The class adopted a new, improved rudder design in the year 2000, with the old design grandfathered. The new design, drawn by David Thomas himself, is generally considered a marked improvement on the old. It's a little deeper and has a different profile that gives greater feel and 'grip', especially when close-reaching under spinnaker in a breeze. You can download the plans below. Peter Duggan built one for his boat, Fly - and he talks about it here. If you don't want to build one yourself, a number of people have bought them from Milanes Foils and other sources.