Compressed air mid-freedive

[5ata]

It is readily apparent that many scuba divers do not have a full understanding of freediving physiology. The mammalian dive reflex had fully kicked in - shunting of blood from the extremities is a physiological response to the MDR - hence, she basically had no blood in her legs to speak of to be able to kick. Secondly, no matter whether scuba or freediving, being at that depth does produce Nitrogen Narcosis. Although we will never know for sure - it is a safe bet that she was suffering from a mild case of it - add to that the MDR having kicked in, flooding her sinuses with sea water to help with equalization and her lungs being the size of small oranges - which btw - are filled with plasma due to another result of MDR - and then the know it alls profess she could have come back to the surface.

Then there is the comment about submariners being able to perfom deep water ascents - gee - let's look at that for a moment - they have their lungs fully inflated with air from the submarine, and then they ascend - of course they can - they are able to keep exhaling due to ambient pressure becoming less as they ascend. Audrey did not have that.

For anyone wanting a better understanding of freediving, please take a course and read Umberto Pellizari's "Manual of Freediving" front to back several times.

 

[Charlie99]

Then there is the comment about submariners being able to perfom deep water ascents - gee - let's look at that for a moment - they have their lungs fully inflated with air from the submarine, and then they ascend - of course they can - they are able to keep exhaling due to ambient pressure becoming less as they ascend. Audrey did not have that..

Is there some reason that should could not have fully inflated her lungs with air (trimix) from safety diver and then exhaled as she ascended? BTW, although submarines are kept nominally at 1ata, the escape compartment is pressurised to ambient just before each group ascends -- otherwise the hatch couldn't be opened.

While you guys are focussed on a specific incident, I'm just trying to understand why people seem to be saying that a freediving can't take a breath of compressed air on the bottom. I've seen it done ---- one DM/mate from a boat dropping down to 60 or 70', taking a gulp or two of air from another DM, swimming around a bit and then ascending.

Yes, he has to let the excess air bubble out while he ascends, but to my understanding his N2 loading is no different than if he had spent that same amount of time freediving to the same depth.

Ignoring the specific freediving accident that you have in mind, do you agree or disagree with the paragraph just above?

 

[Marlinspike]

Is there some reason that should could not have fully inflated her lungs with air (trimix) from safety diver and then exhaled as she ascended. BTW, although submarines are kept nominally at 1ata, the escape compartment is pressurised to ambient just before each group ascends -- otherwise the hatch couldn't be opened.

While you guys are focussed on a specific incident, I'm trying to understand why people seem to be saying that a freediving can't take a breath of compressed air on the bottom. I've seen it done ---- one DM/mate from a boat dropping down to 60 or 70', taking a gulp or two of air from another DM, swimming around a bit and then ascending.

You could always ignore what we are saying and try swimming up with a chestfull of trimix from 500 feet yourself. Doesn't sound like a good idea does it?

~Marlinspike

 

[Charlie99]

So what you are saying is that she shouldn't have breathed off of scuba but just started ascending?

I'm saying that, if the dive plan was so screwed up that the safety diver didn't have enough trimix to get her up to the next diver, then she should have taken a few breaths from the safety diver, then ascended as fast as possible up to the next diver. And then repeated it. She doesn't have anywhere near as great of inert gas loadings as the safety diver, and is not restricted to 60fpm anymore than a freediver must restrict him/herself to 60fpm.

 

[Charlie99]

You could always ignore what we are saying and try swimming up with a chestfull of trimix from 500 feet yourself. Doesn't sound like a good idea does it?

In really simple words, please explain the problem if 1) I let out the gas as I ascend, and 2) I have done a high speed sled descent immediately before my as-fast-as-possible ascent.

I doubt that I'd make it all the way to the surface, but my problem would be drowning, not either DCS or lung expansion injury.

 

[5ata]

This is evidently something that certain people who have no understanding of freediving are going to make assumptions based upon pseudo knowledge - as I stated earlier - take a freediving course.

Now I know why I gave up tank diving...

 

[dumpsterDiver]

Thats how I think also, but I'm not really sure about it.

However, maybe due to the narcosis and the extremely compressed lungs and the fact that the lungs begin filling with fluid (due to an extreme "lung squeeze") that a diver at that depth really can not move their diaphragm and breath? The depth she was at is unimaginable to me. I think that if she could breath, then she could have breathed just about anything and made it up.

The hardest part for me to understand is why they did not have an emergency redundant bouyancy bail-out planned. It seems that the safety diver could have clipped of a self-inflating lift bag to her back and sent her flying to the surface.

 

[mattroz]

if we don`t understand explain it to us.. all we want to know is what is the problem if she took a couple breaths, let the blood go back to her legs, swim (while exhaling) to the next diver, repeat repeat repeat. What is bad about that... She has next to nil nitrogen loading as she was dragged down by a sled and was only there for a minute amount of time. PLEASE EXPLAIN and stop being condesending to us tank divers

 

[Marlinspike]

I'm saying that, if the dive plan was so screwed up that the safety diver didn't have enough trimix to get her up to the next diver, then she should have taken a few breaths from the safety diver, then ascended as fast as possible up to the next diver. And then repeated it. She doesn't have anywhere near as great of inert gas loadings as the safety diver, and is not restricted to 60fpm anymore than a freediver must restrict him/herself to 60fpm.

Are you even reading what 5ata is saying? SHE COULD NOT KICK HERSELF TO THE NEXT SAFETY DIVER! At 500 feet you cannot swim or fin like you do at 200.

THIS ISNT THAT HARD TO UNDERSTAND.

~Marlinspike

 

[Marlinspike]

Step by step.

1. You get to 500 feet freediving and your body no longer behaves like it does as a scubadiver. Your body is undergoing physiological responses (mamalian effect, etc) to preserve life, at the expense of muscle control and strength.
2. It isnt so much a matter of her not being able to THEORETICALLY, gulp a little mix and shoot to the next safety diver (who wasnt there because he didnt exist). It is also a matter of just plain not being able to physically swim any distance and not having the brain function to do so.


~Marlinspike