Posted by RaiderKarl on March 17, 2001 at 20:48:10:
My Suunto Vyper dive computer, state of the art in Europe currently, with its Nikkola SME algorithm, which is about 10% more conservative than the PADI RDP tables and DSAT, does not give decomp credit for anything less than 20 feet.
I executed my deepest dive in my life today, the fourth really deep dive that I have ever done, and when I reached my own personal maximum allowable depth limit, which I discovered today, I began a slow egression after a very sharp J turn, first to one half of the deepest depth achieved, where my friends were waiting for me to rejoin them, although our group leader had maintained visual contact with me the whole time throughout my dive, although he didnt proceed with me to my depth. He is a great dive leader, and probably the most experienced diver in our dive club. His certifications are NAUI, PADI, and TDI.
I then continued to hang out at that depth with my friends, and they did their recreational diving thing there, which was a deep dive for them as well. Then after a few minutes at that depth with them, I slowly headed back up to 30 feet, my first preplanned U.S. Navy / NOAA decomp stop, and remained there for my pre-planned 3 minute stop.
Then I signaled to our group leader that I had 1000 psi remaining in my 120 cu ft tank, and he waved me back home, so I signaled OK and waved goodbye, and headed up to 20 feet for my second decomp stop of 5 minutes, where I hung onto the kelp to deal with the mild surge. It was here at 20 feet that my dive computer first started giving me decomp credit. It didnt even begin to give me decomp credit at the 30 foot stop, to say nothing of the first deep stop.
Finally I egressed to 10 feet, creeping up to it slowly from below because of the strong surge at this level, holding onto the kelp, and spent the remainder of the dive computer's own calculated stop there, which was more than sufficient for the Navy/NOAA tables.
Visibility today at the Deep Monterey Trench off Monastery Beach in Carmel, Northern California was over 50 feet, and the temperature at depth which normally runs around 54 degrees F was instead 48 degrees F, meaning that this was one of those much hoped for up-wellings that brings crystal clear blue water up with it from the pelagic deep.
When you reach your own personal depth limit, you know it. It must be unique for everyone, because mine was significantly less than I imagined it would be, and I exercise, and jog, and gave up drinking any alcohol months ago and I dont smoke. But I could not have gone a single foot deeper, nor stay at that depth a single minute longer, before the basketball sized white tunnel that was surrounded by the jet black wall would have closed in all the way.
Thats what it is like. Dont try this at home.
I now completely agree with Mike about using the right gasses besides air to make a really deep dive. Definitely take all or most of the nitrogen out. Throughout this all, my ScubaPro S600 and Mark 20 reg system performed flawlessly, and I didnt even have to engage the forced assist feature, I just kept the available air knob turned open all the way.
Right now, I am guzzling apple juice by the jug as I try to rehydrate from a really fantastic dive.
See you laterrrrrrrrrrrrr**************............. !!!
/s/ RaiderKarl
[i raid things of value from the Ocean floor]