Routing for Cruisers


We’re headed for Panama now, and while this route will generally have winds from the aft quadrant, we are using a combination of tools to look ahead and see what the weather gods are planning.

Using programs like SailMail, UUPlus, and Ocens we are currently getting used to the new GFS weather model and getting reacquainted with NOGAPS as well.

Then there is a new routing tool being developed for cruisers. This is an offshoot of one of the most successful ocean racing programs, Nick White’s “Expedition”. The racers need all sorts of complex calculations with a variety of ways of playing “what if” games. For cruising we want it much simpler and easier to use. That’s one of the things we have been working with Troy Bethel on, an example of which is above.

This is a routing, using the performance of Wind Horse, degraded for head winds and head seas and enhanced for downwind acceleration when wind and waves are behind us. The program looks at the projected weather data, and then our performance polar, and calculates how long it will take us for the passage, in this case to Panama from Ensenada, Mexico. As a part of this process the program displays wind data for each segment of the route.

Now to the image above. You will note that 25 to 30 knots ate showing coming out of the Gulf of Tehuantepec, and port quarter headwinds approaching this area. These are not pleasant conditions.

So, we use the routing software to calculate what would happen if we were to depart a few days later.


Light and variable and from the stern. Much more conducive to marital harmony!

While we are using the routing tools to check the wind conditions we are likely to face, Wind Horse is able to maintain her cruising speed up or down wind pretty much regardless of conditions. But in a sailboat you typically need favorable winds to make good progress. By loading the performance polars for your boat into the routing program, the program will tell you how fast you are likely to be – and the optimum course to steer – during each leg of your passage. This is such a powerful tool for getting there quickly that all racing yachts now use some form of routing.

It is an even more important tool for shorthanded cruisers. We’ll keep you up-to-date with how Troy’s program development is going with demonstrations of its use over the summer.

Posted by Steve Dashew  (April 16, 2008)

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