The math is easy.- and it was only 12 feet deep max, but most of our stuff was done 6 feet or less. Not even 1 atmosphere, so how much can the air expand in 12 feet? I don't know the math.....
(Depth/33) + 1 = ATA (Absolute Pressure) in sea water
(Depth/34) + 1 = ATA (Absolute Pressure) in fresh water
Assume a 12 foot deep pool. So (12/34) + 1 = 1.35 ATA
So if she left the very bottom of the pool with full lungs (1.0) it would have expended to just over one and a third at the surface (1.35). That's enough to hurt.
A 6 foot rise in a pool to the surface would be 6/34 + 1 = 1.176 ATA. Much lower... (Amended - Thanks Racer184...)
Thanks for the math help! I would never have expected that much expansion in 12 feet. Good to put it all in perspective, and I bet all of us on this thread appreciate these types of discussions, even if only as tough reminders of our training......
I wonder if this can be implemented in the OW course. Fill a small plastic bottle at the deepest part of the pool with your octo. Seal it with the cap and let it go. It probably won't explode, but will be quite nicely pressurized, maybe even deformed once it hits the surface. Or a small balloon maybe. Will try that on my next pool session and see what happens. If a class saw that it would give them a visual reference to remember.
Edited by shadragon, 01 August 2008 - 06:20 AM.
Post split from another thread to highlight excellent info regarding pressure changes in shallow water.