: Here is another photo of the problem
I've got the same thing on a couple of my boats. It won't get any worse, but it sure is ugly. The problem starts when the epoxy fill coats are not thick enough. Then the glass is sanded into and varnish applied. As the varnish gets baked in the sun, the glass becomes exposed. I would not put any varnish over the spots. It may affect the epoxy repair later. I am going to sand the varnish off and re-apply epoxy. I am not going to replace the glass. I am not convinced that the structural integrity is compromised enough to warrant that much work and expence! Hope that helps! :) Roger