Figure Out the Wind Patterns
by David Dellenbaugh
The first, and usually most
important, step you must take in creating a strategic game plan is to figure
out the wind. Changes in the wind direction or strength can have a huge
effect on which boat comes out ahead. so before the start, try to predict
what the wind will do during the first leg. If you can do this, it will be
easy to figure out the favoured side of the course.
Collecting info about the wind
In order to predict wind patterns after the start, you need to
gather as much information about the wind before the start as you can. Here
are some ideas.
A simple way to keep track of changes in the wind is to write your
compass headings for each tack in pencil on the deck. I like to write
the lower numbers on the left side and the higher numbers to the right
(as shown above). This way I can quickly see the range of headings on
each tack. It also helps me keep track of what the wind is doing over
• There are two basic ways to collect wind information. The first is by
listening to or receiving predictions or forecasts. The second is by using
your own powers of observation to gather data.
• Normally, but not always, you get forecasts before you leave the dock each
morning. In the U.S., these might include NOAA weather radio, the weather
service that gives you forecasts by fax or e-mail.
• Observations of the wind are usually made once you are sailing around in
the course area. These include all the telltale clues you see (e.g. flags,
clouds) as well as all the data you collect (e.g. compass numbers on each
• When making observations, don’t just sail around the starting area and
look upwind. To get good information you should try to sail to each side of
the course and experience what’s there.
• A third, and very valuable, way to get information about the wind in your
racing area is local knowledge. Before you go out, make sure you talk to
sailors who have spent a lot of time in that racing area. This is a
combination of predicted and observed information.
• You should usually give more weight to your own observations than to
forecasts. That’s because observations are specific to your racing area and
the time of your race, while forecasts are usually quite general. For
example, if the weather radio calls for the wind to shift clockwise, that
may happen over the course of a day or an afternoon. But it may have nothing
to do with your 15-minute first beat.
• Forecasts and predictions will have less and less relevance when your
races are shorter and there are more geographic effects in your racing area.
The weather channel, for example, cannot know what will happen to leeward of
a point of land near your windward mark.
Rules of thumb for the wind
One generalization you can make about the wind is that it is almost always
changing. While there are some times when you may feel certain of a
predicted shift, you never know for sure. so you must always keep your head
out of the boat and view each moment of the race as completely new and
• If you want to predict the wind, you must be proactive, not reactive. By
the time you feel the wind on your neck or read it on your instruments, the
shift or puff has already happened. So keep your eyes out in front of the
Here is one way to visually represent changes in wind direction over
time. The beauty of this kind of graph is that you can extrapolate into
the future and make a pretty good guess about what the wind will do
You can create this graph with a bunch of true wind readings, or use
your headings on each tack (as shown in graph 1). The darker line shows
how an oscillating breeze shifts back and forth *usually fairly
regularly) around a median (average) direction.
The lighter line shows a breeze that is shifting persistently. That is,
it shifts steadily in one direction (with small oscillations) over time.
• On some days, you may not have the slightest idea of what the wind is
doing. That’s OK because wind patterns are not always so obvious, even for
the best sailors. In these situations, just keep watching for more clues,
and stay in a position where you can take advantage of whatever happens.
• Before the start, you must always assess the relative importance of wind
versus other strategic factors. For example, will you go left for better
wind or right for better current? Wind is usually more important because
slight shifts in direction or increases in velocity can make a big
difference. But this is not always the case.
Wind direction and velocity
When you’re collecting information about the wind, there are two important
considerations: 1) changes in the wind direction: and 2) changes in wind
velocity. Here are some ideas for each.
• When you are looking for wind velocity, the appearance of the water
surface is key. In general, darker water means more wind because of the way
wind ripples reflect light from the sky. However:
- Glare from the sun can sometimes make more wind look like less wind, and
- Sometimes what looks like more wind is really the effects of current.
- Ripple-less water does not always mean no wind because occasionally wind
stays just above the water.
• When you’re trying to find shifts in direction, it’s very hard to tell
much by looking at ripples on the water. you have to rely on clues like the
angle of other boats sailing farther up the first leg.
• The pattern of windshifts usually falls into one of two general categories
- either oscillating or persistent. Before you settle on a strategic plan,
one of the most important things you have to decide is whether you will play
the wind shifts as oscillating or persistent. How well you make this
decision throughout the race will have a lot to do with your success.
• In an oscillating breeze, how much information do you need to collect
about the puffs? I usually record only the range of the shifts (e.g. the
high and low compass numbers) and not their timing. That’s because the range
of the shifts is normally what determines when you should tack, and it’s
more reliable than the timing.
• Another important strategic factor is deciding on the relative importance
of wind velocity versus shifts in wind direction. In other words, when you
are sailing up the first beat, will you sail for better pressure or the next
In the 1992 America’s Cup, we had a sophisticated system for collecting
wind data before each race. This included three tenders with wind
instruments spread across the course (above). one boat was about a half
mile to windward of the first mark, while the other two were slightly to
windward of the corners of the course. Before the prep signal, all their
wind data came in to a computer on America3 that displayed a running
graph like the one in graph 2.
A good guideline is that velocity is usually more
important in lighter air while shifts are more critical in breezes.
Since the wind direction and velocity are so important in your strategy,
spend a good part of your time before the start collecting information about
them. And don’t forget to keep doing this throughout the race as well.