These are the things I came here to find out. I am pretty new to boats. I am not saying I have or dont have rot but I m on the fence about it. Boat floor is original and solid with no rot or anything. But at the same time I am like the boat is 29 years old so there as to be some type of rot if that makes sense.
I know this wont tell me rot but can i cut access hole in the floor and drive a pipe to the bottom to get a sample of the foam at the bottom to see if its soaked ?
That would tell you if the foam had water in that one spot, yes. When I was pulling foam out of my boat, one side was pretty wet, the other had some wet areas and some that seemed pretty dry. If I had spot checked into one of the dry spots, I would have missed a lot of wet foam...
Unfortunately, the only real way to know if the structure is sound is to core sample. The appearance of the fiberglass, or the sound it makes when you tap it, don't really tell you much.
Have you core sampled the transom (from the inside)? You also might search the Restoration forum here for other threads on Sundowner 225s to get an idea of where you might be able to access the stringers for a sample.