I'm refinishing our kayaks, first time since built. Artic Tern 17 and 14. I started sanding, believing I need to remove ALL of the old finish. But I'm running into glass more often than I like. Is it neccessary to remove all the old? Can I just lightly sand old finish and spray new on top of old? Will new finish clear up the glass or do I need to touch up with epoxy and sand before I refinish? Original finish was clear urethane. I planed on having them sprayed with a 2 part auto-body clear-coat. Will the clear coat have to be sanded down to epoxy next time I refinish them? If so, I might be sorrry I did it a few years from now. Thanks for any feed back and advice.