Moisture meters ca be fooled. There are also layups that can wick water
Wicking: our 1984 Camper Nicholson was laid up with the greatest new stuff of the day. Solid glass below water, cored above to the toe rail. Decks cored between teak beams. Teak deck
. Added to this, two layers of Kevlar below water and one above.
It happens that Kevlar of the day wicks water. The smallest flaw would let water into the layup
where it would travel, accumulate and delaminate the outer 1/2 inch. It took weeks to chase these down, grind and repair. The rudder
was a total loss.
Teak: you can’t measure moisture in the deck through teak. In fact, fiberglass
deck moisture (in the core) cannot be measured with any assurity through non-skid. The fillers retain water and will give a false reading. Your best, most accurate reading will be from inside. I pinpointed my wet deck cores with the headliner
removed. Deck measurements were way wrong.
If you remove teak, you must remove all of the screws, fill and fair all of the holes, apply a fiberglass scrim over all of the deck that covers the former screw holes. Only then can you apply the new finish and non skid. If you strip away a teak deck
and screws you can measure the core moisture.