Mark Chisnell – Leg 2 Week 1 – And so the Game BeginsUncategorized
It’s been a flying start to the second leg, with some great sailing, big breeze, bigger mileage and some fabulous footage from the first week as the crews got a pasting. But while the sailing might have been tough, the strategy for the first couple of days was relatively straightforward.
We talked about the problems for the first section of the leg in our preview last week. The short version is that after the upwind leg to the Cape of Good Hope, the usual strategy is to head south or south east to find good breeze from the low-pressure systems circulating in the Southern Ocean.
It turned out that no one had to go very far south at all. The wind was right there at the Cape, thanks to a low pressure system moving east under the African continent at just the right time. We can see the fleet’s position after the first couple of days in Pic 1 from Friday afternoon, 21st November at 16:45 (All times are UTC). Team Alvimedica are leading at this point, but there’s not much in it, with just five miles separating the front five boats.
The track shows the fleet beating south out of Cape Town, then easing onto a south-easterly course in a breeze that had gently rotated from south-east to south-west. There was nothing else gentle about it, as it was blowing 20+ knots and the boats were doing speeds in excess of that through some rough water.
Riding the Wind, Dodging the Current
The fleet’s course over this first couple of days had two goals – to keep them in the good breeze from the low pressure and to keep them out of the worst of the Agulhas Current. This warm water current flows south down the east coast of Africa, around the Cape and then meets the cold water and the eastbound storm systems of the South Atlantic off Cape Agulhas, a shallow water projection of the continental shelf into deep water.
The combination of storm systems, foul current and shallow ground makes for one of the world’s roughest pieces of sea, never mind the fact that the current is also trying to push them backwards. But after a couple of days of going more or less east the fleet were past the worst of the Agulhas Current and thoughts turned to heading in the right direction.
Er… isn’t Abu Dhabi North of Here?
After all, the finish line is in Abu Dhabi, and that was almost due north from their position after two days of sailing. It was time to start thinking about an exit lane. They were all sailing east on starboard gybe in a south-westerly, and a gybe to port would have allowed them to turn and point at the finish. Tempting… the problem was the South Indian Ocean High.
We talked about finding the right exit lane from the Southern Ocean in the Preview, the objective being to thread a route around the western side of the South Indian Ocean High. Leg 2 is effectively the second part of Leg 1 (when the teams had to find a way around the St Helena High), but in reverse. This part of the leg is all about turning north at the right moment to skirt around the western side of the High.
The first gybes came on the evening of the 21st November – right after Pic 1 – and for the next 24 hours there was a lot of swerving around the ocean, as everyone wrestled with matching their weather strategy to the risk they were prepared to take relative to the rest of the fleet. If we look at Pic 2 from 20:24 on 22nd November, we can see the fleet have come back together after a sequence of gybes.
The most significant was the leverage that Abu Dhabi Ocean Racing, Team Vestas Wind and Team SCA took to the south. It didn’t appear to have done them much good – Abu Dhabi Ocean Racing went from 8 miles off the leader and fourth place to 21 miles off the lead and fifth place. The damage for Team Vestas Wind and Team SCA was worse, both trailing the leader – by 42 and 53 miles respectively – by the time they cashed in their leverage.
If you look at Pic 3, you can see the reason for all the indecision – the South Indian Ocean High is centred well to the east, as it should be. Unfortunately, it is ridging all the way past Madagascar almost to the African coast. The result is a band of very light air stretching from west to east, almost from Africa to Australia. Thou Shalt Not Pass.
Taking it On
It was Abu Dhabi Ocean Racing that took it on first in a fairly dramatic change of strategy – after taking a dive to the south, they were now first to gybe to the north just after the 20:19 time of Pic 2. After sailing a tight tactical race in Leg 1, it appears that skipper Ian Walker has decided to change his strategy and let his navigator, Simon Fisher loose on some bolder moves.
The rest of the fleet followed in the next six hours and 24 hours later at 20:19 on the 23 November we had the situation in Pic 4 – with the whole fleet headed for what appears to be a windless void, and Abu Dhabi Ocean Racing nearly 60 miles to the west of the pack. And with that kind of leverage there’s always the possibility of tears – but whose?
A Little Low
It’s not quite a windless void (it rarely is) – a closer look at Pic 4 shows us that a band of north to north-easterly winds (blowing around the western edge of a southern hemisphere high pressure system) can be seen to the south-west of Madagascar. In fact, there’s actually quite decent breeze off the southern tip of that island, and overall, it looks like better breeze to the north and west than to the east. It looks like Walker and Fisher were right to head that way first…
Let’s fast-forward another 24 hours, to Pic 5 at 20:14 on 24th November, Monday evening and almost up to date. The better breeze has resolved into a little low pressure forming to the west of the fleet, and this has brought a building north-easterly wind funnelling between the little low, and the big high pressure system off to the east.
