M_Boats: Refinishing the rudder

Hi all. I'm stripping the nearly 50 year old varnish from my M17's stock rudder, and man is that varnish sturdy. I'd love to replace it with something as durable -- what would you all suggest? There are some cracks near the bottom that were repaired with fiberglass and resin, which I plan to re-do as well. Cheers! --Jen