By Greg Fisher

Over the past couple of years, there has been an increasing trend towards tighter rig tension in popular one design classes. Whatever the method of tensioning the rig, be it lever, magic box or turnbuckle, the intent is the same -the jib luff must be kept as straight as possible.

Picture a Day Sailer sailing close hauled in a 10 mph breeze. An 18 mph puff hits, forcing the skipper to ease the mainsheet a foot to keep the boat on its feet. The upper part of the mainsail dumps off easing power...or does it? As the main is eased, the leverage created by the boom and main pulling back on the rig is also eased, allowing the rig to rock forward and the forestay to slightly slacken. Since the jib is still drawing at near maximum power, the forestay sags towards the mast. This sag actually "shoves" extra cloth into the jib, making it fuller, which is exactly what we are trying to avoid in a puff. If we can eliminate this sag, or even just reduce it, the jib remains flatter, not overpowering or hindering our pointing ability.

If we can tighten our jib halyard (or our shrouds). we can delay this "sag" until higher wind velocities. I say delay since it is virtually impossible to eliminate all sag in the jib luff. However, the more sag we can eliminate, the more constant our jib shape will remain through the puffs and lulls.

For the tight rig to be effective on a Day Sailer, we have found it is best to keep the rig tight enough so that the leeward shroud will not go slack when we are sailing closehauled until the wind is blowing at least 8 mph. This "rig tension" is best for 80 percent of the conditions. If the wind is heavier (above 12 mph), it would be best to pull the jib halyard tighter by about 1 1/2". If the wind is lighter or we need power, it is best to ease the jib halyard off 1 1/2". This way we can build fullness into our jib for light air or when it's choppy and we need power, and by pulling it up tighter, we can flatten the jib. A magic box or lever will give the proper muscle to alter the rig tension through adjusting the jib halyard.

It is important to remember that luff sag and jib luff cloth tension are not the same adjustment. Cloth tension puts tension directly on the cloth of the sail, regardless of what the sag in the luff of the jib is doing. Tighter luff tension will pull the draft forward in the sail, just like the Cunningham on the mainsail. Ease the jib cloth off and the draft will move back. Luff sag simply gives the jib the fullness it needs, and the jib cloth tension positions this fullness.

As for positioning the rake on the Day Sailer with the shrouds, be sure that when the rig is pulled up tight enough that the leeward shroud does not go slack until it's blowing at least 8 mph, and that the mast does not have a reverse bend in it. Sight this by looking up the slot of the mast up the side to notice the fore and aft bend. With the rig pulled up this tight, you should notice a nice gentle, positive fore and aft bend. That is, the slot of the mast at the middle should be at least 1/2" to 3/4" forward of the back edge of the mast at the upper band at the gooseneck, and at the upper upper band at the head of the main. If our shrouds were too tight, we would see too much positive mast bend down low, and if our shrouds are too loose, we will see too much reverse bend or a very straight mast up to the spreaders. Again, we are looking for a nice even bend, with the leeward shroud not going slack before 8 mph.

This is an ideal time to slip into a discussion about mast bend and the Day Sailer, and what variables control this bend and how we can use these variables to make our Day Sailer go even faster. We'll talk about this in the next issue of the Day Sailer Quarterly. If you have any questions, please feel free to give me a call at (614) 221-2410!

Editor's Note: Greg is president of Shore Sails Midwest, a loft which specializes in one design sails for boats under 20 feet.