Sounds like delamination
If the deck near the attachment points gives a dull sound when rapped with a rubber hammer, then the fiberglass has delaminated from its balsa core. This is not good, especially at a major stress point. It can be fixed, but it is a messy job, especially if the problem is widespread. If you really like the boat, have it surveyed by a professional. He can tell you how serious it appears, and whether its worth fixing.My surveyor found minor delamination on the deck of my boat before I bought it. He didn't think it was a big deal, and told me how to stop it from spreading. If your surveyor finds delamination, you can use the information to renegotiate the price.