They use "T" foils on the rudders of the international 14 (skiffs) to quite amazing performance improvement over boats without them. They are able to change the angle of attack simply by either "tilting" the entire rudder or having the foils "tiltable" independent of the rudder rake. They can lift the bow (or depress it) upwind or down and it has made the boats so much more controlable and faster that I don't think they would be without them ever again.Anyway, they are illegal in the F18's at present.
Darryl J Barrett.