A CLIMATIC TRIO
The Vendée Globe solo racers must permanently tamper with the weather systems. These are made of anticyclones - rather stable and moderately windy high pressure zones – and depressions, usually generating strong winds. This confrontation between high and low pressures determines the strategy to adopt in each zone of the course of the Vendée Globe. The North-South trajectory to go down the Atlantic and the South-North way back up are perpendicular to the general movement of perturbations whereas crossing the Indian and Pacific in the Southern seas is done in the same direction as the weather systems.
During the first phase between Les Sables d'Olonne and the cape of Good Hope, at the tip of South Africa, solo racers must sail along the anticyclone of the Açores in the North Atlantic, followed by its equivalent of Saint Helen in the austral part. The game consists in finding the good balance : far enough from low pressure centers to avoid the strongest winds without getting stuck in the high pressures. The second phase consists in taking advantage of the weather phenomena coming from the West so as to be pushed rapidly between Good Hope and the Horn. The third phase looks like the first one with the anticyclones of Saint Helen and of the Açores to be avoided. It's also necessary to manage the passing from one hemisphere to the other : it's the intertropical convergence zone (ITCZ), commonly called the Doldrums. At this place, hot and humid air masses brought by trade winds of the two hemispheres meet and generate unstable air where white calm and stormy squalls alternate without any logic. Vigilance and intuition are indispensable to escape this trap.
On 8thNovember 2020, starting day, two situations are possible : if the anticyclone of the Açores stretches out to the West of Europe, getting out of the Gulf of Biscay will take place in manageable conditions. On the contrary, Atlantic depressions which rush in between Newfoundland and Spain could generate strong and adverse winds. This beginning of race between LesSables d'Olonne and the tip of Finistère could be achieved very quickly in one short day or prove to be a difficult start... Once past the Portuguese coasts, the fleet will slide toward the Cape Verde : contenders must be careful not to endure perturbations off the islands (Madeira, Canarias, Cape Verde), nor take the risk of being trapped in the calm of the anticyclone of the Açores... This critical moment actually impacts the future point of entry in the Doldrums, generally between the 27° and 30° West parallel. The point of entry also determines the point of exit : North-Easterly winds turn to South-Easterly ones on the other side of the ecuator ! The closer the trajectory to Africa, the shorter the route to go around the anticyclone of Saint Helen...
The high pressures of the South Atlantic are fickle at the end of the austral spring : the goal of the solo racers is thus to sail along the Brazilian coasts as offshore as possible and catch one of the depressions which appear in the bay of Rio and die in the Indian ocean! If the high pressure system breaks up into ephemeral and mobile cells, the fleet ends up scattered in small groups with very different weather conditions : the split is often critical...
CATCHING THE TRAIN IN THE GREAT SOUTH
In less than a month, the frost of Vendée makes way for equatorial heats, tropical rainshowers and then subantartic polar cold. The Southern seas, which represent almost 3/5th of a round-the-world, offer a chain of depressions originating from Brazil, Madagascar, New Zealand… Solo racers must preserve this train of downwind conditions, sliding from one perturbation to another without being absorbed by anticyclonic tentacles. Powerful North-Westerly winds, fronts with violent Westerly squalls, switchover to South-Westerly freeze, the sequence is very trying for the sailors as well as the machines..
To limit the risk of encounters with icebergs, the Race Direction establishes a zone prohibited to sailing, the Antartic Exclusion Zone (AEZ), which goes around the Antartic between the 45°S on the Crozet Islands side and the 68°S off Cape Horn. Consequently, this demarcation for safety imposes a rather Northerly trajectory which flirts with the anticyclone of the Mascareignes (Indian) and Easter Island (Pacific). Competitors can get caught in high pressure systems while their opponents are surfing on a depression !
THE LONG WAY HOME
If rounding Cape Horn after 50 days at sea reduces drastically the stress of breakage and marks the increase in temperatures, the 7 000 miles left to sail to reach the Sables d'Olonne aren't the simplest ones, especially if other competitors are right behind you! Once you've passed Patagonia, there is still the anticyclone of Saint Helen to avoid while negotiating stormy depressions coming from Brasil. Adverse and irregular breezes, important wind shifts, fronts to cross, far from being an easy ride...
Once the Brazilian coasts are more or less within sight, the Doldrums loom at the horizon before reaching the trade winds of the North hemisphere. Once again, racers must avoid getting trapped in the fearsome calm of the anticyclone of the Açores in order to finally reach the Atlantic depressions which can be more devastating than their austral equivalentsin January... After 70 to 80 days at sea, the winner of the Vendée Globe 2020 will finally be able to see the Nouch buoy which marks the finish line of the Vendée Globe in Les Sables d'Olonne.