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Jess, to make it easy, use this shortcut: compare tables on the dive you are
doing ( I do not know your gasses). Notice the relationship between the stops
and between the bottom times - you will see that, like most decay curves , the
points , or stops , are related very much like a Fibonnacci sequence. Take the
relationship of your bottom time to your 20 foot stop - this will depend on
depth and intermediate gases ( if you are using 130 aed and 1.4 ppo2, with 1.6
max ppo2 for each deco switch ) and use that ratio to determine your 20 foot
stop. You then take the next Fib number up for your ten foot stop and reverse
the sequence from 20 feet for the other stops. At 1, do that for the next four
stops. This is a riot , as it looks like a Bulmann model with deep stops.
Or, since you will have lots of time on your hands, do the rough
approximations of the calculations - see Decompression, Decompression Sickness,
and translate it from the German, or just look at the formulas (they are in
math).
When I went to Central Florida to take my cave divin', the goobers taught
me
this, including the German and the math.
Here is an example of a Wakulla dive : 285 for 60 (air form 190, 35 from
120, 50 from 70 , and oxy from 20. 14X47 bottom mix:
60 bottom time equates to about 55 at 20, so the ten foot stop is 89
minutes. The 30 is therefor 34, the 40 is 21, the 50 is 13, the 60 is 8, the 70
is 5, the 80 is 3, the 90 is 2, the 100 is 1, 110 for 1, 120 for 1, 130 for 1.
I
would then pad them to what I know is correct, which is to pick up the air at
190 at start breathing that up in one minute increments to the 120 stop, where
I
wold spend a few minutes before resuming. I would also do all of the 10 and 20
at 20, or all three at 30 if there is a way to get out of the water.
At any rate, you can take this sequence and pad it up after finding the
basic numbers, and it will be so close to the actual calculation that you may
never need tables again., or at least not be worrying about overstaying your
bottom time, or understaying it. You just have to know what the basic deco
looks like for different depths and mixes, or what you like to do for deco.
If I know that an hour at 300 is basicly a five hour deco, I can also
work out a schedule. In our case, as we approach the flat part of the ongassing
curve, incremental additions to bottom time no longer translate into equal
chunks of addditional deco, but bvery little more at all, and almost no change
in the oxygen portion.
Where you must be accurate to a degree is where you go from dives that
really require no deco, like 300 for 10 minutes, to dives that mandate it, like
300 for 27 minutes , for example. There is a huge difference between 300 for
15-18 minutes and 300 for 22-30 minutes. From 30 to 60 is pretty linear, and
then above that it shrinks progressively per bottom time increment.
I have done every bottom time in this range repeatedly, and am sure of
these facts in practice. It is amazing what the human body can tolerate. Deco
is
your friend if you shape it right, it will hurt you if do not. If you do too
much, you are hurting yourself. If you need to do too much, don't dive.
George M. Irvine III
DIR WKPP
1400 SE 11 ST Ft Lauderdale, FL 33316
954-493-6655 FAX 6698
Email gmiiii@in*.co*
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