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.