[Vendée Globe 2024 – #1] – On Sunday 10 November 2024, emotions ran high on the pontoons in the port of Les Sables d’Olonne as the 40 sailors lining up for the start of the 10th Vendée Globe took to the water. These top sportsmen and women have climbed aboard their 18-metre IMOCA boats alone to embark on the greatest single-handed, non-stop, non-assisted race around the world. We take a closer look at the legendary route taken by these ambassadors of the seas around the world’s oceans.
As a scientific partner of the Vendée Globe, océans connectés provides scientific insights into the oceans along the course of this 2024 race. Each week, we’ll be highlighting the ocean features crossed by the skippers and the highlights of some of their commitment to science.
by Carole Saout-Grit
Cover photo: The IMOCA boats line up at the start of the Vendée Globe 2024 © océans connectés
One planet, one ocean
The Earth, the blue planet, lives up to its name. With 70.8% of its surface covered by oceans, this gigantic volume of water covering more than 1.3 million km³ is central to life and our climate.
The extent of the oceans is very unevenly distributed between the very maritime southern hemisphere (with 80.9% ocean surface area) and the more continental northern hemisphere (with 60.7% ocean surface area). But in total, the high seas account for 43% of ocean space, a territory without borders, belonging to the whole of humanity.
Geographically, the ocean space is made up of five basins with different characteristics: the Pacific Ocean is the world’s largest basin, covering a third of the globe and 43.5% of the earth’s ocean surface; the Atlantic Ocean is the world’s second largest ocean, occupying 28% of the earth’s surface; the Indian Ocean, the world’s third largest ocean located between Africa and Australia, represents 19.4% of the earth’s maritime surface.
Map of the general bathymetry of the world’s oceans. Source: GEBCO
At the North Pole, the Arctic Ocean accounts for 3.7% of the maritime surface area and 14 million km2. Covered in ice for most of the year, it is the world’s smallest ocean, but plays the role of climate sentinel: over the last 50 years, the Arctic has warmed twice as fast as the global average.
Finally, to the south of the globe, the Antarctic continent is encircled by the Southern Ocean, which accounts for almost 5.4% of the world’s oceans. The Southern Ocean is driven by a marine current, the Antarctic Circumpolar Current, which is the most powerful on the planet!
It is thanks to the Southern Ocean that the oceans connect to each other to form a single global ocean, making it a pillar of the climate machine. The Southern Ocean acts as a pulley for the exchanges of heat and energy that are distributed by ocean currents from the north to the south of the planet, and from the surface to the deepest ocean depths.
Spilhaus projection. Created in 1942 by the oceanographer and physicist Athelstan Frederik Spilhaus, this map places the global ocean at the centre of the world around Antarctica and the Southern Ocean.
A legendary crossing of the three largest ocean basins
For this Vendée Globe 2024, the skippers will cover 45,000 kms (over 24,000 miles) around the globe. In almost 3 months, they will cross the planet’s three largest ocean basins: the Atlantic, Indian and Pacific.
After leaving the Bay of Biscay, the sailors will cross the Atlantic Ocean, first skirting the coasts of Europe and then North Africa. While there was no wind at the start of the race (thanks to a fine anticyclone to the south of Ireland), the descent of the North Atlantic quickly became chaotic as they rounded the tip of the Iberian Peninsula. The famous Cape Finisterre and its rugged cliffs is renowned for being a windy corridor (caused by the presence of the Corunna mountain ranges) and a rough ocean zone (on the border between the Bay of Biscay and the wider Atlantic).
North Atlantic wind map on 15/11/2024 (source: windy)
But it’s when the latitude passes 30°N that the sailors will enter a vast zone of quasi-permanent high pressure off the Azores, a zone of calm known as the Azores High. And this zone can also be seen on the map of ocean currents… In fact, on average across the globe, the wind map is almost superimposed on the map of surface ocean currents. Atmospheric and oceanic circulation is organised around large gyres or circulation loops which, in the northern hemisphere, are anticyclonic and rotate clockwise – and vice versa in the southern hemisphere.
Schematic representation of ocean surface currents and the world’s major ocean gyres, with the North Atlantic anticyclonic zone.
Many challenges in the Southern Ocean
Once they have passed this zone of high pressure, the sailors should be able to cross the equator on around the 10th day of their race and slip into the South Atlantic. Rounding the Cape of Good Hope, at the tip of South Africa, will then mark the transition to the Indian Ocean, a key moment in the course.
The Indian Ocean is characterised by strong ocean-atmosphere interactions, which influence the monsoon cycles in particular. It is from this Indian Ocean that the skippers will enter the mythical Southern Ocean.
The Southern Ocean is home to the main weather extremes (notably the famous howling 40th and roaring 50th winds) and the main maritime dangers, due to the large amount of ice and icebergs. To be on the safe side, the Vendée Globe skippers will therefore have to stay away from the most dangerous zones and not cross a line demarcating an AEZ (Antarctic Exclusion Zone) drawn by the CNES on the basis of satellite observations of ice positions.
Iceberg in Antarctica @ Sabrina Speich – ENS Paris
Obviously, the route will be long in the south of the Indian Ocean and at the limits of the Southern Ocean. It will be around their 35th day at sea before the sailors pass Cape Leeuwin, to the south-west of the Australian continent, and enter the Pacific Ocean.
There, they will pass close to the famous Point Nemo, geographically the furthest point at sea from any land. The skippers will not see land again until around the 55th day at sea, when they round the famous Cape Horn, off the coast of South America. A mythical cape, symbolising an exit from the Pacific and a new entry into the South Atlantic. The final passage for an ascent of over 7000 miles that will take our heroes of the seas to Les Sables d’Olonne and the finish line.
Course of the 10th Vendée Globe 2024. The AEZ is indicated by the hatched white area around the Antarctic continent ©Vendée Globe
This first week of the race has confirmed that the weather conditions vary considerably, and that there is a strong correlation between them and the ocean conditions. The ocean is set in motion at the surface by winds that act in concert with ocean currents. The 40 skippers in this Vendée Globe 2024 must therefore be ready to deal with changes in atmospheric and oceanic conditions at all times in order to perform and take advantage of the best wind and sea forecasts.
