When sailcloth tears from wind pressure it is time for a new sail, but if you snag the sail or punch a sharp object through it, a well-executed repair will restore the damaged area to full strength.Repairing tears
Step one is spreading the sail over a flat surface and carefully realigning the torn edges. Tape the tear closed. For a tear that crosses a seam you need to repair each panel independently, then sew them back together.
In patching a tear, stitch at least 2 inches around perimeter and keep grain of the patch aligned with that of the sail cloth.
Repairing a tear requires a piece of sailcloth of approximately the same weight as that of the sail. Cut a rectangular patch to overlap the tear by about two inches, orienting the threads in the patch to parallel those in the sail. You should always cut sailcloth with a hot knifea soldering iron works finebut if you don't have one, seal the edges of the patch by passing them quickly through a candle flame.
With basting tape or a glue stick, attach the patch over the tear on the side opposite the tape. Sew around the perimeter of the patch with a square zigzag stitch or two rows of straight stitches. Now turn the sail over and carefully cut out the torn part of the original panel about an inch inside the perimeter stitching. If you use a hot knife, protect the patch cloth by slipping a heat shield through the tear and between the sail and the patch; a small piece of plastic laminate will do. If you use scissors, be very careful not to burn the patch when you flame-seal the cut edge. Now add a couple of rows of stitches around the perimeter of the hole and your repair is finished. Batten pockets
Cut away damaged cloth with a hot knife-if you have one.
When sailcloth and battens rub against each other, the cloth always gets the short end of the stick, so to speak. Batten pockets are inherently prone to chafe, and unfortunately so is the sail under the pocket, but batten pocket repairs look more complicated than they are.
The most common pocket damage is a split opening. This is easily repaired by restitching the leech edge of the pocket, but here is an instance where you will do better to make the repair by hand. Waxed sail twine
resists chafe better than machine thread. Use a No.16 sail needle, and put about five round stitches per inch to close up the end.
Repair the end of the batten pocket with hand stitching.
For chafed or torn fabric a patch is required, and that means removing the pocket, at least partially. Use a seam ripper to cut the stitching at the luff end of the pocket and along the sides as far as necessary to expose the damaged cloth. If the pocket has an elastic tensioner, release it from the sail, paying attention to how it is oriented.
Patches never go inside a pocket because their edges can hang up the batten. For the same reason, you don't want to cut out the damaged cloth. Instead, cut a piece of sailcloth (or sail repair tape) just large enough to
cover the damage and glue it over the tear opposite the pocket side. Now darn the tear by shortening the length of your zigzag stitch and sewing over it. With a straight stitch machine, shorten the stitch and sew back and forth over the damage. Next cut a rectangular patch to overlap the damage about an inch all around and sew it to the sail opposite the pocket side, aligning the thread lines.
Cut a rectangular patch to overlap the damage opposite the pocket by about 1 inch all around.
Damage to the pocket fabric is best repaired by replacing the entire pocket, but if it is limited to one end of a long pocket, replacing just the damaged end is acceptable. Be sure you sew the new piece on top of the old one (unless it is the leech end you are replacing) so the seam doesn't create an edge inside the pocket. Restitch the elastic tensioner, then glue the pocket edges to the sail and sew them.
Repair is made to the batten pocket.
Proper care is the best way to extend sail life so keep sails covered, avoid chafe and periodically have your sails restitched. But even cared-for sails wear and snag. If you can get the damaged area of the sail under the presser foot of your sewing machine, you can make the repair and be sailing again in a matter of hours. And hopefully this capability will make you quicker to deal with sail problems the moment you notice them. A stitch in timewell, you know.