Vendée Globe: Forecasting the Finish

(January 6, 2017; Day 62, 17:17 FR) – While the 18 Imoca 60s are sailing in fairly good conditions, the question about the Vendée Globe estimated arrival time is on everybody’s lips.

With the first competitors about to return in the Northern hemisphere, many raise the question of the date of arrival. What is the ETA (Estimated Time Arrival) for the boats in Les Sables d’Olonne? Marie-Martine who is a medium in Les Sables d’Olonne said it would be January 16th.

In practice, the weather models diverge beyond 7 or 8 days. It is therefore not easy to establish an ETA for an arrival planned in 10 to 13 days. To rationalize things, we use the “combination models”.

For an available model, the Americans calculate 20 variations of the model and the European Meteorological Center 50 variations of the model. They modify the initial conditions and look at what happens. It is what we also call the butterfly effect.

The legend says that the beating of a butterfly’s wing can generate a depression 10 or 15 days later. It is probably a little exaggerated, but it is true that a higher temperature of the Gulf Stream or a little stronger cold spell in Canada is going to have consequences on the depressions which are going to form in the North Atlantic. By changing these initial conditions for the whole world, we obtain different models for the long term.

In theory, every model has the same probability as the others of occuring. By routing the competitors with all the available models, we obtain a set of routes. We can then establish statistics with a distribution, as mathematicians do, around the date of arrival. It turns out generally to be rather accurate.

There are two limits in the exercise. The first one is that only the skippers have the exact polars of their boats, even if after 60 days we begin to have a good idea of the performances of each of the boats. The second is that we do not know the breakage that they have on the boats and how it can affect the performance.

With the models of January 6th, 2017, the probability is high that the winner will finish between January 16th and 18th.

Ranking (Top 5 of 29 as of 22:00 FR)
1. Banque Populaire VIII, Armel Le Cléac’h (FRA), 3225.4 nm to finish
2. Hugo Boss, Alex Thomson (GBR), 185.9 nm to leader
3. Maître CoQ, Jérémie Beyou (FRA), 948.1 nm
4. StMichel-Virbac, Jean-Pierre Dick (FRA), 1591.0 nm
5. Quéguiner – Leucémie Espoir, Yann Eliès (FRA), 1595.7 nm

Race details – Tracker – Ranking – Facebook – VendeeGlobe TV

Background:
The eighth Vendée Globe, which began November 6 from Les Sables d’Olonn, France, is the only non-stop solo round the world race without assistance. Twenty-nine skippers representing four continents and ten nations set sail on IMOCA 60s in pursuit of the record time set by François Gabart in the 2012-13 race of 78 days, 2 hours and 16 minutes.

For the first time in the history of the event, seven skippers will set sail on IMOCA 60s fitted with foils: six new boats (Banque Populaire VIII, Edmond de Rothschild, Hugo Boss, No Way Back, Safran, and StMichel-Virbac) and one older generation boat (Maitre Coq). The foils allow the boat to reduce displacement for speed gains in certain conditions. It will be a test to see if the gains can topple the traditional daggerboard configuration during the long and demanding race.

Retirements (11):
November 12, Day 7 – Tanguy de Lamotte, Initiatives Coeur, masthead crane failure
November 19, Day 14 – Bertrand de Broc, MACSF, UFO collision
November 22, Day 17 – Vincent Riou, PRB, UFO collision
November 24, Day 19 – Morgan Lagravière, Safran, UFO collision
December 4, Day 29 – Kojiro Shiraishi, Spirit of Yukoh, dismasted
December 6, Day 31 – Kito de Pavant, Bastide Otio, UFO collision
December 7, Day 32 – Sébastien Josse, Edmond de Rothschild, foil damage
December 18, Day 43 – Thomas Ruyant, Le Souffle du Nord, UFO collision
December 24, Day 49 – Stéphane Le Diraison, Compagnie du Lit – Boulogne Billancourt, dismasted
December 24, Day 49 – Paul Meilhat, SMA, keel ram failure
January 1, Day 57 – Enda O’Coineen, Kilcullen Voyager-Team Ireland, dismasted

Source: Vendee Globe