Max depth for CESA?

[northernone]

Free ascents are without a regulator in your mouth and sometimes with Scuba gear jettisoned. CESA keeps the regulator in your mouth to take advantage of any residual gas in your cylinders that becomes available as ambient pressure reduces. Submarine escape uses very buoyant ascents and often a breathing device, starting in the US with the Momsen Lung and later the Steinke Hood. There may be something newer now.

I prefer doing free ascents because I feel that the regulator makes it less natural to keep my airway open. After a lot of practice I found that I can position your neck and jaw so that it is very hard to close my airway. One of the divers I worked with taught buoyant ascents at the Submarine Escape Tower in New London and helped me refine my technique. Rather than overtly blowing air out I barely exhale and purse my lips to keep the water out and make sure that there is almost no backpressure.

Obviously, this can be fatal if you screw up so test carefully and progress slowly. However mastering it will increase your survivability no matter how much your gear fails. I didn’t need it since I had been doing them for about 9 years by then but he suggested sitting in a pool holding your breath and assume your "position"... looking up, jaw thrust forward, pursed lips. Air will escape when you find your sweet spot and gently pushing on your diaphragm will push air out faster.

You can force air out faster than necessary, which isn’t a big problem in itself since the expanding air will catch up... except that you may naturally try to close your airway and embolise yourself. That is true on a free ascent or CESA.

Start shallow and overtly exhale until you get the feel of it and SLOWLY learn to exhale less aggressively until keeping the airway open is natural and reflexive. Keep your regulator in hand in case you over-exhale and get uncomfortable. You will also learn the feel moderate lung inflation and allowing gas to escape through your lips faster as you get shallower. It sounds a lot harder than it really is. I did one from 180' once because I was doing a lot of diving at that depth and wanted to make sure my ultimate back-up system worked.

Thank you for the thoughtful and detailed explanation.

@Dizzi Lizzi please refer to the post above for the informed answer to your question.

Cheers,
Cameron

 

[Schwob]

Very interesting.

Allow me a provokative question, although I do not mean for it to be provokative:

How to train (in general or scuba specifig) to not panic, to not freeze to not resign?

How do I mean this:
Well, I've seen divers panic UW that where trained to do what they should be doing but could not, I've seen complete out of control panic on the water, I've seen someone give up on the water, stop kicking, fold the hands to pray and go under... countless stories of crackshots freezing up in real battle with death seemingly imminent....

So training to learn what if and to do what if for when if happens and to do it often enough so it maybe even is in muscle memory (not sure how that's realistic for the majority of divers).... I see that as necessary, but if it is done with an "out" (e.g. an air source at hand), if death is not imminent if you don't do just the right thing, then you are not really training to keep your wits when push comes to shuff...

And of course training that way (train as you fight driven to the extreme), will succeed by providing great divers by the process of elimination.... which of course is problematic....

So, some people might fail some aspects of training, wing it, get away with it, but will react right and live one way or another... (until statistics pile up against them too much) ,
others think of themselves that way, but are absolutely not that way, are definitely accidents waiting to happen,
others know it all and do it all right in training, over and over, but fail nevertheless when it is for real
and others do indeed get it all right, even when it counts.

I think it's more of a personality and mindset thing that makes the real difference between the latter two.

But, either way, how to train so the likelyhood to be in the latter group, not just in practise, but when it really counts is really high?

No, I am not forgetting that training and practising to avoid any such situations to begin with matters more. That is not my question.

 

[Bierstadt]

@Schwob When I got back into diving I spent plenty of time refamiliarizing myself with diving incidents. Story after story after story of divers getting into trouble or dying, and as most folks here know, there is a very common thread: panic. Lots of things can get a diver into trouble, but panic is what kills. So your question is a good question. I don't think we know how to train away panic. Most truly serious training seems to focus on preparing people who can handle their fears with how to react in a situation while weeding out people whose panic threshold is too low. I will say that having immediate trained and ingrained responses to dangerous situations is probably helpful - it is harder to panic when you are focused on doing whatever you need to do to get safe. Actually, this makes me want to practice a free ascent in OW - it is better not to be doing such a thing for the first time in years when you are actually OOA.

 

[Steelyeyes]

I made an OOA CESA problem free from 75 FSW once. That was in 1981. I have watched my air far more carefully since. I did know I was low so there was no panic when I got a hard draw on my reg.

The same year four of us were diving (or attempting to) the SMS Cormoran and Tokai Maru from the breakwater in Apra Harbor, Guam. My buddy and I were following a debris field down and were at about 55 FSW. The other two divers were already on the stern of one of the wrecks at about 110 FSW when one of the divers had a second stage failure. Having an octopus was rare then and the buddy was 12 feet away and looking the wrong direction. The diver with failed reg knew there was reliable air 110 feet over his head and ascended. My buddy and I saw them going by a bit faster than seemed right and made a normal ascent behind them. The diver that did the CESA later admitted to coughing up a little blood and was examined at the Navy base clinic. Luckily for him the doc on call was a diving physiologist who read him the riot act for not getting there sooner in case treatment was required or possible.

