Squeteague Sailmakers

Sail Owner's Guide

We have written this guide for sail owners with two purposes in mind:

  1. To help people get the best performance possible from their sails
  2. To give some guidance on handling and care of sails to insure the longest possible useful life.
We hope you find what follows helpful. It you have any questions not addressed here, please feel free to call us at the loft and ask.


Getting the Best
Performance Out of Your Sails

The old-timers used to say, "Its not the cut of your sail, its how you trim it." Well... sort of. The design and quality of construction of a sail are important too, but how the sail is set and trimmed is EQUALLY important--the best designed sails in the world can still look terrible if they are not handled properly. A complete discussion of sail setting and trimming would not be possible here--whole books on the subject are available. What we want to provide you with is a concise guide to the basics to get you going in the right direction. If you don't race, this may be all you need or want. If you intend to race seriously these suggestions should provide you with a firm foundation to build on.


The sail shape controls for a headsail are the halyard tension, sheet lead position and sheet tension. On boats with backstay tensioners, rig tension is also an important control, but very few crusing/racing boats in this area have them so their use will not be discussed here.

Halyard Tension
Halyard tension is an important sail shape control for Dacron sails. As the halyard tension is increased the luff of the sail stretches and pulls the draft forward and reduces the overall depth of the sail. Conversely, easing the halyard moves the draft back and makes the sail fuller. Watch how the sail's shape changes as you adjust the tension. You want a nice smooth airfoil shape that is fuller in light air, flatter in heavy air. As a general rule "the harder it blows, the tighter she goes." But be careful if you have a halyard winch-it is possible to over tension the luff. A vertical wrinkle or hard spot just aft of the headstay means too much halyard tension.

Sheet Lead Position
The fore and aft positioning of the sheet lead on its track is critical for proper sail set. With the boat sailing close-hauled, set the lead on the end of an imaginary line that starts at the middle of the luff and runs down through the clew to the lead. This is a good starting point for the lead. Then look at the windward telltales-they should all be streaming back smoothly (either horizontally or a bit above horizontal, but all at the same angle). If the top windward telltale is fluttering, move the lead forward a little. If the bottom telltale is fluttering, move the lead back. Move the lead just a little each time observing the telltales carefully until the best location is found. If you can't quite find the perfect spot, opt for setting it back a little too far rather than forward too much. Different wind conditions and halyard tensions will dictate different lead positions-so use your telltales and adjust the lead position as necessary.

Sheet Tension
When sailing close-hauled, the last foot or so of sheet adjustment becomes a significant sail shape control. The tighter the tension the flatter the sail and again, "the harder it blows, the tighter she goes." Just don't sheet in so tightly that the sail hits the spreaders.

Many people have an instinct to ease the sheets when conditions get severe in an attempt to lessen heeling. This won't work with a headsail-easing the sheet will only make the sail fuller and the heeling worse.

The leechline is not a shape control. The only purpose of the leechline is to keep the leech from fluttering or "motor boating." While your sail is new, you should not have to tension the leech line at all. If the leech is fluttering, change the lead position and/or the halyard tension. However, as a sail gets older the leech will stretch and get looser due to the big loads leeches take. Fluttering that can't be controlled with the shape controls is the first sign that the leech is stretching out. While this fluttering does not affect the speed of the boat, it can be very annoying to listen to and it will cause the leech to wear out very quickly. Tension the leechline just enough to stop the fluttering and no more. The harder it blows the more tension you will need, just don't forget to loosen it up when the wind drops.


The shape controls for a main are: luff tension (controlled by the halyard, downhaul or Cunningham), outhaul, flattening reef, vang, traveler, mainsheet, full battens, and mast bend. However, not all boats have all of these controls, and how you use the various controls depends somewhat on what combination of controls you have. For the sake of clarity and simplicity, we will stick to the bare bones for now-luff tension, outhaul tension and mainsheet tension.

Luff Tension
Luff tension is controlled by one or more of the following: halyard, down haul and Cunningham. Increasing the luff tension of a main does the same thing as tensioning the luff of a headsail-the point of maximum draft moves forward and the overall depth is reduced. On boats with a fixed gooseneck, the halyard will be your first luff tensioning control. If your sail's luff is almost as long as the distance between the gooseneck and the top of the mast, there will be times when you need to use the Cunningham to get sufficient luff tension. On boats with a sliding gooseneck, the down haul will be the primary tensioner and then the Cunningham if necessary.

