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Which way to go across The Pond?

Ellen MacArthur  and Kingfisher learn the ropes

Roger Badham of team 
Club Med 
 talks about routing

Planning to win a race

French router prefers the challenge
of weather strategy to weather forecasting

For router Jean Yves Bernot, training young Ellen MacArthur to predict the best path on her first solo transatlantic crossing involves weather strategy, not simply weather forecasting.

"When you plan for an ocean crossing you think not so much about what kind of weather to expect, but which route to take. That's not so easy. With modern boats being so fast, there is a big difference in sailing from one point to another," he says.

"Making a strategy is different than forecasting. You think about which angle of wind is best for the boat, how weather systems will evolve and so on. This is much more interesting than simply making a forecast."

Jean-Yves came to routing as a sailor first, a weatherman second. He has built up an enviable reputation as navigator aboard numerous racing yachts, including New Zealand-built mega yacht Mari Cha III, on her record breaking trans-Atlantic run in 1998. 

Of course, living in France, where solo ocean racing is regarded as religion, Jean-Yves has had ample opportunity to pass on his knowledge to skippers in need of weather strategy. 

"In France there is a lot of single-handed racing, which means there is plenty of work in routing. As a result I spend a lot of time educating skippers," he says.

"However, I am not a meteorologist. I am a sailor first. Of course, I have a good education in meteorology and have carried out research in oceanography. In terms of weather and strategy for offshore sailing, I have a very practical point of view."

For Ellen MacArthur on board Kingfisher, the youngest sailor with the newest Open 60 in the Europe 1 New Man solo Trans Atlantic Race, Jean-Yves pre-race advice will be crucial to her success.

In simple terms, skippers can expect westerly winds in the eastern Atlantic, at the start of the race, where they will use frontal systems and low pressure cells to their advantage. In the beginning they will generally choose to sail towards Newport, Rhode Island between the rhumb line and the Great Circle Route. 

About longitude 40W, skippers have to decide whether to continue along this direct route, sail north to catch favourable winds on the right side of low pressure cells, or to sail south and attack prevailing south-westerly winds at the best angle. 

A key factor in making their decision, will be the location of the Azores High - an area of stable high pressure in the central Atlantic that shifts - in summer -  between the islands of Bermuda in the west and the Azores in the east.

If the high sits in the eastern Atlantic, then there is ample room for low pressure cells to develop and track towards Europe, between the high and the North American coast. If skippers can position their yachts to the north of these low pressure systems, or on the right side of the storms, they will have winds off their beam or even stern quarter (remember, lows spin counter-clockwise in the northern hemisphere). They will also have a favourable current of between 1-1.5 knots. Yachts sailing the southern route in this scenario would be on the left hand side of these storms, copping north westerly headwinds.

Trouble with the northerly route is that the Labrador Current brings ice out of Davis Strait as far south as 40 degrees. And this year is a particularly bad year for ice, says Jean-Yves. When this cold current mixes with Gulf Stream eddies and warm southerly air on the Grand Banks, pea soup fog is the result. This, combined with intense shipping traffic, makes sleeping a deadly risk.

If the Azores High sits in the western Atlantic, skippers may choose to sail south and attack prevailing south westerly winds - circling off the western side of the high pressure cell - on their bow quarter. Yachts sailing towards Newport from the northern route in this scenario would face a nasty beat to weather for the last two to three days of the race.

The disadvantage of the southerly course however, is that yachts will have to sail close hauled across the choppy Gulf Stream. Skippers on this course minimise the effect of the Gulf Stream by sailing along its edge, and with the help of a thermometer, this isn't so difficult. As Jean-Yves points out, the Gulf Stream measures about 20 degrees Celsius, whereas the surrounding Atlantic water is just five or six degrees.

"The boundary between the two bodies of water is like a wall," notes Jean-Yves.

Predicting exactly where the central Atlantic high pressure cell will sit (whether it will be a Bermuda High or an Azores High) is not an easy task. Skippers can only receive weather fax charts (both surface and 500hPa charts) satellite images and weather bulletins. But information on the jet stream, particularly jet stream forecast charts are not available. And it is the jet stream which steers surface systems.

Winds at 500hPa are not high enough to show what the jet stream is doing, but they give a good indication. And this chart is what Ellen MacArthur and her fellow skippers will be using to judge how fast surface systems are moving and where they will sit when crucial decisions must be made.

Did you Know?

• For the Open 60 multihulls in this race, the task of putting yachts in the right place is easier, because these machines can sail upwind at 16 knots and off the wind at 20 knots plus - quick enough to move from one weather system to another. For Ellen MacArthur's Open 60 monohull, this task is not so simple, except in heavy weather. In winds of 45 to 50 knots, skippers on monohulls can maintain sail area and speed whereas those on multihulls tend to back off and save their boats from damage.
• The Open 60 multihulls can expect to cross the finish line at Newport Rhode Island about 10 days after starting from Plymouth, England. The Open 60 monohulls can expect to take four days longer.
• Jet stream forecasting is difficult without the help of satellite images showing the path of water vapor at 200hPa. But a 500hPa chart will give a good indication of what the jet stream is doing. A blocking high, for instance, is obvious on a 500hPa chart.
• Wind flow at 500mb will steer the weather pattern at the surface. If there is a westerly wind moving at 40 knots at the 500hPa level, then systems at the surface will move at roughly half that speed. 
• By comparing charts day after day, skippers can judge how fast weather systems are moving.

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