Don't know how the mounts on your boat are fastened. I had a similar problem with a 1986 Hunter. The engine bed was wood and the mounts were held by lag bolts. My repair was to remove the bolt, drilled out the hole to the size of a hard wood dowl . Loaded up the hole with epoxy and pounded the dowl into the hole. Let it cure completely and and screwed the lag bolt back. Worked great.