Their best-by-far results for a natural finish was with a clear made/marketed by POR, call Pelucid.
Pelucid does give a great finish however, it is not intended for outdoor use, which is stated both on the POR 15 site and on the can itself. It also does not last as long as spar varnish. I only got about 5 years out it before the finish failed. It started coming off is sheets on the topside of the wood. The Helmsman spar varnish I redid it with has been on it for 8 years, and is just now starting to show age. I did follow the recommendations of a local woodworker/house restoration expert when I did the refinish. He told me a minimum of 8 coats, sanding with 320 grit between coats. After it had a chance to cure, I did follow up with a coat of automotive wax to bring out the shine.
