Oracle Team USA in their AC45X test boat.
Oracle and Team Japan training in Bermuda.
Land Rover BAR training in their AC45X.
Have you noticed that the AC45X test boats often sail bow down when foiling? One of my best sources helped me understand this. Lift increases with speed and with angle of attack. The rudder elevators generate more lift at higher speed, pitching the boat into the bow down attitude. This reduces the angle of attack of the rudder elevators, providing pitch stability. The longer answer gets into the load per unit area on the rudder elevators compared to the daggerboard wings, and the way pitch – heave coupling can produce either stable (good) or unstable (bad) ride height and and pitch. I’m working on a detailed article about this. Watch for it in a future issue.