espenskogen:Fair point, I guess I didn't want to say 'yes it can be done, but YOU can not do it, because I don't think you're skilled enough', and besides I've spent a lot of time discussing/doing this kind of dives (safely) so I suppose I might have gotten a bit too enthusiastic about the whole thing...
So for the record then - And this one is for you Chris, Mike and Steve - In the case of this diver we're talking about, then DON'T DO IT.
Certain divers with lots of experience and training can do sixty meters in safety. If you are not one of them, then stick to the limits of your training.
Thank you - Checking out
If you're refering to me, I didn't give much of an opinion one way or the other. There's just to much to consider to be discussed in a thread like this I think. In my own technical training I went the deep air rout. If there was another option at the time, I didn't know about it but I do know that there are other options now. I dived to 170 ft on air as a requirement/limit of the class and a few times after and I don't like it. I got through it ok and I think that I could do it again but it wasn't enough fun for me to want to do it again. I had one buddy go completely blank on me at about 165 and that was some one who, in theory, was qualified (at least according to the agencies that teach such things). I think 200 would totally suck on air and I just aint doing it. At 200 ft, I usually have at least 45% helium and usually more depending on the mas depth of the dive. I know other divers who have conducted cave surveys at 250 ft on air but I notice they don't do much of that anymore. While they are likely to be found diving deeper on air than I care to they don't seem to go out of their way to do it these days. Another friend of mine argues with me for years that no one needed helium above 200 ft until he started diving helium and now I don't think he leaves home without it. I've had the chance to discuss really deep diving on air with Hal Watts, who has held deep air records, and trained others who have or do hold records and I don't think that this dive, as outlined, would get his approval. I don't mean to speak for him but I remember what he said when I asked how one justifies or even survives some of the depths he has dived to on air. If you ever get the chance, ask him yourself, especially if you have an interest in deep air diving. He is definately worth hearing before you go off doing a dive like that.
I guess if I had to make a recommendation my first choice would be, don't do it. My second would be to suggest going to 40 fathom and spending some time with Mr. Watts because I think his is the only agency that goes that deep on air. The rest cut it off at 170 or so and beyond that you'll be on some helium mix. Don't get me wrong, for the most part, I don't think much of this certification bunk but it's still a good idea to take advantage of the experience of others. I don't think you'll find many reputable people who actually have air diving experience at 200 ft willing to take someone just so they can see what happens. At 40 fathom they've taken lots of people down the bonsi (sp?) line and I think they bring them all back for the most part. I guy who worked there once told me that they've never lost a diver. He said, it's just a little grotto and they're all just right down there...as he pointed. He offered another piece of wsdome that I found very insightful too. He said...don't pee in my grotto...I don't swim in your toilet so don't you pee in my grotto. I haven't swam in a toilet since and while I have peed in a few grottos, I always think of him when I do.