What (and what words) you should know before buying a sail
Buying a new sail can be a daunting task. There are so many sail lofts, styles, options, prices… and worst of all is the jargon! Some of these sailmakers forget we were all novices at one time…
What follows is an unbiased overview of some of the key terms and concepts you’ll run across in your search.
Crosscut: A sail construction technique in which all the panels are parallel to each other and perpendicular to the sail’s leech. Most Dacron cruising sails are crosscut.
Radial: A sail construction technique in which radial panels emanate from one, two, or all of the sail’s corners (also called the head, clew, and tack). Radial designs are favored by racers for their additional strength.
Cunningham: A control that adjusts the position of the draft in a sail by changing the tension on the sail’s luff. This control is a must for racing and used by some cruisers.
LP: The abbreviation for Luff Perpendicular, which designates the shortest distance from the clew to the luff of a Genoa. Genoa size is expressed in as a percentage, which is the LP divided by J. For example, if a boat’s J measurement is 12 feet, a 150% genoa will have an LP of 18 feet. You may hear a sailmaker use this term.
Outhaul: The control line that pulls the mainsail clew to the end of the boom, tightening the foot of the sail and reducing draft. Chances are your boat is rigged for an outhaul; it’s an important control.
Loose-Footed Sail: An option that allow you to add a substantial degree of extra fullness (referred to as depth and draft) in the lower portion of the mainsail in order to improve performance on reaches and runs. In very light air, the improved performance is achieved even to windward. The extra fullness is removed by tightening the outhaul. When the outhaul is eased, the sail maintains an airfoil shape down to the boom. A Loose-Footed sail is only attached to the boom at the tack and clew. This attachment method is equally as strong as that of the standard foot attached along the boom with slides or bolt rope. Many boats are switching to Loose-Footed mains due to the increased control of sail shape, plus they are easier to remove when necessary.
Telltales: Streamers attached to the sail to indicate wind flow. Don’t buy a sail without these! The fundamental tool for sail trim.
Telltale Window: A small window for providing visability of leeward telltale.
Reefs: Mainsail reefs are used to depower a boat in strong winds. Reefing makes the mainsail smaller. Each row of reefs consists of a heavily reinforced patch with a grommet at the luff for the tack horn and a grommet at the leech for the reefing outhaul. Between the reefed tack and clew may be a row of evenly spaced smaller grommets (called reef diamonds) to provide a means of gathering up and tying off the excess sail. This row of holes is omitted in the case of a flattening reef because there is not enough excess material to worry about. The number of area-reducing reefs varies with the size and anticipated use of the sail. For boats over 26′ two reef points is recommended. If you plan to do any offshore sailing or expect heavy weather three isn’t a bad idea.
Battens: Battens are small, long rods that run through part of the sail parallel with the deck. They stiffen the sail and inhibit flogging. Full length battens run from leech to luff and provide even better shape holding ability, longer life and easier handling. They also induce a smooth airfoil shape to the sail, which improves performance in all conditions by holding up the leech. All major rating rules, IMS, MORC, and PHRF, permit sails with full-length battens with no change of rating. Most cruisers prefer two partial and two full battens. Full battens are installed at the top of the sail, partials toward the foot offering greater ability to adjust sail shape.
Sail Draft: The curvature or depth of the sail i.e the thickness of the airfoil (on the main this would be measured perpendicular to the boom). A deeper draft creates more power out of the sail.
Draft Stripe: A colored, horizontal stripe that helps you determine the draft depth in your sail.
Spreader Patch: Spreaders wear on headsails when you’re close hauled. Spreader Patches should be used wherever spreaders can contact the sail.
Roach: The added material that stocks out beyond straightline leech, for more performance on all points of sail.
UV Cover: A Dacron fabric sewn to the leech of a furling Jib or Genoa to protect the sail from ultra-violet rays while furled. Often referred to as a sacrificial sun cover or shield.
Foam Luff: A foam luff provides better sail shape by flattening the head sail as it is furled. This means improved performance in reefed conditions.
Leech Line: Adjusts the tension along the leech of the sail to stop the leech from fluttering. Fluttering not only impedes performance, but also increases wear on the sail.