Scientists dispute the exact location of the Southern Ocean but sailors don’t need a chart to know. They feel it in the chill wind, the deepening grey clouds and the freezing spray that whips their faces. They sense it in the roller-coaster movement of the boat, the vast waves and an overwhelming desolation of the soul. “When you feel the cooler, denser breeze, you know you’re entering the Southern Ocean,” says Conrad Humphreys, who finished seventh in the last Vendee. “It sends a shiver down your spine.”

The leading pack in this Vendee, concertinaed into a 40-mile stretch of the south Atlantic after three weeks’ racing, are nearing the waters that eddy unhindered round the foot of the world like water draining down the plug. Humphreys, who has unfinished business in the event, believes the entrance to the Southern Ocean poses one of the race’s great psychological barriers.

“After South Africa, there is no turning back,” he says. “The only thing that lies ahead is a vast ocean. If you have any niggling problems on board, they start to play on your mind. I think you’ll find three or four will pull into Cape Town in the next week or so.”

Barring severe damage to his Open 60, Ecover 3, they will not include Mike Golding. The highest British racer has cut the lead of Seb Josse to barely 40 miles and figures from the two most recent Vendees show Golding sails the Southern Ocean faster than anybody else in the fleet. Rather than recoiling from the challenge of surfing down 30ft waves, the 48-year-old regards this as his strength. Where others are tempted to pull back, he pushes on.

“For one thing, Mike’s utterly fearless,” says Humphreys. “I’ve sailed with him and he seems to remove the fear part of his brain. He keeps his foot hard down when quite a lot of skippers take their foot off. He’s also very experienced. He’s been in this class a long time and he knows the Southern Ocean as well as anyone. He’s hungry. I’m not sure if he wants to do this again, so this might be his last chance.”

Golding sounded understand-ably tired in an interview late last week. Relentless pounding upwind has taken its toll on his sleep patterns and he was acutely aware that one mistake now, navigating his way through an awkward high pressure system, could cost him precious time before he breaks into the westerly winds. The trick in the Southern Ocean is to find a depression and roll with it for as long as possible, like a surfer riding a wave. The other trick is to avoid icebergs. “I’m happy with where I am,” he said. “The weather’s done the race a favour by putting in a series of chicanes. If I can get out into the westerlies in good shape, we’ll see if the Southern Ocean can work its magic for me again.

“It’s a place where you’re very tense a lot of the time so the more relaxed you can be, the better off you are. Maybe it’s just that I’m stupid but there’s something special about keeping the pressure on the whole time.”

Back on dry land, at the National Oceanography Centre at the University of Southamp-ton, Dr Brian King highlights three factors that make the Southern Ocean the ultimate challenge for a solo sailor. “If the wind blows over the water for a long distance, it increases the height of the waves,” says Dr King, an expert on the Antarctic Circumpolar Current, which runs from west to east round Antarctica.

“In the Southern Ocean, there is no land mass to stop the wind. The conditions are very variable. Depressions come ripping in, so it can be fine one minute and wall-to-wall grey cloud the next. When the wind works against the current, it becomes very uncomfortable and much more dangerous. The crests of the waves are squeezed together, which makes the face of the waves very steep.” Dr King has seen waves 10-15 metres high and scientists have recently monitored waves almost twice that height.

On board Suhaili, Sir Robin Knox-Johnston had to climb the mast to escape the constant cascade of water burying his boat in the Golden Globe race in 1968-69, the spiritual source of the Vendee. Suhaili was a sturdy 32ft Bermudan ketch, not a 60ft carbon fibre racing yacht, but the passage through the Southern Ocean still tested the relationship between boat and skipper to the limit.

“Suhaili didn’t have the speed to get out of trouble,” recalls Knox-Johnston. “These new modern boats do. But it’s still as much of a mental test. You feel very much alone down there so you’ve got to keep yourself going, keep positive.”

Golding believes the spin through the Southern Ocean will fragment the front pack and leave a small group vying for victory as the fleet rounds Cape Horn.

Two years ago, nearly four decades on from his historic voyage on Suhaili, Knox-John-ston returned to the Southern Ocean in the Velux 5 Oceans race, becoming, at the age of 68, the oldest person to sail solo round the world. He found conditions there very familiar. “It was still just bloody cold.”

Six factors affecting Vendee skippers

North or south:the stronger winds further south carry a greater risk of icebergs

How hard to push:there is opportunity for big gains and equal potential for disaster

To helm or not to helm:tricky conditions require real skills at the helm but helming is physically and mentally demanding

Sail changes:same as above. Changing sails is essential for maintaining speed but can be dangerous and fatiguing

Night moves:some skippers are better than others at night sailing but the risks of pushing hard in the dark increase in Southern Ocean conditions

Mental condition:the best sailors enjoy the experience, many don’t. Much of the challenge is in the mind

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