Navigation and Sailing

Weather Routing Software

You head out to sea because you want to sail to somewhere far away, but which way should you go?

Wind direction can have a drastic effect on your ability to cover ground under your keel. If you are running, it will be slower than a broad reach, and still slower than a beam reach, but certainly faster than if you are beating. What does this all mean?

It doesn’t matter because there is a computer program that will interpret all the weather data and spit out a simple command: “GO THAT WAY”. You no longer need to know what you are doing or why you are doing it because a computer will tell you everything you don’t understand.


The program takes the forecast information and breaks it down into 4 scenarios depending on the models. There is the US and the European model, as well as the Predict Wind version of each. The colorful program even shows you where you will be at each time interval and which direction to go next!


Look at the little boats scoot across the hypothetical screen, aren’t they cute?


Looks like the GREEN boat is in the lead, woohoo!


Come Friday, the yellow boat seems to be the slowest of the pack!


RED and GREEN seem to be neck and neck!


RED has taken the lead!


Here is another lovely example of a program playing the role of Captain while you are merely a deckhand to the computer overlord. Hurricane Chris is looming to the NW of the boat and the computer is suggesting that the GREEN boat should head up into the hurricane and sail on its navigable semicircle.
Why? Because the hurricane is predicted to move straight and this would give you favorable winds to sail quickly.

What if the hurricane turns Easterly? Now what?

Weather routing software is nice to confirm what you have already decided is prudent and best. It can be used to run out theories in your head, but it should not by any means be the Captain of the ship. The software runs under the premise that the forecast is correct and as we all know, the forecast is never correct. This means that the suggested route is not going to be as expected!

If you still feel the need to have a program tell you where to go, don’t go to sea yet. Take some classes on weather and weather routing, read some books, and learn the material yourself. First, so that you can judge if the electronic information is prudent, and second, so that you can still navigate the weather should your electronic leader die at sea.

Transatlantic: Day 22 [Day 43]

We are nearing the end of July, and also nearing the Azores. Soon we will need to turn South towards the island chain and enter the Azores High, an area plagued by light winds and currents. Normally, cruisers will sail across the Atlantic and then motor the last few days once they lose all wind as they enter the High. We don’t have that luxury, which is why we carry a suit of light air sails. I had these sails (a drifter and a light air mainsail) made out of ripstop nylon (spinnaker material) just so that we would be able to sail once we entered the High ourselves.


The closer we can get to the islands without entering the High, the longer we can sail for. To complicate matters further, the Gulf Stream flows through here, so wind or no wind, there is a strong current carrying you to the East. If you miss your island, you might have some trouble sailing back to it against the current with no wind!


Our Australian friends were able to receive this information from Predict Wind, but we weren’t able to see it while we were still sailing. They just gave us a brief version in 160 character text messages to our satellite phone. When we did finally meet up in Horta, they gave me all of these screen shots that he had taken of the weather reports.

The forecast is processed by Predict Wind and run through four models. You have the US model, Predict Wind’s version of the US model, the European model, and Predict Wind’s version of the European Model. The information is broken down into various categories and based on the performance of your boat or the conditions you are looking for, you can choose the route that you think will work best.

Talk about gambling!


It gets interesting when you throw islands into the mix. Some of the models are saying to go North of Corvo, others are saying to go between Flores and Corvo, and others are saying to go South of Flores.

As you approach Faial, the red model is saying to drop south of Faial and come back up to it, while the green model is saying to go North of Faial and then approach Horta from the East side of the island.

The same information goes in, and yet all four models say something completely different. Out in the ocean, it doesn’t really matter where you go because there is just plain old ocean everywhere. When you throw islands into the mix, you now have wind shadows to contend with and you have to wonder: are these wind shadows accounted for?


We had another bright moon light night to show us that the wind and waves were plenty and strong. We continue to sail East, waiting for the signal in the sky to tell us to turn Southward towards Faial.

Transatlantic: Day 12 [Day 33]

We are approaching the Azores High and it would behoove us to head further north to keep with the winds.


We are moving a little slower but still moving right along. The weather around us is stable and we are making great progress, but we know that the large high is rising up from the south and will bring calm winds and seas. The further north we can get, the more chance of keeping up this pace we will have.

The view never changes, everywhere we look, all we see are clouds and waves. The waves tell us what the winds are like right now and the clouds tell us what the winds will be like in the next few days. We haven’t bothered to receive a Weather Fax in weeks since they are so inaccurate. Instead, we get our weather the old fashion way: by looking up at the sky!

Transatlantic: Day 11

Our friends on land tell us that the weather systems around us have normalized!


With this glorious information, we await the 8pm transmission of Weather Faxes and anxiously download the information.


The 1020 line has moved back towards us, the weird gales are gone, and the Azores High seems to dominate the North Atlantic.


Looking at the wind/waves chart, you can really see how the weather patterns have normalized. There is a very nice and consistent flow of circulation in the North Atlantic. Winds are steady and seas are even. The weather is here! It is time to turn North and make our way to Westerlies!

Transatlantic: Day 2

The blue ocean lays out before us as a magical wonderland of flatness. We can not see land, but we do see the turquoise clouds over the shallow waters of the Abacos islands in the Bahamas. There are still a few ships on the horzion, but none are close to us.

Our glorious push from the Gulf Stream is given up as we slowly drift our way towards the 1020 line. Winds are light and seas are flat, but we have hopes of wind once we make it to the 1020 line.

Why don’t we turn north? Let’s look at the weather fax!


Oh yeah, sometimes the weather fax looks like crap! I couldn’t get it to tune in until the region of our location was already over with, so I got a very ugly chart of the weather around us, but not where I am at the moment. What does show is the westward border of the 1020 line.

It was at the longitude of Haiti when we left, but now it has pulled back and is almost at the longitude of Puerto Rico!

Why not just give up on chasing down this mythical holy grail line on a atmospheric pressure chart and just ride the current north? Well, if you look up north, you will see “GALE” written up there. It turns out there were these massive gales that were stationary up there and really messed up the Annapolis/Bermuda race that year. One of my friends was on a boat in the race and the captain actually abandoned the race and returned to the Chesapeake Bay after having so much break on the boat! Needless to say, we wanted a nice “smooth sail” to the Azores, and heading into a gale was not in our cards.

Instead, we continued to drift along slowly.


The pressure chart was pretty worthless for weather planning, so I also collected the wind/wave charts as well, hoping to piece together a cohesive story for what the weather was doing around us.

It appears that the winds north of us seem to be rather squirrely, blowing in all different directions and different strengths. The wave height is pretty uniform as well, so we decided to keep creeping east towards the 1020 line, even though it was now hundreds of miles further away.