David Flynn
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.