' JY' is the measurement from the staysail stay to the front face of the mast. ' IY' is the measurement from the staysail halyard to the deck. ' PY' and ' EY' are, respectively the luff length and foot length of the mizzen of a yawl or ketch measured in the same way as for the mainsail. ' ISP' is measured from the highest spinnaker halyard to the deck. ' JSP' is the length of the spinnaker pole or the distance from the forward end of the bowsprit (fully extended) to the front face of the mast. ' J' is the base of the foretriangle measured along the deck from the headstay pin to the front of the mast. The main deck is where the deck would be if there were no deckhouse. ' I' is measured along the front of mast from the genoa halyard to the main deck. ' E' is the foot length of the mainsail, measured along the boom from the aft face of the mast to the outermost point on the boom to which the main can be pulled or to the black band. ' P' is the luff length of the mainsail, measured along the aft face of the mast from the top of the boom to the highest point that the mainsail can be hoisted or black band. 'Square' Spinnaker Area = Max Luff x Max Girth) = 648 sq ft Spinnaker Area = Max Luff x Max Girth x ( 70-85%) = 453 to 550 sq ft They are rules of thumb, not measurements of a this specific boat.ДЎ55% Genoa = (( J x I ) / 2) x 1.65 = 299 sq ftДЎ35% Genoa = (( J x I ) / 2) x 1.44 = 261 sq ftДЄ more accurate LP calculator is HERE Spinnaker But all things considered, these numbers are close but should not be considered exact.

Also, remember that jib sail area in general is based on the forestay length, I. Sail areas depend on lots of factors, leach hollow, foot round, luff hollow etc.

Starwind 27