Emergency ascents

[wpscortland]

Was reading about OOA incident in the acidents forum which required emergency ascent from 70 fsw :11: . I cannot imagine ascending even 40-50 feet after exhaling and finding no more air to be had, considering must keep exhaling to keep airway open and prevent barotrauma. How can this be safely practiced? Any tips on this scary possibility.

 

[SeanQ]

Was reading about OOA incident in the acidents forum which required emergency ascent from 70 fsw :11: . I cannot imagine ascending even 40-50 feet after exhaling and finding no more air to be had, considering must keep exhaling to keep airway open and prevent barotrauma. How can this be safely practiced? Any tips on this scary possibility.

I have not made an emergency ascent from that depth, but I imagine that running out of air in your lungs would not be a problem. From 66fsw, the pressure would be 3 bar, thus the air in your lungs would expand 3 times on the way to the surface. Because the air is being mixed in your lungs, O2 that has not already diffused across your alveoli cell wall will get the opportunity to do so. Maybe someone with a bit more expertise can shed some light onto this.

 

[Wildcard]

Try it. It's not so hard. Just keep buzzing little bubbles out, your lungs stay full. I had to do one from 40ish feet. Never thought I could do it, it was no big deal. I think it's something that should be done as a skill, not just talked about.

 

[jbd]

As noted by SeanQ the air that is in your lungs will expand as you ascend. One of the the problems with the way this skill is taught, is that people are taught to blow bubbles i.e. exhale. They are taught this when they are asked to swim the length of the pool or some other set distance while the instructor watches to see that there are bubbles coming frmo their regulator. The only way bubbles will come out, when you are not ascending, is to exhale. This is the wrong concept.

When doing one of these ascents you do not need to exhale. You simply need to let the expanding air out. All that is needed is a relaxed, open airway and the air will flow out on its own. If you are asending quickly you will almost feel like you are choking on the escaping air. The ascent shouldn't be this quick though.

I have practiced this ascent from 40 feet several times and do it from 20 feet with students during OW certififcation.

 

[SDAnderson]

Practicing a CESA from 70 feet doesn't have any advantages and can be dangerous. You're better off mastering the skill in 20 - 30 feet of water.

There is a description of how to practice this skill horizontally in the PADI Open Water manual. If you want to practice vertically, use a training buddy who has a lot of experience (preferably an instructor), a sturdy and well-secured up-line and plan the dive carefully. Don't forget to gently exhale continuously, ascend no faster than 60 feet per minute and keep all your gear on, including your regulator in your mouth. Your buddy should have a grip on you and the up-line throughout the drill to prevent a runaway ascent and to remind you to breath if you get flustered.

 

[Charlie99]

Don't forget to gently exhale continuously, .

This is commonly taught, and seems to be the common "wisdom".

One of the the problems with the way this skill is taught, is that people are taught to blow bubbles i.e. exhale. ........ This is the wrong concept.

When doing one of these ascents you do not need to exhale. You simply need to let the expanding air out. All that is needed is a relaxed, open airway and the air will flow out on its own.

My observation, based on doing a practice 85' esa is the same as JBD's. It may be simpler to teach "always exhale", but the actual requirement is that the airway be open.

 

[Charlie99]

I cannot imagine ascending even 40-50 feet after exhaling and finding no more air to be had, considering must keep exhaling to keep airway open and prevent barotrauma. How can this be safely practiced? Any tips on this scary possibility.

Learn how to keep your airway open without exhaling, instead, just let the excess air bubble back out through your mouth and reg.

The only truly safe way to practice this would be in a submarine escape training tower. I chose to practice an ESA one time and took the following precautions:
1) I had people on the surface aware of what I intended to do. It was in warm clear water with 150' viz. They were aware of the possibility of "shallow water blackout" (same as for freedivers).
2) I did it at the beginning of the first dive of the day when my N2 loading was negligible.
3). Rapid descent, followed immediately by a slow ascent -- take your time. If you just let the bubbles stream out rather than actively exhaling, you can ascend very slowly.

Whether the risk of the training/experience is worth the skill & experience gained is something you must carefully consider.

Interesting post on >5 minute ascent from 30 meters/100' in SETT.

 

[alemaozinho]

all done durung the ow course,confined and ow sessions,check your gages and get a pony tank and dont worry about murphy.peace

 

[baltimoron]

all done durung the ow course,confined and ow sessions,check your gages and get a pony tank and dont worry about murphy.peace

Alemãozinho, você é do Brasil? Alemanha? os ambos?

 

[Uncle Pug]

I cannot imagine ascending even 40-50 feet after exhaling and finding no more air to be had, considering must keep exhaling to keep airway open and prevent barotrauma.

If you have already exhaled there isn't going to much air expanding in your lungs for the first part of the ascent... so you don't have to worry about exhaling what you don't have.

As you begin ascending the gas in your lungs (since you can't really exhale it all) will expand... and as others have said, keeping your airway open as opposed to *exhaling* will take care of the expanding air.

The reason you should keep your regulator in your mouth is that at some point during the ascent the ambient pressure may be reduced to the point that you will ge able to get one more breath off of the regulator... maybe even more than one.

Been there done that.