Buoyancy Foam - how do I know if mine is waterlogged?

[catfighter]

Check out a picture of my boat below in my signature.

The three benches are treated wood, covered with fiberglass and filled with buoyancy foam. My question is how can I determine if my foam is still good (or should I just assume that it isn't?)

Also, what is the best means of replacing the foam if I wanted to? I would assume cut the top off of each bench, dig out the foam, reconnect the wood and re-fiberglass, but that seems like a huge ordeal.


Let me know what you guys think.

Thanks!