Sail Cloth for the Average Sailor.

Traditionally sail cloth was made from flax,hemp or cotton canvas.

While cotton sailcloth is still available, most modern sails are made using modern synthetic materials.

These range from cheap and cheerful nylon and polyester to the expensive hi-tec carbon fibres.

Choosing a Sail Cloth

For anyone thinking of making their own sail, especially if it is a small sail and they are new to the process, they can easily and cheaply try out their ideas and make mock-up sails from the cheapest of materials.

Polly tarp is a cheap, cheerful and relatively easy material to test out your ideas on.

My first attempt at sail making was a polly-tarp sprit sail for a dinghy and it survived for a whole season before it began to fray and degrade due to UV light.

Nylon, while it is cheap, light and strong, is normally only used for spinnakers and cruising chutes because it does tend to stretch and is susceptible to UV degradation.

But by far the most commonly used material for leisure boating sails are the various types of Woven Polyester.

Polyethylene terephthalate, commonly known as Dacron is the most popular type of sail cloth for the average leisure boater due to its durability at a reasonable price.

Polyester sail cloth fabrics are sold under various trade names such as Terylene, Tetoron, Trevira, Diolen as well as Dacron.

The woven sail cloth is usually treated with a resin filler, which stiffens the cloth helps reduce stretch and makes it less porous.

Sail Cloth, Ballanced Lug

However, this stiffness and slipperiness does making it difficult to handle.

For small sails, a cloth with a minimal amount of resin filler will be softer, more easy to work on and easier to handle when hoisted.

Polyesters can be either Woven fabrics or Laminated fabrics.

Laminated fabrics have been developed to retain their shape for longer but they are considerably more expensive than the woven variety and the process of sail making is more complicated.

Sail Cloth, Junk Lug

Laminated fabrics are strong, light and will retain their shape for much longer, but at a price.

Laminates as the name suggests are made by gluing together numerous layers of scrim, extruded plastic and woven 'taffeta', all of which has to be paid for.

The other 'price' is the care you must take when handling them.

They tend to be stiff and susceptible to damage from flogging, chaff and careless folding.

They also require a great deal of expertise when building the sail.

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Weights, Weaves and Fillers

Sail Cloth, Standing Lug

Weight is the usual method of classifying cloth.

There seem to be several ways in which this weight is measured.

It can be the weight in ounces per square yard or ounces per linear yard in which case it will depend on the standard with of the weave.

Or it can be in kilograms and meters.

So at best it is only an indication of the strength and thickness a given cloth.

There are two methods for weaving sailcloth, either balanced or unbalanced.

In balanced cloth, the warp (the lengthwise yarns) and the fill (the crosswise yarns) are of the same weight.

With unbalanced cloth one of the yarns will be heavier to provide greater strength in one direction.

Most modern sail cloth has the heavier yarn in the fill (across the material).

Most new sailcloth also has a 'filler' between the yarns.

These fillers help to reduce stretch by bridging the gaps between the yarns.

The cloth is treated with a 'resin' then passed through rollers so the heat and pressure sets the filler between the fibres.

The fillers are also what make the sail cloth feel stiff and crinkly and slippery.

Unfortunately these fillers will, over time and with rough handling, break down.

Caring for Your Sails

A well made Dacron sail should last for years and years if it is looked after.

Over time it will stretch and become a bit baggy but while it might loose its efficiency, it will still be useable.

The two main causes of wear are flogging which damages the filler and UV light which damages the yarns.

Keep both to a minimum.

Make stowing you sails part of the tying up/anchoring process, something you do before taking off your sailing gear and relaxing with that coffee, or something stronger.

It only takes a few minutes to flake and cover a mainsail and while you are doing it check for and make note of any damage that should be repaired before hoisting it again.

If you have roller furling headsails make sure that the UV strip is covering the sailcloth.

It's all down to basic seamanship, look after your boat and her gear and she will look after you.

After all "She is worth it".

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