Tech Tips Archive

So You are Thinking About New Sails
January 1998
by Rod Carr

Nine times out of ten, the first thing I hear when my phone rings is, "I need new sails…..how much for sails for my SAWED OFF One-design?". What follows is more like a police interrogation LAW AND ORDER style than it needs to be. Here are some suggestions that you might consider before you call your sailmaker. If you can answer the numbered questions, you will both make faster progress toward designing, building and setting the sails that will meet your requirements.

1) What kind of boat is it? You should know if it is an AMYA racing class as there will be class specifications that the sails need to meet in their design and construction. If it is not an AMYA Class, does it belong to one of the International Classes; or is it one of the modern kit or "sport" boats made by Kyosho or Tamaya for example? Maybe it is an old pond yacht, or an antique that you've found in a garage sale. At a minimum, you should know the hull length and weight; any data that is obvious about the mast and rigging such as mast and boom lengths will be very valuable.

2) What kind of sailing do you intend to do? If it is an AMYA racing class, you'll be likely to want to race it. Other boats may be sailed for pleasure on Sunday afternoon or on vacations, or they may be family projects that are going to involve the kids. Racing sails are designed with priority given to shape, performance or longevity, in that order. Boats that are not going to be raced will focus on longevity and robustness. If you are restoring grandpa's old pond sailer, you need to find a sailmaker experienced in making cotton sails for display, and soft dacron ones for occasional sailing. By telling the sailmaker what you intend to do, you give him the information necessary for a recommendation of an appropriate sail material.

3) What sail dimension data do you have available? Racing boats can refer to class specifications. Replacement sails for other boats are often made by using the original sails as patterns. Information on the spars will help establish lengths of luffs and feet. Leech roaches (the curved area outside of the straight line from the head of the sail to the clew (lower after corner)) are defined by AMYA class rules, measurable from the original sails, or recommended by the sailmaker based on the intended use and/or the materials selected for the sails.

4) What kind of mast bend do you plan to use? The leading edge (luff) of your mainsail will typically have some round cut into it. The amount of round will include any mast bend that you have, plus some extra to assist in developing the camber or curved shape that makes sails work. If you routinely carry some bend in your mast, you need to know at a minimum the amount the middle of the mast departs from a straight line from the head of the mainsail to the tack (lower forward corner of the sail). Set the boat up, adjust the mast, and then tape a thread at the head and tack. Measure the gap at the middle of the mast. To really make your sailmaker happy, divide the mast up into 10 segments and measure the offset at each segment. This little table of offsets will allow the sailmaker to make the luff of the new sail match the mast shape exactly.

5) How is the mainsail held to the mast? Describe the method you will use to hold the mainsail to the mast. There are lots of them, and each requires a little bit different treatment along the mainsail luff to make mounting the sail easy. If hooks or slides or loops are used, determine where the bottom one is located, relative to the tack of the sail, and then give the spacing for the rest of them going up the luff. If you require a bolt-rope, the width of the sail slot needs to be measured.

Remember, hang your sails up by the heads in a safe place, with all the tensions relaxed on the rig, outhauls, halyards, vangs, …….everything should be loose to remove strains on the sail material that will cause it to stretch, thereby ruining the sail shape built into the sail. Properly cared for racing sails can last in excess of 3 years, even if sailed every week!!!!