J/30 Class Association Forums J/30 Forum One Design Class Rules Class Rules & #1 Genoa Size Limits

Well, I claim no particular expertise in the vagaries of PHRF, but a quick Google shows LP% as LP/J in: http://www.ussailing.org/phrf/fleetstart.asp http://www.ukhalsey.com/LearningCenter/encyclopedia/encyclopedia4b.asp

ISF's Equipment Rules of Sailing only define Luff Perpendicular. The referenced wiki uses the term 'foretriangle length' without definition. I understand your math, but what makes you think it's that complicated?