The leading Class 1 yachts are running a tight-rope as they cut the corner on the South Atlantic High. The high pressure that usually dominates the Southern Hemisphere has moved off to a position west of Cape Town.
The yachts need to skirt the High to miss the calms associated with the area, and all four leading boats are reaching hard down the western edge of the weather system. This is allowing them to cut between 300 and 400 miles off their passage to Cape Town, but it's risky business. The High is usually centered slap bang in the middle of the South Atlantic, and if it decides to revert to it's normal location it could move right over the top of the yachts and trap them in light winds. In 1979 I raced from England to Cape Town, and we attempted to do exactly as the Class 1 yachts are doing, however unfortunately the High moved north and west and we were trapped for six days. It was a long, tedious passage from there to the finish in South Africa.
The flip side of that coin is that the skippers have to take advantage of this move and in doing so, they have to take the risk. The yacht with the most to lose is Bobst Group/Armor Lux, but Bernard Stamm is nothing if not a gutsy sailor and he is leading the charge.
Emma Richards on Pindar and Thierry Dubois on Solidaires are following along, a steady 250 miles behind with both skippers locked in a head-to-head battle. Further to the north Graham Dalton on Hexagon is also rocketing south. His westerly position was allowing him to make good gains on the front boats until the High moved off, and now he is being forced to fall in line behind the leaders. It will be interesting to see how things develop.
The position of the High is dictated by the intensity of the low pressure systems that circumnavigate Antarctica. Particularly large depressions can shove the High to the east and can in some cases can force it to split in two as a new High attempts to fill in off the coast of South America.
If this happens the Class 1 yachts should be able to continue their fast ride to Cape Town, but it will make the trip a lot more difficult for those following from behind. ie: the rest of the fleet.