Sunday, January 08, 2006

How far south?

Overnight ABN AMRO ONE has extended her lead over Pirates from 35 to 115 miles. Given that the gap between the leading two has changed only slowly for the previous day or so its worth asking how Mike, Betty and the boys pulled out so clearly.

To find the answer we must understand what the weather has been down there, which means looking further afield than the otherwise excellent Virtual Spectator.

As you can see in the picture above VS shows the wind direction and strength using animated coloured arrows at the time of the latest data point. VS can also show isobar contour - but alas the code behind that feature isn't compatible with my laptop, and so for me is unusable. The other problem is its only a snap-shot - it doesn't show historical data or forecast what is to come. So we must go searching the web for those that do.

This isn't always easy. Most weather forecasts cover areas of land - and populated land at that. It is only a small minority that cares what the wind strengths are in the depths of the southern oceans. However a few can be unearthed, and an answer to our question can be found.

The follow graphic comes from this site.

The fleet is currently between 41S and 43S and 46E to 52E. In this region the contours are spread out, showing weaker winds. And that is what the on-board telemetry shows: ING at the back has just 10 knots of wind.

However AMN AMRO ONE has its nose just ahead of both the fleet and the front where the contours are just a little more packed and so is sailing in 21 knots of wind. Yet again another example of "to the winners the spoils".

And what do we see coming up? From this site we get the 24 hour forecast.

We can see a finger of weak wind around 45S. Any boat that ventured south of it into the furious fifties would indeed gain much stronger wind - but at the significant risk of iceburgs. So the objective for the next day or so must be to try stay in that band of green where its a rather pleasant 30 knots. And avoid those wind holes.

Pictures from the web sites mentioned and Virtual Spectator

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