After what felt like a very long phase in the Southern Ocean, a completely different, but no less decisive phase of the race begins for the first boats of the Vendée Globe with the rounding of Cape Horn.
At the top, a fierce tactical battle develops between Yannick Bestaven on board "Maître Coq", who passed the Horn first and far out at sea, and Charlie Dalin on "Apivia", who is initially another one closer to the coast chose leading course.
The main question skippers are faced with is how best to navigate around a high that is developing north of the Falkland Islands. It will slowly migrate east towards Sankt-Helena-Hoch for the next 72 hours.
Yannick Bestaven opted for a more easterly route that allows him to stay in a more exposed part of the South Atlantic where the wind blows around the horn and intensifies in the process. Bestaven accepts a not inconsiderable detour. He apparently assumes that the high will shift to the east sooner and thereby block the more direct, westerly route.
Charlie Dalin, who first tried the inside lane, also seems to have recognized the risk this morning that he could run out of wind. After two jibes, he has meanwhile taken the course of Yannick Bestaven.
The danger of a coastal route is on the one hand in the slipstream of the mountains of South America, on the other hand near the center of the high. However, there is also a positive factor: the latest generation of foilers, including "Apivia", are very fast in shallow water; it doesn't take much more than 12 knots of wind to take off. Apparently Thomas Ruyant, who was the third to cross the Cape and probably tried his luck west of the Falklands, is betting on this.
Figure 1: Wave height and direction on Wednesday January 6th. Even the roughest swell from the depths of the Southern Ocean is blocked by the South American continent, so that shallow water conditions make the return journey of the fleet in the South Atlantic bearable
At the moment, the routings still state that Yannick Bestaven can maintain the lead. But it won't get clearer until the boats rounded the east side of the high on Wednesday.
Behind the leaders there is now a considerable gap to the chasing group, which lies between 600 and 700 nautical miles behind - including three boats with conventional plug-in swords such as "OmiWater Family", "Yes We Cam!" and "V&B" alongside foils like Boris Herrmann's "Seaexplorer - Yacht Club de Monaco".
As we have seen for weeks, there were few significant advantages to modern hydrofoil boats in the Southern Ocean; Sometimes they were even at a disadvantage - be it because of a break or because they accelerated too much in the sea just to get stuck in the next wave. But once you get around Cape Horn, the conditions will change completely.
The Horn is so notorious for extreme conditions that it is considered the place of death in the southern polar low pressure areas. These lows have traveled thousands of miles to reach the Horn and build huge waves along the way. As soon as the skippers are east of this point, they are practically immediately transferred to the birthplace of new weather systems - and in completely different, more complex conditions.
Figure 2: the situation on Wednesday, January 6th at 1200 UTC. A high will separate the fleet. For "LinkedOut" and "Groupe Apicil" the difficult decision is to position themselves east of the high or instead to sail north with a headwind
There are two main meteorological features in the South Atlantic that are relevant to the Vendée Globe skippers: high pressure areas such as that north of the Falkland Islands, which Yannick Bestaven and Charlie Dalin are currently dealing with, and the formation of lows along the South Atlantic conversion zone. These "young" systems and the land protection of the South American continent ensure that the sea remains comparatively moderate.
Boris Herrmann on board the "Seaexplorer - Yacht Club de Monaco", together with the other newer Imocas with foils in his group, will look for opportunities that the South Atlantic offers him under these shallow water conditions. In the entire Southern Ocean, it was only able to call up about 80 percent of its maximum speed potential due to the swell. After passing Cape Horn, it should be able to get back to or close to 100 percent of its polar data - and thus exploit its speed advantage over the non-foilers around it.
Figure 3: The routings of the ECMWF ensemble for the chasing group around Boris Herrmann up to a waypoint at 20 degrees south. It is based on the forecast of the European weather model, which is executed several times and then results in a course line for each of these iterations - purple for foil, turquoise for a conventional Imoc60. The spread is quite large
If you look at the weather situation for this group, after the Cape, high pressure remains the determining factor for them too. Because of the time lag to the leaders, however, the high will have shifted, making an eastern route under space sheet conditions much more difficult, if not impossible.
For Thomas Ruyant on "LinkedOut" and Damien Seguin on "Apicil" this could lead to the preliminary decision for 3rd place in the Vendée Globe. If you are sailing high, you will both be on the starboard bow with half wind for a long time, as explained in relatively shallow seas. These are optimal conditions for Ruyant, especially since he still has his foil completely intact on this bow (he had to shorten his port foil with the flex to take the load off the structure that was already cracked on the way south). So it is possible that he can sneak past the core of the high while Damien Seguin is blocked.
Anyone passing the cape after these two will be forced to sail west of the high upwind, which is not much of an advantage for the foilers in this group. But towards Friday a low developed off the Brazilian coast, which offered Boris Herrmann and his competitors a new chance.
Figure 4: Routing of the second group and wind situation on Saturday, January 9th at 0100 UTC. After passing west of the high pressure, a transition to a newly formed low with a south-westerly wind presents itself as an opportunity
You can head northwest and latch onto the west side of the low, which has good southwest winds. However, as this system is young, it is moving east very quickly as the fleet tries to go north. So the benefit won't last long.
At this point in the race, the transitions between the weather systems will be crucial - and the optimal timing. Who can adapt to the changing conditions the quickest and keep their boat at optimal speed for the longest time?
Only around the 20th parallel, the conditions in the regime of the southeast trade wind become more stable. The skippers are expected to reach this part of the South Atlantic around January 14th. Here I think the foilers can go miles. From here you have about 3000 nautical miles in your optimal range in front of you - at a wind angle of 70 to 90 degrees, in shallow seas. Compared to conventional boats, because of the higher righting moment of the wings and the smaller wetted area, they log 5, 6, j up to 8 knots more.
If Boris Herrmann succeeds in leaving the complicated weather systems of the deep South Atlantic cleanly and without a great deal of residue, he has a great chance here to put himself in a strong position for the last stage in the North Atlantic.