Chuck:
When I did the offsets for my Double, I just taped graph paper together and had no problems. Be careful about copying graph paper. Many copiers have a slight reduction when they copy (2%) which isn't noticeable for text, but if you are making graph paper it might be a little smaller. Paul had a good poing about symmetrical hulls in that each side should be the same. I made each section as a half, then flipped it over to do the other half. Then they are going to be the same.

DAVE