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October 5th 2018. By Rupert Holmes.

Guide to sails

Rupert Holmes analyses the pros and cons of different cloths, sail types and batten choices.

It’s often thought that the finer points of sail shape are of concern only to racers and speed freaks. However, good sail shape makes cruising less hassle and more comfortable. In particular, the boat will be easier to handle – poor sail shape results in unnecessary heel, which in turn creates weather helm that makes steering difficult.
Even those who are in the market for the most economic sails need to recognise that the lowest price may well not provide the most cost-effective sails in the long term. The choice of cloth is one of the most obvious factors that create a pricing differential, but there are other significant factors as well. In particular, finishing details are important – the right hardware makes a big difference, while additional reinforcement in high-stress areas such as the leech and around reef points will add to both the reliability and life-span of a sail, but at the cost of increased up-front prices.
It’s always worth getting quotes from a number of different sail makers, but make sure you are comparing like with like when you do so. In addition to the above considerations, different sail makers provide varying levels of service in other respects. Wherever in the world a sail is made, if possible it’s worth getting a sailmaker to visit your boat. That way you can discuss options face to face and the sailmaker is able to take all the necessary measurements. This second point is an important one if, once delivered, the sail doesn’t fit perfectly.

Larger yachts like this Discovery 55 generally have twin head stays for a small and efficient jib, plus a larger genoa.

Types of sail cloth

Woven Dacron (polyester) cloth is still by far the most popular for cruising yachts as it’s both economical and long lasting. Many of today’s fabrics are also superior to older cloths, offering superior shape holding and ultimate longevity, although that may not be true at the bottom end of the market.
Better quality fabrics will stretch less when under load, which helps to maintain an efficient sail shape. This may not sound important to cruisers who are not particularly interested in speed, but that’s not the case. When a sail stretches it produces less forward drive, along with increased heeling force. This in turn increases weather helm, which makes the boat more difficult to steer and can create a more uncomfortable motion.
There are a number of key ways in which the stretch in woven fabric can be minimised when it’s under load. The single most important attribute is a tight weave of quality fibres. After weaving all Dacron sailcloth is immersed in a resin bath to shrink the material and bind the fibres together. Poor quality cloth is overly dependent on this resin finish to hold a loose weave together. The problem is the resin breaks down as the sail ages, severely compromising the ability of an inferior cloth to resist stretch. The more the sail is allowed to flog or flap the faster this process occurs.
Full battens therefore make a lot of sense for a slab reefed sail – they drastically reduce flogging, which in turn significantly increases the lifespan of the sail. This is true even for those who tend to motor-sail to windward, when a sail with short battens will have a tendency to flog. Worse still, the flogging of a short-batten sail will cause hinge failure of the fabric at the inner end of the batten pockets, even if there’s extra reinforcement.
Quality sail slides or car systems make a big difference to the effort required to hoist or lower a sail, especially on boats over around 35ft, where the loads are greater. They also facilitate reefing – the days in which it was impossible to tuck a reef in with a following wind are long gone. This adds to both safety and convenience.
For anything other than a daysailer that’s only used in the best of weather specifying a sail with three reefs is usually the only sensible decision. A possible alternative, however, for a smaller boat that you want to keep simple is a pair of ultra-deep reefs.

In-mast reefing

Similar considerations also apply for in-mast reefing systems, with the arguable exception of mainsail battens. As these have to be vertical they play relatively little role in reducing flogging – instead they are used to support extra sail area in the roach of the sail.

High-tech fabrics

The advent of laminate sails a few decades ago was the biggest change in technology since woven Dacron ousted cotton in the 1950s and 1960s. Irrespective of the type of material used for the yarn these stretch far less than a woven sail cloth, especially as they age. This means a good high-tech sail will retain a shape close to that intended by the designer until the sail is structurally unsound. This is fundamentally different to woven sailcloths that immediate start to lose their desired shape.
In the early days longevity was a problem, meaning these materials were solely the preserve of the best funded racing yachts. But those times are long gone – providing they are not badly abused, and any repairs needed are carried out promptly, a good suit of today’s sails will last for 15,000 to 20,000 miles. Those who clock up most of their distance on ocean passages may well see even larger mileages.
Good longevity is particularly true for fabrics aimed at the cruising market that are predominately made of (non-woven) polyester, Dyneema and similar fabrics, rather than carbon. Traditionally laminate sails relied on a layer of Mylar to hold the fibres in their correct locations. When this begins to break down the sail is nearing the end of its life, again though prompt repairs have the potential to extend this by several seasons.
Some of the latest fabrics, including North’s 3Di Nordac, have eliminated the Mylar layer, which promises even greater longevity, while maintaining minimal stretch throughout the life of the sail. These materials are the closest we have at the time of writing to the Holy Grail of a fabric that has no stretch and yet lasts forever.

Sail shape is important even for cruisers – when the cloth stretches in a gust, or through old age, both the heal angle and weather helm increase to unnecessary angles.