It’s clear from the leaderboard that Abu Dhabi Ocean Racing are right back in the game after their early move north. They are back up to third, just a couple of miles behind leaders Team Brunel and everyone has now tacked to go north with them – imitation is the sincerest form of flattery.
Up to Date
The situation is still very fluid and tricky though and no one can afford a moment’s lapse in concentration. If we bring things right up to date with Pic 6 and the latest fleet report from 09:55 this morning, 25th November, two things leap out. The first is that Abu Dhabi Ocean Racing are now up into the lead. The second is that a big split is developing.
The low pressure is on the move. The centre of the low has moved east and is now situated south of Madagascar, perilously close to Abu Dhabi Ocean Racing. If we zoom in to Pic 7, we can see that second placed MAPFRE are now leading the rest of the fleet into what appear to be stronger winds to the east…
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What Happens Next?
I can tell you it’s messy, we’ve had to use Deckman, B&G’s predictive routing software, to make sense of it all… I’ll be back here next Tuesday to see how it worked out.
And you should be be here next week too, to see if it all pans out as predicted, but you will need to subscribe to my Blog on the top right hand side here to get this ‘What Happens Next’ content.
The section of Leg 2 north from the Southern Ocean and into the trade winds always promised to be one of the most complex. At the end of the first week, we have the fleet poised for a big split to the south of Madagascar, with Abu Dhabi Ocean Racing apparently headed north alone, while the rest of the fleet have gone east.
The weather is complex, so bear with me… the little low pressure system that Abu Dhabi Ocean Racing used to lift themselves into the lead is forecast to fizzle out. The reason it will disappear, is that a new high pressure system will roll east from South Africa, out into the India Ocean. In about three days time, it will join with the South Indian Ocean High, but in the meantime it’s going to create some serious trickiness…
The key strategic question is whether the boats allow themselves to fall under the influence of this new high pressure, or not. Any boat that stays west (that looks like just Abu Dhabi Ocean Racing at this stage) will get a new southerly breeze from the eastern edge of the new high, as it approaches from the west.
The good part about this is for Ian Walker is that a southerly means fast downwind sailing. The bad part is, that as the two highs merge, the wind will go through a potentially very messy transition as it rotates through the south-east into the east, until finally becoming the dominant easterly breeze from the northern side of the Indian Ocean High, AKA the trade winds.
The rest of the fleet look like they are trying to stay in the north to north-easterly wind on the western edge of the main South Indian Ocean High, until they can claw their way far enough north to get into the same dominant easterly breeze to the north of the high. The good part about this is that they stay in the same breeze all the time and avoid the randomness of the wind shift transition, the bad part is that it’s all slow upwind sailing.
To make things even more complicated, by the time they’ve negotiated all that, they may have to deal with a tropical cyclone spinning up north of Mauritius… but I’m not going to go that far up the track.
So how is it going to work out? The B&G team have kindly run some solutions for us on the predicted routing facility on their Deckman software. We’ve taken the position of Abu Dhabi Ocean Racing and MAPFRE at 10:00 this morning as the starting points, and used the standard GFS weather forecast; also available (amongst others) to the navigators on board the boats.
The computer images I want to show you are the predictions for three days time, when everyone should have got far enough north to be in the trade wind zone, and enjoying some happy sailing in the east to south-easterly breeze up around Mauritius (the tropical cyclone comes later).
In Pic 8, we can see the (more or less) vertical red line that Deckman is suggesting is the optimal route for Abu Dhabi running close to the southern tip of Madagascar, before heading north-east for Mauritius.
In Pic 9, the (more or less) vertical red line shows DfW suggesting the optimal route for MAPFRE as much more to the east initially, before ducking back towards Mauritius.
The interesting part is that the (roughly) horizontal red line shows where the boats will get to in 72 hours time – 10am Friday morning. It has Abu Dhabi Ocean Racing ahead by maybe 30-40 miles. Of course, they are the ones that have to deal with the big wind shift and those are the calculations most prone to error. So it could work out well, or…. it might not.
If they go with it, this will be a big play by Walker and team aboard Abu Dhabi Ocean Racing. They could get a leg winning lead, but to do it, it looks like they are going to have to live with perhaps hundreds of miles of separation from the fleet while sailing through some very tricky conditions. And separation always means risk.
So will Ian Walker stick or twist? Follow the fleet, or take a chance? In Leg 1 he showed us that he’s a conservative tactician – but even if he follows the fleet, he will be trying to make their strategy work from a worse starting position. It’s going to be an interesting few days…
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