Headsail Percentage
Hi Bill,the % is the result of LP/J dimensions, with LP being the distance from the sheeting corner to a point at precisely 90 degrees from the luff. On a 34, J is 13'9", and a #1 genoa (150%) would then measure 20'7½". Do not forget however that the % factor is only used as a reference. If you are into racing, then your club handicapper should measure the sail to properly assess your rating. Unless you have access to a very large clean floor, you will need to wait for a dry summer day to measure that sail on a lawn!I am also including an old diagram which should give you some more info. Keep hope, there is only 2 more months to wait.