Posted by MHK on October 30, 2000 at 14:41:26:
In Reply to: Re: Half as bad posted by Ken Kurtis on October 30, 2000 at 12:27:35:
Ken,
I think the above speaks to the ambiguity of your viewpoint, atleast from my perspective..
Let me see if I can make it clear, and I'm only keeping this online because I think it's a useful discussion.
If you are of the assumption that we are taking the position that the Yukon can NOT be done safely on air you don't understand ( or we aren't doing a good enough job explaining it ). In my view the Yukon ( or in a more generic view any hard bottom dive to X, defined by the MOD ), can be done safely under certain circumstances. Assuming we all agree that you should be a certfified diver not diving in conditions beyond your ability than diving is safe, as the term is commonly understood.
But where I disagree with your analysis ( atleast as I understand your analysis to be ) is that let's assume for example that diver A can do a 20 minute dive on air and will reach, let's say the 1st pixal in red on a computer ( if you want we can speak to M-values but I'm trying to keep it user friendly ).. As I understand your position, assuming that diver does a slow safe ascent, complete with safety stop and exits the water with pixals within the recomended *green* area you conclude that since that diver isn't bent it's safe. Other's ( me included ) suggest the following:
1) By using Nitrox, and accepting the notion that mathematical models are not an exact science in terms of tracking bends, that by using a gas with an elevated level of F02 you are allowing a greater distance between what could be a *possible* or a *potential* bends hit on air. In other words, there is less of a likely chance of getting a bends hit on mix than air using the same profile, so in that regard it's a fair statement to say Nitrox is safer;
2) Many diver's run out of available bottom time before they run out of air. By using elevated levels of F02 you can extend your bottom times;
3) Many diver's don't want to SIT out as long as air tables provide for and Nitrox allows for shorter SITS;
4) Many diver's experience a much clearer head when on Nitrox, the equivalent air benefits should not be understated, particulalry in the 100' range.
So what I don't understand about your point of view is that because the Yukon can be done safely on air, it seems to me that you are saying that diver's should ignore a potentially * SAFER* way to dive it, bearing in mind that the hypothetical dive cited above could be done on one day by one diver and not result in a hit, but the exact same profile may result in a hit to a different diver.. The simple fact that a cushion is built in by definition makes it safer. As we agreed, there are other factors involved ( ie; cold, phyical fitness, PFO's, obesity, how hard a diver is working to name a few)
Now, I have also heard you say that a diver saturating a tissue group on air is just as saturated as a diver that saturates a tissue group on Nitrox.. I agree with you, the M-value is what it is but the difference, of course, is what was involved in getting your there ( ie; the amount of time at depth ).
But just so you understand my position clearly, I have never stated that the Nitrox models are set in stone, nor do I remember anyone else using that line of reasoning. Perhaps the fact that the same algorithms and coefficients are used may have lead you to not recognize that what we are saying is that the only change in the equation is the level of F02 and the same variances exist air to Nitrox so since they are parallel it was presumed. What we are comparing is the after variance results, for lack of a better term.
So I guess concluding this go around the answer to your question is, yes the Yukon can be done safe on air, but it can also be done safer, or longer, or with less SIT time and with a clearer head on Nitrox, that's the fundamental disagreement and I'm not sure why I don't understand your position after all these years given a local example, taking OxTox out of the equation and going point by point about your concerns..
The marketing and legal arguements don't make much sense to me, clearly OxTox is a concern but it can be greatly mitigated on the Yukon, the Yukon isn't a dive outside our immediate diving geographics so I still am confused as to your opposition..
Later