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Downwind sails: How to pick the right one and fly it

Sailing downwind can be slow without extra canvas. Rachael Sprot explores extra sail options and lists the pros and cons of downwind sails

The words ‘pink spinnaker’ are enough to send a chill down the spine of anyone who’s ever watched Cowes Week disaster footage. There’s Atalanta of Chester, which dis-masted when their fuchsia-coloured kite wrapped around the anchor of a tanker in August 2011. And who hasn’t seen the iconic image of Silk II as she nose-dived into the Solent in a 40-knot squall? It’s enough to put you off the big downwind sails for life.

But, like it or not, as you bear away through the wind angles you need additional downwind sails to maintain good passage speeds, rather than languishing under white canvas. The good news is that in the last two decades we’ve seen huge advances in sail design and sail handling technology. Asymmetrics, code sails, snuffers, furlers and laminates have all become much more accessible to us humble cruisers. But which of these sails would most suit you, your boat and your cruising plans?

I joined Mathias and Sybille Keim on board their brand new X5.6, Pure Fun, in Southampton to compare their gennaker, Code Zero and Parasailor spinnaker. Under the old racing rules a spinnaker was any sail where its width halfway up was 75% or more of the foot length.

A sail with a 10m foot length would need to be 7.5m across at the mid-height to count as a spinnaker. Anything below this was a headsail. These days, there’s a complex spectrum of sails which fall between a spinnaker and a genoa but few industry-wide definitions for these hybrids. Terms such as cruising chute, gennaker, asymmetric and reacher can all be used to describe the same sail. However, code sails, asymmetrics and the Parasailor are fairly distinct families.

For racing, a Code Zero counts as a spinnaker as its ‘mid-girth’ is more than 75% of the foot length. Less than that and it’s a headsail. In cruising, definitions and measurements are less strict. Photo: Richard Langdon/Ocean Images

Downwind sails: Code Zero

At the closest end of the scale to the genoa is a code sail, sometimes known as a Code Zero. These are big reaching sails, which set independently of the forestay on a furler. They’re usually made of a laminate if they’re designed for close-reaching, and spinnaker-style medium weight nylon for larger sails and beamier angles.

Much of their power comes from the vast sail area, but shape is also important. There’s usually a semi-rigid cable in the luff which gives stiffness and allows the sail to be furled, although some ‘cableless’ sails are now in production.

Whilst the luff is straight, the leech is curved like a spinnaker which accelerates the airflow over the top of the mainsail. This creates power in light airs and should dramatically reduce motoring time. Generally used between 80 – 120° TWA (true wind angle), larger code sails can reach deeper in stronger winds and smaller, flatter sails can point higher. They’re particularly useful for boats with small foretriangles where a large genoa can’t be accommodated, especially boats with self-tacking jibs.

Rigging

Rigging a Code Zero is straight-forward, although it may require modifications to the boat. Firstly, it needs to set forwards of the forestay for maximum airflow. This was easy on the X5.6, which has a sprit with an integral electric furler. Without this you might need to modify the bow roller or fit a removable sprit.

Most boats will use a manual furler with a continuous-line furling drum, with the line taken back to the cockpit. The drum remains attached to the sail, and is removed from the sprit when stowing. Code Zeros also require greater halyard tension to furl well, so their halyards often have a 2:1 purchase system to cope with the increased loads.

A 2:1 halyard purchase is needed for sufficient tension, and to stop the top drum twisting when furling. Photo: Richard Langdon/Ocean Images

Unlike a spinnaker, the halyard should not articulate as that will stop it furling.

The sheet needs to be led well aft, probably to the same point as the spinnaker. A single sheet on the clew will suffice because you can’t gybe or tack a code sail due to its proximity to the forestay, so it needs furling for the manoeuvre. Since they’re used for reaching rather than beating or running this is rarely an issue.

The furled sail can be hoisted to windward or leeward of the headsail. With a 2:1 purchase system on the halyard the hoist is relatively easy, even on a big sail such as that of the X5.6, but there’s twice as much line to pull through so it can be slow going.

