Max depth for CESA?
- Thread starter Bigeclipse
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True enough--was just throwing that lame excuse out there. If you're talking about extreme pressures like in space, anything can happen to anything. And you've got the extreme depths like Challenger Deep. But as you say, not relevant to diving.Meh, dunno about your second explanation.
You could have stuck to your guns and mentioned that all objects are elastic, even steel and aluminum tanks, just not enough to make a difference for scuba diving.
Is space an extreme pressure or just one atmosphere less than we have at sea level?
Mr Carcharodon
Contributor
It seems that CESA’s from 100 fsw or even deeper are pretty safe for those of build up to it and are ready to do it. But in an emergency situation the limit is likely less and highly individual. Practice could likely help push the limit deeper but would it be worth the risk?
How does one build up to it? What does practice do that enables one to extend the range?
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Very good points. You have to think of those free divers who practice breath holding in a pool-- and up to 8 minutes I think. Also agree it is probably highly individual. I am not a good breath holder. That's not with an open airway like CESA, but same idea--no 02 intake.
It might be OK to push your limit maybe 5 feet deeper every now and then, but you may be right that it's not worth the risk to try it from very deep. I think there have been rare cases of embolism even with the airway being open--if a bit of air gets lodged in some nook & cranny in the lung.
I hope some of the people reading this realize that when you do a CESA from depth, you should not hold your breath. You should exhale all the way up. Once you start exhaling, the air will come out pretty well for the rest of the way--it is not like doing it horizontally in the pool without the benefit (or threat) of expanding air. Please, please, please everyone! If you ever have to do a CESA from deep, do NOT hold your breath! You do not have to be a champion freediver to exhale all the way to the surface because of the fact that the air in your lungs is expanding rapidly as you ascend.
I emphatically believe that the very worst message anyone can give a new diver is that they can't do a CESA from depth unless they have freediving experience and can hold their breath for many minutes. That is not true, and if people believe it, they are all too likely to panic and hold their breath--and that WILL kill them.
Mr Carcharodon
Contributor
Going gradually deeper is extending the range. Speaking from the perspective of LA County training ADP did CESAs from 30-40 fsw and UICC did CESAs from 100 fsw. Years ago the classes were 100 plus people, certainly 1000 plus people over the years, with no adverse affects that I know of. But no one was expected to do a CESA from 100 fsw on day one, or under stress. In a sense this is like doing a S drill air share. We used to do those at the end of dives until it became routine. When the actions to resolve an emergency become routine it is not an emergency any more.
That does not mean that someone will be unable to do a CESA from deep if they have not trained extensively for it. People have done it from hundreds of feet in an emergency with no training whatsoever.
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