Heavy Air Downwind Sailing

by Andrew Kerr February 2004

What is heavy air?

For each team this can vary depending on the experience level aboard – but for most teams it is about 20 knots of wind and above – especially in open unprotected water when the seas have a chance to build and are influenced by the current.

Be prepared - get psyched!!

If you don’t like like light air – practice in it as much as you can – the same can be said of heavy air – particularly downwind – go out with your lifejackets on, the rig tightened to the max setting required by the tuning guide and your old sails and go sail in it!

In Lance Purdy’s excellent article on heavy air sailing in the S20 technicalities book – this is exactly what his team did on Sea Bear on a windy day on Fernridge reservoir.

It’s important to change your mind set to a positive one for the given conditions, try and avoid talking yourself out of doing well just because the wind isn’t ideal for you.

In the S20 you want to go over every piece of rigging on the boat – every pin and ring ding- if a halyard or sheet is worn – don’t risk it – replace it. Talk with your team also on the risk management involved with deciding to set the spinnaker or not - there may be a strong case not too, more on that later.

What we have seen on our boat time and time again is the importance off getting around the course clean and in one peace – generally if you can do this with no broaches, gear failure or other incidents you can finish in the top half of the fleet just based on those things. It can be a classic war of attrition out there!

Lets look at sailing dead downwind, ( or as low as possible on a windward/ leeward course) in this article and we will look at heavy air reaching in future articles.

Rounding the weather mark:

When rounding the weather mark keep everyone on the rail to keep the boat flat and be sure to ease the jib out a lot in tandem with the mainsail to keep the boat level. If you don’t the mainsail will flog and the boat will be driven straight sideways by the over trimmed jib!

If it is very windy then a good idea is to ease the vang an inch or two as you approach the weather mark – this twists off the leech of the mainsail and helps the boat bear away. If you don’t do this on some boats the boat will simply not bear away even though the Mainsail is completely eased out!

If you are sailing to an offset mark like we have typically been doing at the Nationals then don’t bother setting the pole until you have rounded the offset mark – keep everyone on the rail as you are likely very overpowered and concentrate on trimming the sails well for max speed and control.

Shall we set and when?

This is the big question!! If you are leading the fleet then what we have done in the past is make sure we are on the correct closest jibe to the mark, made sure the boat is flat and perfectly under control, set the pole and then watched our competition carefully to see how they are doing. Can they hold the sail up effectively or are they having difficulties?

If they are doing fine then we set, if they don’t set then we don’t either as there is no need to risk anything.

At one Nationals we watched two boats set behind us and just as we were thinking of matching them they both death rolled – one capsized, (they came up fairly quickly) and the other rounded up hard head to wind with the chute flogging wildly - seeing this we didn’t set and pulled away with our jib wing and wing on the closest jibe to the mark.

If your team is practiced and the gains seem like they are there to be made then go for it, but here a checklist to make sure it works out as well as can be expected:

Make sure the boat is perfectly level and under control.

Don’t ease off the mainsail controls or the backstay or aft lowers - leave everything on as if you were going upwind – easing them is not going to help performance much and you will not have time to put them back on as the leeward mark will come right at you!!

Make sure you are on the correct headed jibe to the mark – a lot of team set, get on a plane, lose track of the mark and sail lots of extra distance, they can actually be beaten quite easily by teams that sail on the correct jibe with no spinnaker in 25 knots of wind.

Set in a lull – not the biggest puff of the day!

Leave the small jib up with the sheet eased out, it’s one less thing to worry about and it helps stop the chute from hour glassing around the forestay. If you have the Genoa then the advice is to take it down when the boat is under control.

Keep the outboard end of the pole down a few inches from your normal setting – this will tighten the luff of the sail, pull the draft forward and spill the leech – make the analogy of the Cunningham on the mainsail which does a similar thing. In watching the America’s cup final it was interesting to note Alinghi would do this for max control and safety as Team NZ had retired with gear failure and the goal was to get around the course in one peace – that is very true in heavy air S20 fleet sailing as well.

Make sure the windward and leeward twing’s are on tight so that the spinnaker is choked down. Also make sure the guy is around a winch and preferably the sheet as well.

Don’t set until the skipper say’s hoist and make sure everyone is in the correct position.

When the spinnaker fills - over trim the sheet to keep the sail in front of the boat and move the bow and middle crew back to get the bow out of the water and keep the rudder in the water! How far you move aft as a team will be dictated by the size of the waves and the amount the bow is burying. If the bow is aloud to bury in the water the boat will want to round up very quickly and broach.

This is fun – whoops we are starting to roll!!

The fun meter is right up there as your team blasts downwind, with the bow calling the puffs suddenly you hear the call “ here comes a huge blast” and the boat starts to roll hard to windward - what to do? Here’s a checklist:

Skipper – steer the bow directly under the center seam of the spinnaker – if it yaws’s to windward- steered to windward, if it yaws to leeward – steer to leeward. This keeps you right under the sail for max balance.

Middle – over trim the sheet on the spinnaker about a foot and a half to put the sail directly in front of the boat, hike out to leeward a little too if the skipper is sitting on the weather side to keep the boat balanced. Make sure both twings are hammered down to deck level to reduce the oscillating tendency of the sail to a minimum.