If the headsail is set, then hoisting it to windward works better as it will snake its way up the sail, pulling forwards and clear of the forestay once halyard tension is established. With the headsail furled a leeward hoist works better as it keeps the code sail clear of the genoa sheets and furling gear.

You can hoist the Code Zero in harbour and leave up while sailing. Photo: Richard Langdon/Ocean Images

Setting and trimming

One advantage of the Code Zero is that it can be hoisted in port and left furled until you need it. The body of the furled sail can disrupt air flow over the headsail, as well as taking some tension off the forestay, reducing the headsail’s efficiency, but this might be preferable to foredeck work at sea.

Since the wind strength in the central Solent was a good Force 4, we were close to the top of the sail’s maximum wind speed. We found shelter in Stanswood Bay and the electric furler seamlessly opened the sail as we took in the sheet.

A magnificent ivory behemoth appeared. We instantly set off with purpose, making over 8kn in just 9kn of true wind. As we ventured further offshore the wind was stronger and we bore away until we had 10kn apparent just abaft the beam.

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Now the true wind was 13kn from 130°and we were making around 8knots. If we hadn’t had the code sail we’d have either had to cling on to a gennaker, or put up with much slower speeds under the headsail. It filled the gap between these two sails beautifully. We lost the impact of the sail at about 140° TWA, or 110°AWA where the wind dropped to only 7knots apparent. Even so we made 6knots through the water.

Unlike a roller-furling genoa it can’t be used partially rolled up, so it’s for light, stable winds only. The feeling of power was quite intoxicating but I was conscious that a moderate gust could have put serious loads through the rig.

Furling

On a manual furler it would be laborious to douse if the wind suddenly decided to pick up. As it was, the electric furler made short work of it; we simply bore off to blanket it behind the main, minimising the apparent wind speed, and eased the sheet as swiftly as possible without inducing too much flogging, which would work with a manual furler too.

Top tip: A Code Zero is the largest headsail you can have that doesn’t count as a spinnaker. It is defined as a sail where the mid-girth – the width of the sail from luff to leech – is no more than 75% the length of the foot. More than this and you’ve got an asymmetric spinnaker. While racing rules are irrelevant to cruisers, a light sail with a reasonable pointing angle can go a long way to keep you sailing in light airs.

The sail may need a tug when you start hoisting the sock, but once the wind catches it, it will unfurl rapidly. Photo: Richard Langdon/Ocean Images

Downwind sails: Asymmetric

Asymmetric spinnaker are best used for deeper angles without the fluster of polework. They come in a huge range of shapes and sizes and can be optimised for reaching, running or somewhere in between.

Racing yachts would carry several different asymmetrics with a numbering system to differentiate between running and reaching sails and their designed wind strength. Cruising yachts tend to carry one all-purpose sail, optimised for the mid-range of wind angles and strength, often referred to as a gennaker.

The cut of a gennaker depends on whether it is to be used on a furler. Furling sails need a straighter luff which limits how much belly it can have. A furling sail will
have a semi-rigid ‘torsion cable’ strung between the head and tack, but not usually sewn into the sail. This cable is attached to a top-down furling device which winds the sail
away from the head.

Deep running sails can’t be used with a furler as they’re too big and baggy, although technology is improving all the time and this may soon become a reality.

A barber hauler controls the sheeting angle and helps make the sail more stable. Photo: Richard Langdon/Ocean Images

Rigging and setting

Ideally, an asymmetric should be set on a bowsprit to give it clean air. However an inexpensive ‘tacker’ device negates the need for retro-fitting a sprit by tethering the sail’s tack to the forestay, but limits the amount of canvas that can be carried.

Pure Fun had a 225m2 all-purpose gennaker from Elvstrom in a snuffer sock with an inflatable collar (to minimise stowage space). It needs three lines to set: a tack line run to the bow, a pair of sheets run well aft and a halyard running through an articulating block on the mast crane. Ideally, the tack line is taken back to a cockpit winch or jammer so it can be adjusted underway.

Sails on furlers don’t have a tack line as they attach via the furler straight to the deck.

