No, this meter will only provide you with a % of moisture content for wood and building material. It will not provide you with humidity readings.
#3 Need to check moisture in wood-cored fiberglass boat deck. Will it work?
The pins must physically penetrate the material being tested. If you managed to jam them through the boat deck far enough to be testing the wood, you will have created real holes in the fiberglass, so the deck won't be waterproof any more.