Have you tried "system 3"? It's water based, and goes on smooth. It has an additive to make it tougher(abrasion and chemical). I used it on two 'yaks and was very pleased that I didn't have to wait and sand between coats. I'm not sure of it's durability as my boats are kept inside. In use it holds up as good or better than varnish. No complaints so far except the price! :(