5 expert tips: How to use an asymmetric spinnaker in light airs

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Champion sailor Ben Saxton explains to Andy Rice how to use an asymmetric spinnaker in light airs and keep a boat on the move

Just as the best teams seem to find an extra high mode on the upwind legs, often they’re also very good at eking out an extra-low mode on the downwind. Unlike symmetrical spinnakers, where you can square back the pole and sometimes sail directly down the rhumbline, with an asymmetric gennaker you’re always having to work the angles.

In light airs these angles can get pretty big as you work to keep the apparent wind flowing over the sails. If you can keep the flow AND gain a bit of extra depth compared with the boats around you, then you’ve got the opportunity for some significant gains downwind. Here are Ben Saxton’s five top tips for keeping the boat rumbling along in the low lane.

Listen to the trimmer

Keeping up the speed is one of the most vital goals when you’re pushing downwind in light airs and you need to let the spinnaker trimmer be your guide. Whatever size of boat you’re sailing, the feel through the spinnaker sheet is one of your key indicators for how low you can afford to go. An early luff is way better than stopping completely and having to build from scratch again. The key relationship is between the spinnaker trimmer calling the pressure in the sheet and communicating with the helmsman so that the two are in sync.

On bigger boats you can rely more on the target apparent wind angles which are really useful to steer to. In the smaller boats you simply don’t have that kind of data, but going on feel is never a bad thing. Make sure you’re always maintaining a good gap between the back of the spinnaker and the mainsail. If in doubt it’s better to over-trim rather than under-trim the mainsail to maintain that healthy slot.

Sailing the angles with an asymmetric. Photo: Kinetic Catamarans

High or low?

It’s one thing to work your best VMG with no other boats around you, but on a busy race course you’re going to have to work out when to sail higher or lower than normal. There’s no real rule of thumb, but generally if you’re rounding the windward mark with lots of other boats you simply can’t afford to be rolled by five or more of your rivals. So it’s most likely worth sailing the extra distance and going higher than you normally would to keep the apparent wind forward and keep the clean air across your sails.

If you’re in danger of being rolled by just one boat and you’re thinking about gybing away soon anyway, take the short-term pain of a bit of bad air knowing that you’re still well placed for the bigger strategic picture. Sometimes it’s okay to be rolled by one boat knowing that if you keep your leeward position then you’re most likely to be able to dictate terms at the gybe, and maybe get your own back by rolling them out of the gybe.

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Trim the boat

Mostly if it’s really light winds then you’ll go for some leeward heel to help the sails fill and to reduce the wetted surface area of the hull.

On a narrower hull, once there’s enough breeze to fill the sails without the need for gravity, you’d pull the boat upright. But in a boat like the Cape 31 with a really wide transom you’ll still keep the leeward heel in anything up to 8 knots of breeze because the gain of getting the kite round is less than having a big, wide transom in the water.

You want to get weight further forwards in light airs to reduce wetted surface area of the transom, but don’t trim so far that you’re fully lifting the transom because then you’re losing waterline length which is an important factor for boat speed.

Keep all movement smooth and gentle so as not to disturb the boat any more than you have to.

Photo: Rolex

Ease the tack line

If the sea state is flat and you’re aiming to get low in light winds, easing the tack line is an option for having a rounder, more powerful entry to the gennaker. Don’t try this in really light airs where you’re struggling to keep flow over the sails, because in these conditions flatter is faster. But once you’re going relatively low and only gybing through small angles, you can sometimes ease the tack line which helps give the kite a bit more depth, as well as rotating the kite around to windward.

Look behind you

Have someone dedicated to looking behind for the breeze, spotting the best opportunities coming down the race course. Because everything tends to happen quite slowly in light airs, the tactician should have time to do this job. You want to be careful that you don’t have too many cooks, but a two-way conversation can be good for bouncing ideas around – just make sure it’s clear who has the final call for making the next move.

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