Oh the memories!
Any exterior wood paint works. Mix in some sand for the top part if you want non skid. Also, a good idea to caulk the holes; water will get in there and rot your wood. I blew a frame apart on Dolores catching my upstream oar on something and one entire section of my frame just........blew up.
I'm sure you're gonna get lots of posts about specialized, two part, expensive, unusual coatings that require 25 steps to apply and a special use permit, but in my opinion since it's wood, it isn't totally necessary. My own frame lasted years and all it got was a good coating of exterior wood paint when I built it.
And I stored it outside.