CESA Training

[Dody]

There are several main components to learning the CESA:

1. Controlling your ascent rate by venting your BCD
2. Keeping airway open and experiencing that huge rush of air out of your lungs as you near the surface. You won’t feel this if you do a horizontal (pool practice style) CESA
3. Establishing buoyancy at the surface

Things CESA, as trained, doesn’t show you:
- You don’t always get a full breath from your now-empty tank before starting a real CESA. Doing one on your own practice could be more realistic, and helps avoid filling your lungs and risking overexpansion
- You might get additional air from your regulator as you ascend.

#1 could be practiced from deeper depths without nearing the surface by stopping your ascent say at 10m. You lower your risk of issues but still get to work on controlled ascents and hitting stop depths, both valuable skills.

As a variation, you could also do this as a simulated BCD failure as well, so you can check if you are able to swim upwards with your current weighting and empty BCD.

#2 I don’t know if it needs lots of practice as it’s a reinforcement of the need to keep the airway open plus is the most dangerous part. As others said, do it as soon as possible, like first dive of the day, and when you’re equalized and feeling good. Keep in mind that when actually doing this as instructors, we use a safety line to help manage the ascent rate. If you have a similar (anchor or shot) line available, I would use it. Go down to 6m (20’) max and you’ll still feel that 1.6x pressure difference as you come up.

Realistically, though - there are other things worth practicing more, such as deploying your pony, sharing gas, mask flood, gear problems, safe ascents, SMB, etc. given your overall safety attitudes. Doing these smoothly without buoyancy and trim wobbles will go a long way making you a safer, skilled diver.

Thanks. I actually have a checklist of skills to practise regularly:
- Mask clearing. This is a joke. I don't need it. N
- Mask replacement. Y
- Opening eyes and looking aroung without a mask. Y
- Free flow breathing. Y
- SMB deployment, I do it for all my dives. Y
- Sharing gas (giving main and using octo) Y
- LPI connect and disconnect. Y
- Open tank valve at depth. There is no way I can do it even lifting the cylinder. My body is just to rigid. I have to detach the BCD and swing it around on the right side. Y. Also, there is absolutely no way that I would go under water without taking three breath from main and three from octo while watching the SPG. As there is no way that I would go on water without my BCD fully inflated (Negative entry, I pass. Got barotrauma already). This is my routine just before getting into water, after buddy check.
- Orally inflate BCD at depth and at the surface. Y
- Cramp fixing. Don't need it. I do it without using my arms. N

If you have additional advice, additional tests and practise that make diving safer, please feel free to contribute.

 

[The Chairman]

Geez! I was born in 1969 and last year I wondered if I was not too old to learn scuba diving

I've seen a lot of change in diving. Most of it for the better. People who tell me I'm too old or fat to dive usually just get the middle finger! Diving is the most relaxing activity I know.

Most people run out of air because they are distracted. Most people are distracted trying to maintain some semblance of neutral buoyancy. They can't figure it out, because they don't realize that trim comes first. Once you get flat, you can easily achieve being neutral all the time without nary a thought. Not only will you use less air, but you will have fewer distractions, so keeping up with your gas supply is a breeze.

 

[dmaziuk]

That is an absolutely great idea. If you can free dive to x feet, then doing a free ascent from x feet should be easy if on Scuba.

Except for the safe ascent rate. I don't have a problem swimming 25 yards underwater (horizontally) with my airway open, but I do it in some 20+ seconds. I couldn't it in over 2 minutes. This is not a problem if you're not on scuba, but if you need CESA from 30m because you're OOG after a 20 minutes of bottom time there, you may want to go much slower than you did in your freedive lessons. Of course if it's for real and the choices are bent or drowned, then screw the ascent rate, and pool/freedive practice should be just fine.

 

[johndiver999]

There are several main components to learning the CESA:

1. Controlling your ascent rate by venting your BCD
2. Keeping airway open and experiencing that huge rush of air out of your lungs as you near the surface. You won’t feel this if you do a horizontal (pool practice style) CESA
3. Establishing buoyancy at the surface

Things CESA, as trained, doesn’t show you:
.

There should be no huge rush of air out of your lungs. One of the main objectives is to keep a somewhat neutral volume in your lungs and to produce a more or less continuous stream of bubbles and in doing so, keeping the airway open. If the ascent rate is not explosive, there is constant and gently exhalation, there is no "rush" of anything. It is a relaxed and controlled exhalation and the expansion rate is very moderate, maybe the last 5 feet or so, you blow a bigger bubble.

 

[Dody]

Most people are distracted trying to maintain some semblance of neutral buoyancy.

For me, that would be different. I have very good buyoancy and trim... horizontally. And my neck is so stiff that nothing distracts me. Every now and then I have to dive face up to check the environment or check for my buddy. I need to work on my vertical buyoancy though.

 

[rx7diver]

Would it be considered safe to practise CESA training from 10 then 20 and eventually 30 meters?

If you really want to practice it. Do it vertically.

