UK Sailmakers' Encyclopedia of Sails
1.3 - Rig Dimensions
Before we actually start building, we'll need some very specific measurements. If your boat is near one of our lofts, we'll come over and measure; if not, we'll mail you a measurement form. When you see this form, you will quickly appreciate how "customized" every one of our sails is.
The following rig dimensions designated by "I", "J", "P", and "E" are needed to produce a price quote. They are convenient names to use because they are short and are understood throughout sailmaking...
"P" is the luff length of the main-sail, measured along the aft face of the mast from the top of the boom to the highest point that the mainsail can be hoisted.
"E" is the foot length of the main-sail, measured along the boom from the after face of the mast to the outermost point on the boom to which the main can be pulled.
"I" is measured along the front of mast from the highest halyard to the main deck. The main deck is where the deck would be if there were no deckhouse.
"J" is the base of the foretriangle measured along the deck from the headstay to the mast.
"JC" is the greater of the following three dimensions: "J", the length of the spinnaker pole, or the maximum width of the spinnaker divided by 1.8. Under most measurement rules, "JC" is used, along with "I", to determine the size of a spinnaker.
"TPS" or also "STL" is the length along the deck from the front of the mast to the forward end of the sprit in its fully extended position.
"PY" and "EY" are, respectively the luff length and foot length of the mizzen of a yawl or ketch mea-sured in the same manner as for the mainsail.
"IY" is the "I" measurement for the staysail halyard.
"JY" is the base of the staysail foretriangle measured along the deck from the staysail stay to the mast.
Finally, here are two helpful comments. First, measuring your old sails is of little use: think of that approach as asking a tailor to make you a new suit just from looking at an old suit. And a picture is, as they say, worth a thousand words: snapshots of your gooseneck, genoa track location, headsail tack fitting, furling gear, etc. can be of great value to us; these don't need to be fancy, just clear.
There's always the phone. Don't be reluctant to ask questions. We welcome hearing from you and making this process as fun, easy and exciting as it should be.