I think I understand what you are trying to prevent, but I am not sure the proposed rule does it. It sounds like you don't want the little foil at the bottom of the rudder to be able to articulate up and down, depending upon circumstances. But if the foil is fixed in position at the bottom of the rudder, the rule as worded does not prevent you from changing the angle of the rudder to change the angle of the end plate. Right? Or am I reading it wrong?