Having you boat fair is more important than trying to do a perfect mathamatical job. Once you're done, I would pull three long strips down the forms. One down the center (keel) line. and one down each side and tweek the forms to get a fair looking boat. Just fix any dips or bulges that don't seem fair and that's it.

Even computer generated forms can get out of alignment with a 16th here and a 32nd there and before you know it things arn't fair any longer. It's common. If you find one side is perfect and have to build a form out a hair, just glue or tape on a thickness of thin cardboard or layers of duct tape.