 

[Sam Miller III]

OO CESA is no big thing IF you are a water orientated person (aka Waterman) with experience and training -- most divers today have very little waterman ship and training is some what lacking at all levels

refer to post #5

1) George Bond USN made a free ascent from 300+ feet
2) Dick Bonin, founder of SCUBA Pro, while in USN testing regulator performance with/for Doug Fane made a free ascent from 200+ feet under the ice cap
3) LA County UW instructions association UICC (the first and most difficult civilian training program) required a free ascent from 33 feet followed by free ascent from 100 feet.
The LA County basic program required a free ascent from 30 feet
4) I have made a free ascent from "considerable depths "

.....
SDM

 

[Akimbo]

How to train (in general or scuba specifig) to not panic, to not freeze to not resign?

This (panic) has fascinated me for a long time. I found this thread one of the best on Scubaboard: Panic in the experienced diver?

It is long but worth the read. I doubt that there is a simple answer given individual variability but familiarity and reflex are helpful.

 

[boulderjohn]

I prefer doing free ascents because I feel that the regulator makes it less natural to keep my airway open. After a lot of practice I found that I can position my neck and jaw so that it is very hard to close my airway. One of the divers I worked with taught buoyant ascents at the Submarine Escape Tower in New London and helped me refine my technique. Rather than overtly blowing air out I barely exhale and purse my lips to keep the water out and make sure that there is almost no backpressure.

Obviously, this can be fatal if you screw up so test carefully and progress slowly.

A couple of decades ago, a UHMS workshop released the results of its study of training related incidents/fatalities. They determined that practicing emergency ascents like this was the number one cause of these fatalities. The primary reason for removing the regulator was artificial--with the regulator out, the instructor could be sure that the diver was not cheating by sneaking a breath. The workshop recommended that this instructional practice come to an end. Almost all agencies therefore ended that practice and required that all instruction be done with the regulator in the mouth. The one notable exception was Belgium, where to this day emergency ascents are done with the regulator out. As a result, training fatalities related to emergency ascents are almost nonexistent today--except, of course, in Belgium.

In all forms of education, it is important to teach/train the way things are done in the real situation. You never want students to practice skills differently from the way they should do it in the real world. That is why I have been openly critical of CESA training that does not allow the student to "cheat" by sneaking a breath. As an instructor, I absolutely do want my student to keep that regulator in the mouth for an emergency ascent. I want them to be confident that if they feel the need to inhale near the end of such an ascent, the tank will indeed deliver that air at the lowered ambient pressure. If they do inhale and get nothing, it is still better than inhaling water and drowning. I absolutely will never even suggest to my students that they should take the regulator out of the mouth during an emergency ascent.

 

[Schwob]

...I doubt that there is a simple answer given individual variability but familiarity and reflex are helpful.

I certainly agree with that (and I will read that thread ... and panic and the onset of it or the avoidance of or even snapping back to sane... all fascinating stuff)

I would like to add that some training may provide the wrong kind of familiarity... the namny kind of familarity that comes with being guided through every step. All things are announced so there are no actual surprises, no valve is actually turned off, etc... Of course that's a good way to start, and one can, savely, learn the right steps that way. But, if that's all one does one will have no idea how one will react when sh.. actually hits the fan...
That is not to say I condone risky practiceses to get more opportunity at practising actual sh.. hits the fan scenario...
Just saying the whole staying cool headed in control vs. panicing thing is a fascinating thing.

 

[Schwob]

A couple of decades ago, a UHMS workshop released the results of its study of training related incidents/fatalities. They determined that practicing emergency ascents like this was the number one cause of these fatalities. The primary reason for removing the regulator was artificial--with the regulator out, the instructor could be sure that the diver was not cheating by sneaking a breath. The workshop recommended that this instructional practice come to an end. Almost all agencies therefore ended that practice and required that all instruction be done with the regulator in the mouth. The one notable exception was Belgium, where to this day emergency ascents are done with the regulator out. As a result, training fatalities related to emergency ascents are almost nonexistent today--except, of course, in Belgium.

In all forms of education, it is important to teach/train the way things are done in the real situation. You never want students to practice skills differently from the way they should do it in the real world. That is why I have been openly critical of CESA training that does not allow the student to "cheat" by sneaking a breath. As an instructor, I absolutely do want my student to keep that regulator in the mouth for an emergency ascent. I want them to be confident that if they feel the need to inhale near the end of such an ascent, the tank will indeed deliver that air at the lowered ambient pressure. If they do inhale and get nothing, it is still better than inhaling water and drowning. I absolutely will never even suggest to my students that they should take the regulator out of the mouth during an emergency ascent.

Very good, very valid point.
And I am not advocating otherwise.
Just curious how to - safely - panic harden people, maybe even the panic inclined...

 

[dmaziuk]

Just curious how to - safely - panic harden people, maybe even the panic inclined...

Back in the bad old days martial arts training was apparently done full contact with real weapons. Enrollment paperwork included something to the effect of student's life being the teacher's to do with as he pleases -- to absolve everyone involved from legal responsibility in case stuff happened and the student didn't survive the lesson.

Nowadays I guess SEAL training would be as close as you can get.