Even when contained by a snuffer or furler, a spinnaker should be handled with care and not left lying around where it might fill with air – unlike a Code Zero it can’t be rigged in harbour beforehand. The usual spinnaker handling rules still apply: remember to clip on the bag and don’t attach the halyard until you’re ready to hoist or else a big gust of wind could make it ‘live’.

Hoisting the sail in the snuffer is simple: connect the tack line and sheets to the sail and attach the halyard to the strong point on the snuffer. You’ll need to decide whether to set up for inside or outside gybes and lead the lazy sheet inside or outside the halyard. Most cruising boats with short sprits will find outside gybes easier as there’s limited clearance between the forestay and luff.

Keep the control lines on the snuffer tied down until you’re ready to hoist so that the spinnaker can’t take matters into its own hands. Unless it’s on a furler it should be hoisted to leeward like a symmetric kite.

As ever, a deep broad reach where the gennaker is partially shadowed by the main will keep the drama to a minimum when you unveil it. Once the halyard’s set, raising the snuffer is easy; it practically lifts itself once the sail starts to fill with air. Whoever’s on the snuffer lines needs good gloves as there’s no winch between you and the power of the kite.

When Pure Fun’s bright yellow sail appeared from its chrysalis there was an exhilarating feeling of power. She took off and we scrambled to keep up with her.

Top tip: Woolling a spinnaker is an old technique which can come in handy if you want to re-hoist it. Simply work down the luff and leech of the sail, tying it up like a string of sausages every metre or so. You need to use a soft wool which will break easily; natural fibres are kindest on the sail and environment.

Sailing deep angles can be tricky as the sail can be blanketed by the main. Photo: Richard Langdon/Ocean Images

Trimming

Gennaker trim is a hybrid of spinnaker and genoa trim. Flatten it out and turn it into a conventional triangular sail for reaching. When running the sheet needs easing so that it comes out in front of the boat.

When racing the sheet is constantly in play to keep a slight curl on the luff. For cruising, ease the sail and find the curl then tweak it in.

As you bear away you want the sail to take the shape of a more conventional spinnaker and come out from behind the shadow of the main. A slight ease on the tack line can help, but beware of easing it too much, it makes the sail less stable as it sets further out to leeward.

Like a symmetric spinnaker, a barber hauler helps to bring the sheeting angle forwards and keep the leech closed on deeper angles. This is important in stronger winds to improve stability.

Flatten the sail and ease the barber hauler to sail higher. Photo: Richard Langdon/Ocean Images

The key with any spinnaker flying is to keep the pressure in it. When you’re trying to make ground to leeward in light airs this is largely down to the helm: coming up to create some apparent wind in the lulls and bearing away when the pressure allows. It’s hard work to do manually and challenging for an autopilot so you’re unlikely to achieve the same performance promised by sail makers.

On Pure Fun we found the true wind angle range to be between 125° and 160°, which equated to 70°- 145° apparent.

Top Tip: A barber hauler is an adjustable line to control the sheeting angle of a spinnaker. This can easily be added by attaching a block or low friction rig roughly half way between the cockpit and the shrouds. A second block or ring, through which the spinnaker sheet passes, is attached to a line that runs through the turning block and back
to a winch or cleat in the cockpit

Gybing

Gybing a very large asymmetric is challenging. The outside lead of the sheet makes it prone to slipping beneath the sprit and catching around the anchor or pulpit. If this happens mid-gybe it’s likely that the sail will then wrap around the forestay.

The gennaker had a webbing keeper for the sheet to sit in and a ‘gybulator’ batten protruding from the luff to help prevent this but it was by no means foolproof. A batten taped to the end of the sprit, protruding a metre or so horizontally, would improve the odds. As always with teamwork in the cockpit there’s no substitute for practice and coordination.

Alternatively snuffing or furling the sail for the gybe will eliminate the risk of spaghetti.

Top Tip: An inside gybe is where, like a headsail, the body of the sail crosses the boat inside the luff, through the foretriangle. An outside gybe sees the body of the sail fly around the front of the boat with the clew passing forward of the luff.

