The only section that I have had a problem with "so far" is the seating area on the starboard side, closest to the instrument panel, on our 2004 331. I was able to dig the loose black caulk away and I applied Get Rot, I beleive it is called, where the water would come out when I would put pressure on the wood. As I applied the Get Rot, which is very watery, I pushed down and released the wood seat to get the liquid to get under the seat. I did this quite a few times. Later, after it had plenty of time to cure, re-did the black caulk. I sanded the seats and applied the Tropical Sealer that I use. I did this in the spring, so far so good.
www.bumsrest331.blogspot.com Camper pics come up first, but our last trip South in our B 331 comes up later.