Bow – Call the puffs – hike out to leeward a little to counter the weather heel and have a had on the tail end of the vang ready to release it if the boat starts to round up in to the wind. Otherwise make sure the vang is very tight so that the leech of the mainsail has power in it to counteract the power of the spinnaker to help dampen the rolling. A common misconception is to ease the vang downwind to depower the mainsail – this actually increase the rolling and can cause a death roll (Jibe broach to leeward or round up to windward) because there is a large inequity in balance between the mainsail and the overpowering spinnaker.

Pump the mainsail and spinnaker sheet:

As skipper bears away in a puff or the stern lifts on a wave and the bow goes down, ( the apparent wind shifts forward) try pumping the mainsail and spinnaker sheet together – this will accentuate the apparent wind across the sails and promote / prolong a surf or plane. As the bow lifts and/ or the apparent wind shifts aft – ease the sheets back out.

The limitation in the rules on this is you cannot pump more than once per wave or gust and planing or surfing conditions must exist. In the ideal world you would pump the spinnaker guy as well but this can be a little too much physically to do, as the boat is a borderline handful at this point! Pumping the sails when it is windy is a work out but the gains are tangible if it is done properly.

Bad roll to windward – possible Jibe broach:

If the boat rolls really badly to windward then ease the pole forward – this will put the spinnaker behind the mainsail and help you regain composure. We have done this in the big waves off Miami in the SORC, (and other events) many times. The boat is heeling hard to weather and on the verge of jibing and broaching – we ease the pole forward and over trim the sheet to put the spinnaker behind the mainsail, in tandem with the skipper steering under the center seam - it saves the day!

Marginal conditions:

On day’s when the wind is very gusty with lulls followed by big blasts it’s very effective to play the leeward twing and the spinnaker sheet.

projection of the sail, the bow then spots a big gust and the middle pulls the leeward twing line down and over trims the spinnaker sheet to keep the spinnaker and the boat steady and to dampen the rolling – in the subsequent lull the sheet and twing are eased out, the two are essentially a gas pedal.

Boat is rounding up:

If the boats roll to leeward, or a big blast starts to lay the boat over then the action to prevent this starts from the back of the boat:

Skipper pumps the helm to reattach flow on the rudder.

Middle eases spinnaker sheet out.

Bow dumps the vang to depower the mainsail – keep calling the puffs!

Middle dumps the spinnaker sheet completely.

Note: Don’t dump the guy off, as the spinnaker will blow out to leeward and have 5 times the heeling moment in it!


This really is a function of timing and keeping the boat steered under the center seam of the spinnaker.

Good times to jibe include:

In a substantial lull – if available!

On the top of a wave – this enables the boat to be jibed going down the wave with minimum pressure on the sails.

When the boat is planing – this is a great time as there is very little pressure on the sails and the main can be jibed easily.

Key elements include:

The skipper steering the bow under the center seam of the spinnaker and using very little rudder.

The middle keeping the spinnaker chocked down with the sheet and twinged down to reduce oscillation to a minimum.

Every one is ready and on the same page !

Broaches or bad jibes usually occur because of over steering, not being able to jibe the mainsail, jibing in the trough of a wave or with the spinnaker too eased out.

What we have done is jibe the mainsail first and then jibe the spinnaker pole second – similar to the 470 Olympic class techniques.

With the end for end technique which we and a lot of teams use, it is very helpful to be able to lower the inboard end of the pole to gooseneck level and lower the topping lift down as well – this way the bow can end for end the pole from the cockpit very easily and not have to go on the foredeck. Teams who use the trolley system can do this automatically as the pole comes back in to the cockpit.

A technique to practice when it is blowing 20 to 25 is having the bow person help jibe the main across by grabbing the vang, they then jibe the pole across while the skipper keeps the bow of the boat under the center seam of the spinnaker.

The trick is for the skipper not to sail too dead downwind as this can cause a major hourglass in the sail and for the trimmer to keep the spinnaker slightly overtimmed to keep it as steady as possible. Once the bow person has jibed the pole they can jibe the jib across (the leech of the jib has been wandering back and forth across the centerline fairly eased out to enable the pole to be jibed) and cleat the jib sheet on the leeward winch.

If you experience a bad hourglass in the sail because the boat has been held by the lee too much then jibe the mainsail back and the reverse flow off the sail will unwrap the spinnaker – seeing it in practice tends to make believers of that technique !

A very conservative- and very often very effective approach is to take the spinnaker down to windward, jibe the main and jib, reset the pole and if the conditions are right – reset the spinnaker. This can be a great move if it is just too much wind to jibe in or the risk/ reward formula is a poor one for your team. This also works particularly well on short downwind legs.

Alternatives to the spinnaker:

If it is very windy – 25 knots plus – we have found it very effective to wing the jib out and sail as low as we can to the mark. Pumping the mainsail once per wave or puff helps accentuate a surf/ plane.

In one heavy air race the whole fleet was caught out with Genoa’s in 25 to 30 knots and we found it very effective to wing the Genoa out using the spinnaker pole. The boat sailed low and fast to the mark and we got there in great shape.


Get the spinnaker down very early - much earlier than you think! Budget lots of time to store the pole and douse the sail and get cleaned up. Getting around the mark clean with everyone on the rail and ready to go upwind will give tangible gains on teams that don’t.


Like any skill there is no substitute for practice, heavy air is very much a big test of your teams boat handling. Your decisions on how you tackle the heavy air downwind leg will typically be a function of how much experience the team has. Generally conservative tactics with a solid backing in the fundamentals will produce consistency in a series that will help the team realize it’s overall potential in these conditions.