The wind and wave conditions are always changing, and this means sail shapes must constantly change as well. The jib shape that is ideal in five knots of wind would be very slow in fifteen knots. On almost every boat, the jib trimmer has a number of ways to control and change the shape of their headsail. There are four specific tools you can use to alter the three-dimensional shape of a jib or genoa:
1. Jib sheet – controls how far in or out you trim the sail;
2. Jib lead position – can often be moved in both the fore-and-aft and lateral directions;
3. Headstay sag – also called luff sag; controlled by backstay and mainsheet tension; and
4. Luff tension – the tightness of the fabric along the jib luff, controlled primarily by the halyard.
The key to being a good trimmer is the ability to adjust each of these controls so you have the best sail shape for any wind and wave condition. What shapes are fastest? That is something you learn from experience, by carefully observing the trim settings that seem to be fast relative to other boats across a wide range of conditions.
Once you find a fast shape, it’s critical to be able to reproduce that shape in the next race or regatta. To do this effectively you need a reliable system for keeping track of your sail controls.
There are a number of ways you can mark your jib or genoa to help you see its shape and optimize the use of sail controls. Draft stripes are the most common. By putting just one or two dark horizontal stripes on your jib, you can easily see the amount and position of the sail’s draft.
© Rick Bannerot/OntheFlyPhoto.net
Calibrate. Use reference marks and number scales to help measure and record trim settings. Put marks near your spreader tips to help you judge leech position, for example, and figure out a way to quantify backstay tension (see next page). These markings are key for being able to reproduce fast settings when you have similar conditions again.
Organize your numbering system so higher numbers always represent the settings you use for more wind. For example, the scale on your jib halyard should be oriented so the higher numbers are lower on the mast. This way you go to a higher number (i.e. more halyard tension) as the wind increases.
Track. Once you have a good system of calibration, keep track of what settings are fast in various conditions. You can try doing this by memory, but that is usually not nearly as good as keeping a written record of things you learn about your jib or genoa.
Compare. Your competitors are a great source of go-fast ideas about jib trim (or anything else), so keep an eye on them, especially early in a race or series or season (when you see them for the first time and you are open to go-fast ideas).
Look carefully at the shape of their sails (e.g. depth, draft position, twist) and their trim settings. For example, how much jib luff tension are they using? Do they have ‘speed wrinkles’ along the luff and, if so, how pronounced are these? Pay particular attention to boats that are going faster than you, and don’t be afraid to copy their set-up.
Use numbering systems that can be compared to other boats in your class. When you mark your jib lead positions, for example, use the same method as other boats. This way if you find a sailmaker or other competitor who is willing to share, you can transfer their fast settings to your own boat. ■
This article originally appeared in David Dellenbaugh’s Speed & Smarts, The newsletter of how-to tips for racing sailors. If you want to sail faster and smarter, log onto SpeedandSmarts.com.
A resident of Easton, CT, Dellenbaugh was tactician and starting helmsman for America3’s successful defense of the America’s Cup in 1992. He’s a Lightning World Champion, two-time Congressional Cup winner, seven-time Thistle National Champion, two-time winner of the Canada’s Cup, three-time Prince of Wales U.S. Match Racing Champion, and a winner of the U.S. Team Racing Championships for the Hinman Trophy.
