Is my Genoa is a 135% or a 150%? I understand the ratio is the luff perpendicular compared to the J. Since J is 13'6", that would indicate a LP of 18'4" or 20'5". My question is how do I measure the LP? Can I measure while on the boat unfurled or do I need to remove it from the furler and lay it in the grass?
The best way to get an accurate measurement would be to tail the sail down and measure it on the ground.
Don't know what model of boat you have but my Mark I manual says that the foot of a tall rig 130 percent genoa is 19.25 feet and the 150 percent genoa is 21.25 feet. Standard rig is 19.33 feet for the 130 and 21.33 for the 150.
The LP for a standard rig and a tall rig is the same as they both share the same J of 13.5 feet. The foot of a sail is partly determined by how high the clew is off the deck, not just the overlap. The higher the clew, the longer the foot, so, a 150 reacher will have a longer foot than a 150 deck sweeper.
A 130 will have a LP of 17.55 feet (13.5 x 1.3)
A 150 will have a LP of 20.25 feet (13.5 x 1.5)
Deck sweeper or not, LP is only ONE number
luff perpendicular
Thanks everyone for your replies. I asked this to make sure my PHRF application is correct. I will measure LP when it stops raining, when the sun shines again, and when the wind pipes down.
"When the wind pipes down". I was going to add in jest that the easiest way to sort out if you had a 150 up was to see if if you were out of control in a wind over 10 knots:)