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guage depth calibration

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Well-Known Member
Jan 21, 2003
OK all you technical types, here is a odd ball question.

Is there a standard depth calibration for depth guages? Are they calibrated to read accurately in fresh water, sea water, something else, or is it whatever each manufacturer decides?

My reference book says seawater is 3.5 percent heavier than pure water, previous threads reference 2.5 per cent. Either way, a guage calibrated for sea water will read 100 ft at 100 ft in the ocean. If you were in fresh water and that guage read 100 ft, you would really be in 103 ft. Since this affects a pb, I'm real interested.

Thanks for your help

There all different.

I have done dives while using two different gauges and they were off 6' at depth. I first thought that one was broken, but then realized that one was calibrated salt water and the other was calibrated freshwater.

I believe that companies like Uwatec calibrate in feet freshwater, while ohter companies, like Sunnto, calibrate in feet salt water.

It should be written in the manual that comes with the gauge.

Last edited:
Thanks Jon,

I guess I'm not surprized, but it seems like this would be a real problem for deep decompression dives. If I ever switch guages, calibrating new to old is on the list.

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