Leg 3 Strategic Review - Part 1

And we are right in the middle of the first big play. The fleet faced big breeze out of the start gate, but now it’s evaporated and they must tip-toe around light winds in a race to get to the new weather system first. It’s a very familiar scenario...

The strategic picture
Let’s take a step back, and a quick look at the overall strategy for this leg – if you want the full version, then check out the Leg Preview for Leg 3, – but if you don’t have time to follow the link, then the ‘revision notes’ version is that the earth’s oceanic climate features distinct bands, lying horizontally and looping the globe, running out from the Equator to the Poles in a mirror image.

In Leg 3 we only have to worry about a couple of these climates zones; stable, semi-static areas of Subtropical High Pressure, and south of them the Westerly Storm Track; where storms and low pressure systems swirl west-to-east around the globe, circulating the Antarctic with nothing but a handful of tiny islands to slow them down.

The start and finish – Cape Town and Melbourne – both sit at latitudes where the high pressure usually (but not always) dominates. To get between them, the fleet must head south into the Westerly Storm Track.

Keep going south
In the final Leg Review for Leg 2 we mentioned the old strategic rule: keep going south till it’s blowing 40 knots, then turn left and hang on. The point was that the fastest route for this leg has always been to get south away from the influence of the high pressure and its light winds, and down into the Storm Track, where the fleet can find big breeze and bigger waves to speed them eastwards.

We saw this strategy pay at the end of Leg 2, when MAPFRE pushed south harder than the rest of the fleet to get to the breeze from a low pressure system, and were rewarded with a lead that they held to the finish line.

So the opening couple of days of this leg are once again about transitioning into a new climate zone, into the Storm Track, and they will be crucial for establishing the pecking order as the fleet head across the Southern Ocean. This big picture is clear if we have a look at Image 1 from 01:00 this morning, 11th December, showing the track of the fleet south from Cape Town and the Cape of Good Hope.

©Geovoile - Image 1 (Click for larger image)

Through the high
On the left hand side of Image 1 we can just see the anti-clockwise rotation of the wind around the centre of the South Atlantic High. There is a big ridge of this high pressure extending to the east, right across the centre of the image – the light winds indicated by the blue and green areas. And below it, we can see the strong breeze, the red and orange of the westerly wind that’s flowing around the top of a big low pressure system in the westerly storm track. The overall strategic problem faced by the fleet is to get through the ridge of high pressure and into the westerly wind.

Changing priorities
Let’s look at the fleet’s track south in a bit more detail, because there’s an important lesson about priorities. In Image 2 from 17:00 yesterday afternoon, 10th December, we can see the fleet’s track around the Cape of Good Hope. Compare the route of MAPFRE (white) with Vestas 11th Hour Racing (orange). The Spanish team have sailed in towards the Cape, while Vestas 11th Hour Racing have stayed further offshore, going south just as I suggested their strategy should be...

 ©Geovoile - Image 2 (Click for larger image)

Tactics not strategy
Unfortunately, tactics were more important than strategy at this point. There was an advantage to be squeezed out of the Cape of Good Hope, and MAPFRE, Dongfeng Race Team and Turn the Tide on Plastic played it particularly hard – to their benefit. This is a tactical ploy that we’ve mentioned before; if there’s a headland, head for it. In almost all cases, the wind will compress and distort around a headland, bending the wind around it, and benefiting boats that sail close into it.

Aboard Vestas 11th Hour Racing, navigator Simon Fisher admitted their error. “We haven't had a great day. Everyone has been a bit more aggressive tacking into the Cape and we were late on that... Or conservative and just looking to get south into more pressure.” Yes, getting south to break through the high and get to the new breeze is the main strategy, but it was a mistake not to take the gains to be had by playing the coastline on your way south... it’s not easy, this sailboat racing.

Unsurprisingly, everyone went back in for a second hit at the next headland, as we can see in Image 3 from 19:00 yesterday evening, 10th December. Dongfeng Race Team, MAPFRE and Team Brunel led the way south from that point with less than half a mile between them. Now the race south started in earnest...

 ©Geovoile - Image 3 (Click for larger image)

Hitting the high
Everyone kept the pedal to the metal on port tack in the south-easterly breeze until first thing this morning, when they started to get into the influence of that ridge of high pressure we saw in Image 1. The big moment was just after the 07:00 Position Report when the wind went light, down to 6-8 knots and shifted round to the south – as we can see in Image 4 from 07:30 this morning, 11th December.

