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> 
> Rodney
> there is a quiet a difference in the o2 clock at 30 feet on EAN 80 po 2 
> of 1.53 in sea water at 30 feet ( the tables actually call for on the 
> accelerated tables EAN 75 and on the run time tables for air and EANx 
> EAN 78, the trimix tables call for EAN 75 also). As you know o2 at 
> exactly 20 feet/6meters is 1.61 ata and it runs the clock up fast. At 
> the same time their is very little difference in the runtime of a dive.

Tom I'm not aware of the current IANTD tables. They look
complex with ntx 80 being recommended, then 75, and 78!?.
I think the root of the problem is the use of the NOAA
system for "tracking" 02, and a general lack of knowledge 
in the tech diving populace of "before tech".

> 
> I agree we could make tables that started using 02 at a more shallow 
> depth 5 meters would work well and it would simply mean a slight 
> adjustment on the 9 meter stop so that it would become a fraction 
> longer.

That's right, but I would not bother with that.
I use 02 at 20ft, and am careful how I use it.
> 
> Perhaps in the future we will look at that. For the time being we are 
> quiet happy with the tables we are using and the deco clock is 
> considerably lower than when using 02. you have deco soft ware so I 
> suggest you run some comparisions.
> Tom

No-one can argue with keeping the 02 clock in
check for the working part of the dive, and
the NOAA tables work well if you stay
at a max of 1.4.

There is no bias in the NOAA tables for
"resting" deco, and this is obviously at
odds with reality. Personally, when using 02
I ignore the CNS clock, and always take air/
bottom mix breaks. 

You, I and countless others have run the CNS
clock out past 1000% on deep air dives, and 
decoed on 02, without problems, using air breaks.
If this is possible, one could logically question
the applicability of CNS clocks to resting deco,
and whether air breaks play a more important
role in 02 safety, along with constant vigilance.

Rod.

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