Panic!!!

[Mantaray95616]

if you are alone, CESA with no air from 20m (and if there were thirty?) ? breathing what? Are you capable to hold your breath for one minute or more? Are you sure you are able to exhale for a minute and a half continuously?
I don't know of any modern courses where they take you to 20 meters and make you come back up while making you exhale continuously.

However, Marcante was saying that when you descend, you have to descend to a depth that you are capable of managing the worst case with your own strength. This is the connection between scuba and freediving that you are missing.

It is not so much breathing out continuously, but allowing excess over-ambient pressure air escape from your lungs. i.e. an open airway. Theoretically the expanding air in your lungs as you ascend keeps your lungs full of breathable air.

 

[Goonzodiver]

It is not so much breathing out continuously, but allowing excess over-ambient pressure air escape from your lungs. i.e. an open airway. Theoretically the expanding air in your lungs as you ascend keeps your lungs full of breathable air.

This is a very elegant consideration, and it seems very simple. But I don't know anyone who has tried it from 20 meters in an OW course.

...Calmly finning towards the surface at 18m/minute. Expelling air from the mouth, but without blowing!
And in Europe they recommend 10 meters per minute. It's two minutes to go up from 20m. To be managed calmly. On the books
everything seems easy.

 

[Mantaray95616]

So you have no experience with the way scuba was taught in the system that started with Scripps Institute in the early 1950s, then by Los Angeles in the later 1950s, then by NAUI (which came from the Los Angeles program) and is pretty much the way scuba was taught throughout most of the world from then on. You have no experience with the changes in instructional practice moving from lectures to home study to online learning.

A review of course requirements for the last half century or so show that they only skill taught by most agencies back then that is no longer taught is one regulator buddy breathing, which you describe in your incident. A study by former NAUI President, Berkely professor Glen Egstrom, indicated that for a buddy team to be confident in performing a successful one-regulator buddy breathing exercise in real life, they would need an average of 17 successful practice sessions, and that buddy team would have to practice it together regularly to maintain the skill.

The courses I taught in the 70's were sanctioned by NAUI. I certified as a NAUI instructor in 1971

 

[boulderjohn]

if you are alone, CESA with no air from 20m? breathing what?

Even if you have just exhaled, the normal exhale is about half the air in the lungs.

Look up any of the many videos online of navy submarine escape practice. They are taught to exhale fully before beginning their ascents. Then they are told to continue to exhale throughout the ascent. Look at the videos and see the bubbles spewing out of their mouths as they ascend.

We are talking about the ability to manage one's breathing.
It is clear that if a diver has compressed air in his lungs, he has to expel it during ascent.
Only a fool or an ignoramus would retain compressed air in his lungs during ascent.
A diver in the 50s certainly had better training in managing breathing than modern divers. Without a doubt.

PS:
Freedivers by definition are divers who do not use breathing apparatus. . This does not mean that they "hold their breath", all the time.

What do you mean by managing your breathing? When you explain what managing your breathing is, explain how it helps on an emergency ascent.

So free divers do their descents without holding their breath? Interesting. I had no idea.

 

[boulderjohn]

This is a very elegant consideration, and it seems very simple. But I don't know anyone who has tried it from 20 meters in an OW course.

It is not taught from that depth in an OW course, but there have been programs in the past that have taught it from 30 meters. If you are not sure you can do a CESA from your depth, you do a buoyant ascent, which is only different in that you do not try to control the rate of ascent, meaning you usually drop your weights. Submarine escapes using this method have been done in the 90-100 meter range. The only skill involved is exhaling fully first, then continuing to exhale all the way to the surface.

 

[Goonzodiver]

Even if you have just exhaled, the normal exhale is about half the air in the lungs.

Look up any of the many videos online of navy submarine escape practice. They are taught to exhale fully before beginning their ascents. Then they are told to continue to exhale throughout the ascent. Look at the videos and see the bubbles spewing out of their mouths as they ascend.

What do you mean by managing your breathing? When you explain what managing your breathing is, explain how it helps on an emergency ascent.

So free divers do their descents without holding their breath? Interesting. I had no idea.

Of course I didn't say that freedivers breathe on the way down.
But some fishing freedivers exhale gradually on the way up to avoid exhaling all at once with excessive effort when they are in oxygen debt.
This is to answer the unfounded objection that freedivers "hold their breath" by definition, which is wrong.

 

[Mantaray95616]

This is a very elegant consideration, and it seems very simple. But I don't know anyone who has tried it from 20 meters in an OW course.

...Calmly finning towards the surface at 18m/minute. Expelling air from the mouth, but without blowing!
And in Europe they recommend 10 meters per minute. It's two minutes to go up from 20m. To be managed calmly. On the books
everything seems easy.

It would seem that many things taught or not taught today are based on instrutor liability and insurance coverage

 

[boulderjohn]

Of course I didn't say that freedivers breathe on the way down.
But some fishing freedivers exhale gradually on the way up to avoid exhaling all at once with excessive effort when they are in oxygen debt.
This is to answer the unfounded objection that freedivers "hold their breath" by definition, which is wrong.

I'm pretty sure they were holding their breath before they exhaled.

 

[Goonzodiver]

I'm pretty sure they were holding their breath before they exhaled.

Of course, what I said.
But maybe it's just a language problem and we don't understand each other.
Being a freediver does not prevent you from blowing air through your mouth.
It only prevents inhalation, but not exhalation.

 

[Goonzodiver]

It would seem that many things taught or not taught today are based on instrutor liability and insurance coverage

What I mean is that the OW certification allows you to go down to 20m.
But let's be honest, it doesn't really teach you how to handle an emergency at 20m