Compressed air mid-freedive

[freediver]

Her death was unfortunate but what is equally unfortunate is that it would appear every thread on this board cannot be debated in a civil manner. perhaps with something learned by all involved, without it becoming a pissing contest! I, for one, do not feel that science is exact. Perhaps all of you have valid points that show to be within reason. One thing I do know for sure........ disputing incessantly won't take this thread toward a constructive path!

 

[Charlie99]

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.

Heh, now THAT's a real answer.

A lot more real than

1. "They said the safety diver couldn't give her air at that depth because her lungs would explode... "; and

2. "..... 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

3. "At the surface, a freediver starts their dive with proportional amounts of oxygen and CO2 with traces of nitrogen. .... 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"

 

[5ata]

Thank you Marlinspike..

dumpster - unfortunately, there was ego involved in the decision making process (and Pipin has a BIG one). Audrey on the other hand, was driven, but she also understood the risks with the setup she was to dive with so to a certain extent, she knew the risks and they caught up with her. There is a lot of speculation on what ifs, but the reality is, her tragedy has established new bailout systems that don't require safety divers all along the descent line when diving that deep. Her tragedy has help to create more effective rescue mechanisms for future no-limits record attempts.

Charlie99 - not sure if your response is condescending or legit....

 

[5ata]

Her death was unfortunate but what is equally unfortunate is that it would appear every thread on this board cannot be debated in a civil manner. perhaps with something learned by all involved, without it becoming a pissing contest! I, for one, do not feel that science is exact. Perhaps all of you have valid points that show to be within reason. One thing I do know for sure........ disputing incessantly won't take this thread toward a constructive path!

Freediver - yes it was a tragedy...

Unfortunately, the pissing match results when those of us who have studied and trained as freedivers are treated as though we know not what we are talking about. I appreciate someone asking questions as to why - the challenge is when after a logical answer is given, it is contradicted.

You are right - freediving isn't exact science yet - there is still much to be learned and science is learning new things about the human body all the time when freediving.

 

[freediver]

Freediver - yes it was a tragedy...

Unfortunately, the pissing match results when those of us who have studied and trained as freedivers are treated as though we know not what we are talking about. I appreciate someone asking questions as to why - the challenge is when after a logical answer is given, it is contradicted.

You are right - freediving isn't exact science yet - there is still much to be learned and science is learning new things about the human body all the time when freediving.

Fair enough Cliff but in light of your last statement, perhaps Charlie99 doesn't see the logic in your response? I don't think it's his intent to argue rather to get clarification. Maybe his area isn't freediving but you can't fault someone who questions so they can gain a better understanding of the sport.

 

[D_O_H]

Fair enough Cliff but in light of your last statement, perhaps Charlie99 doesn't see the logic in your response? I don't think it's his intent to argue rather to get clarification. Maybe his area isn't freediving but you can't fault someone who questions so they can gain a better understanding of the sport.

I agree. I have been following this thread with interest and still can't say I fully understand why she couldn't have recovered from the MDR by taking a few (a bunch of?) breaths from the safety diver's mix. This is not to say she could have made it to the surface or the next diver, given how far apart it sounds like they were, but she might have had a chance.

Is it possible at all to rescue someone freediving at this depth? It sounds like the lungs and throat may close down and not be susceptible to breathing at all. I imagine there is very little air volume left in the lungs at 500 feet and could understand how some kind of suction type effect could keep the airway closed.

The responses have gotten better from the initial eye rolling and suggestions to read Umberto's book (several times), but I still don't think enough info has been provided here for a reasonably intelligent non-Umberto-follower to get it.

 

[Charlie99]

Fair enough Cliff but in light of your last statement, perhaps Charlie99 doesn't see the logic in your response? I don't think it's his intent to argue rather to get clarification. Maybe his area isn't freediving but you can't fault someone who questions so they can gain a better understanding of the sport.

I understand mammalian dive reflex/ mammalian dive response that was first mentioned in post #21.

What I don't understand is why nitrogen absorption and DCS is so different in freedivers (particularly in the normal freediving range) than in scuba divers. As I noted in my first response to 5ata, I have quite a different understand of the physics and physiology than what he described in post #8. Perhaps you would comment on that post, Freediver.

 

[5ata]

Freediver - fair enough - I stand corrected..

D O H - I understand what you are saying, but since freediving - at least in this country, isn't recognized as something to be taught by any of the certification agencies, I feel it is necessary to not give too much information due to liability.

Suffice it to say, All I was taught by Kirk Krack, Pipin, Ricardo Hernandez and Aharon Solomons, is NOT to breathe off of any open circuit systems when freediving. To be honest - since my experince with freediving is only to 30 meters, I cannot give a concise answer other than what I have so far. To be honest - I have no asperations of going much past 40 meters anyways since my primary focus is shooting video while freediving and teaching any interested scuba diver how to become a better diver through freedive training - which it truly does. I recommend any scuba diver take a freedive course to learn more about what your body can truly do underwater - it makes for a more relaxed and confident scuba diver.

But I highly recommend Umberto's book - it is by far the best piece of information on freediving I have ever come across - I have PFI's course books, IAFD's and IANTD's course books as well. I hope to be able to take Apnea Acadamy's English course in 2008 when it will be taught next.

 

[5ata]

I understand mammalian dive reflex/ mammalian dive response that was first mentioned in post #21.

What I don't understand is why nitrogen absorption and DCS is so different in freedivers (particularly in the normal freediving range) than in scuba divers. As I noted in my first response to 5ata, I have quite a different understand of the physics and physiology than what he described in post #8. Perhaps you would comment on that post, Freediver.

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. The cardinal rule is 5 minute surface interval for a normal dive - if deep freediving, extend to as much as 7-8 minutes to recover. Freeedivers also tend to be more athletically fit than scuba divers - I train 5-6 days a week most of the year so that has a contributing factor as well. Freedivers typically have less body fat - which has been said can contribute to an increased chance of DCS (having more that is). And as a freediver dives more and more, their body becomes more adapted to the aquatic environment. Additional adaptations mof MDR also include the spleen releasing more red blood cels, lowered heart rate, as well as the other physiological manifistations discussed already.

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.

 

[Humuhumunukunukuapua'a]

5ata...take a deep breath and stop trying to look like you know absolutely everything and everyone else is ignorant. You're new to these parts and I think it would be wise to be a bit more diplomatic in your posts.

As you now admit, you really don't have any knowledge yourself of why one could not safely take a breath off a tank after freediving to depth. You've just been told not to. That's an honest answer and you probably should have started with that response instead oof implying you knew all sorts of stuff we don't that you learned in freediving classes.

I doubt the books and courses you are telling us all to take would help clarify, since I assume you yourself have read those books and taken those courses. Yet you still don't know why it couldn't have been done.

The issues with narcosis and MDR are all secondary to the original question specifically asking about breathing compressed air after freediving deep.

Charlie99 has made a lot of sense and, IMHO, been very patient and balanced in the face of rude/illogical posts. I have seen no explanation to contradict his logic that one could concievably take a few breaths of compressed air at depth and ascend without "exploding lungs" etc.

I find the topic of this thread very interesting if not the tone it has taken. If anyone does have a reason why a freediver would not be able to breathe off a tank at depth and work her way up a chain of safety divers to the surface (I know...not in this case), I'd love to hear it.