R lewis of kentucky. Here is the skinny on the leech cord. The leech cord is really not a sail trim devise. It's main purpose is to stop the leech from fluttering BUT it does have some sail trim advantages. When you are sailing upwind you want to tighten it just enough to stop the fluttering. When you are reaching or running you want to pull on it some more. What you are doing is bending the battens to give the sail more shape or depth. The tight leech cord prevents the top batten from bending off. Why is a severely cupped sail not good for closehauled work? Remember when we talked about the wind tunnel example of smoke blowing over the sail? Picture that in your mind and think of how tough it is for the wind to get around a cupped sail and you can see why it is not a good thing. Something else that is not a good thing is too much draft depth. In general terms, about the max amount you want to induce is about 30%. So how much is 30% you might ask? Simple, measuere the foot of your sail. Say it is 10'long. 5' would equate to 50% and 3' would equate to 30%. So if the skipper (or my Sail Trim Chart)calls for a DRAFT POSITION of 50% and a DRAFT DEPTH of 30%, you know exactly what I'm talking about.