I've been shopping around for moisture meters, and I know the Electrophysics CT33 (and its much higher priced American version) are sort of the standard for marine surveyor use. But I found this other one that have very similar specs (pinless design, penetration depth very similar) at much lower cost:
Highly Accurate Non-Invasive Digital Moisture Meter for Wood Lumber & Timber - General Tools & Instruments
It can be found at online discounters for around $63. Digital readout instead of analog. Also has a "hold" button which could be VERY useful for getting readings in places that are out of the line of sight.
Has anyone used this brand of meter? Obviously these things are mostly used by carpenters to get moisture in wood, so any brand (including Electrophysics) needs a conversion chart for fiberglass applications. But this one is about a third the cost of the other ones, and could potentially use the same chart found here
It seems to me that these tools are basically just upgraded stud-finders (just read US patent #4099118
, with quantitative readouts instead of LEDs. Also you need to set an absolute zero instead of zeroing it on hollow drywall like you do with a stud-finder. But this isn't rocket science - it should be easily done. And for about $60, its cost is peanuts in boat dollars.