Seawind Mainsail Shape

I have a Readyset, new this Spring. The mainsail has a vertical curve or roll, along the mast, extending 1/4th the width of the sail. It is persistant, and removing halyard tension does not help. The clew, bottom, inside corner?, is loose, also. The halyard goes through the forward hole in the masthead crane. The halyard connections to both sails was redone, with a loop reaching beyond the head of the sails, so they are not pulled oddly. There is no backstay or forestay tension.

Is this normal? What is a solution? Are Tippecanoe sails better, in this regard?

Can you post a couple of pictures? I presume that you have tried increasing and decreasing tension in all the adjusting lines to no avail?

Alan,despite mass production there can be slight variation in the amount of luff curve built into the main sails. Check if the bulge disappears into a smooth curve when backstay tension is increased producing fore and aft mast bend. If that works it may be necessary to put a small amount of mast bend into your mast even when under no tension so you can get a good sail shape when sailing in light winds. Gently bend the mast to put a slight curve in it with the convex curve towards the bow. It shouldn’t need much at all as the sail will take a curve when under wind pressure so a slight bulge aft of the spar before filling with wind is quite normal.

These are photos of my sail.

Analysis of sail shape and/or defects are easiest to accomplish with the boat heeled a bit on a close hauled setting to the wind, and with a wind of 2 - 5 mph filling the sail to its “flying shape”. Pictures of a sail taken indoors don’t really contain much information that can be used to diagnose what may be wrong with the sail. Rod Carr, CARR SAILS

Alan, your sails look to all intents and purposes identical to mine, which are from a brand new kit version and my boat goes like stink! The bulge you are seeing is the body that is built into the sail to give it its shape. When the sail is made it is cut from flat material but the luff (the long section that goes into the mast) is cut on a curve, not a straight line. When the curved luff is pulled into the straight mast, it induces body into the sail material that gives it its three-dimensional shape which is essential to it achieving an aerodynamic wing shape that gives it its lift when sailing. So the short answer is: the curve you are seeing must be there - it’s what gives your sail its power. If, as Mike says, you increase backstay tension and put curve into the mast, then you make the curved luff of the sail fit a curved mast and the result is a flatter sail, which in turn leads to less power - useful in higher wind speeds to depower the rig.