The kind of advice available from Sussex Yachts in their Brighton Marina chandlery in the UK, is the advice they follow themselves in their Brighton sail loft. Brighton is on the South Coast of the UK and a mecca for sailing enthusaists. As a location Brighton is at the hub.
Sailmaking and Sail repairs
Handle sails with great care, make sure your hands are clean and the working area is free from patches of grease and dirt. Because of their flimsiness, light nylon ghosting sails and spinnakers should be handled very gently.
Sails are made from lengths of polyester or nylon cloth, cut into strips and sewn together The shape and configuration of the strips will control the shape of the sail and its fullness. Although modern sailcloths are stable, they will stretch if pulled diagonally across the weave. Stretch is not only affected by the direction of the pull, but also by the age of the cloth. Old sailcloth stiffens and stretches less than new. When repairing a sail, match the weave of the patch to the weave of the sailcloth, and use old sailcloth to repair an old sail.
The sail and the patch are likely to stretch when the sail is in use. Arrange the stitches that hold the patch so that they give slightly. This is achieved by working the stitches at an angle to the weave of the cloth.
A selection of sailmaker’s needles, a palm, a block of beeswax, and some polyester thread will be needed for repairing Terylene or Dacron sails. Nylon sails should be sewn with nylon thread, and cotton sails with cotton thread. Needles should be large enough so they part the weave sufficiently for the thread to pull through. A needle that is too large will cut the sailcloth fibres. If too small a needle is used, the cloth may be damaged by the thread. Most modern sailcloths can be sewn with 14-17 gauge needles.
Because of the manufacturing processes involved, modern polyester and nylon sailcloth can be cut without the need for heat sealing at the edge, or turning and sewing a seam. Both of these methods of preventing fraying, tend to distort the sailcloth and may impair the sail’s performance.
Older sailcloth which is likely to fray should be cut with an old knife heated over a stove until it is red-hot. As it cuts it melts the end of the fibres and prevents the cloth from unravelling.
Holding the sailcloth
One of the problems with sail repairing is that the areas of sailcloth are so large that it is difficult to keep the parts to be sewn in their correct alignment. Small patches can be glued with a few spots of Bostick Clear Adhesive before sewing. The glue will dirty the sail if it is used on long seams, and pins are likely to cause the seam to pucker. Sailmakers use a double-sided adhesive tape with which they glue the sailcloth before sewing. Rolls of this are commercially available and those planning to undertake extensive cruising should carry some of this tape with them.
The only other item of equipment that may be needed is a sailhook. This is a strong sharp hook tied to a lanyard which in turn is fastened to a convenient
post or fitting. It is used to hold the cloth while it is being sewn. In the absence of a hook, a woodworking clamp or similar simple device will serve instead.
Starting a seam
Tie an overhand knot an inch (25mm) from the end of the twine. Make the first stitch passing over the tail of the twine, which should then be laid in the direction of the seam and held down by subsequent stitches.
Knot and thread the new twine. Re-sew the last stitch and tuck the end of the twine between the pieces of sailcloth that are being sewn together.
Make a double stitch at the end of the seam and then back-stitch up the seam. Pass the needle beneath a couple of stitches and cut off the thread.
Sail repairs in Brighton Sail Loft
Chandlery retailing thrives in their busy Brighton Marina Chandlery, but Sussex Yachts has an equally successful business in their Brighton Sail Loft.
The herringbone stitch is used to repair tears in canvas or sailcloth. The cloth is laid flat and tensioned. The repair is started a short distance back from the rent, with the tail end of the thread laid along the edge of the tear. Each pair of stitches is pulled tight before making the next. If the cloth is weak, or tears easily, stagger the stitches.
A round seam is sewn by holding the edges of the seam together and passing a series of fairly loose stitches over the edge and through the sailcloth. The stitch must be loose, otherwise the twine will tear the cloth when the seam is rubbed flat. A double seam is made by reversing the cloth and folding a new seam. A second seam, similar to the first, is then sewn.
Sail patches are sewn with a flat seam. These are sewn with the cloth lying flat, and the tension in the stitching can be adjusted as the sewing progresses.
When a new length of twine is needed, the tail end of the old piece is withdrawn through one layer of sailcloth so that it lies inside the stitch and is sandwiched between the cloths.
Sewing leather or canvas reinforcements
Where additional strength is needed in a seam, a saddle stitch is used. A needle is threaded at each end of the thread, a sailmaker’s needle at one end and a round-sectioned needle at the other. Both needles pass through the same hole, a twist of thread being hooked over the sailmaker’s needle as it
emerges from the seam. As the thread is tightened, it forms an overhand knot inside the cloth.
Patching a sail
The repair patch must have similar stretch characteristics to the sailcloth, otherwise it will distort the sail, reduce its efficiency and cause stress to the new seams.
Cut a new patch to size, position it carefully over the rent in the sail, tape it and sew with a flat seam. Turn the sailcloth over, cut back the torn fabric so that it has a margin with the patch seam of approximately 1-2 inches (25-50 mm). Mitre the corners to allow for a 1/4 inch (6mm) fold and sew the inner seam.