[Tiny]

I've seen several where, from over many years of impacting the trailer when loading or beaching the boat the keel is worn straight through to the keelson (the wood). Likely if this is the case, all the wood is rotten, not really a big deal as there is heavy glass over it. The repair is a pretty easy one, grind back (from the outside) to good glass, and re-glass.

Be sure to check in front and behind your trouble areas...for other thin areas.