I built my S&G kayak about 8-10 years ago and every couple of years I've given it a light sanding and reapplied marine varnish. It's time to do it again, but the boat has a few deeper scratches on the hull that appear to have cut into/through the fiberglass. What's the best way to deal with these? Should I just apply varnish over them after sanding, cover them with epoxy before varnishing, or do I need to put a fiberglass patch over them?