One of the painful lessions I've learned over the years is that it's better to fill any weave with epoxy since it chemically hardens and is thicker and harder than paint or any fillers. You could give your boat a thin coat of epoxy and have a surface thats like glass then you would wet sand it with 200 grit in prepairation for either varnish or paint. Wet sanding is easier than dry since it also removes blush while you're at it. You could use a filler (primer) as the other person stated but then your just sanding again anyhow. The bad side:If you epoxy again, you should wait at least a long week before painting or varnish to make sure its totally cured and not still releasing any gasses or blush. That's a week in warmth not cold where the epoxy stalls. good luck