I had the same problem with mine and cut about 7/16 off each rudder arm and drilled a new hole for the screw. It seems that one of my hulls is canted more than the other. With the boat upside down I put a 8' straight edge on the hulls right behind the dagger boards with the boards in down position. I then took a framing square 2' up and 1' out and lined up the bottom of the square with the dagger board and measured the difference between the board and the square at the top. I had about a 3/8 difference you could really see the difference looking from the back of the boat. I did mount the rudders and they lined up with the daggers, but you could really see the extra cant in the starboard hull. Since the rudder and dagger line up it looks like the hull must have the beam pockets off a little.