Compressed air mid-freedive

[Humuhumunukunukuapua'a]

Nitrogen absorption doesn't take place because the freediver isn't exchanging air during their dive. They begin and end their dive with the same volume of air. Since respiration doesn't take place, there is no exchange of gases. No exchange of gases - no increase in nitrogen absorption.

How does this statement make sense when you then go on to say...

There are recorded instances of DCS with freedivers - specifically - deep spearfishing freedivers - who make numerous ascents and descents without giving sufficient time at the surface to off gas the little they have in their systems. They gradually build up nitorgen in their systems and eventually get bent - but it is extremely rare.

Nitrogen absorbtion DOES take place with freedivers. Respiration has nothing to do with it. That's why they (rarely) can suffer from DCS. If you take one lungful of air and descend deep enough for long enough, you will most certainly absorb Nitrogen. That's basic physics.

Gotta say, I'm not really tempted by the books and classes you've mentioned at this point...if they tell you that you can't absorb Nitrogen without respiration. That's just wrong.

 

[spectrum]

After reading the prior 41 posts let me ask/add.

1. If her lungs and airways would have accepted open circuit gas at depth would she have been able to make a CESA to the next support diver up the line. As noted strength to swim would be severly limited. Her suit buoycancy would be very slight, unlike a scuba diver who may have significant buoyancy to drive a free ascent.

2. Had the support diver escorted her up on his profile she would have assumed his profile for all intents and purposes assuming he got to such a depth just prior to her descent.

3. Wouldn't her ears have taken a major hit? I can't imagine the shock, pain and damage that would have inflicted though better than death.

Pete

 

[gracefulc]

Wow. I go away for a day and I discover my question has turned into a bit of a verbal brawl...

So, anyone who wants to can call me stupid or lacking any form of sense, etc, but I still am interested to know the answer to the following question:

We have established that this particular diver didn't have enough safety divers to be able to just jump from one to the next and get to the top fast. BUT, lets just suppose for one moment, we are back in that situation. She has 1 diver with her at 500 feet, and the next diver is at 250 ft. She can't swim b/c of the mammalian reflex, etc. WHY couldn't she take some breaths off the safety diver that was with her (buddy breathing for example), to at least give her a chance of surviving to the next diver, then doing the same with him? I mean they could send more tanks down on a line, in theory, so lets ignore the whole, consuming air at twice the rate thing and assume the scuba diver and her buddy breath, with him essentially carrying her up to the next diver. Why didn't they try that? There must have been a reason obviously b/c they would have known that without air it was a death sentence at that depth...:06:

Thank you!

 

[slingshot]

I am unfamiliar with free diving at the depths being discussed, but am curious if I could hear more about the role of a support/safety diver. If breathing cylinder gas is not possible or otherwise unsafe for the freediver at depth, it seems the support diver could do little to assist the freediver in distress. In what ways can the support diver assist the distressed freediver, besides, and please I mean no discourtesy or disrespect in this, bringing a body to the surface?

 

[minnesota01r6]

This may be a stupid question, but if she breathed off the support diver for a minute, wouldn't the mammalian dive reflex go away? I mean, the safety diver doesn't have it because he is breathing gas, so if she does the same, her dive reflex goes away? I realize that when at 500 feet, the lungs are squeezed and blood & fluid rushes in to the chest cavity from the extremities to take the place of the lungs. But, if the lungs are allowed to expand then the blood & fluid go away. Also, I have seen on TV that free divers must let go of the balloon and do a controlled 60fpm ascent from 60 feet to avoid passing out due to the lungs sucking all the oxygen out of the blood or something. Would this happen at depth if someone breathed scuba? Maybe such a vaccuum has been created in the chest cavity that a freediver runs the risk of sucking in water into their lungs if they try to take a breath off scuba?

I dunno - but I would be interested to hear the answers to my questions

 

[Marlinspike]

I am unfamiliar with free diving at the depths being discussed, but am curious if I could hear more about the role of a support/safety diver. If breathing cylinder gas is not possible or otherwise unsafe for the freediver at depth, it seems the support diver could do little to assist the freediver in distress. In what ways can the support diver assist the distressed freediver, besides, and please I mean no discourtesy or disrespect in this, bringing a body to the surface?

There is nothing stupid about your question. The bottom safety diver has a cieling he can't violate or he will be in trouble and then you have 2 dead divers. The freediver breathes off the safety diver's supply and stays alive by becoming a scubadiver at that point. Using a profile specifically calculated for the freediver in case of such an emergency, she could be passed from one safety diver to the next having a continous supply of gas, because she is now a scubadiver and not a freediver.

What is stupid is that she only had maybe half of the safety divers she needed to form a chain to the surface.

Think about the danger already faced by the tech diver at 500 feet. That is not just another dive.

~Marlinspike

 

[5ata]

-

 

[5ata]

after the chastising I recieved, I'm keeping out of this conversation unless necessity warrants a response. Think I'll head back to Deeperblue where the freedive discussions are more informed..

 

[Lead_carrier]

Amongst all the problems she had, there were only about half the number of safety divers in the water than the numbers used and required by the other and more respectable freediving organization.

The guys that planned Audrey Mestre's dive are hacks.

~Marlinspike

If I'm not mistaken, her husband did most of the planning, checking of equipment, etc.

 

[Marlinspike]

If I'm not mistaken, her husband did most of the planning, checking of equipment, etc.

Yes, please read the earlier posts in the thread.

5ata knew what he was talking about and too bad people who are less informed but more belicose have driven him back to the purely freediving boards. I wish people would do a little background research before posting egregiously bellicose nonsense. (Like that could really happen...)

~Marlinspike