When I had to repair the leech on my genny, I searched the internet for information to repair sails. There is a great deal of info on the subject. I pulled the sail, and using a standard sewing machine, repaired a 6' foot section with a zig zag stitch and some polyester thread. The leech section I replaced was the part that holds the leech line. The only regret I have is that I should have replaced the entire piece. While I haven't detailed how to do it, the point is that YOU CAN do it. Helpful tips: sail cloth is slippery. tape or double backed sticky tape the pieces to intend to stitch. This keeps them from sliding away from you. Do tests to get the right zig zag stitch. I tried to emulate the stitching on the sail. If you are cutting sections of cloth, use a flame to singe the edges to keep the fibers from unravelling (similar to treating the end of cut lines. Get someone to help you feed the sail through the sewing machine. Good luck.
