In context may I add this related to the Texel Race from Steve Green (BAMA)...
Texel.NDL (G.Ruesink, Nico Boon et al) and SCHRS.EU (Sunnuncks, Newhirst) w/SCHRS.US (Schneider) confirmed no 2013 rating adjustments for T-Foil Rudders (see Nacra F-20 Carbon S-Foils w/L and T-Rudder SkyDrive.LINK). Maybe next year.

Team Oracle has gained some knowledge of exacting the angle of attack for the theory by practicing with the adjustable elevators. Now, in beach cat terms...

My guess is the NACA on the A Cat foils was 4 - 6%. The angle of rake/attack was not mentioned in the discussion. Innovation and safety go hand in hand.

Allowing the daggerboard rudder in production trimaran racing was hinged by the safety element. Watch out for the Farrier 22 - If you see it, you'll likely want to sail it!