The outhaul moves the clew in and out along the boom. Moving the clew out flattens the lower sections of the sail, moving it in makes it fuller.

When a boat is sailing close-hauled, the mainsheet becomes a very important sail shape control. As the boom and sail are pulled in to close-hauled with the main sheet, the boom gets to a point where the sheet no longer pulls it in, it pulls it down. As the boom moves down, the shape of the sail changes-the leech pulls into more of a straight line, trimming the head of the sail in (decreasing the twist), the sail become fuller, and the point of maximum draft moves back.

However, as you continue to tighten the sheet, pulling down on the boom even more something else starts to happen-the sailcloth starts to stretch and the way the sail changes shape reverses. In other words, as the leech is pulled straight and starts to stretch, the sail becomes flatter, the draft moves forward and eventually, the head twists off again.

What all this means is that one simple control-the mainsheet-can be used to change the shape of the sail to accommodate a wide range of conditions. In light air or waves the sail should be full, the point of maximum draft about in the middle (fore and aft), and the head trimmed in. To accomplish this, pull on the sheet until the top batten is parallel to the boom and everything else should happen automatically. In heavy air or relatively smooth water, the sail should be flatter, and the point of maximum draft forward some, and the head should twist off a bit. In this case, pull the sheet in more until the sail looks flatter and, once again "the harder it blows, the tighter she goes."

Two other shape controls deserve some mention here because they are pretty common equipment and you may have one or both. They are the adjustable traveler and boom vang.

The traveler controls the angle of attack of the sail when sailing close-hauled while the mainsheet is being used as a shape control.

For example, if you are sailing along with the sheet tensioned to the sail shape you want, and the main is being significantly backwinded by the headsail, you can adjust the traveler to windward to reduce the backwinding.

Second example. You are sailing along with perfect sail shape and you notice that your leechtails are stalling (curling around behind the main), indicating that the main is in too tight. Rather than easing the sheet, which would allow the boom to rise and change the sail shape, you reset the traveler to leeward a little which allows the boom to go out without going up and changing the sail shape.

Third example. You are sailing along in a good stiff breeze with the sheet tensioned to flatten the sail and a puff hits. You want to let the sail out to compensate, but you don't want to loose your flat sail shape. Instead, ease the traveler off to let the boom out and pull it back in when the wind drops back after the puff. There is one practical problem with this particular use of a traveler. Most cruising boats don't have a lot of purchase on the traveler, so a lot of muscle is required to make adjustments of this type. So in practice, even boats with adjustable travelers use the sheet to adjust the boom in and out in puffy conditions because it is so much easier. Unfortunately sail shape is sacrificed in the process... unless you have a vang.

The vang pulls the boom down and affects the shape of the sail the same way the downward pull of the sheet does when sailing close-hauled. This is very handy in blustery weather as you can set the vang to flatten the sail for big wind and then use the main sheet to spill air in puffs without losing your nice flat sail shape. The vang is also good for holding the boom down when needed on points of sail other than close hauled, something the mainsheet can not do.

Regular battens are not an adjustable shape control. All you have to do is put the thin more flexible end into the pockets first for them to do their job properly.

Full battens are a powerful shape control. If you have them see our separate full batten handout.

The leechline on a main is a significant shape control only when used in combination with full battens. Otherwise it is just a flutter controller. (See leechlines under headsails.)

Asymmetrical Spinnakers

Modern asymmetrical spinnakers are very versatile sails. Here are a few neat little tricks to help you get the most out of yours.
  1. In very light air, drop the main as well as the genoa and fly the aspin alone. Under these conditions it is just getting in the way.

  2. In very light air, tacking upwind through 120 degrees with the aspin may very well get you there faster than drifting along under the main and genoa. It will certainly be more fun than firing up the "iron wind."

  3. When sailing dead downwind, wing the aspin out on the other side of the boat from the side the main is on. If you have one, try using a whisker pole or spinnaker pole to hold the clew out.

  4. Watch your sail trim and keep adjusting the sheet as needed. As the boat picks up speed when you first put the sail up, the apparent wind will move more forward and the aspin will have to be trimmed for a closer point-of-sail to keep it full and performing at its best.

