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Tuesday
Sep162008

We are back at it

We had to take last week off from square sails to build a couple of laminate race sails, a cruising spinnaker, and a boom furling main. But we have pushed most of that to the side to put in a good chunk of time on the square sails. Lance and Justin are getting more time on the sails than I am, but in between sail sale calls I have been able to sew ropes, install some cringles and re-cut the mizzen bonnet. We are actually in the home stretch on the first three sails. Things are going much more quickly as we have all become competent at roping and the other basics of making these sails.

I got a shot today of Justin in the act of worming, parcelling, and serving a clew and Lance running the computer driven cutting table. It is amazing to see how much sailmaking has changed in the last 400 years! Not only have the processes changed but the basic structural design of sails has changed.

Square sails are essentially a membrane that floats inside a rope frame. The roping around the edges provides much of the structural strength of the sail as well as providing the 3D shape. When sewing the ropes we gather the cloth so that when the sail is hoisted and the edges stretched the cloth is stretched less and takes a shape. Structurally the sail "membrane" is mostly a single layer with a tabling around the edges and a a double layer along the leeches. These reinforced areas primarily provide a transition from the membrane to the edge rope which carries the heavy loads.

In modern sailmaking the membrane of the sail not only carries the loads but also provides the shape though broadseaming and luff curve. The corners of a modern sail are built up with multiple layers of cloth to transition the loads from the corners into the body of the membrane. The leech and foot edges on a modern sail are merely finish details and the luff is reinforced enough to interface the sail with the spars. Shape is imparted on a modern sail membrane by attaching two curved edges(or a curved luff to a straight mast) to create a 3D shape. All of the seams between panels and the luffs of modern sails are shaped this way. the computer has made 3D shape easily repeatable and sails have become very consistent in shape. One of the great things about this classic sailmaking project is watching the shape being created inch by inch by the deliberate use of needle and thread by human hands.

And today was a very good day as the hands in this loft kept all blood on the inside!

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