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breath hold scuba descent

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JasonWelbourne

New Member
Aug 17, 2004
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Never mind the danger, stupidity, etc.

Lets say a person had the necessary physiological adaptations necessary to do freedive descent while holding their breath.

Okay so, I hold my breath. I sink from 0m to 50m in say 1:30. I come nack up to 0m.

Now lets say the same person, a scuba diver, does a normal scuba descent to 10m. After getting a good breathe up, he does a max inhale, and sinks to 60m in 1:30. They return to 10m, and resume breathing on normal scuba.

Is there any difference in these two activities?

Does the fact that there is twice as much oxygen present decrease the rate at which the oxygen partial pressure changes?
 

efattah

Well-Known Member
Mar 2, 2001
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O2 pressure at 60m will be similar; however, the diver is carrying twice the amount of nitrogen, which could increase the risk of DCS. Further, CO2 toxicity would be an issue, because the diver carries twice the amount of O2 (in molecules, not pressure), this would delay the CO2 breathing reflex.
 
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JasonWelbourne

New Member
Aug 17, 2004
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Basically I am trying to figure out if air at pressure allows you to hold your breath longer. i asked someone once before and they said no because it's not about the amount of air you have but about the pp of O2 that determines the balckout point. But if you have twice as much O2 that doesn't mean you consume it twice as fast.
 

efattah

Well-Known Member
Mar 2, 2001
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If you take a breath at 10m you can hold your breath way longer until blackout, perhaps 50% longer. For example, the unofficial record for holding your breath on 100% O2 is 22 minutes.

Although I don't recommend it, I have often taken breaths from air pockets in shipwrecks; this is compressed air. Then, I freedove for a while on that compressed breath, and then exhaled as I ascended. Don't attempt that!
 
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JasonWelbourne

New Member
Aug 17, 2004
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thanks for the info. I have freedove down and breathed from a second stage at 80 feet. I also wouldn't advise anyone not thoroughly familiar with SCUBA to try something like that. The PADI manuals say never stop breathing. I am just trying to personally debunk that as being overly cautious even though it is perfectly well important if you are playing around with neutral bouyancy or new to diving. I also wanted to confirm my suspicions about o2 consumption at depth. Once again, Thanks!
 

FreeFloat

Underwater Tourist
Jun 5, 2003
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PADI manuals say never to stop breathing because they consider it too 'difficult' to try to train students that they can indeed hold their breath while divnig compressed air - as long as they remember to exhale any time they ascend, no matter how insignificant the ascent. Certain tech agencies advocate complete breath hold while stationary and neutrally buoyant at depth......... it's the ascend/exhale thing that needs to be emphasized any time there's compressed breathing gases involved.
 

FreeFloat

Underwater Tourist
Jun 5, 2003
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Oh by the way there's a fundamental problem with your hypothetical situation. Scuba divers use their breathing patterns to control their vertical position in the water column. If the diver in your example did a "normal" descent to 10m he'd be neutrally buoyant, or close to it, at that point. In order to descend once he's breath holding, he'd need to dump air from his wing/BC. That would make it very difficult to attain neutral buoyancy once reaching the 60m point, and in fact would require very close attention on teh ascent as he'd need to vent just the right amount of air from his wing/BC in order to prevent a runaway ascent. Scuba divers (good ones, at least) control nearly all of their buoyancy and vertical movement using breathing cycles alone. For myself, I only use my wing for gross buoyancy adjustments and my lungs for all other adjustments up to 10-12' +/- (that's 3-4m) my chosen position in the water column.

Not saying it couldn't be done, just that it would be tricky and not very comfortable.............
 

JasonWelbourne

New Member
Aug 17, 2004
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The hypothetical was just a stage to ask about the relationship between the increased amounts of oxygen present in compressed gas and one's ability to perform max apnea. I used descent as the backdrop because it is, IMHO the only safe situation in which to hold your breath in SCUBA.
 

NotariuPublicus

New Member
Sep 22, 2004
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Holding your breath

This Fattah know nothing about the record with pure oxygene, there is NO-ONE that have done 22 min. There is one, mr Pelizzari, that have done close to 19 min in a chamber. They took him down to 10 meter, where he have the last breath. Then they slowly took him "up" to the surface. (this was with pure oxygene)
There is a diver that with same test with normal air have done 10'45"....but I don't know if this is the best time ever.

:)
 
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Alison

Offline
Mar 6, 2004
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Originally posted by efattah

Although I don't recommend it, I have often taken breaths from air pockets in shipwrecks; this is compressed air. Then, I freedove for a while on that compressed breath, and then exhaled as I ascended. Don't attempt that!
Definately not! This air may be oxygen depleted from the oxidation of the shipwreck or whatever, a breath of this could land you in it neck deep :(
 

DeepThought

Freediving Sloth
Sep 8, 2002
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Re: Holding your breath

Originally posted by NotariuPublicus
This Fattah know nothing about the record with pure oxygene, there is NO-ONE that have done 22 min. There is one, mr Pelizzari, that have done close to 19 min in a chamber. They took him down to 10 meter, where he have the last breath. Then they slowly took him "up" to the surface. (this was with pure oxygene)
There is a diver that with same test with normal air have done 10'45"....but I don't know if this is the best time ever.

:)
Ahh.. is this a joke? did you intend to make to most stupid post (I've ever read) on deeperblue? (though I admit I don't usually read scuba theads;))
 

Alison

Offline
Mar 6, 2004
1,898
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LOL I suspect because he (or she) has "chosen not to participate with karma" is either having a laugh or out to stir it up!
 

FreeFloat

Underwater Tourist
Jun 5, 2003
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Re: ...please

Originally posted by NotariuPublicus
The truth can somethime look's stupid... but it's still the truth.

/NP

Sure it is - I believe everything I read on the Internet ;)

If you want to be believed, cite examples.
 

Bill

Baron of Breathold
Oct 17, 2001
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Interesting stuff. If you inhale 100% O2 at 10 meters, you will have 10 times as much O2 in your lungs at the start or about 5 times the total O2. With some way to get rid of CO2, half hour statics might be possible, but with the same logic, you would be able to hold 50% longer at 10 meters than the surface, depending on CO2. I don't know. My experience seems to indicate easier, yes; longer, no. Either way, the return to the surface and the danger of SWB is the problem.
In your example, the diver that starts at 10 meters with double the O2 in his lungs could probably go back to 35 and return to 10 with the same chance of a samba as the diver starting on the surface.
Aloha
Bill
 

donmoore

New Member
Aug 19, 2002
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Freefloat,
I’m a real low-tech scuba diver. I use a back plate with a 40cu pony bottle and a very cheap regulatory that only works if it’s horizontal. I weigh myself the same as freediving, neutral around 11 meters. When going down, I take a freestyle breath on the surface, turn the regulator upside and kick my way down. When I stop I turn the regulatory back too horizontal. If I am below 11 meters I swim up a little to maintain position.

To decompress I grab onto something, usually part of an oilrig, to keep from floating all the way up. I don’t worry much about DCS, because with only a pony bottle my time is pretty limited anyway, but with freediving lung efficiency I can almost stay down as long as a smoking scuba diver with an 80cu tank.

My scuba dives to freediving ratio was 2 too about 40 this last year. I’m not much of scuba diver and don’t care to be. I guess I don’t fit “good ones” profile.

On subject of taking compressed air breaths while freediving, I remember Pipen has done some incredible deep dives with taking one or two breaths from a spare air bottle. I can’t remember if he was fining or on a sled. They were like unofficial one and two breath depth record dives.
don
 
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