The Vendée Globe is the world’s ultimate race course: one non-stop lap of the globe. The course starts in Les Sables d’Olonne, France, on 10 November. There are three marks of the course – the Cape of Good Hope, Cape Leeuwin and Cape Horn – all of which must be rounded to port, before finishing back in Les Sables d’Olonne. Beyond these marks, we skippers must choose our own way around the world and that navigation will be primarily defined by weather, rather than geography.

Aptly named by the French as Le Grand Sud, the Southern Ocean section of the Vendée Globe race is the most remote, relentless – and for me personally the most formidable – part of the course. Only a handful of sailors in the fleet could call themselves ‘familiar’ with this unbroken stretch of water and I have yet to hear an anecdote that started ‘it was a nice day in the Southern Ocean’. This is where the fleet will actually circumnavigate the globe, skirting Antarctica, taking between four and six weeks to reach Cape Horn.

The Ice Limit

The ice limit will play a significant part in strategy and navigation during the following weeks. Because the shortest route around the world is found at the highest latitudes, race committees over the various runnings of the Vendée Globe race have needed to manage risk by setting limits on how far south skippers can go.

In previous editions ice gates have been imposed – virtual waypoints through which competitors must pass, which encouraged them back to the north.

However, the race organisation now favours an ice limit, or Antarctic Exclusion Zone: a series of GPS points around the globe below which a boat might not sail without penalty.

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The ice limit will be defined by the race committee in collaboration with meteorologists and glaciologists tracking the position of icebergs and their drift, which is linked to currents and changes in sea levels, over the next three months. It covers the Antarctic zone, Pacific and Indian Oceans.

The initial ice limit is delivered to competitors as early as one month before the race start to allow planning, but it can be modified and updated ahead of the lead boat to react to real time information as the race progresses. From memory we received around 10 updates to the ice limit during the course of my 2020 race.

Australian Rescue Limit

The ice limit is only broken by a small shelf in the course along the longitudes of Western Australia, bringing competitors up to 45° south for a stretch of around 600 miles. This limit is defined by the range capabilities of the Australian search and rescue authorities.

Synoptic chart showing the train of depressions circulating around Antarctica.

Riding the fronts

The ability to catch and ride a cold front is key to progression in the Southern Ocean. Fast moving depressions are the overwhelming weather feature of the south.

These systems will develop in known areas such as the semi-permanent cold front off Brazil, then slingshot into the Southern Ocean, where they will deepen, strengthen and make their way east around the globe.

The trajectory of each low-pressure system will be in a south-easterly direction. The younger depressions have active cold fronts which are of particular strategic benefit to Vendée Globe skippers. Ahead of the front there can be found ‘relatively’ flat water and north/north-west winds which provide super-fast reaching conditions to make miles east. Each time a new depression arrives, a skipper will need to decide how close to the centre of the depression they wish to position their boat – further north there will be less wind and less risk.

Once in position the trick will be to set up the boat, put your foot to the floor and sail hard ahead of the front banking as many miles as possible. These weather fronts will travel at between 30 and 35 knots so eventually will catch up and overtake a boat, so the incentive is to keep the pressure on for as long as possible. Any inclination to slow down will accelerate the front’s closing speed.

Once the front has passed, the wind direction will back to the west, the sea state will become rough and confused and there will be multiple squalls making it impossible to continue sailing fast and hard. As the depression moves east, the wind will drop and boats may be left in a ridge of high pressure waiting for the next depression to arrive, often carrying competitors from hundreds of miles behind, to their position.

The ice limit and pinch points between it and Cape Horn and the southern tip of New Zealand

The Indian Ocean

Passage into the Indian Ocean is dominated by the presence of the Agulhas current, which flows from Madagascar down the east coast of Africa to the tip of southern Africa, where it turns north and is then forced by the prevailing wind loops back to the east. It’s a warm current, a lot like the Gulf Stream in the North Atlantic, and can flow at six knots in places.

This current makes passage into the Indian Ocean challenging, not only from the resulting brutal sea states, but also because the warm water attracts marine mammals (whales) who feed on its contents. The use of current GRIBs and noting the sea temperature will help ascertain the position and course of this feature.

In the Vendée Globe qualification races over the last two years, race management has been working with marine ecologists to specify exclusion zones around these areas known to attract large marine life.

It’s likely that the Vendée Globe course will include marine mammal exclusion zones, around both the Azores in the Atlantic, and the Agulhas current, which will be defined before the race, but open to change ahead of lead competitors – as with the ice limit.

The route from Africa to New Zealand will be governed by depressions and risk management. Sailors will use synoptic charts and GRIB files to spot depressions forming to the north, then position their boats to ride each front as it comes along. Between depressions will come the opportunity to repair and regroup.

Windy.App image showing the Agulhas current that, having run south from Madagascar to the southern tip of Africa, then loops back to the east

The Pacific

The Pacific provides two pinch-points in the course which can force the fleet to contend with bigger weather. The gaps between the bottom of New Zealand and the ice limit, and Cape Horn and the ice limit, are relatively small – bringing sailors south, closer to the centre of passing depressions with no escape route north. Timing is critical when passing through these gates and some competitors may be forced to slow down, hanging to the north and west while a depression rolls through, rather than risk being clobbered by 60-knot winds with nowhere to run.

The ice limit must naturally drop south on the approach to Cape Horn, meaning that sea and air temperatures will plummet. Often there can be snow in the squalls, the sea temperature at the ice limit could be as low as 4°C, and with no insulation provided by our carbon hulls, we will not just be battling the cold, but the inside our boats will be permanently slick with condensation. Any competitors with heaters will reap benefits during our two-week crossing of the Pacific.

Cape Horn

From mid-Pacific the approaches to Cape Horn will be of primary concern: the distance between the Cape and the ice limit is less than 200 miles and the close proximity between South America and Antarctica form a wind acceleration zone of sorts increasing gusts by 10 knots or more. Finding the right route and timing to pass through this gap is critical. Competitors need to be wary of small depressions forming further north on the land and driving south. This is also one of the only areas on the course where we will encounter land, so we must be ever wary of being trapped on a lee shore if considering an approach from the north-west.

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