Compressed air mid-freedive

So I tuned in to watch the David Blaine stunt and they talked about the woman freediver who was killed when her sled failed to take her back up. They said the safety diver couldn't give her air at that depth because her lungs would explode... Thinking about it as a scuba diver, as long as she exhaled her air from the surface before she took a breath, I don't see why her lung would have burst... Can anyone enlighten me? :06:

gracefulc:

So I tuned in to watch the David Blaine stunt and they talked about the woman freediver who was killed when her sled failed to take her back up. They said the safety diver couldn't give her air at that depth because her lungs would explode... Thinking about it as a scuba diver, as long as she exhaled her air from the surface before she took a breath, I don't see why her lung would have burst... Can anyone enlighten me? :06:

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You are right (I think. ) She could have aborted her free dive and become a scuba diver and from the time she took her first breath of compressed air she then would have had to acend like a scuba diver at not more then 60 feet per minute and she'd also have to watch other limits like NDL and would likey have to do a deco stop

If she was very deep, say below 220 or 250 she couldn't breath air due to the O2 partial pressure. She'd have to breathe whatever gas the scuba divers was using at that depth and then stick with him like glue and copy his assent.

Uh... I think freedivers use the sled to go down, don't they? As for breathing compressed gas at depth, I don't see why she couldn't do that and exhale while surfacing. As opposed to, you know, dying.

Per the report: They use the sled to go down and then a balloon on the sled inflates and takes them back up really fast. She was at somewhere around 500 ft, but the safety diver was at that depth b/c he grabbed her as soon as it malfunctioned and started taking her up, so he must have been breathing the right mix for that depth... it just seems like she could've breathed off the safety divers that were staggered throughout the depths and they could've sent more appropriate mix tanks down on a line and such so she could do a gradual decompression... I mean worst case scenario she gets DCS and has the chance of dying, but this way she died for certain...

Not trying to fault anyone, I am just not understanding why this situation ended up this way...?

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

I trained with Pipin and Audrey for my IAFD Freedive Instructor rating the May before her fatal accident - She was a very sweet woman who had a gentle spirit. I was somewhat involved with reporting the events surrounding what actually occured for Deeperblue.net - it is very sad what happened - it was preventable is all I can say. Rest in peace Audrey...

5ata:

I trained with Pipin and Audrey for my IAFD Freedive Instructor rating the May before her fatal accident - She was a very sweet woman who had a gentle spirit. I was somewhat involved with reporting the events surrounding what actually occured for Deeperblue.net - it is very sad what happened - it was preventable is all I can say. Rest in peace Audrey...

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It is tragic, so sorry to hear about the accident. Can you possibly shed some light on why a freediver can't take breath of a reg with out damaging their lungs? I know nothing about freediving, but this doesn't make sense to me.

At the surface, a freediver starts their dive with proportional amounts of oxygen and CO2 with traces of nitrogen. During descent, you maintain the same percentage of gasses, but they become denser the deeper one descends. On comletion of the dive, you literally end your dive with the same volume of air that you had on your descent. The potential for DCS is almost nil. Once you breath off a tank, you introduce a fresh supply of air, which also then introduces the small percentage of nitrogen. Since it is compressed at depth, it is at a constant pressure - reascending, of course means the nitrogen will expand - you have become a scuba diver and can no longer freedive for the rest of the day. Freediving rules apply only as long as you do not breath off of a scuba tank - many of the dive physics and physiology laws apply to freediving, but in addition, some do not. This isn't something that can be explained in a public forum - one needs to have a qualified freedive instructor teach this material - suffice to say - dont breathe off a tank and freedive - you are setting yourself up for getting bent severly.

5ata:

At the surface, a freediver starts their dive with proportional amounts of oxygen and CO2 with traces of nitrogen. During descent, you maintain the same percentage of gasses, but they become denser the deeper one descends. On comletion of the dive, you literally end your dive with the same volume of air that you had on your descent....

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My understanding is that the breathing reflex is triggered by the level of CO2 in the body. If that is true, then why introduce CO2 into the lungs at the start of the dive? Why not use something else?

Bill.

gracefulc:

So I tuned in to watch the David Blaine stunt and they talked about the woman freediver who was killed when her sled failed to take her back up. They said the safety diver couldn't give her air at that depth because her lungs would explode... Thinking about it as a scuba diver, as long as she exhaled her air from the surface before she took a breath, I don't see why her lung would have burst... Can anyone enlighten me? :06:

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Unless I missunderstood what you are asking, P1V1 = P2V2. Once she breathed compressed gas, she wouldn't be able to keep holding her breath. She would have to continue breathing on scuba.

Bill.