when you go to drill the hole thru the hull, measure on the inside of the boat where the paddle wheel will fit, then drill a 1/8" diameter hole from the inside of the boat out. This will allow you to hit your spot, rather than drilling from the outside in. Make certain you do not hit the chines or strakes on the bottom. Drill your 2" hole from the outside to the inside, less flaking on the edge of the hole. Take a small piece of sandpaper and carefully place about a 1/32 to 1/16 radius on the edge of the hole(make certain you get thru the gel coat with this, you should be able to see the discoloration difference between the gel coat and the fibre glass), both sides, this will remove the stress riser on the edge and help prevent cracking. Be certain to place your paddle wheel where it is A: going to give you accurate readings, and B: you can remove and replace it with ease. Enjoy your perfect pass, best thing I've ever got for my boat. Anyone can drive and give you a tournament class pull.