Richard, If you want any kind of air foil to your fin and rudder, itis best to establish it before you sheet the the surfaces. What I did was to tack the rudder to the fin with 3small dots of medium CA on the fin trailing edge. Then I used a long block 12" X 3" to taper the assembly fore to aft,top to bottom. Again, marking a center line along the leading edge of the fin, over the top of the fin/rudder joint, and down the trailing edge of the rudder will help you accomplish symetrical airfoil sections on both sides of the assembly. After I had the airfoil I was looking for, I separated the fin and rudder, sheeted both sides of each of them, and rounded as necessary. Even with this technique, several areas of the fin sheeting became very thin. Oh well, weight saving!!!