Reply by Rick M.

I like low maintenance for decks because the harder the finish, the more work it takes to refinish it and the worse it looks as it ages. I believe your best bet is something like Thompsons because it has UV inhibitors that will help prevent graying and will be easy to reapply.

I don’t know much about spar varnishes but a varnish could be either a urethane or oil.

-- -- Rick M.