Dive mode and dive computers

[Robert Helling]

Hi Berthold,

just a few quick comments:

> On 28. Jan 2019, at 00:00, Berthold Stoeger <bstoeger at mail.tuwien.ac.at> wrote:
> 
> I'm trying to make sense of the code in maintab.cpp. The way I read it, the
> dive-mode (Open circuit, CCR, pSCR, Freedive) can be edited per dive computer.
> I'm just wondering how that could ever make sense. I see how you can switch
> from open circuit to rebreather and vice-versa, but I don't get the connection
> with the dive computer(s). Shouldn't the mode rather be a function of time
> (there *are* dive mode change events, after all)? Are we talking about modes
> that the dive computer(s) are in, not of the dive itself?

As you mention, dive mode is now a time dependent property as there can be bailout (historically, it was per dive and bailout was indicated by setting po2 to 0), so the setting in the dive computer is only about the initial dive mode before the first event that changes it. Note that also events (and thus in particular dive mode changes) are per dive computer and not per dive. I agree that most of the time all computer should agree about the question of what you are breathing. But please note that in particular for planned dives the different “dive computers” are also our vehicle of storing different versions of the same dive (e.g. for bailout planning or comparing the actual dive with the original plan). And for those versions it can be that they differ in what they believe what the dive mode is at 42min into the dive.

> It gets even more curious when multiple dives are selected. Then the n-th dive
> computer of all these dives will have their mode edited. Is that correct?

I agree that this makes less and less sense. If anything, all dive modes should be changed (so a user can turn her last ten dives into CCR dives of which the dive computer wasn’t aware of as it was in gauge mode).

Does that make sense?

Best
RObert
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