dealing with unused tanks

Jan Schubert Jan.Schubert at GMX.li
Fri Dec 28 14:21:09 PST 2012


On 12/28/12 15:14, Dirk Hohndel wrote:
> Jef Driesen <jefdriesen at telenet.be> writes:
>
>> But even if a gas mix is marked active, it's not necessary used (as in switched 
>> to that gas) during the dive. That can be because the device always stores the 
>> full set of gas mixes, regardless of whether they are actually used or not (this 
>> is very common and almost all devices work like this), or it might be that the 
>> diver carried a tank with that gas, but never switched to it. The problem is 
>> that we can't tell the difference between those two cases. If we decide to only 
>> report mixes that are really used during the dive (because there are gas 
>> switches for it), then that works well for the first case, but not the second 
>> case. In the second case the unused gas mix would get dropped. The question is 
>> now whether this is acceptable or not? If I'm not mistaken, this is exactly the 
>> issue Dirk wanted to raise too (@Dirk: correct me if I'm wrong on this).
> Absolutely correct.
>
> My logic here is that this will be correct for the vast majority of
> cases; I would bet that there are a thousand times more recreational
> divers that have a computer that reports gases that they may have
> configured when playing around with their computer, or that may even be
> configured by default, but who will never ever dive with more tank, than
> there are tec divers who carry an extra stage tank that for some reason
> they never switch to. This of course doesn't take CCR divers into
> account (who bring bail out tanks to every dive and hope never to have
> to switch to those except for training purposes). But again, the ratio
> of recreational divers to CCR divers is quite huge...

>From a technical divers view (I'm representing the CCR community in
here) my whishful thinking would be to see all gases defined and marked
as active in my computer regardles if they are used or not. As of now -
as Dirk and Jef stated - there are also gases reportet which has been
marked inactive. This makes things difficult as at least in OSTC it
seems to be a bug in the firmware itself and there seems to be no other
way right now. However, ldc and subsurface should be able to handle this
situation for computeres reporting the gases correctly.
Use case: I usualy carry a helium rich backgas and in addition several
bailout stages which never got used in the last 250 dives (except from
training/excercising which resulted also in switching to theses OC gases
in the computer). Checking my profiles afterwards, it would be really
helpful to see which bailout I had with me.

>
>> I believe this isn't a major problem, because I assume the gas mixes that are 
>> actually used during the dive are the most important ones.
> I completely agree. So this is the direction I think I want to go with
> that...

I agree also, but if we get the "unused" gases reportet also I would
like to see them also in subsurface. No problem if they are marked as
unused and displayed "somewhere else". And for the time beeing we could
handle "inactive marked" gases the same way until we are able to
distinguish between gases markes active and inactive. From my point of
view, there is no need to save/show gases marked inactive and never used
in the dive once we know this.

Jef, what is the status for the Predator in here? Right now I also see
all gases - are the inactive ones marked in some way in the Shearwater
protocol?

Thx,
Jan


More information about the subsurface mailing list