Downwind secrets of ocean sailors

How do you choose which sails to set or what course to steer, and can you stop the boat rolling? Toby Heppell talked to sailors preparing for the ARC to find out what works best for sailing downwind

Gin and tonic in hand as a light breeze wafts you along, or an unpleasant experience of rolling down waves, worrying about accidental gybes and struggling with wayward sails: running downwind is by no means an easy point of sail.

Whether you’re sailing across the Atlantic, or on a short coastal cruise, knowing how to set you boat up, trim the sails and what course to steer can make all the difference.

We went to Las Palmas de Grand Canaria to meet the Atlantic Rally for Cruisers fleet as they made their final preparations before heading off to St Lucia.

Skippers walking down pontoons in the ARC village

The Atlantic Rally for Cruisers attracts both experienced and novice sailors. Credit: James Mitchell/WCC

Part of the appeal of the event, for many, is the variety of crews it attracts each season, from the very experienced with many ocean crossings under their belts to the first timers for whom this will be their first experience of crossing the Atlantic.

What is true of every crew is the huge amount of preparation they have done in the build up to the event in order to be ready to sail day and night for at least two weeks to make the 2,700nm crossing.

Thinking differently for downwind sailing

‘I always considered myself a good sailor and have done thousands of miles in my years of cruising,’ remarked Marcus Wool, preparing to set off in a Sigma 38 for his second crossing.

‘However, when I started looking in fine detail at all the things you often skim over, I realised that when I’m sailing around the coast I’m mostly just allowing the boat to be blown along. When you start to think about how safe a setup is for downwind sailing at night when there’s only one of you on watch, it really makes you think about the best way to actually go about it. It’s a bit like starting all over again.’

This expression was a theme we came across again and again as crews made their final preparations before setting off.

A bonus with the ARC setting off from Gran Canaria is the vast majority of the fleet will already have sailed many miles merely to get there in the first place, so have had the opportunity to test out their sail plans, rigs and tactics on some pretty long passages already.

With this in mind we walked the pontoons to see what tips we could pick up from those soon to set off.

White sails

A common setup many of those looking to set out on this year’s ARC was to rely on white sails, particularly at night or when the weather was poor.

The reasons given for this were usually the same; control, safety and ease of handling were all flagged up.

Twin headsails is a good, stable option for tradewind sailing. Set from a single foil, they can also be furled together.

Twin headsails is a good, stable option for tradewind sailing. Set from a single foil, they can also be furled together. Credit: Christophe Favreau/PPL/GGR

White sails downwind can mean many things to many people and setup will vary for most of us depending on a number of factors including: preference; kit already on board; conditions; time of day and more.

The options

‘We’re looking to take it fairly easy this year as it was only the three of us,’ said Jim Macdonald, preparing to set off on his Moody 419.

‘We’ve done the crossing on a number of occasions but this is the first time one of our daughters will be joining us in a sailing capacity – we did the ARC previously as a family but that was back when the girls where a bit young to really help out. As we will be trying to take it easy an all-white sails setup is something we used quite a lot. It’s not always the quickest way to get from A to B but it does get you there with peace of mind and in a comfortable fashion.

‘Much of the way we’ll use two headsails poled out and without the mainsail up, especially at night as it gives you lots of control. We’ve tried on a few occasions to put the mainsail up with a third reef in and centre it to stop any rolling, but I found you have to zig-zag a bit to keep it full on one side or the other to stop it slatting. In the end I’m not sure it has a great effect on preventing rolling, but my wife and daughter both feel it does, so I guess we would say there was a split opinion on how effective it is.’

When downwind sailing, A poled-out hedsail needs a pole downhaul to control the leach of the sail.

A poled-out headsail needs a pole downhaul to control the leach of the sail. Credit: Alamy

‘Our rule onboard is that anything up to 30 knots we will have the spinnaker up day or night,’ says Ross Appleby who skippered the Oyster Lightwave 48, Scarlett Oyster once again this year – its seventh ARC.

‘Once we drop the spinnaker we switch to twin headsails with the windward one poled out and keep the mainsail up. I find that a really good setup. The mainsail does blanket a portion of the leeward headsail but the wind is forced across the windward headsail onto the leeward, which really helps to keep any rocking motion under control.’

