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Pina, you asked: Luckily, I have available to me sources > of information far superior to what this guy is working with - but > what about the newcomer who does not? A "newcomer" who is supposed to breath nitrox must be expected to have passed a nitrox education. If he has no cue and refuses to listen, let him go, in case he would expose himself to a real danger I would advert the diving director or/and boat captain. In case he is open to advice I would seem right to help him find a lawyer to get his money back he paid for the nitrox cert( except helping him find out the real facts). Matthias > pina schrieb: > > list - > > the following is my reply to a private email I received, but I am > removing the identity of the person to whom I am responding in case > anyone else would like to read this.... I have also edited slightly > and removed any lines from the email which may have been intended to > be private or would indicate the person's identity in any way. The > original question is still there, below my reply to it. > > ----------------------------------------------------------------------- > > When I asked the divemaster if he had an air tank, I was thinking that > the Sea Emperor was 80'-85' max depth - I haven't done that dive in a > while (I don't like it much) and couldn't remember the max depth for > it. When he told me the max depth was 70', I backed off - even though > I knew I had gotten over 70' on that dive - what he said at least led > me to believe I was wrong about the 80-85' part. I wasn't worried > about toxing on the dives at all, but figured I would get about an > hour on the first dive and an hour on the second dive. The second > dive was supposed to be a 60' reef, but it has been my experience that > sometimes that ends up being in the 70's range, too, depending on > where I go and where we are dropped. When I analyzed the gas myself, > one bottle was 38.4% and one was 38.6% and I tend to assume one > percent higher always just to be safe. > > I have never personally felt any lung damage at all after dives, but I > usually don't dive hot mixes either. I wanted a 32 and a 36, but I > took two "36" bottles because that was what the dive shop had ready > right when I needed them. I thought the dives would be two 60' reef > dives - that was the original plan of the captain, but apparently > while I was jogging the diver's requested the Sea Emperor for the > first dive instead of the 60' reef. The bottles I got were not 36% > when I analyzed them, they were 38.4% and 38.6% as I have indicated > above. The reason I didn't want to dive 38.4% @ 80-85' for an hour > followed by 38.6% @ 70' for an hour was that I didn't want anything > interfering with my running schedule so was slightly concerned about > the possibility of any lung damage whatsoever. I am not about to > expose myself to higher ppO2 for hours at a time with no breaks. My > understanding is that 1.4 is the maximum spike ppO2, because the lungs > are going to start reacting to the higher partial pressures and > building extra layers of cells to protect themselves and also swell > and create more mucous to protect themselves, effectively bringing the > ppO2 to the body back down anyway and inhibiting gas transfer on the > way out. On dives longer than an hour I usually keep it under 1.2, > really more like 1.1 at most. I see no reason to expose myself to > something like that as there is clearly no "advantage" and it is not > necessary anyway. As it turned out I kept my depth right around 60 or > less on both dives, except for a brief excursion to 70 on the first > dive. > > The guy struck me really the wrong way because he, without any > knowledge whatsoever of the reasoning for my concern nor the slightest > clue that I might know fully well how to calculate partial pressures > in my head and have been through more math education than he could > likely even consider, proceeded to inform me that 38% was safe to > breathe at the depth of the Sea Emperor - something I know quite well > anyway, whether the actual max depth of the stupid thing is 70' or > 85'. His presumptiousness put him immediately on my bad side. Then, > when I saw him diving with Karla (whom I didn't realize was Karla from > techdiver, but could see was off the idiocy charts by leaps and > bounds), the image I had created for him really made sense. Maybe he > meant well, but it didn't matter nor even occur to me if this were the > case - all I saw was the attitude and his obvious underlying > assumption, which was glaringly wrong. This kind of officiousness in > a vacuum of any accurate information is not only extremely annoying, > it can be outright dangerous. Luckily, I have available to me sources > of information far superior to what this guy is working with - but > what about the newcomer who does not? > > peace, > --pina > > ----------------------------- the original message (edited slightly, > only to preserve anonymity) > -------------------------------------------------------------- > > Hello Pina- > > I was wondering about something that happened on the boat > Sun. morning. I am curious about your reluctance to dive > nitrox on the first dive - 38% to a max depth of 70'-75' > ? > > I believe that GUE uses a max PO2 of 1.4 for all working > dives and I agree with this. Am I missing something? When > I do the math, 38% at a 1.4 PO2 has a MOD of 88'. And that > assuming a max depth of 75' on the Sea Emperor, your max PO2 > would have been 1.25. Well below the 1.4 limit. > > Any info you could provide in your thought process would be > helpful. I am always curious to see how others plan their > dives. Take care and safe diving. > > -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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