Understanding the wind - Clean up your language

If you've ever travelled very far abroad, you know how hard it is to communicate with people who don't speak your language. Being on a sailboat can be a lot similar, especially when you're talking about the wind. Oscillating shifts, gradients, persistent veers, vertical instability, velocity shifts, knocks, backs . . . the list is endless.

Since wind is probably the single most important clement in sailboat racing, let's take a closer look at the language we use to describe it. Pretend that you drive down to your local beach and walk out to the end of the breakwater. When you close your eyes, you hear the gentle sloshing of the waves and feel the refreshing rustle of the breeze on your face. Now you're in a perfect position to watch what the wind is doing.

There are three characteristics about the wind that people usually include when describing it:

1. Direction. This is normally expressed in terms of the compass heading from which the wind is coming. For example, "The breeze is northwest" or "The wind is 315°."
2. Strength. In some countries they describe the velocity of the wind in meters per second, while in others they use the Beaufort Scale (see page 10). In the United States we use knots, or nautical miles per hour: "The breeze is blowing northwest at 14 to 16 knots."
3. Pattern of change. When you give the breeze a direction and strength, you've described it for only one moment in time, since the wind is always changing. To fully explain the wind you feel, you have to describe how the wind direction and strength are changing over time. This requires watching the wind for a while to see the pattern.

Typical wind patterns

If you think the wind is steady, be careful. There are almost always subtle changes in direction, which the good guys use to their advantage. When you notice that the wind is steadily shifting in either a clockwise or counterclockwise direction, you have a persistent shift. In the Northern Hemisphere a seabreeze is usually persistent because it shifts clockwise as the day wears on. If the wind is shifting back and forth around a fairly steady average direction, then we say it is oscillating. A cool, pul't'y northwesterly is a typical oscillating breeze.

Often the patterns are combined. For example, a breeze usually oscillates back and forth as it shifts persistently, especially near a front or new weather system.

Describing shifty winds

Any description of an oscillating breeze should include 3 things:

1. Magnitude of the shifts. You want to know how much {he wind is changing in direction. For example, "The wind direction is ranging from ^95° to 325°."

2. Median find direction. After figuring out the range of the wind, pick a wind direction that seems right in the middle. This is called the median. In the example above we'd probably choose 310° as the median.

3. Timing of the swings. Besides knowing how much the wind is shifting, it's helpful to know the time between shifts. This can be difficult to determine, however, so don't worry about it too much.

Changes in wind velocity

When the windspeed temporarily increases or decreases, then you have a puff or a lull. When the wind gradually increases or decreases over a longer period of time, you have a building or dying breeze.Watch out for changes in wind velocity that seem to bring a change in wind direction as well. Often a puff or a lull will make it appear as if the wind had shifted to the right or left when, in fact, the direction has stayed constant. This is known as a velocity shift.

The wind you feel afloat

Out on the end of your breakwater the reddish setting sun casts a glow across the sky and the rippled water surface. While you're staring into these colors a friend comes sailing along the beach. He makes a perfect landing on the lee side of the rocks, and you step aboard. Now you have a chance to watch the wind from a moving boat.

When you were sitting on the breakwater the wind you felt was the true wind. What you are feeling now is the apparent wind - the combination of the true wind and the wind that's created by the movement of your boat. It is usually described in terms of its velocity in knots and the angle it makes with the bow of the boat.

The faster a boat goes, the greater her apparent wind velocity and the closer this wind is to her bow. A typical keelboat, for example, might sail upwind with an apparent wind angle of 25°, while an iceboat would have an angle much less.

Veers, backs, lifts and headers

While you're racing, it's important to be able to describe accurately any changes in the wind direction. When the wind shifts in a clockwise direction, it is called a veer. A clockwise shift is also commonly known as a "shift to the right." A counterclockwise shift is called a back, or a shift to the left.

Sometimes it's more useful to describe windshifts in relation to the heading of the boat.

A lift is when the wind shifts away from the bow. Lifts are often expressed in the number of degrees they allow you to head above the median. For example, if the median is 310° and you're steering 320° on starboard tack, you might say, "We're lifted 10 degrees."

A header (or "knock") is when the wind shifts toward the bow, and the boat has to bear off a bit to keep the jib full. Like lifts, headers are described in compass degrees:

"We've been headed five degrees," or "We're a bit below median."

These are some of the basic terms that most sailors use to describe what happens with the wind. If everyone in your crew uses the same language, it will make for better communication, and that will help you sail faster. •

How to describe wind and waves

Explaining the relationship between wind and waves definitely requires some unique terminology, and this is essential for optimizing sailtrim and other speed-related variables.

Here are the descriptive phrases I use:

"More wind than waves'

This situation exists when the water is flatter than you'd expect for the existing wind. It occurs during a building or offshore breeze, and it's perfect for shifting into point mode.

"Equal wind and waves."

Most of the time the wind and waves are roughly matched in the strength and height you'd expect.

"More waves than wind."

This happens when the waves are bigger than what you'd expect for the existing wind. It occurs in a dying breeze and when you have lots of motorboat slop. It requires full, powerful sails and much patience.

When I was a kid, our local radio station would broadcast weather reports from their plane. Because their wind speeds always seemed so inflated compared to our drifting conditions, we used to joke that they must have been holding their anemometer out the window. Even if they could have corrected for the plane's apparent wind, however, they still had to consider wind gradient. Often there can be 15 knots of wind aloft and nothing down below!

David Dellenbaugh, former starting helmsman for America3, publishes Speed&Smarts, a monthly newsletter of how-to information for racing sailors. For subscription information call: 800-356-2200. To order a new subscription, click here.