Since the rudder is hinged on the starboard side, the port side of the rudder moves to port when the rudder swings to port. The rudder contacts the port side of the aft edge of the vertical stab well before the necessary 30 degree displacement has been obtained. The port aft edge of the vertical stab has to be relieved. I started by marking off 1/4" to be relieved and started to apply abrasives.