Off the wind, extra sail power is needed to keep the boat moving, and it’s a great feeling. Photo: Richard Langdon/Ocean Images

Dropping

With any down-wind sail, Newton’s first law of sailing applies: what goes up must come down, and it usually comes down in a hurry. Although furlers and snuffers have simplified the sail handling they haven’t fully tamed the beast.

When it comes to dousing a large spinnaker the first thing you need is foresight to not leave it too late in the first place. After that a combination of good technique and a sense of determination will see you through.

On a boat as large as the X5.6 you need liberal amounts of both. Even the incredible hulk would find it nigh on impossible to snuff or furl a big sail without depowering it first. Bear away and blanket it behind the main, simultaneously giving a generous ease on the sheet. At this point the sail will collapse and the foredeck crew can heave on the snuffer or furling line. Taking the snuffer line around a cleat or a block gives purchase and control.

If your furler or snuffer fails, it’s important to know how to drop the sail without it. Releasing the tackline, pulling the sail through the letterbox of the mainsail and down the companionway hatch is the conventional method and would work if a snuffer fails.

If a furler fails it’s more difficult since the tack is fixed to the furler. In this instance try to blanket the sail behind the genoa and mainsail as best as possible, take a deep breath, channel your inner octopus and gather it down the fore hatch.

Parasailors are designed to be flown pole free, and without the mainsail up for simple downwind cruising. Photo: Richard Langdon/Ocean Images

Downwind sails: Parasailor

From a distance a Parasailor looks like a spinnaker with a pressure relief valve, and crudely speaking that’s what it is, much like the vast J-Class spinnakers used to have cutouts in them to create airflow. But the paraglider wing inserted into the sail serves several purposes and isn’t just a vent. It’s designed to solve many of the challenges posed by conventional spinnakers so I was intrigued to see how the sail compared with the gennaker.

Neither Mathias, Sybille or I had ever sailed with one before, so we enlisted the help of Istec Parasailor trainer, Stuart Anderson, to help us learn the ropes. The sail itself was a 251m2 Istec Parasailor, which was bought second-hand.

The wing stops the luff collapsing as much, and makes it more forgiving when it does. Photo: Richard Langdon/Ocean Images

The theory behind the sail is that the horizontal wing gives the sail structure, creates lift and allows air to pass through it, rather than around it. The wing acts like a ‘soft batten’, helping the sail take shape on a wide range of wind angles and without the need for a pole. It also makes the sail less likely to wrap by giving it more structure.

According to the designers, the upwards thrust of the wing reduces the tendency for the bow to be buried in a seaway and, as you’d expect, the wing aperture helps gusts to ‘vent’. Furthermore, the Parasailor sets best without the main, eliminating the threat posed by the boom and reducing the likelihood of a broach. Jimmy Cornell, world cruising guru, has said that he ‘would recommend it to anyone who is considering buying a new spinnaker’.

I have to confess I was somewhat sceptical as to whether the Parasailor would really live up to its bold claims and celebrity endorsement.

It can take some effort
to pull the snuffer over
the bulk of the wing. Photo: Richard Langdon/Ocean Images

Rigging and setting

Like a gennaker, a Parasailor is controlled by a tack line led to the bow, and a sheet led well aft. It can be flown from a pole, but it isn’t necessary and most people are attracted to the simplicity of going pole-free. In order to gybe you need a lazy guy and lazy sheet, so, rather like a conventional spinnaker, there are four lines in total, plus a halyard.

Parasailors are nearly always used in combination with a snuffer, and Istec have designed its own with colour-coded clips to prevent the clews from twisting.

We set off on a broad reach down Southampton water with 14-knots true wind behind us. Stuart explained that when opening the snuffer it’s important to pause after the first few metres in order to pull on the tack line and bring the sail towards the bow. Once the tack was just off the bowsprit the snuffer could be fully hoisted and the working sheet taken up.

There was some resistance as the mouth of the snuffer negotiated the bulk of the wing, but after that the sock raised smoothly. We all found ourselves smiling when the sail popped out: there was no huge shock load on the sheet, the sail just took shape and started flying.