To maintain a decent course on a trade wind passage requires quite a bit of setup and sorting in order to make sure the boat maintains a reasonable level of performance but will happily sail itself through watch changes, under autopilot or windvane, and to ward off the ever-present threat of chafe.

Twin headsails is a relatively complex setup for day-to-day coastal cruising but it is worth considering if it is a possibility to set up onboard ahead of an extended downwind passage when you won’t want a spinnaker.

Trimming

In terms of their actual shape, whether sailing with twin headsails or a headsail and mainsail, the aim downwind is for sails that set as full as possible in order to generate maximum power.

The easiest and most obvious control to use at first for this is the outhaul, which should be eased significantly to allow depth into the bottom section of the sail.

Downwind white sails

The pole jaws are a key point to watch for chafe on the sheet

At least that is the traditional thinking, but we heard two differing schools of thought on the matter in Gran Canaria before boats set off, with a couple of crews saying they sail with the outhaul relatively tight.

‘We tend to not let our outhaul all the way out on the main,’ explains Wool.

‘To my mind, once you have a bit of shape in the sail then all you really do by letting it off more is reduce the amount of the sail being presented to the wind. We typically aim for something around one-hand’s width between the mainsail foot and the boom.’

Those without a loose-footed mainsail will need to take this as a rough guide.

Whichever option you choose, you are still looking to keep a decent amount of draught in the sails and the outhaul is just one small factor in this.

The draught of the mainsail is primarily controlled by the halyard, the outhaul and the backstay.

Downwind white sails

Twin headsails (sometimes called wing on-wing) is a very stable setup for sailing downwind

In practice, you often need to use a bit of all three.

Control via the backstay is a little more complicated as it will depend on a number of boat-specific factors.

Increasing backstay tension on a masthead rig offers little effect on mainsail shape.

On a fractional rig, the backstay has a more pronounced effect, bending the mast forwards in the middle and flattening the mainsail.

This effect is reduced if you have much tension on lower stays as they will limit the amount of forward bend the mast will produce in the lower section and so limit the draught increase.

Though the overall effect will vary from boat to boat, the basic rule is that backstay tension gives the sail more draught remains.

‘We use our backstay quite a lot to control the depth of the main,’ says Wool. ‘For us, with a fractional rig, I would say it is the key sail control for the main sailing downwind or upwind. It has a huge effect on depth of sail.’

If you have draught lines on your mainsail then it is well worth taking some time to tension and ease these controls one by one and note the difference they make to the sail depth across the whole sail.

In reasonably stable conditions you should be looking for maximum draught at around 50% back from the mast.

In light winds it should be 60%, and in strong winds about 40%.

Twist

Twist is another key mainsail control and downwind, is almost entirely changed via the kicker or vang while the mainsheet is used to set the angle of the sail to the wind.

Generally, you apply kicker tension to reduce twist and power up the sail.

Downwind white sails

Here, one sail is free-flying and one is on the headsail foil, though a foil with twin luff grooves would allow the sails to be furled together

You ease the kicker to induce twist, spill wind and de-power the sail. Be careful not to allow the mainsail to twist too much as this can induce rolling.

Those we spoke to setting off for the ARC tended to aim to have the vang overstrapped with the top leech telltales stalling much of the time, to ensure rolling was limited despite sacrificing a bit of power.

A poled-out headsail should be treated as a mainsail forward of the mast.

Usually much of our headsail trim is dominated by the relationship between the two sails when they are on the same side of the boat, but when poled out they essentially function independently of each other.

The pole serves as a boom and its uphaul and downhaul act in the same way as the mainsail’s topping lift and kicker, the sheet, as with the mainsheet is only used to control angle to the wind.

‘With the twin headsails we were not using a pole downhaul on either,’ says Macdonald. ‘We ran a twin guys, and twin sheets system that gave plenty of pole-end control.’

It is worth noting that you do need to remember to ease the downhaul if you are pulling the pole aft on the sheet and tighten it if you are moving the pole forward any significant distance.

The pole’s angle will have the greatest impact on the draught of the sail.

