Mailing List Archive Mailing List Archive
> Thanks for the clarification. My point was the limited useful ness of taking an > "air break" for the O2 clock using air vs. another mix at that depth (or near it). Oh, O.K. - my misunderstanding. > On of the other things I was questioning is that George uses a different > standard of "safe Narcosis" than you do, if I understand your gas switching > techniques. I believe that you once explained your techniques on TD and used > a transit mix (EAN 32) to 130, Bottom MIX for bottom, and O2 for Deco. Is this still true > and are you still using the standard of PPN2 no higher than 4.0? That was when I did mixed-gas OC dives. With the rebreather, I now switch to the helium diluent at about 90 feet, so during most of the dive the PN2 is about 2.3 ATM (EAD is still 90 feet, when you assume O2 is rougly equipotent for narcosis - which it may or may not be at those levels). More nitrogen than this, I'm a little fuzzy. Less than this, and I'm too "wired". On the way home, I usually flush with nitrox at about 140 feet or thereabouts. I barely notice any narcosis change from the 90-foot EAD when I do this - just a slight calming effect. For the profiles I'm doing, it actually works out that more helium at depth is better from a decompression perspective, so it all fits fairly well. > I would expect that George would opt for a mix other than AIR at 190 as > this might pose an unacceptably high PPN2 in an overhead situation. Given > the number of gasses used by WKPP and the labeling method, I would expect > that the rational that AIR is easier and will live with the narcosis is not in George's > character.... do it right or not at all. My opinion is that an optimal mix is a better > way to dive this situation (enough helium to lessen the PPN2). I'll let George elaborate, but as I said in my last message, he knows what he is doing, and his concern for safety and respect for the dangers of narcosis are greater than most people I know. As he has said before, his project involves a lot of intertwined variables. If one variable is tweaked, there are many ramifications for other variables. Also, it's not fair to compare what I do to what he does - we are in extraordinarily different environments. As much as he likes to suggest that his methods are the best for all environments, I know and he knows that he's just talking out the wrong end of his digestive system when he suggests such things. I do what's best for me, and he does what's best for him. The fact that I use lower PN2 in my dives does not in any way suggest that he is wrong for using higher PN2 during portions of his dives. I've spoken on his behalf enough -- let's see what he has to say. Aloha, Rich
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]