deco calculations

Dirk Hohndel dirk at
Fri Jan 4 16:14:09 PST 2013

Jan Schubert <Jan.Schubert at> writes:
> Shouldn't be that tricky to switch to CC, in fact it should make life
> even easier as the pO2 is constant - OK not really flat on computer with
> integrated cell readings.

That's already in place. As long as the pO2 in the samples is correct
things should work correctly. I believe this should be the case for the
Shearwater and the OSTC.

>> I have some issues with this (as noted in the commit messages). My
>> biggest concern is that apparently changing the GFlow and GFhigh values
>> has no impact on the deco curve whatsoever. And that is a huge red flag
>> to me...
> In my dives overlay using mot current subsurface I can see clearly
> differences when changing GF settings but only in the calculated deco
> depth, not the duration!

Yes, you tested a later version - but may not have read the announcement
as I mentioned there that I took a first stab at CC support.

> Some notes:
> - seems there is a fixed last stop at 3m implemented as of now, in the
> long run this should be configurable as some people believe 6m is better
> (not me) and personaly I'd also like to have to opportunity to switch
> this last stop of or change to 2m or even 1m - just to play around and
> see what the difference is on dives with 6 hours of deco.

Currently all it does is calculate your actual ceiling (and optionally
break this down into 3m "decostops".

Once I push out the planning skeleton you'll be able to pick whatever
first and last depth you like. You'll be able to do stops at 14m, 11m
and 4m, if that's what makes you happy :-)

> - looking at the outcome of your calculations compared to my real ones
> done at CC I get the impression the calculation is to optimistic (maybe
> there is a wrong gas used for calculations?) and especially the deco
> duration in total seems to be to short, but I'll have a look to this in
> more detail

Yes, I really would like to get more comparisons in. When I compare the
data with my dive computers on the few deco dives that I have I can see
that the Uemis with my settings roughly maps GF 25/80 (except that the
Uemis also does deep stops).

> Thx a lot, this is really exciting news!

I though you might like it. I hope others do, too :-)


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