: I used Flecto Natural Oil finish which is not "natural" like tung
: or linseed oil but it dries faster and is harder. Tung oil is a bit better
: than linseed oil for outdoor use but neither is as good as the Flecto.

Oil is easy. It's also useless in a water environment. Unless you want to re-oil after every use. Water will still rise the grain and absorb into the wood.

If you mix an oil finish like "Watco Exterior" with some spar varnish you can still apply it with a rag and build up a waterproof finish after four coats or more. Whenever your paddle gets scratched up, sand lightly with 220 wet-dry and water, dry and add another coat of the oil/spar varnish finish.

This is also a great and easy furniture finish.

All the best,
Rob