CESA Training

[Dody]

1 - that is not gas management. it is good that you are always aware of your current gas pressure but you will eventually have enough experience to know roughly how much gas you are using at a given depth. then when you look at your gauge, it will only be to confirm what you already know. you should also practice calculating your SAC rate and re-evaluating those calculations as you progress.

Thanks for your advices.
As for gas management, I do that too. I monitor my SAC during all my dives and study it relatively to my shape, the dive conditions,... Today, I can safely say that in normal conditions (no near panic and no fight againt strong current that I have never experienced), my SAC is between 11 and 16 l/min and it depends mostly on my fitness and my stress level (breathing control). I also mentally calculate my air consumption based on the depth. In fact, when I did my deep diving course, I computed an Excel spreadsheet calculating available air time based on depth, variable SAC and cylinder pressure. So even when I dive to 35 meters, I know how fast I consume air et double check with my gauge. I plan to buy a transmitter though. My computer is compatible.

 

[rick00001967]

Empty Oxygen Tank During a Dive? You Need a CESA..

this is basically the same way i do it in ow classes in a pool. this would also be a safe way to safely practice a cesa after certification.

 

[Dody]

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.

I got trained to deep diving but my personnality makes that I always prefer to wear both a belt and suspenders when doing risky activities . Diving to 40 m is my limit but I can carefully plan it and I haven't discerned the effects of narcosis ( never stayed more than 3 minutes) even if it is there. 30 meters is pretty much reached in all my dives, not for the hubris or the love of the deep but because I will do a liveaboard in Thailand in March and I need to have at least 10 dives below 30 meters.

 

[uncfnp]

I am in the camp that if you have experience and are comfortable in the water I see no reason not to practice a CESA under controlled circumstances if you choose to do so. It is a skill that is worth having and attempting it under ideal conditions is a much better alternative to doing it for the first time when the unexpected happens.

If I were to do this I would start shallow, do it at the beginning of a dive or at least when far from my NDL and make sure my buddy is on board with the plan. And no more dives that day. So it would pretty much be a dive day just to practice skills.

 

[Dody]

Empty Oxygen Tank During a Dive? You Need a CESA..

this is basically the same way i do it in ow classes in a pool. this would also be a safe way to safely practice a cesa after certification.

Thank you very much. Very useful.

 

[The Chairman]

My first introduction to Scuba was less than optimal in 1969. My instructor never got in the water with us. Also, I dove with no SPG, but rather had a J-valve. On the first pucker, you reached behind your back with your left hand and pulled on the rod leading to the lever. Then you made your way up. Unless... unless the lever was already down. At that point the big pucker happens and things get interesting. The first time this happened I was probably at 50/60 feet. Yet, without ever having the benefit of doing a CESA in a class, I swam towards the surface. It's pretty damned instinctive. It's pretty damned easy, too. I think I've done this four times. The last two times I had checked the lever before I put on my tank. I really loved it when I first dove with an SPG. I've never run out of air since.

 

[TMHeimer]

There has been a fairly recent thread on everything pro & con about the CESA, including "why is it taught if we shouldn't ever practice it, thus will forget how", etc.
I practice it all the time (maybe every other dive). Not sure why so often, as it's not rocket science and something you'd forget if you only did it once every 2 months. But, the deepest I'll do it from is 30' (10 meters), and often from less than that. My dives' maximum depths are that depth, so there isn't a substantial amount of Nitrogen in me. I will do a CESA when I ascend to check my location.
I would not practice it from deeper than that, though I imagine I could.
I also practice it starting with half full lungs, as opposed to the "big breath" the instructor tells students to take. If you can take a big breath in real life situations, you have enough tank air to begin a normal ascent.

Usually I have no problem making it on half empty lungs from 30', but must say I never really notice the air in my lungs expanding (though I know it does--perhaps because I am always exhaling of course).
So that's what I do, and have had no problems over 16 years.
No sense in teaching it to you once then never practicing it again on your own-- IF you do everything right. That is assumed-- of course if you hold your breath...it's dangerous. Otherwise teaching it IMO is 100% a waste of time. Without post OW course practice, I would suspect learning all or most of the basic skills is also a waste of time.

Saying that you should never practice it because you shouldn't be stupid and run out of air makes no sense. There are catastrophic events, and also things can happen--wicked current?-- and once in a while people ARE stupid. That's like saying you shouldn't carry a cutting device because you should never be stupid enough to get entangled in anything.

Another reason I practice it is that almost all my diving is solo. But, you can also buddy dive, get separated, and be OOA.

 

[Gareth J]

My first introduction to Scuba was less than optimal in 1969. My instructor never got in the water with us. Also, I dove with no SPG, but rather had a J-valve. On the first pucker, you reached behind your back with your left hand and pulled on the rod leading to the lever. Then you made your way up. Unless... unless the lever was already down. At that point the big pucker happens and things get interesting. The first time this happened I was probably at 50/60 feet. Yet, without ever having the benefit of doing a CESA in a class, I swam towards the surface. It's pretty damned instinctive. It's pretty damned easy, too. I think I've done this four times. The last two times I had checked the lever before I put on my tank. I really loved it when I first dove with an SPG. I've never run out of air since.

I still remember the signal for a stuck J valve.

I was originally qualified by PADI, so i did do a CESA exercise during my course. I believe it was a horizontal exercise. i.e not from depth to the surface, but as a horizontal swim at a fixed depth. (I could be wrong?)

I was reintroduced, when I did DM to help out one of the shops I used to help.

Interestingly, although a free swimming ascent is discussed in BSAC, it is never done as a practical exercise. Instead we do a lot of work in prevention. Buddy skills are fundamental, probably because it is not unusual to dive in low vis' environments. We seldom dive in groups, most divers are in a pair, very occasionally a three. (Unless on a course or a lesson then its one instructor to two students as a general rule). There are a lot of AAS ascents throughout training and CBL's (Control Buoyant Lift). If the instructor isn't certain you can get your buddy safely to the surface, you don't get qualified.
There is general move towards redundant configurations very early by most BSAC divers. Ponies used to be ubiquitous with BSAC divers, now its twinsets.
Generally, the only divers diving single rigs are Ocean divers (PADI OW equivalent), within my branch. By the time they reach Sports Diver they are diving twinsets or single rigs with ponies.

 

[mc42]

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.

 

[Dody]

My first introduction to Scuba was less than optimal in 1969. My instructor never got in the water with us. Also, I dove with no SPG, but rather had a J-valve. On the first pucker, you reached behind your back with your left hand and pulled on the rod leading to the lever. Then you made your way up. Unless... unless the lever was already down. At that point the big pucker happens and things get interesting. The first time this happened I was probably at 50/60 feet. Yet, without ever having the benefit of doing a CESA in a class, I swam towards the surface. It's pretty damned instinctive. It's pretty damned easy, too. I think I've done this four times. The last two times I had checked the lever before I put on my tank. I really loved it when I first dove with an SPG. I've never run out of air since.

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