESA in the checkout dive, for a couple of reasons:
1) experience and practice
2) when you do the CESA from depth, it takes a few kicks to really start going up, but you accelerate as you go up, so it doesn't take very long to go up 30 feet (maybe 30 seconds total)
3) air expansion in your lungs from depth makes it a little easier to keep breathing out slowly
4) by the time you get that far, you've done so many other challenging things, that you won't let one little thing stop you

I did run out of air to breathe out about 6-7 feet below the surface in both cases, but you cover that distance within a few seconds. Just keep trying to breathe out.

I also changed from the "a" sound to the "e" sound like some people here suggested, since saying "a" can make you breathe out too fast.

Was it the sensation of running out of air the freaked you out, or manually inflating your BC after all of that?

If it's the feeling of running out of air, you can practice taking a big breath and very slowly letting it out (for 30 seconds) any time you like, until it's not scary any more. And remember that even if your lungs are empty, you don't need oxygen immediately.

If it's manually inflating the BC, that gets easier with practice. Also realize that you're not *that* negatively buoyant without the BC; you can easily fin to keep yourself up for the minute or less it takes to fill the BC.

---------- Post added April 26th, 2012 at 03:22 PM ----------

BTW, we did our freediving practice in the pool while wearing the same weights and wetsuits we wore with the scuba gear. I thought the instructor was crazy. I was surprised that I could still swim easily with the weights on and no tank or BC. It's really only the negative buoyancy of the tank that you have to fin against at the surface while you inflate your BC.

 

[Herb-alaska]

one way that I have been working on my Cesa skills is be increasing the distance each time. Start by cesa while swimming the width of the pool then the length then turn and try for more than one length . When you actually are going to do it the expansion will help you so that you not run out of air. The practice part is to keep a steady exhale for the entire swim which works will in a pool on a horizontal line. I started being able to make it about 50 feet and can now do about 90 feet which in my thinking means that I could effectively Cesa from at least -90 not that I will want to try it.

 

[blue steal]

I practice swimming across the pool as well. I can go 25 meters/ ~75' on one breath, using short fins.
But I wonder how this compares to coming up vertical from 75'. Easier?

 

[boulderjohn]

Just to emphasize what I said earlier....

There is no real comparison between horizontal CESA and vertical CESA. Vertical is MUCH easier because of expanding air. A friend who did a CESA from 75 feet (in a real situation rather than a drill) said it was easy. Once he started letting air out, it would have been difficult to stop.

When you are at 75 feet, you are at 3.3 atmospheres of pressure. That means that a lung full of air will have 3.3 times as many air molecules in it as at the surface. That means that if your lungs were balloons sent to the surface, they would arrive at 3.3 times the size they started. All that air has to come out, or you can guess the consequences. When you do it horizontally in the pool, the pressure remains the same, so there is no air expansion.

 

[Splitlip]

When I did my cesa in I think 1979, it was from 60 or 65 ft. Left hand held the inflator of my ( borrowed) bcd and second stage was out of mouth in my right hand. Think of h's and not k's or hard c's "ahhhhhh". I think I'm better for it.
Only squirrelly part for me was flaring at 20 or 15. It was an added task. Still very easy however.