Logging CCR dives

Davide DB dbdavide at gmail.com
Mon May 8 08:59:15 PDT 2017


Having just consumption in liter in stat tab also for oxygen would be
greatly appreciated.

May I give some suggestion on how fill those equipment fields?

Il 08 mag 2017 17:24, "Robert Helling" <helling at atdotde.de> ha scritto:

> Davide,
>
> On 8. May 2017, at 17:15, Davide DB <dbdavide at gmail.com> wrote:
>
> I've logged the first few CCR dives with a Shearwater Petrel and a SF2
> unit.
> I discovered that most fields get filled by data coming form the
> Petrel and some doubt arose on how to correctly log these dives.
> Basically I find the equipment tab filled with my default cylinder (3
> liter) and the CC gas set on my Petrel. i.e 3L 18/45 and a column
> called "use" with the value "OC Gas".
> I can only change it with "no use". What does it mean?
> I would expect "CC use". It's my diluent. Of course in my Petrel I
> have the same mix set as bailout gas but I guess it isn't.
> Moreover for each dive I have to add another cylinder to record my
> Oxygen tank setting initial and final pressure.
> Once I go in the stats tab I find gas calculation only for the 18/45
> mix, no trace for the oxygen consumption.
> Why I do not find any data for the Oxygen? Would it be very useful add
> these tanks by default. I don't know CCR units without a Oxygen tank
> and actually Oxygen consumption is the most important parameter. Isn't
> it?
> If I understand correctly the logic behind I guess I should add my
> bailout tanks marking them as "no use".
>
> If someone is already using Subsurface proficiently with CCR logs
> could you give me some hints?
>
>
> as was recently discussed on github “OC gas” is a misnomer, the text
> should be changed to “gas used”.
>
> To be honest, Subsurface currently does not really do any reasonable gas
> calculations for CCR dives. As always, it only considers gas used if it is
> ever switched to and has the implicit assumption that at any moment in
> time, the diver is only breathing a single gas. Both is of course wrong for
> CCR dives. Apart from displaying the initial and final pressures of the
> cylinders anything more advanced is really hard to do (like interpolating
> pressures for example). For oxygen in CCR dives, I would only make a linear
> in time interpolation (independent of depth) while predicting diluent use
> as a function of the depth profile is really hard to do right.
>
> Best
> Robert
>
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> Physics
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