Sailing / Whitbread Round The World Race: Rising to the challenge of rolling swells: Grant Dalton, leading skipper in the Round the World Race, who is writing for the Independent, on the perils of the Southern Ocean

IN the past few days the pace has really cracked on so I think we are earning our money now and really testing our mettle.

We know how hard we are pushing this boat, so when some of the 60s cover even more miles in a day than we do they are fairly flying and we have immense respect for them. The guys are tired. This is a big boat and we are working very, very hard. These have been the toughest two weeks of my life for some while.

Helming a maxi at full bore through the Southern Ocean in the middle of the night borders on the terrifying. The fatigue, both physical and mental, is constant, as is the cold and damp. So the longest stint is no more than two hours - often only one - and when the going gets really tough it can be as little as 20 minutes.

The incessant noise - like a rushing train - will have taken its toll while you are resting below. On deck it adds to the anxiety and the feeling of being vulnerable to making a catastrophic mistake.

The strain on arms and shoulders can be intense. As the boat is constantly shifting direction, so the wheel has to be wrenched over to counter the bow when it tries to swing.

All the time the boat is being sailed to its limits, so every now and then you are pushing closer to the edge than you would like, and sometimes right over it. There are several disasters lurking when you start to steer down a huge wave. You can bury the boat in the back of the wave in front, sending huge amounts of water running over the deck, knocking over the crew, and slowing the boat down by making it heavier. When that happens, the masts want to keep going forwards and consequently fall out of the boat, and the wave behind is catching you up.

If it does, it can pick up the stern and push it round. If you don't anticipate it, either the sails take over and the boat whips round in a screaming rush into the wind. Or, even worse, the stern goes through the direction of the wind. This is called a Chinese gybe and it is the most terrifying possibility.

At night you can lose your most valuable sense, your vision. It can be so black you cannot distinguish between the horizon and the sea and that is when good instinctive sailors are so valuable. A lot of them have their background in dinghy sailing and they can feel what the boat is doing almost before it happens.

There is also the problem of 'sailing by the numbers', which is much like flying a high performance plane entirely on instruments. On the yacht this means watching the read-outs, and knowing exactly how they behave, particularly the time delay between what is happening and its appearance in the instruments.

In both cases, controlling the boat or interpreting the numbers, mental fatigue can exert a bigger toll than physical tiredness, once again especially at night. You have to keep the boat-speed up to the maximum at all times, yet try to do so safely. And in numbing cold, constantly drenched with freezing spray.

We will be at Prince Edward Island at about the same time the All Blacks face England, and there will be a lot of interest on board about the result of that one.

At least the boat is still in great shape and there has been no serious damage to people, though some of the guys are complaining about sore arms and one or two have forearm supports. But, then, they are driving the hell out of the boat.