I have been thinking a lot about deep air lately, and as the board has been generally civilized lately, I thought it might be a good time to revisit it as one of the traditional "hot button" topics. Two things in particular that I read gave me lots of food for thought.
OxTox footnotes. Two other things that jumped out at me from those passages were about O2 toxicity. During his recompression treatment, Richard Pyle was briefly hooked up to pure oxygen at 7.7 ATA (about 220 fsw equivalent). I had assumed that would kill you stone dead, but Richard reports they just took the mask off when they realised the error and he survived unscathed. Similarly, for our deep air record setters, even on air they were breathing oxygen at a partial pressures of 3.23 ATA (Gilliam) and 3.45 ATA (Manion). Bret talks about spending 5 minutes at depth, but doesn't detail his decompression schedule, so we don't know the time of exposure (although I recall Bret is on SB from time to time, so if he reads this, maybe he can answer?).
Certainly lots of food for thought and discussion in there, even for those who are staunchly opposed to the idea of deep air diving.
- The first was this blog by Richard Pyle about the time he got bent (which was linked in another thread). No one suggests that Richard's dive profile for that day was smart, or even sane (being forced into doing IWR, and then going back in for another 140 foot dive?). But what was sort of interesting to me was frankly how far Richard was able to push it before he got into trouble.
- The second was various bits from Bret Gilliam's book on Deep Diving, now available online couresy of Google Books (see Chapter 1 - History of Deep Diving). Bret talks a lot about various attempts (including his own) to set the world record for deep air diving. Again, as harrowing as the failures are (it seems that about half of the attempts resulted in death, some reported in appropriately gruesome fashion by Bret), what interested me was the two record setting attemps by Bret himself and later by Dan Manion. Brett dived to 475 feet on air, performed various narcosis tests, and although he suffered some incapacity, certainly didn't seem to be insensible. Conversely Dan Manion (and Archie Forfar and Anne Gunderson, who died) appeared to be completely incapacitated, and had no recollection of his time at depth. Clearly narcosis affects people differently, but it did kind of astonish me that Bret could be that deep on air and still function (in much the same way but to a greater degree that it amazes me that the John Chattertons and the Gary Gentiles of the world used to pentrate wrecks at 230 odd feet, or even deeper).
OxTox footnotes. Two other things that jumped out at me from those passages were about O2 toxicity. During his recompression treatment, Richard Pyle was briefly hooked up to pure oxygen at 7.7 ATA (about 220 fsw equivalent). I had assumed that would kill you stone dead, but Richard reports they just took the mask off when they realised the error and he survived unscathed. Similarly, for our deep air record setters, even on air they were breathing oxygen at a partial pressures of 3.23 ATA (Gilliam) and 3.45 ATA (Manion). Bret talks about spending 5 minutes at depth, but doesn't detail his decompression schedule, so we don't know the time of exposure (although I recall Bret is on SB from time to time, so if he reads this, maybe he can answer?).
Certainly lots of food for thought and discussion in there, even for those who are staunchly opposed to the idea of deep air diving.
