How to pick the best downwind sail

Yachting World

How to set up your boat for smooth, stress-free downwind sailing and how to pick the best downwind sail: Rachael Sprot examines the options

For the coastal sailor, upwind sailing skills are critical: there’s nothing like a lee shore to focus the mind on tacking angles and leeway. For the ocean sailor the challenges are VMG, handling swell and avoiding a crash gybe, but ongoing developments in hull, rig, sail and hardware design have generated huge variations in how we do this. There’s a confusing array of kit and tactics to choose from, so it’s important to spend time on research before spending money on equipment to ensure you get the best downwind sail and setup for your needs.

The first rule of any big decision is to know yourself, your boat and your crew. Neil Mackley, of North Sails, explains: “The thing I most enjoy is sitting down with people and finding out about them. Are they comfortable handling a pole? Are they happy working on the foredeck or would they prefer to manage things from the cockpit? How much stowage space do they have?”

When it comes to the boat, one of the most important metrics is the efficient downwind sailing angle. Broadly speaking, light, flat-bottomed, modern yachts will sail much faster on a reach than on a run. Comparing the new Swan 48 with its predecessors illustrates these changes: the current model is 14% faster on a heading of 120° TWA than 150° TWA. The previous generations only have a 7% difference.

A spinnaker is an essential part of many tradewind cruisers’ sail wardrobe. Photo: Tor Johnson

Scrutiny of the polars for the 1995 Frers Hallberg-Rassy 46 gives a similar picture. When flying a spinnaker in 14 knots it makes 7.1 knots on a TWA of 165° and 8.4 knots on a TWA of 120°. The extra 1.3 knots accumulate to a 400-500-mile gain over a transatlantic passage, but the 45° difference in angle will cost far more in extra distance.

Heavy-displacement, traditional cruisers won’t make exponential gains by reaching. “Wherever possible I run the data through a velocity prediction program to find out where the sweet spot is,” Mackley says, “and for most cruising boats it pays to sail deep.”

Another consideration is how much you’re prepared to use the engine. The east-west transatlantic route is often light airs to begin with and reliable 20-knot tradewinds building through the passage. If the tradewinds are well south, do you carry enough fuel to motor to find them? Weight is a vicious circle: the heavier the boat the slower it is in light airs… To break the cycle you need a sail which can get you moving in under 10 knots of wind, but that may be a specialised sail with a narrow window of operation.

Symmetric spinnakers

“For a transatlantic crossing from Europe to the Caribbean where there’s a high proportion of deep angles, it’s hard to beat a symmetric spinnaker,” says Peter Kay of OneSails. Symmetric spinnakers are the traditional solution to running and they’re still a truly effective option. The pole brings the sail area out from behind the mainsail enabling wind angles of 165° or more.

Weather guru Chris Tibbs flying a symmetric spinnaker on an Atlantic crossing. Photo: Paul Wyeth

There are significant drawbacks, though. The pole work is labour intensive and tiring for a small crew. A 60ft boat flying a symmetric kite will need almost 200m of line for the pairs of sheets and guys. Add in an uphaul and downhaul and there’s a lot going on in the cockpit.

Reaching performance is limited. Although you can set the pole well forwards, you’ll normally need a jockey pole to push the guy clear of the shrouds and stanchions and a running sail will be cut too deep to work well on a reach.

“Although the spinnaker is one of the best tools for a transatlantic, most people don’t go for them because once you’ve arrived on the other side they’re less versatile,” Kay continues.
Andy Tarboton of Elvstrom agrees, pointing out that a spinnaker’s broad shoulders puts “more sail high in the sky, which can exacerbate rolling”.

Asymmetrics are usually flown from a bowsprit or the bow roller. Photo: Jean-Marie Liot

Asymmetric spinnakers

Removing the complexity of the pole, an asymmetric spinnaker is flown on a short sprit or the bow roller. Also known as gennakers and cruising chutes, there’s a huge array of asymmetric spinnakers on the market, with an equally confusing array of names. “Asymmetric describes a whole range of styles and performance envelopes,” explains Kay, “from something trying to be a genoa right through to something trying to be a spinnaker.” They all have one major advantage though, which is the ease of sail handling, making them the obvious choice for short-handed crews.

A running asymmetric can be designed to achieve very broad wind angles, almost comparable with those of a symmetric spinnaker. The luff of a running sail will rotate around the forestay as the sheet’s eased, giving wind angles approaching 165° TWA.

If you want to be able to furl the sail though, you’ll need something which is flatter cut and more of a reacher. “Realistically, you’re limited to angles of about 135-145° for sails on furlers, depending on sea state,” explains Mackley, “and then you’re covering a lot of extra distance.”

Oxley parasailers maintain their own shape without the need for a pole.

