This spring I have spent countless hours fixing white bang marks on my stripper from doing a rescue last year. There's no easy fix and I sanded the surface and touched up the white ding marks with artist oil paint and varnished over it. I wished I took some photos to share. I helped someone get back into their boat last fall and the water was rough and their boat was banging into mine for quite a while. It's the one real downside of cedar strippers. They have structural strength but the skin is very venerable to bruises which turn white because the glass fibers get fractured. And if you sand off a section of glass, it's almost impossible to match the surrounding color because you have to identically match the sanding you did when building it. Fine sanding makes it lighter and coarse sanding makes it darker.