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Lots of hard work in the doldrums Constant sail changes, tricks at the
helm, and November 22, 2000 The leading skippers of the Vendee Globe 2000 are right in amongst it ... And the wind in the doldrums is all over the place! Ellen MacArthur (Kingfisher) describes it like this: "I am in the doldrums, and yes it's hard going, but at 3 am this morning (November 21) the easterly wind came back and I've been going steadily at nine knots since. At the same time I have managed to make good all my repairs, and done an enormous amount of boat maintenance over the last two days...I haven't been wasting my time!" Josh
Hall (EBP-Gartmore): "It¹s a really difficult part of the race, more so
probably than the Southern Ocean. The wind changes all over the place, I spend
the whole time changing between spinnaker, gennaker, spinnaker... The first time
I raced down here I was so frustrated and aggressive, which is pointless. Right
now I'm getting an 8 knot Northeasterly wind and the boat speed is 7.5 knots.
But it'll change in 5 minutes."
Yacht positions as of November 21, 2000 This image, courtesy of Virtual Spectator, shows the leading yachts in the thick of the doldrums. Wind arrows give an idea of how the north-east and south-east trade winds converge. Note the wide spacing between isobars. Also note how the west African coast does terrible things to wind flow and direction! East really means least here. There's not much gradient wind in the doldrums (wind circulating around high pressure zones), and skippers need to take advantage of winds being blown out of squall clouds to get through this zone quickest. However, if this image is correct, the south east trades are not far away!
Making the most of it! All three of these skippers are mere miles from each other, with Ellen furthest to the west, and hoping to sneak under the Inter-Tropical Convergence Zone with the best wind ... what there is of it! Yves Parlier and Mitch Desjoyeaux, who chose to cross this zone of variable winds east of the usual longitude - 25-30 degrees west - slowed up first, but both remain very much in the front-running. Catherine Chabaud and Dominic Wavre, who strayed far to the east have paid dearly for their irrational decision. East means least when it comes to wind along the equator, because conflicting trade winds from both hemispheres face further 'shadowing' from the West African mainland.
North Atlantic cloud
patterns Image courtesy of Intellicast. This one is worth waiting for: 1.6mb (about 10 minutes download time) of animated .gif showing the movement of cloud, every three hours, across the North Atlantic. Each frame will load one after the other, so you can get an idea of what's on offer. Once loaded, the image will run at 10 frames per second showing a smooth movement of cloud across the North Atlantic basin. The overall picture is what we're trying to present here, rather than minute detail. This image shows the coldest cloud tops (the highest in the atmosphere) as purple and the warmest (lowest) as white. Red is pretty cold too, indicating plenty of rain, and this animated image has a lot of red cloud. Not how the massive trough east of the Grand Banks seems to 'suck' a band of tropical cloud towards it. While the equatorial band of cloud is quite high in the sky - probably 30,000 feet - it must be affecting the surface, as moist oceanic air associated with the north-east trades flowing underneath it will be able to rise higher than normal, cooling to create more clouds, more rain, and more wind. See if you can observe the two wind cycles swirling over the ocean - There's an upper level traveling east and a lower level traveling almost contrary: Together these winds represent an important planetary cycle, with upper layers bringing warm and humid tropical air to the poles and the surface winds bringing cooler polar air towards the equator. Where the surface winds meat, is called the Inter-Tropical Convergence Zone (ITCZ), and this is where the Vendee Globe skippers are doing battle for the leading positions. All those who have been here before reckon longitude 25 to 30 degrees west is the right place to cross. Here there is the greatest chance of wind because here is where there is usually the greatest cloud activity. Where there's cloud, says Bob Rice, there is inflow and thus wind. Interestingly, the greatest cloud near the equator in the animated image above is exactly over the 30 degree line. Ellen MacArthur, furthest west, should benefit best. In fact, she has sailed more miles in recent days than any other competitor, yet has not lost any ground, which proves she has had the most wind for the longest.
Unusual cloud patterns The ITCZ at the moment is not following an unusual pattern (what is usual in this zone?!), with cloud spreading north and south over several degrees. Boats as far north as eight degrees are finding variable winds and calms - quite a distance further north than 'normal'. No doubt the extensive cloud activity right across the north Atlantic is contributing to his phenomena. Meanwhile, the South Atlantic High is strengthening, after lying somewhat dormant for the previous couple of weeks. If this trend continues, the leading yachts should feel blessed trade winds sooner, rather than later.
South Atlantic pressure Image courtesy of OceanWeather. These animated pressure maps show the South Atlantic High as it moves east across the South Atlantic, building and then fading over St Helena Island (That's why they call it the St Helena High, the South Atlantic's version of the Azore's High). The blue arrows show wind direction and speed in knots, reported by ship. The pressure lines are produced by the US aviation model, and represent forecasts 6-18 hours ahead. While the pressure lines weren't actually what happened at the time, they are pretty darned close. Bob Rice prefers the AVN model, and he is an expert when it comes to routing. For the Vendee Globe skippers, an ideal situation would include the South Atlantic High centred over St Helena, with a low and its associated front developing off Argentina. Winds would circulate around the high counter-clockwise, and be sucked south towards the low along the eastern edge of the frontal cloud. A low pressure area south of Brazil working with the St Helena High would do the same trick. Either way, skippers could 'cut the corner' and sail closer to Cape Town than nature would otherwise allow, thus saving valuable miles. A worst-case scenario would include one seen in the South Atlantic just a fortnight ago, when the high was 'stuck' on the western side of the ocean with very little wind on the eastern side. Skippers would have to work hard to get out of a large light and variable wind region before beating to windward, south along the high's eastern edge, before collecting the steady westerly winds about latitude 40. This route would be longer, and harder, and much more frustrating. All eyes will be watching the South Atlantic in coming days to see what materialises.
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