Mysterious disappearing gelcoat stains

[Quint4]

On rainy days there are several spots of gelcoat discoloration on my top deck. On sunny days it is nearly invisible unless you look hard for it.

Old damage repair?......or maybe factory hull mold defect?

 

[Fred]

I had a new car once that had the same problem on the hood only. At first the discoloration disappeared in the sun but not after some time.
A re paint cured the problem.