Easing the pole forward will increase draught but be careful as allowing the pole too far forward can have the effect of making the headsail billow out and spill wind from its leech.

The trick is to keep both sails pulling with equal pressure.

You may find that the boat can have a tendency to pivot around the leading edge of her keel, but you can use the kicker and up/downhaul to combat this, essentially using the kicker to tighten the leech of the sail and prevent the boat from rolling.

Rolling comes from a difference in pressure on both sails throughout the length of their leech.

If you have too much twist in either headsail or mainsail then the wind detaches from the top of the sail and spills, creating a reduction in power up high and so rolls the boat.

The key with a headsail poled out is to match the leech profile on both sails, giving consistent power the entire length of the sail.

Top tip from Gareth Glover

Gareth Glover
Boat: Beneteau First 47.7
Number of crew: 11
Preferred sail plan: Symmetrical spinnaker
Make sure you have properly set up your autopilot and ensure everyone knows how to use it

Spinnakers

The range of different spinnaker setups by those heading off for the ARC demonstrated that there was no particular consensus among the fleet about one specific favoured option.

However, very few had actively selected a cruising chute out of choice, those that had, simply already had one and were not inclined to purchase a new sail and equipment for a single ocean crossing.

The main difficulty with a cruising chute is that, although they are easier to set and handle, when dead downwind they have a tendency to become blanketed by the mainsail and so work at their best on a broad or beam reach.

There are a range of spinnakers for downwind sailing

Cruising chute, symmetrical spinnaker, poled-out headsail or twin headsails offer a pay off between east of use and boat speed. Credit: Colin Work

You can goosewing a cruising chute which increases its flexibility to some extent, but they can be tricky to control compared to a poled-out headsail.

Though tradewind sailing is not always dead downwind, the general consensus was that, with plenty of time to prepare for a hoist then the limitations of a cruising chute far outweighed any advantages in terms of ease of use.

For coastal use, the opposite is broadly true.

Sailing up onto a broad reach will not see a significant loss over a relativley short passage in terms of time to destination, and you can always goosewing it for a short time dead downwind.

‘You have so many more options with a symmetrical spinnaker that it just makes sense to use one,’ explained Gareth Glover, skippering a chartered First 47.7 from Global Yacht Racing.

Preventing the spinnaker from blowing to windward is key via clew control when downwind sailing.

Preventing the spinnaker from blowing to windward is key via clew control when downwind sailing. Credit: Rick Tomlinson

‘When it comes to any downwind sailing then I think options is a good thing. Sailing angles in a bit of wind is all well and good and might get you there as fast, but when there is not a lot of wind, then I think it is good to have something that will allow you to make some reasonable miles sailing deeper.’

There are some issues when using a symmetrical spinnaker, that you need to be aware of, however.

In light winds even the slightest gust can accelerate the boat so that she sails through her apparent wind, leaving the spinnaker drooping lifelessly. In these conditions the best option is to head onto a broad reach, so apparent wind, and therefore boatspeed, will be higher.

At the opposite end of the scale, increases in wind strength can go unnoticed as the boat accelerates with the wind.

When it comes time to drop, you may be going forward in windier conditions than anticipated.

Pole and spinnaker tactics

‘One of the main reasons we have settled on 30 knots as the windspeed we drop the spinnaker is that, by that time, you are sailing so deep that the spinnaker tend to roll around the front of the forestay and makes the boat roll a lot. We also find that when sailing on a dead run in big breeze twin headsails and the mainsail is pretty much just as fast.’ explains Appleby.

If you find the boat is rolling under spinnaker then this is mostly likely because the spinnaker is able to blow round to windward of the forestay.

The best fix for this is to pull the pole aft some more and sheet on a little, which should bring both clews back in line.

A useful option in this instance is also a tweaker line leading from the sheet usually on a pully or low friction ring down to the toerail and back to a cleat.

Keep the spinnaker pole horizontal and roughly in line with the boom when downwind sailing

Keep the spinnaker pole horizontal and roughly in line with the boom when downwind sailing

This allows you to pull down on the sheet to keep the leeward clew under control and stop the top of the spinnaker rolling to windward.

