A slippery slope

You know that feeling that no matter what you do, today's just not going to go well for you? That will surely be the mood onboard team AkzoNobel, Turn the Tide on Plastic and Sun Hung Kai Scallywag in the middle of the South Atlantic Ocean today. The reason? They are falling off the back of the strong winds in front of a southern hemisphere cold front and will see the wind shift, drop in strength and will fall further behind the leaders.

Last week when the fleet was still working its way down the Brazilian coast, all eyes were on this system as the navigators onboard tried to hit a moving target and line themselves up for the fast blast eastwards that they have been enjoying these last few days. Back then, the concern was that they might "miss the bus" and be forced to watch the system head to Cape Town without them. Now, the backmarkers are being kicked off that bus, left to wallow in its wake. Let me explain.

It is all about sailing fast and keeping pace with not only our competitors but also the weather. If we slow, the front will roll over us and our progress will slow dramatically

Simon Fisher, Navigator Vestas 11th Hour Racing

Southern hemisphere depressions, or storms, rotate in a clockwise direction, the opposite direction from the northern hemisphere. With westerly winds at the top of the system and easterlies at the bottom, the most profitable sector for the sailors is the front top corner, in front of the cold front, where strong northwesterly winds blow hard over a relatively well-organised sea, allowing for fast speeds and spectacular surfing. This is the promised land for Volvo Ocean Race sailors!

It is important to push because behind us the conditions over the next 24 hours could be worse for boat speed, so we have good speed (now) and we are working hard on this.

Pascal Bidégorry, Navigator Dongfeng Race Team

A cold front is a mass of cold, dry air chasing a warm air mass and its arrival comes with dangerously strong gusts, a dark line of cloud followed by clear skies and a wind shift to the south-west (this is clearly seen in the satellite photo above, the dark cloudless patch is behind the front). Once the front passes over you, the new wind is now blowing across the established swells and waves built up for days by the previous wind, creating a bumpy ride that further slows progress.

Shifty, unstable winds combined with cross seas further hinder progress and push the unlucky boats out of the stronger winds and into the clutches of the high pressure (light winds) ridge that follows the depressions like night follows day.

The key takeaway here? A small lead on the fleet when riding in front of the front can balloon into hundreds of miles as the weather systems favour those at the front and punish those at the back. Routing calculations show that the boats that fall off the system will be forced to sail a dramatically different route than the leaders, adding miles that will be doubly penalising.

The fleet was all lined up a couple of days ago going into the system, now ETAs for Cape Town are spread out over a more than a day!