scuba diving deeper than 300 feet

[MBH]

For the OP here's a easy to understand definition of PP02 and it's effects on a diver at depth. http://www.answers.com/topic/partial-pressure

 

[Hallmac]

I have heard a similar one and some think it’s serious, but in all reality it's a joke. The Navy did and does a good job at keeping divers surfacing and returning safely.

yep, and it started with Navy divers who were relieving stress. As you stated it is all about conditioning, age, selection process, and years of record keeping of the highest degree. As we age or become damaged with time, those times become even more dangerous and must be approached with caution.

 

[Jimmer]

It's not a big deal, low hydrogen percentages in air brought out over platinum wool in the intermediate pressure line was used by divers at Scripps to warm and humidify their breathing mix.

Very interesting, what kind of dives were these divers performing?

 

[fweber]

Thallas or Gene,

Don't those really deep dives(400m+) require some form of power assisted breathing? I thought I read that at those depths the density of the breathing media was soo great, that the lungs could not move it on their own.

Just curious,

 

[Thalassamania]

Very interesting, what kind of dives were these divers performing?

Rather silly, they did not like wearing hoods in San Diego and this did the trick.

 

[muddiver]

Deepest recorded dive is 1750', was not done on SCUBA, probably done by Comex, HPNS and heat loss becomes the controling factor past 300 FSW. If you are going to dive that deep and use the appropreate thermal protection (i.e. a hot water suit) you might as well go to surface supplied diving with a dry bell.

 

[Gene_Hobbs]

Don't those really deep dives(400m+) require some form of power assisted breathing? I thought I read that at those depths the density of the breathing media was soo great, that the lungs could not move it on their own.

Here are the profiles from the Atlantis series at Duke.
Atlantis I (460m - 1509fsw)
Atlantis II (650m - 2132fsw)
Atlantis III (690m - 2250fsw)

None of this was done with any breathing assistance. I am currently scanning Bret Stolp's PhD thesis for inclusion in the Repository. Bret's (current UHMS President) Thesis was on respiratory mechanics and gas exchange on these deep dives.

There was a nice video of a horizontal piece of paper being let go at the top of the chamber. It drifted down like letting go of a dive table horizontally in a pool. That's pretty dense in my book.

This may also be of interest:
Physiological responses to exercise at 47 and 66 ATA.
Salzano JV, Camporesi EM, Stolp BW and Moon RE.
J Appl Physiol. 1984 Oct;57(4):1055-68.
PubMed ID: 6438026

There is also a section on this dive series on the GUE DVD: The Mysterious Malady: Toward an Understanding of Decompression Injuries.

 

[jrvyota]

Kind of a long read, but perty interesting.
http://home.earthlink.net/~divegeektoo/mixhistory.htm

 

[drbill]

I can't even imagine going to 1,750 ft unless I was in a JIM suit like Sylvia Earle wore.