for Changes in Wind Direction
by David Dellenbaugh
One thing you can say for sure about
the wind direction is that it’s always changing.
Even when it seems like a nice steady day, the
wind is constantly wriggling back and forth at
least a little bit. And whenever the wind shifts,
it creates a large opportunity to gain distance
on the other boats in your fleet.
Wind shifts are generally the most significant
strategic factor of all. Each time the wind changes
direction it re-shuffles the fleet standings,
and in almost every race the potential gains and
losses due to wind shifts are greater than any
other factor, including boatspeed!
For all these reasons,
it’s very important to understand what the
wind is doing - both before and during your race
- and how best to use the wind to your advantage.
the next shift
When the wind direction is
changing, your basic strategic move
upwind is to sail in the direction where
you expect the wind to shift next. For
example, if you think the wind will
veer (shift clockwise), sail on port
tack toward that shift (and vice versa).
By doing this you will
end up on a higher “ladder rung”
when the wind shifts, and therefore you
will be more advanced in the race. Of
course, there could always be reasons
(e.g. current, wind pressure) when it
might pay to sail away from the next shift.
- Many windward
legs are only 10 or 20 minutes long so general,
large-scale forecasts (like the ones you get
on the web, radio or TV) are not very helpful.
It is much, much more important to rely on:
Local knowledge: In the specific
venue where you are racing, what does the
wind usually do when it blows from each direction?
Use your own experience from past regattas
and ask local sailors to tell you what happens.
Your own observations: These
are even more important than ‘local
knowledge’ because they apply to your
race area on the specific day when you are
racing. Be sure to collect these before the
start, and keep observing during the race.
are many reasons why the wind changes direction.
These include the movement of weather systems,
thermal heating, changing current, clouds
and geographic effects. Keep your head out
of the boat and try to understand which of
these apply to your particular situation -
this will help you know which way the wind
will shift next.
- Sail toward the next shift!
When you expect that the wind will change
direction (it happens every beat!), the key
idea in your strategic gameplan should be
to sail in the direction of the next windshift.
- When making a strategic
plan for your windward leg, the relative importance
of windshifts will depend on several factors:
In light air, windshifts are less critical;
wind pressure and current are more important.
The importance of windshifts
is proportional to their size.
Shifts are more critical on longer beats where
the boats get more separation (farther apart).
- Windshifts almost always
fall into one of two categories - they are
either oscillating (shifting back and forth
around a median direction) or persistent (changing
steadily in one direction). If you want strategic
success, you must constantly ask yourself
one simple question during each windward leg:
Is the wind direction oscillating or persistent?
The way you answer this question
will make a huge difference in how you play the
shifts. For example, if you think the wind is
oscillating and you get headed you should tack.
But if you think the wind is shifting persistently,
you should keep sailing into the shift.
Sometimes what appears
to be a wind shift is really a change in wind
velocity, not in its direction. If you are
sailing along and the wind velocity suddenly
drops (without changing direction), your apparent
wind will shift forward temporarily and it
will seem like you’re headed.
- Be careful not to treat
this “velocity shift” like a real
change in direction. If you suspect a change
in velocity, wait 30 seconds or so and see
if the ‘velocity shift’ disappears
once your boatspeed adjusts to the new wind
are different every day. Sometimes
it’s very easy to see them on the water;
other times it’s impossible. Sometimes
when a shift hits your boat it is solid right
away; other times you have to sail farther
into the shift to make sure it’s real.
When you are trying to make a gameplan to take
advantage of the shifts, there is nothing as valuable
as sailing around in your race area before the
start, just watching (and recording) what the
wind is doing.
Dave publishes the newsletter
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