My friend and I are making a log rail, like the ones in the Killington Natural Park. It will be about 1-2' wide and around 12' long, and a half-circle shape. Therefore we will cut down a tree (large in diameter), cut a 12' section of the tree, and then cut that section in half making a half circle shape, and then the bark will be stripped from the outside of the log. The only two things that I'm confused about is what type of sealant/coating would be best for the log, and how to make the top of the log rideable (the flat part lol). I already had a couple of suggestions for products to prevent rotting such as Shellac or Marine Varnish. Lastly, we were thinking about sanding the top of the log (the part that you ride) to make it rideable, would there be anything else that we would need to do to protect our boards/make the surface slick or soft enough to ride?
Here is a pic of what I'm trying to make:
Thanks for the help!