Trimming

Once up it can be set much like a conventional spinnaker, flattening the sail using the sheet and tackline on a reach, and easing as you bear away. When running, the aim is to keep the clews the same height, so a barber hauler on the sheet is useful.

We set the sail for a comfortable broad reach with an apparent wind of 8 knots at 135° and a true wind of 14kn on 153º. Pure Fun made an easy 7 knots through the water. It was composed and comfortable. As we pushed her up through the wind angles we took in on the sheet, achieving 8 knots on 100° apparent before she started to wobble.

We sailed her as high as 80° AWA but there was a lot of lee helm without a mainsail up and a Force 4 felt like too much wind for the higher reaching angles. Performance on a deep run was sedate and predictable, we trundled along at 6 knots with the wind dead astern and even sailed slightly by the lee without complaint.

When we put her through an ‘accidental’ gybe the sail inverted but as soon as we gybed back again it instantly recovered its shape. It was impressively forgiving, if a little underwhelming speed wise. Stuart commented that the X5.6 should have had a sail which was 5-15% bigger, which would have improved performance.

Gybing is easy with no pole or main, but still requires changing from working to lazy sheets. Photo: Richard Langdon/Ocean Images

Gybing

Gybing involves rotating the whole sail around the boat much like you would a symmetric spinnaker. With four lines to manage it could be daunting short-handed, but the process can be done in stages, easing the working lines and taking up the lazy lines as the helm holds a course deep down wind. It was easier and less stressful than gybing the gennaker, partly as there’s no mainsail to manage.

On a benign day in the Solent we couldn’t test the Parasailor’s stabilising effect in swell but many people testify to this.

Dropping

The primary difficulty we had was dousing it with the sock. Since there’s no mainsail up it’s hard to collapse the sail and depower it without letting the sheet completely off.

It took two of us to bring the sock down in 15-16knots. Admittedly the X5.6 is a big yacht, but we weren’t operating at the top of the sail’s wind range and the sail was slightly under-sized for the boat. I wondered what would happen when a squall hits. Leaving it up and hoping the vent works well might become the only option.

Keep an eye on true wind speed. It’s easy to forget how windy it really is when running with the wind. Photo: Richard Langdon/Ocean Images

Conclusion

All three sails got us moving downwind when the mainsail and genoa lacked oomph and any of them would be an asset. I’m drawn to the thrills and spills of the big yellow gennaker which certainly helped Pure Fun live up to her namesake but does need careful handling and the right conditions.

The Code Zero was glorious, and at a time when we’re all trying to wean ourselves off hydro-carbons it’s a useful tool for very light airs.

The Parasailor was far more effective than I imagined: it’s kind on novice crew and is one of the few sails that works deep down-wind as well as on a reach. It scored full marks for versatility and temperament. However, it won’t deliver the same wow factor as a Code Zero or gennaker operating within their optimum range.

I asked Mathias and Sybille how they’d come to carry all three sails on board, when most people would have opted for either a Parasailor or the combination of Code Zero and gennaker. ‘I only chose two sails actually’ replied Mathias, ‘the gennaker and the Code Zero’. ‘The Parasailor was my choice,’ Sybille said, ‘I wanted it for the ARC’.

Choosing your sail wardrobe is just as personal as choosing your own outfits, and what works for one occasion won’t always suit another. Buying second-hand sails for a specific passage also makes perfect sense.

If you can only carry one, then the gennaker is a rewarding option for experienced sailors, while the Parasailor is a pragmatic choice for short-handed or novice crew. If you decide on a second sail, then the Code Zero compliments either of them well.

Top Tip: It is tempting to lean towards buying sail cloth of a heavier, rather than lighter weight, as it seems like it would last longer. In reality, most cruisers only fly spinnakers in light airs, and a heavier cloth would tend to collapse more and be harder to set.

A lightweight spinnaker will last as long, and be used more. Once the sail cloth does get old, it will become less stable, making the sail harder to set and trim, and more likely to induce rolling, so a new sail is easier to handle.


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