Parasailers

A sail which attempts to solve the compromise between reaching and running is the parasailer. It looks like a symmetric spinnaker with a pressure relief valve, but the mechanics behind it are very different. A large panel is removed from the upper part of the sail and a paraglider-style wing is suspended in its place. According to designer of Oxley sails, Ralf Grösel, this does several things: it creates lift, it gives the sail structure (similar to a soft batten), and it dampens the rolling motion that conventional spinnakers can generate deep downwind. The opening also acts as a vent, taking the bite out of gusts.

The wing lends structural support to the overall shape so you don’t need a pole. A parasailer can be flown in front of the boat like a symmetric or from the bow like an asymmetric.

There are two control lines on each clew: one running aft to stop the sail pulling forwards, and one running down to midships to counteract the lifting action of the wing. Ideally it is used without the mainsail as the wing performs better in an uninterrupted airflow. This will also help to keep the helm light.

A wing sail is quite an investment and will probably cost more than a single sail, but they should work for a wide range of wind strengths and sailing angles. “It’s like you’re getting two sails in one; a reacher and a downwind spinnaker,” says Grösel.

Handling-wise, a parasailer is a sheep in wolf’s clothing and, other than price, its main detraction is that it won’t deliver as much raw power as a standard kite. If you’re looking for something forgiving, it’s a serious contender.

A double tradewind sail is flown goosewinged but set on a furler. Photo: Shahid Hamid

Tradewind sails

Another slightly left-field option is the loose-luffed, double headsail, such as North Sails’ TradeWind sail, or Elvstrom’s Bluewater runner. Made from stretchy nylon like a spinnaker, but cut more like a large genoa, the pair of free-flying headsails are set on a furler making them easy to douse. They’re designed to be flown in a goose-wing configuration, with the windward sail set on a pole and the leeward one flying off the end of the boom.

It’s ideal for trundling down the rhumbline – known as the 180 freeway, says Mackley. “The rig is much more balanced. When you’ve got a mainsail and headsail up the forces are acting on the boat in different places. With the TradeWind sail you’re being towed from the stemhead.”

Article continues below…

downwind-sails-OneSails-Integrated-Furling-Structure

These can transform cruising yachts, giving them sufficient power to sail in light airs when previously crews would have been…

Meteorologist Chris Tibbs offers some pointers on downwind sailing…

After arriving, you can link the tacks together to create a single sail for light airs’ reaching up to about 100° TWA. The drawback is they’re not suitable for confined waters and are more costly because of the necessary furling equipment, and the fact there are two sails instead of one. The furler could be shared with a Code sail, however. Being made from lightweight polyester they are also no more squall-proof than a spinnaker.

Headsails

A poled-out headsail is consistently rated the most stable and stress-free downwind rig by ARC crews. It has a wide angle of effectiveness, from a dead run up to about 140°. From a safety perspective it’s a forgiving configuration: if you round up the headsail simply backs, which can be remedied by bearing away again. Dacron can cope with most weather that the Atlantic can throw at you so you won’t feel quite as vulnerable to squalls.

Most headsails can be poled out, though you want to keep the sail flat to reduce flogging in swell so a large genoa might have to remain partially furled. The key is to keep the pole and the sail independent of one another by giving the pole a guy which is separate to the headsail sheet.

Poled out headsails, whether in combination with the mainsail on the other side or another headsail, are rated as the most stable of downwind rigs. Photo: TimBisMedia

The headsail sheet needs leading to the end of the pole and routing aft. A snatch block attached with a strop or soft shackle to the beak works well. The sheet lead will be longer than normal so you might need to use a spinnaker sheet instead of your standard headsail sheets. Depending on the height of the clew, this can be hard to reach once the sail is up or furled, so needs planning.

Once the pole is braced into position, it’s a case of unfurling the sail to leeward, heading on a deep run and gybing the headsail across to the pole, being careful to quickly take up tension on the new sheet to prevent the sail from wrapping around the forestay. Position the pole at clew height and flatten the sail as much as possible.

To furl the sail, ease the sheet and furl it or, to reduce the load on the furler, gybe it across to leeward and furl it behind the main. Because it’s independently set, the pole can be left in position while the sail is furled if you need to manoeuvre or ride out a squall. Once the wind exceeds 18-20 knots most cruising boats will make good speed under this configuration.

Sailing wing on wing on the Oyster 575 Angels’ Share. Photo: TimBisMedia

Another variation for vessels with twin grooves in the forestay foil is to set two headsails and no mainsail. One can be set on the pole and a second sheeted to the end of the boom, which needs to be braced out using the preventer. It’s a bit of a performance to rig and de-rig, but once up it’s a stable rig which works from broad reach to broad reach. Since there’s no work involved in gybing, it could be a great short-handed solution.

