I used some Minwax Helmsman marine spar polyurethane, did not last 6 months, I was disappointed. Looked good till about May or so when the sun came out, & underneath it still looks new. I did recommended # coats etc., all sides after drilling. I am in a landlcked state & that was the "best" I could find, I have since learned some good stuff can be bought online, I was told McCloskey's Man-o-War was a good choice. brian