In terms of pole height, on a run always aim to keep the clews level, to ensure the sail is balanced.

Adjust the pole height on the mast accordingly (the pole itself should be level, too).

Once you have everything set up and are sailing the boat, you’ll notice the spinnaker starting to fold, or ‘break’, at the luff.

Watch that it folds evenly down the entire luff. If the luff starts to fold at the top first, then lower the pole a little.

If it folds at the bottom of the spinnaker first, raise the pole.

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‘We have a decent number of crew for this crossing so we are not likely to be all that shorthanded. Even so, we will often just set up the spinnaker trim for the direction we want to go and then steer to that, heading up until the luff starts to break and then back down to keep it filling,’ explains Glover, adding that this is a particularly useful setup when sailing shorthanded as it does not require anyone actively trimming the sail.

On a reach, with the pole further forward, raise the pole, thereby opening the leech and widening the sail at the shoulders.

This gives the spinnaker less draught in its upper part.

If the breeze increases, you may need to lower the pole to stabilise the luff, creating more of a ‘forestay’ effect.

‘As a broad rule of thumb, we try to just keep the spinnaker pole roughly the same as the boom angle,’ says Wool.

Thus if you are dead downwind with the boom all the way out at something like 90° to the boat, the spinnaker pole should also be square.

As you come up to the wind and sheet on the mainsail, the pole should be dropped forward accordingly.

Typically it is better to have the spinnaker pole too far to windward than too far to leeward, as this will prevent it slowing the air to the mainsail and backwinding the main in the forward portion.

Top tip from Marcus Wool

Marcus Wool
Boat: Sigma 38
Number of crew: 4
Preferred setup: Symmetrical spinnaker
The backstay is a key control on a fractional rig for offering control of mainsail depth

Autopilots

Cruising sailors tend to under-utilise autopilots, usually simply turning them on and walking away.

Learning how to trim and set up your pilot to suit the conditions will not only get you to your destination faster, but should reduce battery consumption and make for a smoother ride.

Speaking to those taking part in the ARC, many had clearly spent a great deal of time – often in the miles sailed getting to the start – to better get used to setting up their system.

It is worth spending time to understand your autopilot fully

It is worth spending time to understand your autopilot fully

Compass is the default mode for most autopilots and once activated, it will steer the compass course selected.

Typically many people just leave it at that, but if you want your autopilot to work better you need to look closer at the settings.

‘We tend to only use compass heading as a quick fix option,’ says Wool. ‘Typically it is used if whoever is steering needs to quickly go and complete a task and will come back to the helm soonish.’

More options

Wind steering is a much better option allowing the pilot to steer to the wind direction.

Those we spoke to who had spent a lot of time sorting their pilots tended to switch between true or apparent wind angles as conditions change.

A boat sailing downwind

Make sure your sails are trimmed for optimal downwind sailing. Credit: Graham Snook/Yachting Monthly

‘I’ll use true wind angle when sailing downwind which means it is not affected as the boat accelerates and decelerates on waves and the apparent changes,’ says Glover.

As such, typically apparent wind angle is used to steer autopilots when sailing upwind.

As changing between true and apparent wind modes is not always straightforward, a few crews we spoke to had taken the wise step to have a simplified version of the instructions easily to hand so that no one needs to get the manual out if they are unsure.

Many – particularly those on charter boats – had employed this for a number of instruments on easy to follow laminated cards.

Response settings on an autopilot broadly change the number of corrections per minute the pilot makes to stay on course.

As such, it is often referred to as sensitivity.

Response settings are normally not too hard to adjust and something a few crews had played with on the long passage to the start.

Typically you will want a fairly low response setting in light winds to keep power consumption down and prevent too many minor course alterations slowing you down.

As the wind increases, the response time should be increased as the pilot has to work harder, this is also true as the wave state increases too.

‘Setting up an autopilot is a bit of a black art,’ says Appleby.

