CESA from 100 feet?

[Blackwood]

However "bent" can often be permanent and "embolised" is usually fatal.

Rather than do that its far better to eliminate any need for a free ascent by proper training and equipment.

You can never eliminate the possibility of an emergency situation, however good your equipment. That's why proper training must include techniques for dealing with emergency situations.

 

[Dan Gibson]

It might be a bit more than musty. I'm thinking nasty lung infection. I don't think I would want to find out how hard it would be to get rid of that.

Have to admit I'm curious -- there's nothing inherently posionous to a BCD. Might be musty, but not likely to contain the plague.

 

[String]

You can never eliminate the possibility of an emergency situation, however good your equipment. That's why proper training must include techniques for dealing with emergency situations.

With modern equipment and practicses free ascents should never happen. Scuba equipment is very reliable. People should be carrying an independent air source. Add to that a buddy with the same and there really is no reason for an incredibly risky free ascent. Im quite surprised padi still teach it. I can think of agencies that definately dont.

 

[Iruka]

Having done them hundreds of times from 20~30', teaching OW students, I was curious as well about the feasibility of doing one deeper. So, I did one for practice from about 90' (day off...no students!!)...the main challenge was actually controlling my ascent speed. The shallower you get, the greater the air expansion, so I had to "let" more air out as I got shallower, to avoid going up too fast. (I kept an eye on my depth gauge & made sure to take at least 3 seconds per meter.) So, it took a bit over 1 1/2 minutes to the surface....and I had full lungs when I arrived there. An important point a few people have made earlier is that you don't "blow" the air out...just let it come out as it expands. The biggest problem I see in doing the (easy) 20~30' CESA for OW class, is that people tend to over-compensate to the "don't hold your breath" mantra, and actively force the air out. Often, this is before they've actually begun to ascend, and their lungs are almost empty before they begin.

One way of looking at it....I don't really do any free diving, but I can get down to 80' or so....so that's a 160' "round trip," and the first half of the trip (down) requires some work/swimming to get to the max. depth. And in free diving, there's not as much a concern with a fast ascent, so I might be kicking to get to the surface in a hurry. In the CESA, it's pretty much effortless, since you're just letting positive buoyancy (full lungs) bring you to the surface. Since you're only getting one breath (unless you get some more from your tank on the way up) you want to make the best use of that air, and not exhale any more than you need.

 

[Sideband]

I ahve a question for all of the people that say they have "practiced" this from the 90 to 100 foot range. How many did it starting with empty lungs? When you run out of air it is realized on the inhale that doesn't happen because the tank is empty. Add in the couple of seconds it takes to realize that you are out of air and decide to blow and go and how well do you do?
I had a student, thinking he was being funny, turn off my air at 15' in a pool. I was occupied with another student at the time and suddenly couldn't breath in. I tried exhaling (again) and that worked. Tried to breath in again and nothing. Then it hit me that I was ooa. It probably took 5 or so seconds before it sank in that I really couldn't breath. It probably took me longer to come to the ooa conclusion because I had 2500psi in my 80 not more than 5 minutes before but it wasn't an immediate conclusion. My point being, it's going to be a different experience when you have no starting breath and a bit of panic.
btw, they are still looking for the body of that student jk

Joe

 

[Sideband]

In the CESA, it's pretty much effortless, since you're just letting positive buoyancy (full lungs) bring you to the surface. Since you're only getting one breath (unless you get some more from your tank on the way up) you want to make the best use of that air, and not exhale any more than you need.

If you got a full breath then how did you know you were out of air?

Joe

 

[Grajan]

My recollection of the CMAS test was that you would be facing the examiner at 130'. He would watch you exhale and then remove the 'Embout' (mouthpiece) from your mouth. You were required to give him the OK signal and then make a controlled ascent to 15' where you had to stop and do a 360deg and then ascent under control to the surface. I do not recollect it being anything like as taxing as the recue work. The residual air after a normal exhalation soon filled your lungs. I would not try this casually - we trained for a long time before doing this test.

I ahve a question for all of the people that say they have "practiced" this from the 90 to 100 foot range. How many did it starting with empty lungs? When you run out of air it is realized on the inhale that doesn't happen because the tank is empty. Add in the couple of seconds it takes to realize that you are out of air and decide to blow and go and how well do you do?
I had a student, thinking he was being funny, turn off my air at 15' in a pool. I was occupied with another student at the time and suddenly couldn't breath in. I tried exhaling (again) and that worked. Tried to breath in again and nothing. Then it hit me that I was ooa. It probably took 5 or so seconds before it sank in that I really couldn't breath. It probably took me longer to come to the ooa conclusion because I had 2500psi in my 80 not more than 5 minutes before but it wasn't an immediate conclusion. My point being, it's going to be a different experience when you have no starting breath and a bit of panic.
btw, they are still looking for the body of that student jk

Joe

 

[Rick Inman]

I ahve a question for all of the people that say they have "practiced" this from the 90 to 100 foot range. How many did it starting with empty lungs? When you run out of air it is realized on the inhale that doesn't happen because the tank is empty.

Well, I only tried this once, about a year and a half ago, but I breathed a tank down to empty at the end of a dive.

Yes, I knew it was coming, but I definitely felt enough hard pull on the last breath and a half to know I was about out.

Yes, I did get a good final hard breath before the tank ran dry. I knew I was out because the intake ceased at the end of the breath.

It was just one time, so I'll have to test this again.

Back in the 70's we always breathed our tank down until the breathing stopped, then pulled our J valve reserve. I owned a Scubapro Mark something, which was balanced, and I could still feel when I was on my final breath.

But that was a long time ago.

 

[serambin]

Just thinking about how you would find yourself ooa at say, 80 Feet. Option one, you really ran the tank dry. Ok, as someone mentioned, you still have at least 60 Lbs of air left. As you asend, you get at least 2 full breaths from bottom to surface (not in a linear flow) so the first 1/2 of the ascent would have to be faster, then you could slow in the last 40 feet to reduce bubble formation.

But what about an equipment failure? Can the reg or tank fail in a way not to offer any more air at all, even on ascent?

Stan

 

[String]

Can the reg or tank fail in a way not to offer any more air at all, even on ascent?

I suppose reg could get knocked off the tank (especially if using A-clamp not DIN).

Although ive never heard of it i also guess that a first stage could destroy itself.

I know my hoses contain enough air for 2.5 breathes for me even with tank off.