Code sails

Although not technically downwind sails, Code sails are free flying headsails for close reaching in light airs. They do a similar job to a big genoa so are useful on yachts with fractional rigs and small foretriangles, and are popular on multihulls. There is a place for them when cruising, especially if you’re keen not to resort to the engine when the wind is light. For example, OneSails’ Flat Furling Reacher or FFR is a cross between a Code 0 and a genoa, with a range of 50-130°. It fills in the gap between a headsail and a deep running asymmetric so is a useful addition to the sail wardrobe but is unlikely to play a big role in a tradewind crossing.

A big light airs sail for a big boat: a Jeanneau Yacht 60 reaching under code sail. Photo: Gilles Martin-Raget

Headsail handling: Furlers

Spinnaker handling has been revolutionised by furlers, allowing the sail to be doused from the cockpit. Continuous line furling technology has developed across from Code 0s but with one key difference, spinnakers are better furled from the top and not the bottom. On a Code 0-style furler the tack is fixed to the furling drum, on a top-down furler the tack is free to swivel.

The furling motion on a top-down furler is transferred to the head of the sail via a heavy duty anti-torsion cable. Furling a spinnaker this way is much more effective as the sail cloth locks down on itself making it less prone to spilling open.

The OneSails Integrated Furling Structure sail uses continuous fibre technology to replace the
anti-torsion cable. Photo: OneSails

There are also reaching spinnakers with luff cables built into the sail, and more recently, ‘cableless’ furling sails which have a structured luff using laminate technology, micro-cables woven into the sail or soft luff cords. Removing the anti-torsion cable saves weight and makes the sail easier to handle, but it might not furl so well in sub-optimal conditions. The systems with a torsion cable will probably cope better when you’re caught off guard.

The advantages of a furling spinnaker for short-handed crews are obvious. Not only do they make a single-handed spinnaker douse from the cockpit possible but they also reduce the volume of the sail, making it easier to stow.

However, there are drawbacks. Most furling sails will be too flat to perform well on deep angles. Sails with an external luff cable will do better than those with inbuilt cables because they’ll be able to project around the forestay more, but you still can’t have a proper, broad-shouldered runner on a furler.

It’s tempting to leave a furled spinnaker up to sit out a squall, but that’s not recommended: even ‘locking’ furlers are not totally reliable. If you do decide to leave one up, Neil Mackley suggests using a soft shackle or carabiner to secure the drum. Be aware that most spinnakers also won’t have UV protection.

Spinnakers are easiest to douse top down with a snuffer. Photo: Richard Langdon

Headsail handling: Snuffers

Getting a spinnaker down is always the hardest part of the process. Snuffers have been around since the 1980s when French designer Etienne Giroire refined the DIY socks which solo sailors such as Eric Taberly were using.

Giroire realised that the lines for raising and lowering the sock needed to be contained within a separate sleeve to prevent them from tangling with the sail. He also noted that the two control lines had very different jobs: the line for pulling the sock up can be light weight because once the sail starts to fill, the snuffer practically raises itself. The line for pulling the sock down needs to be strong and of twist-free construction. He went on to found ATN, which has sold over 30,000 snuffers. The oval plastic mouth has been replaced by a canvas hoop for larger yachts, while some manufacturers now offer inflatable rings to make stowage easier. Other than that, the design has changed little over the years.

The one drawback is that they require someone on the foredeck to heave down on the sleeve, which can be hard work in high winds. A ratchet block on the deck gives a bit more control over the down line. Bearing away and sheeting in will blanket the sail, and – if that still isn’t enough – you can blow the tack and the sail will flag behind the main.

Snuffers can be retrofitted to most sails including big symmetrics. They are a bit less elegant than furlers, but much more economical and a bit less tricksy.

No system is foolproof, and both snuffers and furlers can fail. If they do, you need to be able to drop the spinnaker conventionally. Make sure that you’re all clear on how you would do it on your boat.

Regular rig inspections are essential on downwind passages. Photo: Tor Johnson

Conclusion

When it comes to downwind sailing, the only thing most people can agree on is that a poled-out headsail is the bread and butter. What you choose to add on top of that is up to you and will depend on variables such as budget, crew, boat, and other cruising plans. Even with a perfect sail set-up, sea state can make it impossible to hold an optimum course – as last year’s ARC participants found when a nasty cross swell developed.

Very few sails can deliver both reaching and running functions, apart from the parasailer and ‘tradewind’ sail, neither of which are high-performance options.

Elvstrom’s Andy Tarboton notes that the most common choice for people taking a single sail is somewhere in the middle ground, such as a mediumweight asymmetric. Peter Kay at OneSails would choose a deep running asymmetric spinnaker, if he could only have one, and a FFR (Flat Furling Reacher) if he could have two. North Sails’ Neil Mackley was drawn to the symmetric spinnaker: “It’s a very efficient sail downwind, but because of the pole it’s a hard one to have in the inventory.” The tradewind and a Code sail would be a versatile combination for more conservative cruising.

Understanding the sail’s capabilities and your own limitations will make for efficient sailing. Work out where your priorities lie on a scale of fun to comfort and ask an experienced sailmaker to narrow down the options.


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