CESA from 40ft

[Thalassamania]

as a side note there is not really such thing as a controlled bouyant asscent, once you get bouyant and are ascending it is all but impossible to control.

That depends on what you mean by "contol." While most can not stop a buoyant ascent, the speed can be controlled between about 45 fpm and 300 fpm.

unofficially, and not reccomended however in the been done catagory, you can do a controlled swiming ascent from as deep as 120 feet. (I have personally done it from 60).
the problem as I see it is that if you are doing it when you have to you will not be in the state of mind to do it properly unless you are able to control you thinking in an emergency.
If you are a swimmer then swimming maybe 75 ft underwater on one breath should not be too much of a challenge. and at that depth you actually have about 4 breaths (due to the air being compressed). if you breath out small bubbles you will feel as if you are about to be out of air for a very long time. also remember that most people can hold their breath (on the surface) for about a minute. at 60 ft/m that is plenty to get you to the surface without dying.

... and if you've learned to hold your breath in complete comfort for two minutes, then you're golden, no?

in all if you have no deco obligation, you are somewhat fit and a decent swimmer, then you should not have a life threating problem at any recreational depth if you run out of air and you keep your head.

And if you have reason to be and are confident in your skills, then you will, "keep your head."

You read my mind!

Something else which is not really taught in class, is the rate at which you have to exhale. PADI says say "ahhhhhh", which makes perfect sense. But there's "ahhh" and then there's AAAHHHH!!!!!" Would you at least feel the building outward pressure in your chest cavity to let you know you're not exhaling quickly enough?

It's not a rate, it is just a matter of keeping the airway open (as Lynne noted).

This conversation is making me do my old-school curmudgeon thing again! First of all, I refuse to call a free ascent CESA (Controlled Emergency Swimming Ascent) — a burdensome acronym that sounds far too ominous (probably intentionally). The recreational training industry has been playing-down the value of free ascents, or blow & go, progressively for the last 40 years.

Free ascents are very simple, as long as you know enough not to blow your lungs out, and slowly work up to them. I practice a free ascent at least once a year from at least 130'. Intellectually I know I can do them after all these years, the important part is not having to think about it. Any trepidation defeats what in my view is the primary purpose and could make a bad situation worse.

It is NOT like holding your breath and swimming the same distance horizontally. It is far easier. You are buoyant, only slightly if you do it right. The gas is expanding and being expelled, so CO2 buildup is far less.

The US Navy’s ascent rate has been 60’/minute for most of my life and there was no such thing as a safety stop. Hundreds of thousands, probably millions, of dives have been made safely during that period. The point is speeding up ascent is highly unlikely to cause decompression problems and preferable to certain drowning. When practicing, make the free ascent at the very beginning of the dive, before you absorb much Nitrogen. Then head back down and enjoy the rest of the dive. The exercise takes a few minutes.

Trained freedivers typically ascend and descent at 1 meter/second, or 200’/minute. That rate might actually get you bent. However the possibility of getting bent is far less of a medical emergency than the certainty of asphyxiation before reaching the surface.

The virtue is knowing deep in your soul that you are not going to die, thus there is no reason to panic.

OK OK, maybe I need less caffeine. Diatribe over.

I'm with you. And what is the rate of ascent for submarine escapes with the new buoyant suits. 300 fpm? or is it 600?

Since no one else has said it- 10 year old son- 80 ft- inside a wreck? Please, correct me if I am wrong, but I thought a junior diver had a max depth of 40 ft. Not to mention, no overhead environments...

It should depend on the situation and the maturity and skill of the divers involved. I would not take most adults down 80 feet and into a wreck but I know a few preteens and lots of teens that I'd be happy to have there as buddies.

I guess the scuba police were busy investigating another case and missed that infraction.

Couldn't hear the siren, I had water in my ears.

 

[Akimbo]

...I'm with you. And what is the rate of ascent for submarine escapes with the new buoyant suits. 300 fpm? or is it 600?...

I can’t remember for sure, but it has to be faster than 300’/Min. For others reading this, keep in mind they are breathing wearing a Steinke Hood.

http://www.youtube.com/watch?v=Zm03uhCSfXI&NR=1

Based on the YouTube video I calculate the rate somewhere between PDQ and Trident Launch speed.

Doing 200'/Min wearing long fins is not a very aggressive kick. I am sure I can kick faster and easily reach 300'/Min up or down. Freedivers figure that 200’/Min is somewhere near the optimum compromise for Oxygen consumption versus time.

 

[Moerby]

This conversation is making me do my old-school curmudgeon thing again! First of all, I refuse to call a free ascent CESA (Controlled Emergency Swimming Ascent) — a burdensome acronym that sounds far too ominous (probably intentionally). The recreational training industry has been playing-down the value of free ascents, or blow & go, progressively for the last 40 years.

Free ascents are very simple, as long as you know enough not to blow your lungs out, and slowly work up to them. I practice a free ascent at least once a year from at least 130'. Intellectually I know I can do them after all these years, the important part is not having to think about it. Any trepidation defeats what in my view is the primary purpose and could make a bad situation worse.

It is NOT like holding your breath and swimming the same distance horizontally. It is far easier. You are buoyant, only slightly if you do it right. The gas is expanding and being expelled, so CO2 buildup is far less.

The US Navy’s ascent rate has been 60’/minute for most of my life and there was no such thing as a safety stop. Hundreds of thousands, probably millions, of dives have been made safely during that period. The point is speeding up ascent is highly unlikely to cause decompression problems and preferable to certain drowning. When practicing, make the free ascent at the very beginning of the dive, before you absorb much Nitrogen. Then head back down and enjoy the rest of the dive. The exercise takes a few minutes.

