Be careful with the wind shadow
The competitors, with the exception of Didac Costa, are sailing in the trade winds. They have to manage the wind shadow of the islands, which is not an easy task.
The competitors, with the exception of Didac Costa, are sailing in the trade winds. This wind which is blowing from the northeast is not always as stable in force and in direction as we might believe. It begins by passing the Canary Islands which are more than 3700 meters high. It has to by-pass them, either passing above or around the sides of the islands. It creates disturbances that we can spot very well on the models and sat pictures.. The blue and green spots in the first image show the light wind zones.
The yellow zones show the acceleration between the islands. That is why skippers are trying to pass a long way from the islands to avoid these big wind shadows, which are followed by strong accelerations.
Initiatives Coeur, the red boat which is the closest to the Canaries, is 100 miles from the island of Palma and 150 miles from Tenerife. We see on the satellite picture that Tanguy is sailing in the “scrolls” which mark this funneling effect. He is therefeore affected by the wind shadow. His speed is fluctuating and he is not doing so well in the rankings.
The group of leading boats which is situated at more than 200 miles (370 km) from the island of Tenerife seems to be avoiding the light wind zones.
Thus the strategy to round these islands has to be thought out a long time in advance. For the Canary Islands, the skippers planned their crossing point from the beginning in Les Sables d’Olonne.
Today, the leading boats are going to enter into a stormy cloudy mass which we see on the satellite picture in front of their bows. These clouds are also going to disrupt the trade wind. Skippers will have to manoeuvre under the squalls to maintain a high speed. The trade winds are clearly not that stable.
by by Vendee Globe