The trunk is constantly being pushed around by the centerboard
, Bracing the trunk over to the sides berths might be an option but would make getting around the cabin
Maybe some of the other 'Potters' online would have better ideas. Have you fielded the question to any Potter groups? Here is the one from Trailer
will need to be down to the laminate, not on top of paint
or gel coat. I would spring for industry-grade materials versus box store stuff. The repair may need to be treated like a cavity, where failed material is removed and replaced, versus a topical application with a still-weakened panel or corner underneath. As you mentioned, the flexing issues will need to be addressed to solve the issue once and for all.
The Don Casey 'Complete Sailboat Manual' has about 10 pages with sketches, in my copy it's about page 200. Finding a video or two at 'Boatworks Today' or the like might be more direct.
Your friend's cycling journey to work
on your boat