December 7, 2015
Quantum Expert Answer
LP is the "luff perpendicular." This is the shortest distance from the clew to the luff (hence, perpendicular to the luff). It is a true measure of the width of a headsail. Unlike foot length, it is not affected by clew height. LP is often stated in terms of a percentage of the "J" dimension; the distance between the headstay/stem intersection and the forward face of the mast. A 120% headsail would mean that the LP was 1.2 x J.