  5. Your tack downhaul is also a shape control. The closer to the wind you are, the tighter the tack downhaul should be. Loosen it up for downwind work.

One-Design Boat Sails

Each class of small one-design boats usually employs a number of unique sail setting and trimming tricks. If you are racing the boat, knowing these tricks is critical. Contact the class association for your particular boat and request any literature they may have and subscribe to their newsletter. They may also be able to provide you with the titles of books written on your particular class. Other sailors in your class are an excellent resource. Talk to them and find out what their favorite tricks are. All of this information will give you an excellent starting point from which to start collecting your own fine tuning techniques. Remember that most one-design boats do not have one-design sails, meaning that not every sail is cut to the exact same pattern. Usually the class rules establish maximum and sometimes also minimum dimensions for sails and as long as the sail will measure in, sailmakers can build the sail to any design they want. In most cases this allows for a huge difference in sail designs for the same "one-design" class. Even sails cut on the same pattern will not set the same way forever. As a sail ages, the stretch characteristics of the cloth changes and differences in handling will be necessary.

What all this means is, even if you are already an experienced sailor in your class of boat, you will still need to spend some time learning to fine tune your new sails to get maximum performance from them on the race course because they will not tweak out like your old ones.

If you are not a racer, setting and trimming your sails will not be as critical, but you will still want them to set nicely. Start by looking for obvious wrinkles and hard spots on your sails while you are sailing close-hauled and adjust the various sail shape controls (halyard, outhaul, downhaul or Cunningham and boom vang), one at a time to correct the problem. Sails are not a set-and-forget piece of equipment, and what works under one set of conditions may not work under another. Get into the habit of looking at your sails often and making adjustments as needed.

Developing an "Eye"

In order to make the best use of your shape controls, you need to develop an eye for sail shape. The best way to do this is to LOOK AT YOUR SAILS OFTEN. The more you look at them and adjust the shape controls under different conditions, the better your eye will get at knowing what looks right. If you have a knotmeter, keep tabs on it, too. It will tell you if your eye is on the right track.

Dealing with Excessive
Weather Helm and Heeling

A little weather helm (a tendency for the boat to turn into the wind) is good. It gives the helm a nice positive "feel" and angles the rudder a bit off center which adds a little lift to the hull. However, weather helm can become so pronounced that it takes two strong arms to hold the helm and the rudder is at such an acute angle that it is acting like a brake slowing the boat down. At this point the boat is not only sailing inefficiently, it is no fun either. To reduce weather helm:

1. Use your shape controls to flatten both sails.
2. Keep the headsail in tight.
3. Ease the traveler off to leeward, or tighten the vang to keep the sail flat and ease the sheet.

Heeling also increases weather helm due to the shape of the parts of the hull that are underwater when heeling. To reduce heel, keep the sails flat with the draft forward and the head of the main twisted off. Also, get your crew members to sit on the windward side of the boat.

Even with proper sail trim, at some point heeling will become enough of a problem that it is time to shorten sail. Ideally, whether you reduce the headsail area or the main area first should be determined by how the boat is balanced. In general, reduce headsail area first. Then when the weather helm starts to get bad, reef the main.

However, not all boats should reduce headsail area first. If your boat tends to have quite a bit of weather helm under average conditions, you will most likely need to reef the main first. Some boats even balance well sailing under a big headsail alone. Just make sure you haven't given the boat a lee helm-a tendency to head off when you let go of the tiller.

Experience is the best teacher. Keep track of how your helm behaves under different sail combinations and conditions. You should be able to get the boat to sail nicely with reduced sail area no matter how it was designed to balance with full canvas. It is just a matter of finding the right combination of main and headsail areas.

Care and Maintenance

Sail Killers: Things to Look Out For

Flogging--uncontrolled flapping of a sail or part of a sail--will wear out a sail faster than anything else. Flogging first breaks down the finish of the cloth causing the sail to lose its shape, and eventually it weakens the cloth fibers and the sail loses its strength as well. Avoid motoring with the sails up, leaving the sails up while on a mooring or when beached. Use the leechline to control leech fluttering that can not be eliminated by adjusting the sail's shape controls.