@Dody,

The open water certification course I took (a university, semester-long, for-credit, PE course taught to YMCA and NAUI standards in 1986) simulated a CESA during pool training:

1. Three submerged divers, A, B, and C. Shallow, 25-yard pool.

2. Divers A and B, at one end of the pool, submerged and holding and breathing off of a tank.

3. Diver C at the other end of the pool, submerged and holding and breathing off of a tank.

4. At the start, Diver A leaves, swimming underwater from one end to the other, releasing a steady stream of bubbles all the way, traveling at a rate of one foot per second (to simulate a CESA from 75 ffw/fsw, using a 60 fpm ascent rate). Upon reaching the opposite end, Diver A receives the tank from Diver C, and Diver C leaves to swim underwater back to Diver B, releasing a steady stream of bubbles all the way, traveling at a rate of one foot per second. Et cetera.

Divers wore no gear except swimsuit, fins, and weight belt. (No mask!) All Divers had to complete 10 trips across the pool, with each trip requiring at least 75 seconds (i.e., >= 01:15 mm:ss). None of the Divers could surface nor breathe surface air once the exercise began. The tank hand-off had to be "controlled" and "clean". Any "violation" by any of the three Divers required the exercise to begin again, from the start.

One other thing: To reduce risks, a TA swam directly above the swimming Diver, each entire trip, monitoring and ready to intervene if necessary. (The riskiest part of this exercise occurred each time a Diver first left the tank to begin a trip across the pool, since his/her lungs would be full of compressed air. And, of course, there is risk whenever a Diver does not breathe for too long!)

Upshot: This was my instructor's way of having his students practice a CESA relatively safely. FWIW.

rx7diver

 

[Dody]

@Dody,

My open water course (a university, semester-long, for-credit, PE course taught to YMCA and NAUI standards in 1986) simulated a CESA during pool training:

1. Three submerged divers, A, B, and C. Shallow, 25-yard pool.

2. Divers A and B, at one end of the pool, submerged and holding and breathing off of a tank.

3. Diver C at the other end of the pool, submerged and holding and breathing off of a tank.

4. At the start, Diver A leaves, swimming underwater from one end to the other, releasing a steady stream of bubbles all the way, traveling at a rate of one foot per second (to simulate a CESA from 75 ffw/fsw, using a 60 fpm ascent rate). Upon reaching the opposite end, Diver A receives the tank from Diver C, and Diver C leaves to swim underwater back to Diver B, releasing a steady stream of bubbles all the way, traveling at a rate of one foot per second. Et cetera.

Divers wore no gear except swimsuit, fins, and weight belt. (No mask!) All Divers had to complete 10 trips across the pool, with each trip requiring at least 75 seconds (i.e., >= 01:15 mm:ss). None of the Divers could surface nor breathe surface air once the exercise began. The tank hand-off had to be "controlled" and "clean". Any "violation" by any of the three Divers required the exercise to begin again, from the start.

One other thing: To reduce risks, a TA swam directly above the swimming Diver, each entire trip, monitoring and ready to intervene if necessary. (The riskiest part of this exercise occurred each time a Diver first left the tank to begin a trip across the pool, since his/her lungs would be full of compressed air. And, of course, there is risk whenever a Diver does not breathe for too long!)

Upshot: This was my instructor's way of having his students practice a CESA relatively safely. FWIW.

rx7diver

I have two questions. 1) Did your students get better and better as they reproduced the exercise? 2) Why wouldn't it be possible to stretch from 75 ft to 100 ft?

 

[rx7diver]

I have two questions. 1) Did your students get better and better as they reproduced the exercise? 2) Why wouldn't it be possible to stretch from 75 ft to 100 ft?

Not my students. I was one of the students. Moreover, I was the old man in the class since I was a doctoral student in a class of very young, and fit, undergraduate students!

This was one of the required pool skills. We each had to pass each of the pool skills on a list of several before we were allowed to go on our open water practicum.

And yes, as we neared our 10th trip across the pool--especially after having false-started a couple of times--we each had a real sense of just how slow one foot per second really is, and we were all easily exceeding that 75 second minimum required time.

rx7diver

 

[BoltSnap]

I teach CESA in openwater simply because I am required to do it by my agency otherwise I'd never do it with students in openwater. Doing it with students from depths of 20 meters or deeper is dangerous and is inviting somebody, the student or the instructor, to possibly get bent or worse.

I'd recommend that you take a freediving course that takes you to the depths you want to go to and forget about CESA from these depths.

 

[TMHeimer]

I teach CESA in openwater simply because I am required to do it by my agency otherwise I'd never do it with students in openwater. Doing it with students from depths of 20 meters or deeper is dangerous and is inviting somebody, the student or the instructor, to possibly get bent or worse.

I'd recommend that you take a freediving course that takes you to the depths you want to go to and forget about CESA from these depths.

There is logic here. If it were not taught in open water, I would have no reason to review it on my own-- just wouldn't occur to me.
Teaching is horizontally in the pool however, would also make no sense.
I don't think the OP was asking about it being taught from 20+ meters though-- but whether a certified diver should progress to trying it from those depths (which I would say not a good idea, for me anyway).