When thinking about the care, maintenance and repair of sails it helps to have some understanding of the properties of the ever growing range of modern sailcloth and the fibres they are made from, as opposed to the traditional canvas sails of the past.

Many boat owners send their sails off to their sailmakers to be laundered, checked, repaired and stored for the winter. Whether it is the sailmakers who do this work or the owners themselves, they should then be stored in safe conditions for the winter, out of harm’s way. It is a false economy to leave sails on the boat or store them in a damp garden shed as this will more than likely shorten their life considerably.

One of the most critical things to do is to wash or hose down the sails to remove dirt and salt. The other is to store the sails where they are safe from moisture, extreme temperatures and pests, all of which can inflict damage to sails over prolonged periods. Before going into details of basic sail care advice and maintenance, here is a quick aide memoire on types of sailcloth and sail construction.

Types of sailcloth

Some sail fibres are tougher than others, some are very light, others are more stretchy, some are best for racing sails, others for cruising sails, some are ideal for spinnakers, some are designed to stand up to the harshest marine environment. Added to which, sailcloth varies in price quite considerably.

Being aware of what materials your sails are made from is a good idea, as some materials require more sensitive treatment to others. For example, flex resistance is critical to the longevity of a sail. If a sail can flex without being damaged then it is going to last longer as the fibres that make up a sailcloth are flexed every time a sail is folded, creased or flogs in the wind.

Other sailcloth is impregnated with UV inhibitors to protect it from the sun’s harmful rays, providing a sailcloth which is both tough and durable.

The main types of sailcloth are:

• Polyester – the most commonly used sail fibre, being strong, long lasting, has good UV resistance, good flex ability and is comparatively inexpensive. Woven polyester is often called Dacron, the brand name given by DuPont to their Dacron yarn introduced in 1951 and known as Terylene in the UK. Polyester fabric is used as a stand alone woven sailcloth and is also a component part of laminate sailcloths which are impregnated with resin to reduce the stretch and make them airtight. This gives better sail performance than basic Dacron but on the downside means they are less durable. PEN polyester is one such variation.
• Nylon – lightweight and strong, making it ideal for spinnakers and gennakers. It absorbs shocks well and is stretchy, which is less of a problem for downwind sails as it is not so critical for them to hold their shape as it is for upwind sails. Note that nylon is easily damaged by exposure to chlorine, so never use bleach when cleaning nylon sails.
• Aramid – fibres include Kevlar, Twaron and Technora. These are all lightweight performance fibres which are used for racing sails. They are also used in some laminated cruising sails. Aramid fibres are sometimes mixed with carbon fibres, resulting in very low stretch, high strength sails.
• Vectran – a liquid crystal polymer fibre. This has excellent flex life and low stretch on the plus side but poor UV resistance and is expensive.
• Ultra PE – fibres are processed polyethylene and include Dyneema and Spectra. These fibres have good UV resistance, very high strength and very low stretch. Ultra PE is expensive but has a long life and is often used for upmarket cruising yacht sails.
• Carbon fibre – has very low stretch and very good UV resistance. Carbon fibres are used widely for top end high performance racing sails. Their weakness is that the fibres easily break if they are flexed sharply, for instance if the sail is creased when a sail is folded, making them vulnerable if they are not properly handled.

Sail construction

Sails are designed to have depth in their shape to make them work as efficiently as possible. One way a sailmaker adds shape to a sail is to add some curvature to the edges, particularly to the luff and foot but also to the leech. So when a sail with curved edges is hoisted up a straight mast the result is the sail has depth in it, which will help its performance.

Another way the sailmaker creates depth is to add curvature to the seams of panelled sails. This has a distinct advantage over edge curvature because depth can be added exactly where it is needed to give the best performance. A combination of these two factors is desirable and knowing this can help when ordering new sails.

Ultraviolet exposure

The two worst enemies of sails are salt and sunlight. All sails suffer from exposure to ultraviolet rays although certain sailcloths are more susceptible than others. The UV rays degrade sailcloth and stitching by changing the chemical properties of the material, breaking down the chemical bonds of the fibres and rotting the stitching through the process known as ionization. This causes the sailcloth to become weak, easily torn and eventually it breaks down completely. During the sailing season, the best protection from the sun is to remove the sails immediately after use but this is not always practical on larger boats where several crew may be required to do this.

The importance of having UV protective strips for furling headsails and boom covers for mainsails is therefore vital. If part of a mainsail is left exposed by an ill-fitting cover then it will degrade quickly and likewise an incorrectly furled headsail can leave sections of the sail unprotected if the sail has been furled the wrong way round – the UV cover has to be on the outside, which is a mistake easily made. So it is always worth double checking your sails are UV protected as much as possible through the sailing season to prevent them from becoming damaged, ensuring mainsail covers and UV strips are used and maintained properly. The stitching of covers and UV strips is susceptible to damage and is likely to need replacing more frequently than the sails’ stitching.

UV damage warning signs

The first signs of UV degradation of a sail is stitching failure. To check, look first for any stitching that has become unstitched, which will more than likely be caused by UV damage.

You can also test the strength of the stitching by plucking it gently with a sail needle or pointed tool. The thread should be able to be plucked without breaking but if it is in poor condition it will be easily broken. If this happens then ask your sailmaker to take a look and they may advise re-stitching the sail to strengthen it.

Another obvious sign of UV damage is discolouration of UV strips and any coloured materials on the sails, especially reds, oranges and yellows which fade more quickly in the sun than blues and greens. Also, white Dacron sails fade to a grey colour as they become UV damaged, a sure sign of a weakened sail nearing the end of its life.

Read more about sail checks, cleaning, stain removal and sail care tips in: Sail care and maintenance – part two here.