Safely Practicing CESA

[captain]

I don't bother, as I always have some form of redundancy.....

Safe diving,

Rich

Ah, but do you have redundancy for the redundancy. That might be the cesa.

 

[DeepBound]

Ah, but do you have redundancy for the redundancy. That might be the cesa.

And what if you get the hoses from your redundant systems tangled all up and can't use them? *smirk* I know, don't do that. But after experiencing that in a very safe situation where I was just messing around with trying things out, it made me wonder what else could go wrong that would make your redundant gas supply not be available.

But it sounds like CESA drills are risky, I'll just work on gas-switching drills instead to make sure I'm comfortable with it when the time comes.

 

[dherbman]

In the late 70's, OW required a CESA from 30' and IIRC AOW required a 60' CESA. When working with students, we always performed the skill on the first dive at the beginning of the dive.
While I'm confident that I could do a CESA from any recreational depth, I now avoid them like the plague. I'm not 20 yo anymore.
I think that free diving is an excellent tool for developing proficiency at CESA. A successful CESA is largely dependant upon mental discipline and deeper free dives allow you to develop competence and confidence in your ability to ascend from depth.

 

[Scuba]

I think that free diving is an excellent tool for developing proficiency at CESA. A successful CESA is largely dependant upon mental discipline and deeper free dives allow you to develop competence and confidence in your ability to ascend from depth.

Good points.

Practicing visualization techniques, instead of frequent, actual activity practice, may also help if and when it ever needs to be used.

 

[Mambo Dave]

Making the "ah" sound will keep you safe and works even if you don't have voluntary control of your airway. OTOH, if you know how to keep your airway open, you can make a much, much, slower ascent by merely letting the air bubble out naturally.

This is an interesting post describing a 5 minute ascent from 100' at less than 20 feet per minute ascent rate, in a Submarine Escape Training Tower.

Thanks for that link Charlie

 

[BigTuna]

Practice this in water between 20 and 30 feet deep. Deeper than 30' is not recommended.

Wouldn't it be safer to do it between, say, 99 feet and 66, to reduce the chance of embolism?

 

[SDAnderson]

Wouldn't it be safer to do it between, say, 99 feet and 66, to reduce the chance of embolism?

Taking advantage of Boyle's Law by reducing the pressure gradient, thus reducing the chance of embolism. That seems like a good idea but the dagnabbit real world is more complicated than that. By solving one problem you are creating several others - let's see how many I can come up with off my cuff:

• The skill needs to end with the diver on the surface, where he can complete it by orally inflating his BCD.
• Runaway ascents are a real threat when practicing the CESA. They're scary from 33 feet, terrifying from 99 feet. It isn't just embolisms but DCI that can hurt you.
• Part of what makes the CESA work is the doubling of volume between 2 ata and 1 ata and many divers will find that it doesn't work at (or from) depth.
• For lots of reasons, new divers shouldn't be anywhere near 99 feet.

There are more but these are enough to illustrate the point. The CESA is dangerous enough, don't make it worse by messing with the program.

 

[Amphibious]

I don't bother, as I always have some form of redundancy.....

Safe diving,

Rich

+1 I rig my kit so that a CESA should never be an option. if my back gas fails I have a slung AL30. murphy would be working overtime to have them both fail on the same dive.