On 12.11.2014, at 23:33, Anton Lundin <[email protected]> wrote: Anton,
> Depth is often mentioned in a length unit, but what we care about is
> pressure. When diving in fresh water the pressure is lower than the same
> depth in salt water. This adds support for using different salinities in
> planning.
of course I agree that the relation between depth and ambient pressure depends
on the density of water and thus on the salinity.
Of course, I don’t know about you, but I myself don’t take a yard stick to the
water but rather used depth gauges (e.g. my dive computer) that pretend to
measure depth but in reality measure ambient pressure (and don’t take into
account the salinity). So what we call “depth” in diving is, most of the time,
actually not really depth but “effective depth” being the pressure equivalent
depth assuming some standard diving liquid.
What I am trying to say is: It’s true that it is an error of not taking it into
account, but when running a deco schedule against a depth gauge do do this
error twice in opposite directions and thus it cancels out. Your patch
eliminates this error once, but strictly speaking, the resulting deco profiles
should then be measured with a yard strick rather than a pressure based depth
gauge, otherwise they are wrong (although probably only by a tiny amount that
does not really make a difference). But then the error in the first place was
probably not significant. But as a plus, it makes the user believe we take
everything into account… ;-)
Best
Robert
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Robert C. Helling Elite Master Course Theoretical and Mathematical Physics
Scientific Coordinator
Ludwig Maximilians Universitaet Muenchen, Dept. Physik
Phone: +49 89 2180-4523 Theresienstr. 39, rm. B339
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