‘Certainly some are better than others and, given the option, I would always go for something with a gyro built in with smarter software. These newer models avoid the old problems of the pilot getting caught in a feedback loop where the boat rolls to leeward and the pilot interprets that heel as a course change and corrects it, making it worse, then needing to overcorrect the other way, which can be slow, dangerous and a drain on power as it is working overtime.

a yacht with windvane steering leaving for the ARC

Windvane steering is a power free option. Credit: James Mitchell/WCC

‘My best bit of advice when it comes to the pilot is to take over every so often. Sometimes you can take over and realise the pilot has been fighting the boat and might need tweaking in setup terms to get the best out of it and the boat. If you are familiar with your boat you’ll probably be able to feel that anyway, but hand steering for a bit is a great way to double check all is okay.’

If you want to avoid power-drain altogether then a good option is to go for good old windvane steering.

‘We want to avoid the power drain of the autopilot,’ says Macdonald.

‘The windvane does a very good job when downwind sailing in the tradewinds and doesn’t take any power to use. I think it’s the best option once you are in the trades.’

Brakes & Preventers

Most of those setting out on the ARC planned to use a boom preventer or brake of some description and if you plan on sailing downwind for more than a short distance then you’ll most likely want to set one to eliminate the risk of an accidental gybe.

Without one, should the wind get behind the mainsail at any point causing a gybe, it could cause damage to the yacht or injury to her crew.

A proper preventer holds the boom forward and needs to be strong – strong enough to stop a gybe if the main is backed.

A brake relies on friction to slow the boom

A brake relies on friction to slow the boom. Credit: Graham Snook

A brake tends to require more setup and fiddling with as it relies primarily on friction to slow the boom.

The friction is usually controlled by the number of turns the preventer line takes around a central hub, which can be a simple, smooth round drum or a grooved hub.

Brake or preventer?

In some cases, to carry out an intentional gybe while using a brake, you may have to come off your course until the wind is on your quarter, resulting in significant course deviation, which is far from ideal if you’re hurtling along with a steep following sea.

Among the crews preparing for the ARC, there was no consensus view on what was best, but mostly people seem to prefer a brake over a preventer.

‘I’m not a fan of the preventer,’ says Wool.

‘I take the view that you are trying to limit the possibility of damage if the worst happens and I feel that means something that allows you to keep sailing properly and trimming easily and for me, that is a brake. Where possible, I try not to use them at all and we tend to rig ours only when we know the seastate or wind are going to be particularly bad.’

A strong rope, but with a little stretch, such as braid on braid, is best as a preventer to absorb some of the shock loads in the event of a gybe.

A strong rope, but with a little stretch, such as braid on braid, is best as a preventer to absorb some of the shock loads in the event of a gybe. Credit: Lester McCarthy

‘We’ve used a preventer in the past,’ says Macdonald, ‘but now we used a French-made boom brake and I think that is my preferred option. It’s not a bad option using a preventer but with our [brake], now if someone does make an accidental gybe or does something silly, you just get a controlled gybe.’

Appleby, however, offers a different view: ‘We generally have enough crew on hand that it’s unlikely that we are going to get an accidental gybe. However, I think a preventer is an important bit of kit. For me a key purpose is in the light winds when you might get the main going a bit sloppy as you sail down a wave and a preventer stops it coming across. My preference if cruising is to use a preventer much of the time and reef the mainsail. There is always the possibility that if you do accidentally gybe then you can get pinned by the main being held on the wrong side, but with a fairly big headsail up you can often get the boat back on it’s feet again. As the preventer will go to a winch, you can ease it a bit to help and, when cruising, you can even put the engine on, to help get some way on and get you going again. All in all, I’d say preventer and a well-reefed main is a good option.’

Top tip from Jim McDonald

Jim MacDonald and his wife
Boat: Moody 491
Crew: 3
Preferred setup: All whitesails, twin headsails
All white sails allow for a controlled setup which is easy to use – vital when shorthanded

VMG and angles

Sailing the angles to keep a boat moving in light weather is a key consideration of getting to your destination in the fastest way possible.

The easiest way to understand this is to use VMG or Velocity Made Good.

Typically you will be able to find a VMG option on most electronics packages on a boat and broadly speaking it is merely a function of heading and speed, usually towards a waypoint.

If our destination is dead downwind then we can, of course, sail straight to it along the rhumb line.

