%LP

[Tom Wanderer]

How does one calculate the %LP? Thanks

[Derek Rowell]

I think this is correct:LP is the perpendicular distance from the clew of the jib to the luff (headstay) measured along the sailcloth, expressed as a percentage of the boats J dimension (tack of jib to mast).Derek

[Tom M.]

For every right triangle, you need the lenghth of two sides or one side and one angle ( not B angle:90) knowing this : leach devided by LP : co Sine angle A, leach squared - Lp = perp. which half or most the length of the luff call it X luff - X = remainder of luff call it Z Z squared + LP squared = length of foot, Z times LP devided by 2 = sq ft of bottom sect. AA leach times LP devided by 2 = sq ft of upper sect BB, aa+bb = total sail area.

[Been there]

Any triangle's area equals the length of a side multiplied by the perpendicular distance from that side to the opposite vertex. The triangle does not have to be right; most jibs aren't. It doesn't matter whether the perpendicular ends on the side or on the line extension of the side, though for jibs, it will always end on the luff.

[Been there]

I left that off the first sentence.