Trade wind shut off means a light wind start
Leg 2 from Cabo Verde to Cape Town, South Africa is 4,600-nautical mile (nm) open ocean leg that should see the IMOCA crews able to push their foiling yachts to their full potential in some classic tradewind sailing conditions.
It will also be the first time that we see how the IMOCAs – sailing in fully-crewed configuration – will perform in the expected strong winds and big seas of the South Atlantic during the final section of the passage.
The route for Leg 2 takes the fleet south out of Cabo Verde, across the Equator close to the coast of Brazil, down the coast of South America avoiding the mid-Atlantic Saint Helena high pressure system, and then into Cape Town on the southern tip of South Africa.
Normally, the strong and steady north-easterly trade winds that characterise the Cabo Verde islands would mean a fast exit for the five-boat fleet of 60-foot foilers. However, the unwelcome recent arrival of what meteorologists classify as a ‘cut-off’ low pressure system to the north of the African archipelago has shut off the trade winds almost entirely.
As 11th Hour Racing Team’s British navigator Simon Fisher explains, the knock-on effect of choking off the northern hemisphere trade winds is a steady expansion of the Doldrums – the transient band of persistent light and unstable winds that straddle the Equator, blocking the fleet’s passage to the south.
“If we had left a couple of days ago I think it would have been a quite straightforward trip down south,” said Fisher (who is racing in his sixth edition of The Ocean Race – more than any other IMOCA fleet sailor), speaking the day before the leg start. “But it is going to be a lot trickier now because the Doldrums are expanding.”
Fisher predicts that the north easterly trade winds will start to re-establish not long after The Ocean Race fleet leaves Mindelo bound for Cape Town.
“Those first three or four days down to the Doldrums are going to be pretty important. It’s about getting away from Cabo Verde smoothly and then somehow picking up the beginning of the trade wind rebuild efficiently. After that it’s about finding the right spot in the Doldrums.”
Plotting the fastest route across the Equator means choosing the narrowest section of the Doldrums. Normally at this time of year the preferred crossing point is over to the west on the Brazilian side of the Atlantic.
This time, however, starting from Cabo Verde means the yachts are beginning the leg well to the east – so finding a way to the west will be more challenging.
“In previous races on this route across the equator you would always take the earliest opportunity to position yourself to the west,” Fisher explains.
“If you ended up passing close to Cabo Verde you would be quite nervous about how you were going to get back to the west. Now we are here starting in the east but the safety is still in the west.”
Whatever route the teams manage to find to pick their way through what is expected to be a fraught Doldrums crossing, once in the southern hemisphere they will be on the hunt for tradewinds that will help drive them quickly along the South American coast before making the left turn towards Cape Town.
However, the direct route to the finish is blocked by a persistent light wind weather phenomenon known as the St Helena high pressure system. This amorphous mass of warm weather and light winds changes shape at will and the crews will need to be wary of it as they squeeze between its western edge and the South American landmass.
The latter stages of the leg could produce some of the fastest sailing of the entire race as the crews make the most of some fast downwind sailing conditions on the way to Cape Town.
Previous editions have seen the crews dig deep into the South Atlantic in search of a ride on the fast-moving storm systems that regularly hurtle eastwards towards Cape Town.
“Once you get down past Rio de Janeiro and through the South American semi-permanent cold front, you start looking for something to help you turn left and hitch a ride towards Cape Town,” Fisher explains.
This time, however, he believes the sailors on the foiling IMOCAs will not need to go hunting quite as hard for big breeze conditions to achieve maximum performance.
“These boats go pretty damn fast in 20 to 25 knots of wind and that’s probably what would be ideal – any more wind and it kicks up a nasty sea state that can really slow us down because of the foils.”
At the end of what is sure to be a tough and hard fought leg, the final approach to the finish line off Cape Town’s Victoria and Alfred Waterfront can often be challenging and the weary crews may need to stay on full alert for being becalmed as they pick their way carefully past the enormous wind shadow that the city’s iconic Table Mountain can sometimes cast.
With race management predicting a 14-15-day passage time for Leg 2, the leading boats are expected to arrive in Cape Town on or around February 8 or 9.