Trained freedivers typically ascend and descent at 1 meter/second, or 200’/minute. That rate might actually get you bent. However the possibility of getting bent is far less of a medical emergency than the certainty of asphyxiation before reaching the surface.

The virtue is knowing deep in your soul that you are not going to die, thus there is no reason to panic.

OK OK, maybe I need less caffeine. Diatribe over.

Thank you very much for that ... it is quite reassuring to know these things. Plus it made me realize what lies at the heart of my concerns re. CESA. In my line of work we don't shy away from practicing dangerous emergency procedures (if anything we practice them more often) even though we sometimes get hurt practicing them. I guess I'm simply wired by now to only feel comfortable doing a potentially dangerous emergency procedure once I've actually done one. So to mentally put this to rest I may just have to try a CESA myself from 40ft one day when I'm on a dive with experienced divers who have both done it before and are okay with watching me do it. Of course, both me and my daughter will keep practicing all the other safety procedures as well.

 

[matt_w]

Free ascents are known in many circles around the world to include ascents that are free of, or unaided by, assisted breathing devices. My Navy training (salvage diver as opposed to submarine escape or combat swimmer) said dump weight, but it was well understood as meaning “as and if” needed.

I never drop gear when practicing free ascents anymore, both for convenience and training for a worse case. Semantics was by far my lesser point, but clarification is useful to the discussion.

I was not really disagreeing with you, just did not want to confuse the new people. My OW class in the 80s taught to dump the weight if you need too to. I suppose they actually teach the same thing today and just label it two different things. I think the distinction was done to show the buoyant ascent as a true last resort because it is more dangerous and in most cases divers can easily ascend from recreational depths on the air in their lungs without doing it.

 

[matt_w]

I can’t remember for sure, but it has to be faster than 300’/Min. For others reading this, keep in mind they are breathing wearing a Steinke Hood.

YouTube - ‪US NAVY Submarine Escape‬‏

Based on the YouTube video I calculate the rate somewhere between PDQ and Trident Launch speed.

Doing 200'/Min wearing long fins is not a very aggressive kick. I am sure I can kick faster and easily reach 300'/Min up or down. Freedivers figure that 200’/Min is somewhere near the optimum compromise for Oxygen consumption versus time.

Awesome, thanks

 

[Kingpatzer]

Frankly, I think worrying about CESAs is the wrong focus. Good buddy skills, good dive planning, good gas management, good situational awareness and good gear make the need for ever doing a CESA outside of class or practice essentially non-existent. Running out of gas from something other than catastrophic mechanical failure is simply unacceptable and demonstrates a lack of awareness and care in a diver that is fundamentally inexcusable (and is a good indicator that the person should not be diving -- they are simply unsafe.)

Focus on being a great diver and exceptional buddy and you will not have a reason to worry about doing a CESA.

 

[Thalassamania]

Here's a video with the escape suit I was thinking about. About half way through, note the Nuytsuit behind the hatch.

YouTube - ‪Submarine Escape‬‏

 

[ccx2]

While you all are on the subject, please help me understand better how let's say at 80' i run out of air for some reason and probably wouldn't realize OOA until it was time to Inhale,so now I don't have a full breath and I'm needing to inhale badly and now. I look up to the surface and start up , Ahhhh, I should go up at normal accent rate 30' min but stress will make that a quicker trip so let's shorten it to 60 seconds for 80', I think realistically that's abOut as slow as someone who hasn't practiced CESA would be able to keep there assent because I would think they would be terrified they won't make it to the surface. I know that although I didn't get an inhale after my last exhale I still have some air in my lungs compressed to about 3xatm that would expand as I assend, I don't see how ( as I sit here at sea level and try) I could exhale slowly to keep an open airway for 60 seconds or longer without blacking out. Would the little bit of air still in my lungs after an exhale at depth really expand enough giving me more air for me to do this without feeling panic and convulsing?

 

[Moerby]

While you all are on the subject, please help me understand better how let's say at 80' i run out of air for some reason and probably wouldn't realize OOA until it was time to Inhale,so now I don't have a full breath and I'm needing to inhale badly and now. I look up to the surface and start up , Ahhhh, I should go up at normal accent rate 30' min but stress will make that a quicker trip so let's shorten it to 60 seconds for 80', I think realistically that's abOut as slow as someone who hasn't practiced CESA would be able to keep there assent because I would think they would be terrified they won't make it to the surface. I know that although I didn't get an inhale after my last exhale I still have some air in my lungs compressed to about 3xatm that would expand as I assend, I don't see how ( as I sit here at sea level and try) I could exhale slowly to keep an open airway for 60 seconds or longer without blacking out. Would the little bit of air still in my lungs after an exhale at depth really expand enough giving me more air for me to do this without feeling panic and convulsing?

I'm the last person to be handing out advice on this, but during our pool dives the instructor closed our tank valves so we can feel what it feels like when you run out of air fairly suddenly. You can actually feel it coming for a breath or two. That said, I'm sure there are situations where you won't even have the luxury of a breath or two and at 80" down, that's going to suck.

 

[Akimbo]

Frankly, I think worrying about CESAs is the wrong focus...

The value is knowing how easy it is to do a free ascent, thus you can easily make it to the surface [-]if[/-] when everything turns to crap, thus there is no need to panic. IMHO, most divers are trained to be entirely too dependent on equipment and their buddy at the expense of what I have always considered basic skills.