My new to me Rendova 5.1m (16') has the same cockpit deck over tank as all of them seem to have. It's held down by 14 2.5" wood screws and some of mine seem loose. I backed one out and there was some loose material - couldn't tell exactly what - on the threads. I THINK these go into some material inside the hull but I can't access this area. The drains on each side (at the stern, into the bilge) are dry.
Does anyone know the typical construction here? I'm hoping it's not encapsulated wood fore-aft members like stringers but having an idea would let me know if I should flood with CPES, overdrill, fill, and drill new holes.