David Flynn
December 7, 2015
Quantum Expert Answer
You're in good hands because we've done work for the Coronado 25 for many years and have all the rig information. In recommending a headsail size for your boat we would need to know your home port. A boat on San Francisco Bay needs a smaller headsail than a boat in San Diego etc. Headsail pricing varies depending upon size. Check here on our website for a Quantum loft near you or call us at (888) 773-4889.
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The percentage refers to one dimension on a headsail: the measurement from the luff to the clew, measured at right angles to the luff. That measurement is described as a "luff perpendicular", also known as LP. 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. The J of a Coronado 25 is 8.92 ft. So a 100% jib for your boat would be a jib with an LP of 8.92 ft. A 135% headsail would have an LP of 1.35 X 8.92 or 12.042 ft. Contrary to popular belief, the percentage does NOT define the sail area, it only gives you an idea of the amount of overlap. The area of a headsail is luff x LP divided by 2.