The wingtip skid on my glider had become worn down and I didn't catch in time. I landed on a concrete runway. The under surface of the wingtip scrapped on the runway wearing off the paint. There seems to be no damage to the fiberglass just scratched gelcoat. The scrape is about two inches wide and 4 inches long. The wing tip is painted red but white gel coat shows where the paint has been scraped off.

Does anyone have some suggestions on how to repair this? I was thinking of of applying a layer of white gelcoat to build it back up then repainting the over the gel coat as it seems this is how the wingtips have been done.