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Weather - Passage Planning

The past few weeks we have been heading back south from Sweden... making bigger jumps and pushing to get back south. Up in Sweden everyone had quit sailing and boats are all put away for the winter. So it was time! It got me thinking about planning for passages and how we learn about the weather and conditions for a new sailing area. It seems we are always sailing in a new place and have to learn new rules and weather conditions.

Traditionally we have “Pilot Charts” that summarize the winds, waves currents and typical sailing routes for various areas of the world over the last number of years. In the old days they were all you had to gauge what conditions to expect. But they are really just averages of past years. So they will only give you a probability of average winds. So for us planning a return to Britain from Sweden we could see we would have many days of southwest winds. In advance I used this to plan our schedule. Knowing we would often have headwinds I built in a number of delay days for our passage plan. We also planned to return across Sweden via the Gota canal since we could always do that regardless of headwinds.

But as the time gets closer it is possible to use some of the amazing resources of the Web to get better information. Watching up to 10 days in advance we can see if we should hurry off now with a minimum weather window or hold on for improving conditions.

Here in Europe I have a few nice sites that give long range predictions... <-- 7 day winds animation <-- 10 day pressure predictions

But looking at the pilot charts and the current forecasts isn’t going to make you into a weather expert (not immediately anyway!). My biggest problem is that we are always new to an area and don’t have “local knowledge”. Here in the North Sea area winds often prevail from the southwest - but does that mean 2 out of 3 days the wind is from that direction or for 10 days followed by 5 days from somewhere else? I have found studying the weather patterns from previous years can help with this. Pilot charts are a statistical summary, but now with the internet you can go back and study in detail what happened in past years.

I take a few hours and look around to see what the weather looked like in past years. From our crossing of the Bay of Biscay I found some amazing sites going back years with detailed information - here is a specific site with sea buoys in a variety of places.

Got to run - off across the IJsselmeer toward Amsterdam!
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