Originally Posted by deltaten
I'm having some trouble digesting the text stating; " The LP defines the sail size in terms of percentage increase beyond the J measurement as in the following examples." with the chart immediately below. It shows, under the "LP" column, a direct correlation to unit "J" past the "I" line.
It appears that roller furlers need the "LP" figure to relate the amount of sail exposed, as that's the direction of reduction; but regular (geometric term) foresail calcs rely on straight "J" numbers.
Am I missing something??
Doesn't the "IJ" fore-triangle calc describe a geometric area potentially filled by a headsail at 100% (not necessarily the actual measurements)? As I was led to believe, the increase in percentage was a function of the amount of the (base/"J") jib triangle passing the mast (height/"I") of the theoretical/geometric right triangle??
Its really VERY SIMPLE once you define 100%LP dimension that equates to the "J" dimension. Once you arrive/calculate (or do this 'graphically') all further dimensions will be directly proportional (ratio'd). Eg. a 120% LP will have is 'foot dimension' at ~120%
of the 'J' dimension. .... you just have to first establish the 100% LP dimension in relation to the J dimension, .... first.