Yachts in the BT Global Challenge are preparing for heavier weather later today, as the remnants of tropical storm Helene pass over them. Quadstone, still in the lead from BP Explorer by 41 miles and heading straight down the track, had lighter winds this morning, possibly indicating that Alex Phillips and her crew were close to the centre of that area of low pressure. Some 200 miles behind and to the north, however, Andy Dare and crew on Team SpirIT had 40 knots of wind and were making over nine knots under reefed main, storm staysail and No 3 yankee.

Positions at the front of the fleet have changed little in the last few days, but further behind there have been some more interesting developments. For some of the boats at the back, light winds were compounded by adverse currents as they crossed the Gulf Stream. Despite a wealth of information being available by satellite about the position of the Gulf Stream, movements at the ever-changing margins alter by the minute, effectively making most data retrospective. Only a sharp temperature gradient confirms that you’ve reached the warmer water of the north- and east-going current – and by then, it’s often too late to do anything about it. The information is useful for determining the position of more stable eddies and favourable counter-currents, and the width of the current at a given point, but getting it right still requires a lot of luck.

LG FLATRON was not one of the lucky ones; she took a hitch north to sail out of adverse current and is now the most northerly of the leading boats. This may not be to her disadvantage if the wind veers to the north-west or north in the next few days, as is forecast, because it may give her a faster angle than yachts to the south.

The option of going north is a decision facing other skippers as well. The possible gains of a modest flyer at this stage are looking more and more attractive, but if they go north, skippers must also weigh against this the more awkward seas that would be kicked up on the shallower northern route if the forecast winds arrive.

But LG FLATRON was not the only boat checked by the Gulf Stream. Yesterday, Manley Hopkinson, skipper of Olympic Resources, reported that he had fallen into light winds and at one stage had actually gone backwards at a knot and a half. Over a 12-hour period, he and his crew made a miserly 18 miles in the right direction.

Norwich Union’s fate just gets worse. Her crew have also had light winds and have fallen over 300 miles behind the leader. Now disconnected from both the main part of the fleet and from the boats that were trailing along with her a few days ago, Neil Murray and his crew need a small miracle to avoid arriving in last place.