Next to flogging, exposure to the sun will destroy your sails faster than anything else. Good Dacron cloth can be reduced to tissue paper in a few seasons if left constantly exposed. Nylon breaks down even faster. While you are actually sailing your boat, there isn't much you can do to protect them, but you can protect them completely when you aren't using them. Sails left furled on the boat should have sailcovers. Make sure your covers cover everything-anything that sticks out from under the cover will be damaged. Roller furling headsails should have sunstrips on the leech and foot. Look at the furled sail carefully the first time you roll it up each season. The sunstrips should face out where they will protect the sail. If they aren't, the furling line on the drum needs to be set up to turn the drum in the other direction. Every year we see roller-furling sails with sun damage on the leech and foot due to being furled backward.

Dacron fibers aren't actually damaged by water, but mildew will grow on damp sails and make them look dowdy. When ever possible let sails dry before furling or bagging. Salt left in a sail from repeated wetting and drying will draw moisture out of the air causing sails to remain permanently damp. The salt crystals can also abrade the cloth fibers and resination and hasten the breakdown of the material. To prevent salt damage sails should be rinsed with fresh water when they get too salty.

Nylon materials are damaged by water. Nylon loses up to 50% of its strength when saturated and becomes three times stretchier. Most of the strength and stretch resistance is regained when the cloth dries out--but not all--some of the damage is permanent. For this reason it is particularly important to keep spinnakers and other Nylon sails from getting wet, and rinsing out salt and drying them promptly and thoroughly when they do get wet.

Rough or sharp objects that come in contact with a sail repeatedly with normal use can chew through a sail amazingly fast. At the beginning of the season, cover all pins and turnbuckles, and check all stanchions, the spreader, the mast, pulpit and radar mounts, etc. for anything sharp, and check all shrouds for "fish-hooks." Whenever you notice worn spots on a sail, look for possible causes by carefully checking over anything that might contact the sail at that spot.

Improper reefing or shaking out of a reef can cause spectacular damage to a sail. Be sure to tie the reef tack and clew securely and tension the reef clew out sufficiently. Remember that the intermediate reef points are not meant to take any strain. Their sole purpose is to hold the reefed away portion of the sail up out of the way. Tie them loosely after the reef tack and clew are secured, and always untie them first when taking a reef out.

Emergency Repairs
Tears and popped stitching can usually be temporarily repaired pretty effectively with a generous dose of tape. "Temporarily" means until you get back to the mooring and drop the sail. As soon as the sail comes down, take the tape off. Tape that stays on a sail for any length of time leaves a very heavy, sticky residue behind when it is removed. Although this residue can be removed with dry cleaning fluid and a lot of elbow grease, it is at best a difficult and unpleasant job. Remember that we can do routine sail repairs in 24 hours, so there's no need to sail with tape repairs for more than a day.

Annual Maintenance
Proper annual maintenance can greatly extend the life of a sail. Patching small holes and repairing broken stitching can prevent catastrophic failures and costly repairs at the height of the sailing season. Washing is advisable if a sail is soiled or salty. In general small boat sails and headsails get exposed to more dirt and salt and should be washed every year. Mains for larger boats can usually go for two years between washings.

Storing Sails
Sails should be stored for the winter in their bags in a clean, dry, rodent free place. If they need to be washed, do it before putting them in storage. (Wash the bags, too.) In general, garages, attics, basements and the boat are not good storage places as they tend to be damp and are popular hang-outs for mice. BEWARE OF MICE--they love to nest in sails and will happily tunnel right through layer after layer of nice new Dacron or Nylon sailcloth to find a cozy spot.

Reference Books

There are many excellent sailing books available that cover every aspect of sail handling. We highly recommend Sail Power by Wallace Ross and The Art and Science of Sails by Tom Whidden and Micheal Levitt. It covers everything having to do with sails in depth in a nice readable style. If you intend to race and are willing to do some studying to go fast, get this book.


Wind deflected from a forward sail onto the sail behind it. Most typically from a headsail onto the leeward side of a main.

A fitting or control at the tack of a sail that tightens the luff; also, a control line to pull down the main boom when it has a sliding gooseneck.

The amount of curvature in a sail.

A fitting by which the boom is attached to the mast. May be fixed for sliding.

Sheet lead
A device, typically a block, that controls the angle and direction in which the sheet of a headsail is led. May be fixed or adjustable.

A sliding device used to control the athwartships position of a sail, usually the mainsail

A device to pull down the main boom to tighten the leech