What is the deepest you can do an OOA?

[String]

at any depth, it would be worrysome. even being bent is better than being dead

Being unbent AND undead is even better. Hence nice redundancy air sources.

Although being bent is better than dead it can sometimes be the same thing. Various decompression injuries involving bubbles in the blood stream due to rapid formation can kill (not just holding breath). "Bent" can also mean "paralysed" or at least leave some kind of permanent physical damage. Its a lottery. Best to avoid putting yourself in a situation where theres an increased risk of it over an alternative solution.

 

[mikerault]

String...as others have said...you do not hold your breath. In the Navy they did studies where they did ascents from 140 feet safely (simulating a submarine rescue/escape scenario) of course these were using steinke hoods (basically a canvas hood that trapped some air that you put over your head in the escape trunk before exiting and ascending, you were supposed to ho-ho-ho all the way up.

There is an idea for a scuba gadget...a clear plastic hood with one of those springy round rings at the bottom for use in a cesa...as you exhaled on the way up it would capture the air and let you rebreath it if it was needed...could be weighted to offset the buoyancy of the air volume...

Mike

 

[String]

Not holding breath is a given but even if you do exhale normally you run the risk of AGE or similar. And even with expanding air its going to be very difficult to ascent for a long time with no "incoming oxygen" (to avoid confusion) with fairly empty lungs and a ton of stress.

 

[HowardE]

that still doesn't make me want to carry a redundant air source for ''recreational'' diving

 

[cerich]

Not holding breath is a given but even if you do exhale normally you run the risk of AGE or similar. And even with expanding air its going to be very difficult to ascent for a long time with no "incoming oxygen" (to avoid confusion) with fairly empty lungs and a ton of stress.

Call HMS Dolphin in Gosport and see how many AGE from CESA they have had, you'll be shocked to find very,very few, mostly eardrum issues. They train 30M free assents all day...

As you assend your lungs go from feeling empty to not feeling so.

You really should try it before speaking with such authority....

 

[Soggy]

you're by yourself with a single tank that won't give you air.

Why would you allow yourself to be in that position?

 

[mikerault]

The most recent submarine rescue devices are similar to dry suits and have been successfully tested from 600 feet...

Mike

 

[cerich]

The most recent submarine rescue devices are similar to dry suits and have been successfully tested from 600 feet...

Mike

Recent???the British did 600 in the early 70's... Michelin man suits have been used since the 50's

 

[gangrel441]

Even with expanding air managing to not breathe for several minutes with a half empty lung and stressful situation is beyond most people. As is slowing down to keep the ascent rate safe.

I dont class 20m/min ascent rate as safe. Emergency maybe but its the wrong option to take. If you have to risk rapid ascent rates like that and increase the chances of a bend, take some equipment with you which eliminates the need to play roulette like that.



Depends on the nature of the OOA. If its simply breathing tank down due to stupidity fair enough, if a tank o-ring or first stage has gone it wont work.

Certifying agencies were teaching 60 fpm (1 ft/second) for years. Last I checked, PADI still does, though they strongly encourage ascending slower than that. While I personally feel safer coming up at 30 fpm, I wouldn't be too aprehensive about coming up at 60 in an emergency.

You, my friend, are not playing within the rules. The vast majority of us would prefer to have some form of redundancy. The scenereo of this thread assumes you have none, and is simply dealing with direct CESA procedure. Be it through a buddy, a pony bottle, or diving doubles, I doubt most posters would generally find themselves in this position.

 

[MXGratefulDiver]

Call HMS Dolphin in Gosport and see how many AGE from CESA they have had, you'll be shocked to find very,very few, mostly eardrum issues. They train 30M free assents all day...

Therein lies the issue ... they train for it. Furthermore, unless I'm misreading, the HMS Dolphin would be a naval vessel ... which means the people who train for 30 meter CESA's are young, in excellent physical shape, and receive skills training far in excess of what your typical recreational diver will ever get.

If that's the case, it's not a good comparison. The difference in mental approach alone would be a huge factor determining the success or failure of the exercise.

Furthermore, as with all training, when you first try something you are generally going to suck at it. You make mistakes. You get stressed. You generally fail at it the first attempt ... and perhaps the first few attempts. In the real world, doing a CESA isn't something you want to fail at.

Recreational divers don't train for doing a CESA ... nor, IMO, should they. The risk of hurting yourself outweighs the potential benefit. A better effort is to plan and train for ways to avoid ever putting yourself in the situation where it is necessary.

This thread may be an interesting mental exercise ... but a far more practical question would be "What should I be doing to make sure I never have to make a CESA?"

... Bob (Grateful Diver)