I just bought a new sail,and it has a cord with a tiny cleat at the bottom running up the leech of the sail. Can you tell me what this ajustment is called, and how to use it properly when sailing?
Dan Dickison responds:
Thanks for your question. What you're referring to is called the leech line. You can use the leech line to adjust the tension along the leech of the sail. That much is probably obvious to you. This is not one of the most important adjustments on a sail, and it's often overlooked, but it can be beneficial to your boat's performance and to its longevity.
Essentially what you do with this control is to "tame" the leech. If you find that the leech of your sail is fluttering, and this can happen quite dramatically depending upon the wind conditions, you want to pull just enough tension on the leech line so that the fluttering ceases. As I mentioned, this fluttering can actually be a deterent to your performance and it is definitely a source of fatigue for the material that the sail is made out of. So use the leech line when necessary to promote better performance, and make your sail last longer. However, you don't want to over-tension the leech line either because that will be detrimental to your boat's performance. A leech line that's tensioned too much tends to make the leech of the sail hook to weather, thus disrupting the flow of air along that part of the sail.
You'll find that some sails have a continuous leech line that terminates at the bottom of the luff near the gooseneck. This is usually the case on larger boats where it might not be easy to access the clew of the mainsail because the end of the boom is so high.
Here's hoping that this information is useful to you.