The choice between high and fast and low and slow is less pronounced over a 2,700 miles course and for heavier boats with displacement hulls

The choice between high and fast and low and slow is less pronounced over a 2,700 miles course and for heavier boats with displacement hulls

We could be running with a poled-out genoa or perhaps with a spinnaker or cruising chute. If there’s any sort of following sea then this is an uncomfortable point of sail, and if we’ve not rigged a preventer then there’s the risk of an accidental gybe.

By turning away from the rhumb line a bit we can bring the wind around onto the quarter.

This is a much better wind angle, giving us airflow over both sides of the sails, so the boat will sail faster as well as feeling much more comfortable.

If we can sail fast enough on the new heading to make the same VMG as we were making dead downwind then, provided that we gybe part way down track, we will get to the destination in the same time as we would have on a dead run, but we will have had a much more enjoyable sail in the process.

Typically, this will need a reasonably light and fast yacht that can really accelerate to make this strategy work.

In reality, few cruising yachts, particularly laden with supplies, are likely to see enough of an increase in speed to make this approach genuinely faster.

However, sailing away from dead downwind may help reduce rolling and get the sails filling properly, making life on board much more comfortable.

Using VMG will allow you to weigh up whether altering course, and any impact it may have on your passage time, is worth the gain in comfort. Inshore that is a fairly easy calculation to make and sailing directly by VMG numbers is a rewarding thing to practise.

Offshore the calculation becomes much more complex and it rarely pays to deviate too far from the rhumb line when that means sailing even a slightly longer distance.

Pointing the right way

‘We don’t worry too much about our VMG,’ says Macdonald. ‘most of the time, we are just looking to sail the rhumb line or heading where the weather is best.’

‘We use a fairly simple rule onboard,’ says Appleby. ‘We always ensure that we are pointing within 30° of the finish, that way, whatever boat speed we are doing, at least 90% of that total boat speed is still directly towards the finish, the direction we want to go.

‘If you look at the weather for the ARC, it almost always looks better to dive quite far south – down towards the Cape Verdes even – where you should pick up the stronger trade winds. In reality it is dead downwind to get there and then as you start to feed into the trades the angle changes and turns it into a dead downwind to St Lucia. All the miles you put in running south are not getting you any closer to the destination, only to get you into stronger winds, but winds which are not a good direction for travelling quickly and comfortably. We do use VMG to check we are sailing the fastest angle within the frame of 30° towards out destination but it rarely pays to exclusively look at VMG on a full crossing.’

Top tip from Ross Appleby

ross Appleby
Boat: Oyster Lightwave 48
Number of crew: 12
Preferred setup: Symmetrical spinnaker/two headsails & mainsail
Even if you are looking to sail into better winds, always try to be sailing predominantly towards your destination. Ground made to the south, to better winds, does not directly get you to St Lucia any quicker

The 7 step downwind checklist

  • Sail Choice: You need to decide what will work best for your crew. A symmetrical spinnaker offers lots of options and plenty of speed, but does require more work. All-white sails offers an easy to control and, to a degree, more of a set-and- forget option.
  • White Sail Trim: Rolling can be a problem. Try to keep the leech of your headsail and mainsail similarly trimmed. If using twin headsails, hoisting a small amount on mainsail centered via the mainsheet can help reduce rolling.
  • Spinnaker Trim: Instead of trimming the spinnaker to your course, set the spinnaker and steer the boat to the spinnaker. Keep the clews under control to prevent rolling.
  • Tactics for Night vs Day: At night you will probably want a safer setup as it can be harder to see the seastate and waves. Even with a watch system there are likely to be more people to help out in a difficult situation during daylight hours.
  • Preventer or Brake? The choice is yours but it is worth having something that will slow or prevent the boom sweeping across quickly if you do have an accidental gybe
  • Autopilot Setting: Try to understand your pilot settings for different conditions and modes. You should adjust the responsiveness of the pilot in different condition to avoid unnecessary power drain.
  • Route Planning: On such a long passage the shortest route is usually your best option. However, weather will be a major factor. It is often worth sailing a bit further to pick up a favourable weather system even on a relatively slow boat

 

Source: Yachting Monthly

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