Make water salinity editable

[Dirk Hohndel]

> On May 17, 2019, at 9:17 AM, Willem Ferguson <willemferguson at zoology.up.ac.za> wrote:
> 
> On 2019/05/17 16:52, Dirk Hohndel wrote:
>> I recall many, many threads on this mailing list that point out that editing salinity isn't really useful.
>> At least when diving with a dive computer you are almost CERTAIN to make things worse by doing so. Your dive computer records pressure, not depth.
>> 
>> I won't try to rehash all of these discussions here, just point out that I wonder if this is a good direction to go.
>> 
>> /D
> 
> 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