What exactly do you detect with these other than salt water?
You are testing for Ionized Sodium Chloride [NaCl]. Normally in Sea water. So if you are on fresh water, no use for a sailboat detection.
So if you find water in your boat, you can detect if it is from the sea.
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Procedure...
1) Dip some sea water and put a strip in it. The strip will show you the NaCl concentration. [Control point]
2) Test the water in bilge. Compare result against #1.
Now if #2 is much lower, but has some NaCl, it could be a rain water leak washing some deck crystalized NaCl.
You can flush your bilge with fresh water, then measure later to see if you have a sea water leak.
I use it to make sure engine oil has no water intrusion. Do same procedure but test new oil in #1.
Repeat test with Antifreeze.
It works.
No water, no NaCl ionization.
Jim...