Holes, tears in canvas. Dry sail. Cut patch of canvas, making cuts parallel with weave of cloth. The patch should overlap the hole in all directions at least 1". Allow 1" extra to compensate for shrinkage. Place patch in position on sail parallel to sail weave, turn under edges and draw line on sail around patch. Then baste patch in place, allowing some give in the fabric around the edges. Then stitch around the patch close to the edges. Use linen or cotton thread. Turn sail over and trim out edges of hole, but leave a margin. Turn under the sail edges. Then sew these down with zigzag stitches.
Holes, tears, rips in nylon or Dacron. Dry sail. Cut a piece out of adhesive-coated nylon or Dacron sold by marine dealers, smooth over hole, and let dry.
Rips in canvas sail. With doubled cotton or linen thread, stitch together with herringbone stitch. Do not knot the thread at start or finish, but cut it off 3" or more beyond the ends of the stitching. This will permit sail to shrink without puckering.
Stitching in batten pockets worn. Remove batten. Stitch pocket to sail with doubled cotton, linen, or synthetic thread.