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The default setting is 1, should it be changed for seawater dives?
If so what would it be for say diving around the UK and then Eygpt

I'd choose 1.03kg/l for the North Sea:

http://www.mumm.ac.be/EN/NorthSea/facts.php

And I'd increase it to 1.04kg/l for the Mediterranean Sea:

http://www.britannica.com/facts/5/408372/salinity-as-discussed-in-Mediterranean-Sea

If you click on the map on the following link, you'll get the salinity everywhere in the world.

http://en.wikipedia.org/wiki/Salinity

I'm starting to doubt about what I previously wrote. It seems that the units represented both in the map that Mornemont pointed out and my links are related to parts per million, or miligrams per kilogram. Assuming that more or less one kilogram of fresh water takes 1 litre of volume, the most common measures would be of miligrams per litre.

OSTC asks for kilograms per litre, so I think there's something wrong with the decimals. For example take that you are going to dive in an ocean with a salinity of 35 ppm/psu. Translating that into kg/l (total weight of a litre of sea water), that would be 1.000035 kg/l.

What's wrong then?

The scale of the map is in grams of salt per kilogram of water, thus for a salinity of 35 (g/kg) (see this link for PSU definition), you have a density of 1kg/l + 35g/l = 1.035 kg/l.
What you said is right.

Mornemont Wrote:
-------------------------------------------------------
> The scale of the map is in grams of salt per
> kilogram of water, thus for a salinity of 35
> (g/kg) (see this link for PSU definition), you
> have a density of 1kg/l + 35g/l = 1.035 kg/l.
> What you said is right.


Ok then. Just one thing then. As we can see on the map, salinity throughout the Earth flutuates only from 31g/kg to 39g/kg. On the OSTC we only have the choice of 30g/kg (1.03) and 40g/kg. How does it affect to the depth measurements not being able to have the ability to input the data with more precision (specially with the more common 35g/kg salinity waters such as the Mediterranean sea)?

My OSTC is still on its way so I don't know yet the range of the settings.

Yet the error is maximum 0.5% if you round the salinity to dg/kg, thus about 1m every 200m. This sounds good enough, isn't it?

That should not be complicated to change in the code but maybe it's not so worthy.

Guy's a salinity of 35ppt or 35 PSU doesn't mean a density of 1035g/l, more like 1027 at typical sea temperatures.

Right, I made a mistake! PSU is not g/kg at all. I'll try to find a conversion.

Maybe then, for the sake of clarity, the salinity adjustment menu of the computer should present the options in PSU, as it seems that most places use those units.

Find an easy convertor (PPM->kg/m3) here:

http://www.csgnetwork.com/h2odenscalc.html

Still got to get a PPS to PPM converter... That seems to get very complicated.

Today I made a dive at Lake Como, I had the OST and the VR3, VR3 marked the 90 meters at 90 meters but 92 meters on the ostc.
I set the salinity on the ostc to 1.00 is adjusted for the lake??
Why this difference meters depth?? Is that right?
thanks oscar