[hiccup]

First, I think every Tiara owner (or any cored boat) should own and understand how to use a moisture meter.  I think it is prudent to use it on a regular basis to identify moisture before it becomes a problem...maybe in the spring and again in the fall...or something like that.  It sounds like you're aligned w/that thinking.

With all that said, I've found you do have to be careful with them and never believe the meter over your lying eyes.  I had moisture showing around my portlights w/the meter.  But now that I have removed them I can see that the coring is A-OK.  The meter appears to be picking up moisture in the foam on the interior of the boat.  The portlights had been leaking through the gasket and it had been dripping down into the foam.  Also the meter will spike when close to metal, so you cannot expect meaningful readings too close to the portlight frames.  However, just because the meter is not accurate around metal does not mean it is useless.  I have put my meter on many Tiaras and other cored boats.  Many of them show coring saturation well away from any metal etc.  This is what you're trying to catch early.

My approach is to re-bed anything questionable and confirm the condition of the core when doing so.  Once everything is back together use the meter to establish baseline readings around the boat.  Then when doing periodic checks compare readings not to the absolute scale but to your baselines, and recognize that you just cannot use the meter in all locations (e.g. right up close to metal).  The known trouble spots are where water can pool around core penetrations--anchor locker drain, air intake/flower box drains, windlass area w/flat horizontal sections, etc.

If you're getting high readings immediately following a rain storm, and then it dries up, that does not sound like moisture in the coring--it takes a long time for water to travel through end-grain balsa--years.  That sounds more like you have surface moisture from the rainfall (which most meters will trigger on) or water running down into the cosmetic foam or against an interior wall.