BRIAN HANCOCK REPLIES

It’s actually quite an important piece of a sail, even though most sailors like yourself have never touched it or made any adjustments to it. When the wind exits a sail it creates small vortices, and these vortices can set up a vibration along the leech causing it to flutter. Although the leech tape goes a long way toward solving this problem, on most boats you will still need a leech line installed along the very edge of the sail to keep the trailing edge of your sail still. A leech line, as you know, is a small-diameter, lowstretch line that can be adjusted and fastened-off in most conditions. When the wind increases and the sail begins to flutter, all you have to do to correct the problem is tighten it a little. In light winds it can then be eased off, so that the extra tension won’t cause the trailing edge of the sail to cup inward when there is less air pressure on it. Bottom line: you should probably take the sail in and have a sailmaker install a new one, since the fluttering will not only be annoying, but over time it will degrade the fabric. s