Bullcrap. That's all the comment this moronic statement deserves.
MD
equipment configuration
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Bullcrap. That's all the comment this moronic statement deserves.
MD
That's a good SAC for coldwater SJ. When I was actively DM'ing in the tropics, my SAC was .35
Still, your reasoning is accurate and anyone who would contemplate a 200' deco dive on a single 80 is nuts.
MD
SeaJay
Contributor
Wow... That's impressive. I've hit .4 a couple of times, but my normal "working" dive is usually between .5 and .55. If I'm working hard, I might get into the .6's. My "relax and drift" dives are usually as low as .45... But .35 is awesome.
...But don't you plan for .7? When I do my planning I do it for .7 unless I know for sure that it's going to be a really, really relaxing dive... In which case I plan at .6 or even .55.
Anyone that would contemplate a 200' dive on air is nuts. But hey, that's just an opinion I guess.I don't think the dive profile that he mentioned is even possible. In fact, according to my calculations, a four minute descent, sixteen minute bottom time (for a total of 20 mins, just in case that's what he meant), 30 fpm ascent to ceiling, and then proper deco would take 96.3 cuft of air, even if he had a SAC of .35. Of course, if the diver were to switch to a deco bottle at depth, then it might be possible, but not a good idea for a variety of reasons.
...And of course, that's assuming a SAC of .35 - and that his buddy never has an OOA, and never needs any gas himself...
To imply that tourists regularly made this kind of dive is ridiculous. He must be mistaken or leaving out some vital info.
I have VPlanner set for .75 for dive and .45 for deco. Actual gas usage indicates both are somewhat high, but that is as is should be.
I agree deep dives on air are not highly intelligent. The statements were already at a level of stupidity such that I didn't think it necessary to add to them
MD
SeaJay
Contributor
Lol...
Yep, we're on the same page... Vplanner here too. I did the first set of calcs with just a calculator (I wasn't at my own computer, where Vplanner was) but the last set of calcs was Vplanner.
Even if you did have enough gas... 200' on air... Aside from the narc issue (which could easily kill), the PPO2 issue is pretty serious, too. I don't remember offhand what MOD is for 21%, but I seem to remember that it was something like 212 feet... NOAA tells us that you shouldn't exceed a PPO2 of 1.4, but that 1.6 is "doable." I seem to remember that a PPO2 of 1.4 on 21% was something like 186 feet... The point being that 200' on air would be dangerously close to severly high PPO2's.
...And in case this is Greek to someone out there, that means that someone diving 200' on air is dangerously close to underwater convulsions called "oxygen toxicity," or "OxTox." When I say "convulsions," we're talking about the major seizure kind - the sort that if you have, you can't keep the reg in your mouth... You swallow your tounge... Eyes roll back... You go unconscious... You know, those sort of convulsions.
Of course, you'll be too narced to know that you're convulsing - and too narced to care that you're about to drown...
Of course, it doesn't matter anyway because this diver wouldn't have enough gas to make it back to the surface anyway.
Yep, we're on the same page... Vplanner here too. I did the first set of calcs with just a calculator (I wasn't at my own computer, where Vplanner was) but the last set of calcs was Vplanner.
Even if you did have enough gas... 200' on air... Aside from the narc issue (which could easily kill), the PPO2 issue is pretty serious, too. I don't remember offhand what MOD is for 21%, but I seem to remember that it was something like 212 feet... NOAA tells us that you shouldn't exceed a PPO2 of 1.4, but that 1.6 is "doable." I seem to remember that a PPO2 of 1.4 on 21% was something like 186 feet... The point being that 200' on air would be dangerously close to severly high PPO2's.
...And in case this is Greek to someone out there, that means that someone diving 200' on air is dangerously close to underwater convulsions called "oxygen toxicity," or "OxTox." When I say "convulsions," we're talking about the major seizure kind - the sort that if you have, you can't keep the reg in your mouth... You swallow your tounge... Eyes roll back... You go unconscious... You know, those sort of convulsions.
Of course, you'll be too narced to know that you're convulsing - and too narced to care that you're about to drown...
Of course, it doesn't matter anyway because this diver wouldn't have enough gas to make it back to the surface anyway.
Not true.
While I don't recommend any one go to 200 on air it was only a few years ago when no one was using helium and this was done every day. I know divers who have done accurate cave surveys way deeper than 200 ft on air. Some of those divers still think helium is a wast of money unless they're going below 200 ft. I don't agree but it's hard to tell them it can't be done when they've been doing it for so long.
In my own training we did 170 ft on air. I didn't know any better at the time and did what the the instructor required. I won't say that I wasn't narced but I sure would have known if I was convulsing.
SeaJay
Contributor
I think Hal Watts is selling a "Deep Air" course that's like 270' on air...
But your PPO2 is definitely above recommended limits at that sort of depth... And the narcosis is surely there, even if you're able to deal with it ("tolerance").
...So I don't mean to imply that 200' on air = "you're dead," but the risk is definitely raised through the roof.
After having done deep air, wouldn't you agree?
But your PPO2 is definitely above recommended limits at that sort of depth... And the narcosis is surely there, even if you're able to deal with it ("tolerance").
...So I don't mean to imply that 200' on air = "you're dead," but the risk is definitely raised through the roof.
After having done deep air, wouldn't you agree?
Narcosis is real and it increases risk. I use a lot of helium even at fairly shallow depths. Partially for safety but the main reason is because it makes the dive so much more enjoyable.
While Hal Watts has or has helg deep air records and currently trains divers in deep air he does not argue the fact that narcosis is a problem. I never had any interest in those classes or doing what he does but he is one interesting guy to talk to.
I asked Mr. Watts about oxtox concerns. His response was that they're bounce dives and he keeps his work load very small and hi breathing under control. At the depths that he's gone on air I think that even the slightest CO2 build up would be a disaster.
I wouldn't do it.
BTW, his standard courses I believe only go to 240 ft. I think that's because that's where the grotto bottoms out.
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