Graph documentation [was: Re: Meaning of GF settings]

Pierre-Yves Chibon pingou at
Tue Jan 8 12:35:08 PST 2013

On Tue, 2013-01-08 at 21:14 +0100, Jan Schubert wrote:
> On 01/08/13 21:01, Linus Torvalds wrote:
> > On Tue, Jan 8, 2013 at 11:49 AM, Pierre-Yves Chibon <pingou at> wrote:
> >> Attached are the two first dives I did with my computer, the first dives
> >> of the trip as well.
> >> We did have a deco stop during the second dive (#9) but we 'only' did
> >> the safety stop 3min/3m during the first dive (#8)
> > Ok, that doesn't look horrible, and I think it's just a result of the
> > default parameters set to "somewhat conservative"
> I agree saying that it does not look that unhealthy. And there might (!)
> still be some unwanted features in the code as all of my dives using the
> dive computer generated deco also ends before the ceiling calculated by
> subsurface.

Attached is the whole trip, the dive #11 was more surprising for me. As
my computer was being so conservative the divemaster pretty much decided
to ignore it (at his discharge, mine was giving me 11min of deco while
his was still at deco - 2 min). Good thing it was the last dive of the
trip and I had planned 48h before flying back.
(again beginner inside, I followed the divemaster, maybe I shouldn't

I was actually surprise not to see the last /!\ turning red or a warning
being printed that I should not dive for at least 24h (if current
date/time < dive date/time + 24h). That might be an interesting feature
to add.

> >
> >> I used the default parameters btw (GFlow 30 and GFhigh 75).
> > If those are more conservative than even a suunto, I suspect we should
> > make them less so for the default "show" to not make people worry.
> >
> > Then, for dive *planning* we should probably default to something very
> > conservative indeed. I dunno.
> I wouldn't do so (now) but just wait what happens to the deco
> calculations in the next days when we get more knowledge about the
> missmatchings.
> Just a note: Suunto is not using Bühlmann and GF settings at all but
> RGBM which has a little different approach and might (!) allow divers
> surface earlier than Bühlmann in case it thinks there are no
> (mentionable) bubbles in your tissues. There are dive computers around
> which implements VPM backed up with a Bühlmann GF High of 95% to avoid
> such occurences and to be really sure from both worlds.

>From what I can see in the pdf of the documentation of the DC, it uses
RGBM with 9 compartments. O2 and nitrox exposition (?) are based on the
work from R.W. Hamilton.

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