On 2019/05/17 19:07, Dirk Hohndel wrote:
Hallo Dirk,
Allow me to ask a few questions. 1) If I am in a situation where salinity is
not recorded by the dc, would it be pointless to edit the salinity, even if
editing was restricted to cases where the dc has no salinity value? Jef assures
me some dive computers do not report salinity. 2) If it is pointless, why does
Subsurface bother to implement salinity in both the dive computer as well as in
the dive structures?
Most of the discussion I am aware of revolved around dive planning, not on
logging a dive after the fact.
So let's say your computer doesn't record salinity. Then how did it translate
pressure to depth? Freshwater? Saltwater? Somewhat in between?
And what do you wish to accomplish by editing that value? Adjust the displayed
depth?
The best part of all this is that (outside rare circumstances) the salinity of
the water you dive in isn't constant.
In most cases, the measuring error of the sensor and the effect of surface
waves will have a higher impact than the adjustment of the salinity.
The relative position of your dive computer (on your wrist, maybe) to the core
of your body will have a bigger impact.
Etc.
This is false precision.
But I'm not sure that me arguing for this will make any difference. Linus and
others have written pages and pages about this.
/D
Hallo Dirk,
The log unfortunately does not record the pressure encountered on a
dive. It gives *depth* versus time, not pressure versus time. I
understand totally that the dc user pressure to implement its deco
algorithm, not depth. But this pressure is not presented to the user in
the dive log. In order to reconstruct the pressures we need information
about depth as well as several other smaller factors, e.g. altitude and
salinity. Without reasonable pressure data Robert's fancy ceiling
calculations are worth much less.
Secondly, I do not know of a single training agency (and I am involved
with three of them as well as DAN) that encourages its trainees to
neglect water type. We do a lot of altitude diving around here and
accurate pressure determination is a serious thing for us. Seeing that
diving is a potentially risky activity, the safest way to deal with this
is possibly to let the diver decide which approach to take, not to
enforce any one of several points of view.
I respect your point of view. I really do. The question is how do we
deal with this in a way that makes Subsurface easy to use and to broaden
its user base in a way that is consistent with current diver training.
My apologies if I appear hard-arsed or inflexible. My whole life I have
been trained to question, so discussion about an incongruence is natural.
Warm greetings from my side,
willem
--
This message and attachments are subject to a disclaimer.
Please refer to
http://upnet.up.ac.za/services/it/documentation/docs/004167.pdf
<http://upnet.up.ac.za/services/it/documentation/docs/004167.pdf> for
full
details.
_______________________________________________
subsurface mailing list
[email protected]
http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