Roller reefing headsails

The advent of these revolutionised sailing, but at a cost. Even with a padded luff it’s impossible to build a sail that will maintain an efficient shape both when unreefed in light airs and when deep reefed in strong winds. Part of the problem is the need for a heavy-duty UV strip that protects furled sail from the sun. As each successive reef is rolled in, the effective extra thickness at the top of bottom of the sail means the middle becomes baggy.
However, there are alternatives. Many performance oriented boats eschew the convenience of the UV strip for a cover that zips over the furled sail. While this is a hassle to rig, the performance of the sail is markedly improved. A half-way alternative is a light-weight uv-strip – or even one that’s painted on – to give some protection to the sail while it’s not being used during a cruise. The full cover then only needs to be rigged once the boat when the trip is over.

Deep reefed roller genoas with heavy UV strips invariably set badly, with far too much bag in the middle of the luff to be efficient.

Heavy weather and storm sails

Storm jibs and trysails are important for the safety of offshore yachts that may meet challenging conditions. However, it’s not simply enough to carry these sails on board – it must also be possible to deploy them easily.
For a trysail this invariably means a separate track mounted on the outside of the mast so that the sail does not have to use the same track as the mainsail. This arrangement allows the sail to be set up at the base of the mast before the onset of heavy weather, ready for quick deployment when necessary. As well as the advantage of it being a smaller sail, using a trysail eliminates the possibility of damage to a deeply reefed mainsail in severe conditions.
Consideration also needs to be given to how storm jibs are deployed on yachts with roller furling roller reefing genoas. There are some types that are designed to pass around the reefed genoa, but these can be very difficult to set up in a big wind and heavy seas. A much better option is a removable inner forestay that allows the sail to be set up next to the mast and in readiness for stronger winds. In the past these stays were invariably made of stainless steel and therefore relatively unwieldy – Dyneema is a better option and has acceptable longevity.
This stay can also be used for a hanked on heavy weather jib that can be used to make ground efficiently to windward when the wind speed is well above 20 knots. This sail can even be made extra robust and with a slab reef so that it can be reduced to storm jib size.
On yachts above around 40-45ft designed for serious passage making it has become increasingly common to have twin headstays permanently rigged. A roller furling genoa is set up for general use on the outer stay, along with a smaller heavy weight jib, also with furling gear, on the inner stay.

Downwind sails

The last decade has seen an enormous change in the simplicity of gear for handling asymmetric spinnakers and Code Zero type sails, much of it as a result of developments in the long-distance solo and double-handed racing arena. As a result it’s now feasible to equip even heavy cruising yachts with efficient sails that will keep them moving without resorting to the engine when reaching and running in light airs.
Code Zeros are very effective close reaching sails in light airs, when they can provide enough power to drive a yacht as fast as the true wind. As the breeze increases, they can be used as more of a reaching sail, with a 90 degree true wind angle in 10 knots or more, and with the true wind angle as far aft as 130 degrees in significantly stronger breezes. It’s worth noting that Racing Code Zeros are something of a compromise sail that’s larger than ideal so the rating rules see it as a spinnaker, rather than a genoa. This, perversely, can make cruising Code Zeros more efficient sails than their racing counterparts.
Modern asymmetric spinnakers have a very different shape to old-school cruising chutes. The latter were relatively flat cut sails with very little area that could project to windward of the forestay, with the result that they would collapse behind the mainsail on a broad reach and need to be poled out to goosewing on a run.
In flat water the best of today’s asymmetric kites, however, can be used with wind angles as deep as 150-160 degrees, with a significant proportion of the sail’s area projecting to windward of the forestay. In a quartering sea it won’t be possible to keep the sail as stable this close to a dead run, but luffing up around 10 degrees is generally all that is needed.
Don’t be talked into a very lightweight fabric for a spinnaker on a cruising yacht – anything below around 0.75oz for ripstop Nylon will lack robustness in exchange for the benefit of being only very marginally easier to fill in light airs. Code Zero fabrics are generally a very light weight laminate material – even though they are normally only used in very light airs, as the wind angles are further forward they experience stronger apparent wind speeds.
Both Code Zeros and asymmetric spinnakers can be fitted on furling gear – usually mounted on a short sprit – to facilitate sail handling. This equipment even makes gybes easier as the sail can be furled before the manoeuvre and then unfurled once the boat has settled onto its new course.

A Code Zero – usually set on a furler on a short sprit – can transform the experience of sailing on a reaching course in light airs.

Sails for new boats

Most new boats are sold only with economy sails as standard. These are often of a lighter and lower-grade cloth than you might choose, which means they lose shape early in their lifespan and ultimate life can be disappointingly short. It’s therefore always worth asking the dealer about upgrades for sail options – or even asking for a price for the boat without sails that allows you to choose your own sailmaker independently.

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Rupert Holmes has more than 70,000 miles of offshore cruising and racing experience, in waters ranging from the North Sea to the Southern Ocean and Cape Horn. He writes about all aspects of boat ownership and marine travel, including destinations, seamanship and maintenance, as well as undertaking regular new boat and gear tests. He currently sails around 5,000 miles per year and in the past couple of seasons has cruised from the UK to the Azores, as well as winning his class in the 2014 two-handed Round Britain and Ireland Race. He also owns two yachts, one based in the Mediterranean and the other in the UK.