 ©Geovoile - Image 4 (Click for larger image)

There was a little shuffle for the lead pack in the next few hours, the outcome of which we can see in Image 5 from 11:00 this morning, 11th December. MAPFRE took the lead from Team Brunel, while Dongfeng Race Team slipped to third, but there is so little between these three – less than a mile – that it doesn’t count for much but kudos.

 ©Geovoile - Image 5 (Click for larger image)

Placing the bets
More interesting were the bets taken by Team Sun Hung Kai / Scallywag (grey) and Team AkzoNobel (purple) – the former played the light shifting winds to take a position to the east of the leading pack, while the latter did the opposite and ended up to the west, and further south.

The south pays
It took just two hours for the south to pay yet again, as we can see in Image 6 from 13:00 today. Ignore the fact that Team Sun Hung Kai / Scallywag are at the top of the leaderboard, this is just a reflection of their closeness to Melbourne to the east. The interesting thing is that Team AkzoNobel have scooted round the outside of MAPFRE, Dongfeng and Team Brunel to now lead this pack to the south – where the new wind is coming from.

 ©Geovoile - Image 6 (Click for larger image)

We can see this much more clearly in Image 7, also from 13:00 today, 11th December – but zoomed out. The fleet are skirting round the bottom of the high now, and heading for a big building breeze, much stronger to the south than the east. The boats furthest to the south and west should get it first and strongest and they will be on their way... headed for five thousand miles of Southern Ocean, racing in the Westerly Storm Track.

 ©Geovoile - Image 7 (Click for larger image)

Riding on the storm
The strategic goal will be to keep the boat in the band of strong north-westerly winds to the north-east of the centre of a low, riding with it as it moves east towards Australia. They don’t want to get too close to the centre, especially if it’s a really, deep powerful low as the boat will get hammered and they could break gear. Equally, they don’t want to get too far north either, where the winds get lighter and the boat might slow too much and let the low pressure move away ahead of them – nothing worse than getting dropped by a low in the Southern Ocean.

Or maybe there is... getting trapped to the south of the centre, where they will find themselves battling headwinds. It’s very slow, and very unpleasant. These days that’s pretty hard to do because the race officials have set an exclusion zone to keep them away from the ice breaking off Antarctica and drifting north. It’s a line stretching from west to east and it is marked on the Race Tracker in red. It’s set at 45S initially, then moves north a couple of degrees. 

Exclusion Zone
The Exclusion Zone should keep them safe from the ice, but it becomes an important element in the strategy. The boats can no longer sail freely to stay in the right position on a weather system – as we’re about to see...

Check out Image 8 from 05:00 on the 13th December. It shows the Predicted Route of the fleet from their current position (top left of image) tracking to where they will be in a little less than two days’ time. The low pressure system that they are about to pick up is still just about visible in the westerly flow to the south-west of the fleet. 

 ©Geovoile - Image 8 (Click for larger image)

Gybing north
The predicted route thinks they should be gybing at this point, and repositioning a bit further north – north? Why? You may well ask... the reason is the new low pressure system starting to form to their north-west in Image 8.

Purple churning maw
If we now look at Image 9 from 20:00 on the 13th December we can see that things have changed with frightening speed. If your reaction to that picture isn’t a sharp intake of breath then check your pulse for signs of life. The new low pressure system is now fully formed and it’s a monster. That purple churning maw will be coming at them from the north-west and it will hunt them down. It will fling them east and it will be all about seamanship and nerve – holding the boat together and staying fast.

 ©Geovoile - Image 9 (Click for larger image)

Trapped by the Zone
And the biggest strategic problem will be the Exclusion Zone. Once that low pressure slams into them they will reaching with 30-40 knots on their beam and they will be converging with the Exclusion Zone – just visible to the south of the fleet in Image 9.

To stay north and above the Zone they may have to harden up, narrow their wind angle. Sailing closer to the wind can be both dangerous and slow in that much breeze and big waves. So it’s going to be really important not to get too far south too early, and the position of that gybe in a couple of days’ time (visible in Image 8) will be critical to both speed and safety. It’s going to be a major few days in the story of this race, do not adjust your set...