Carlos CW dive at altitude

[glennv]

Check out some news about Carlos Costes recent dive

http://www.apnea-amsterdam.com/forum...opic,64.0.html

[naiad]

Amazing!

Thanks for the link.

[efattah]

When diving at altitude, it is the perfect time to use the FRC method. The FRC method is not much affected by the altitude.

Think of it this way. The oxygen saturation in the blood, even at 3800m, is still over 90-93%, whereas the amount of O2 in the lungs is much decreased. Therefore, at altitude the oxygen store in the blood is not much affected, while the oxygen store in the lungs is severely affected.

Therefore a style of diving which relies more on a blood oxygen store would work better, I think.

The energy required to perform an FRC dive at altitude is still the same; the energy required to perform an inhale+packing dive at altitude is still the same as at sea level; the main difference is the change in the oxygen store. In the packing case, the oxygen store at the start is reduced by a greater percentage at altitude, compared to FRC.

Anyway, congrats to Carlos for his dive!!

[Walrus]

I thought if you use full packing at altitude the %O2 in your lungs would be the same as at sea level. ie on a normal breath the air pressure is less therefore a lower %O2 but full packing would have the air at the same pressure as full packing at sea level ?

Cheers,
Wal

[Mullins]

The ambient pressure is lower, so if you tried to fit the same amount of air it would take up a larger volume (assuming an elastic rather than a rigid vessel). If you tried to pack 1atm of air into your lungs at altitude there would be a hell of a lot of pressure on your ribcage/diaphragm.

I would have thought that inhale dives would be harder at altitude because of the greater/faster buoyancy change. You're starting with the same volume at lower pressure, but the water pressure increases at very nearly the same rate, meaning that volume decreases faster. Imagine if you could dive in an environment that was 5atm (without ox-tox etc...). Your buoyancy would hardly change in the first 20m, because the proportional change from 5-7atm is nowhere the 1-3atm we experience at sea level. The opposite would be true with greater altitude/lower pressure.

I'm no physicist so this may well be (and most likely is) entirely wrong

[Donna]

wow.... nice pics too

[naiad]

Originally Posted by Walrus

I thought if you use full packing at altitude the %O2 in your lungs would be the same as at sea level. ie on a normal breath the air pressure is less therefore a lower %O2 but full packing would have the air at the same pressure as full packing at sea level ?

I think you would have to pack very heavily to pressurise the air! I don't know if this is possible.

[Rémi]

The problem is the difference of pressure between in and out of the lungs. That will give you your limite before to burst.
If there is less pressure out, you can pack less pressure in
So even with packing you still have less O2

[Walrus]

That makes sense, although thinking of the lungs as being elastic is over simplifying. I don't think it is a huge increase but packing does increase pressure as well as volume, otherwise there is no limit to how much you can pack !
The lungs are reasonably elastic but as you pack the diaphragm can only push so far down into your internal organs, and likewise the ribcage has limits on how far it expands. If you think about when you pack, to start with it's really easy, and when you pack near your max it becomes a lot harder. This is the pressure increase, you can also feel it on your throat trying to hold the air in. So yes packing to the max somewhat compensates for the decreased atmospheric pressure, exactly how much I don't know.

Cheers,
Wal