Understanding the Wind
America3 navigator By Baldridge shares his secrets about how to decipher and profit from wind shifts.
By Baldridcfe is one of the most respected mid sought-after navigators in the world. A resident of Seabrook, Texas, he was an integral part of the America3 after-guard that won the America's Cup in 1992. By navigated Kialoa to a Maxi world championship in 1984 and did the same on Matador2 in 1991. With his sharp tactical mind, good numbers sense and extensive racing experience, he is extremely qualified to talk about wind, weather and. sailing fast.
DAVID: What information about the wind do you gather before heading out to the race course?
BY: It's important to know what the weather has been doing over the last few days, especially if you're sailing away from home. You can always call 1-900-WEATHER to find out what's happening. The other thing is to pump the "locals" for info on typical wind patterns and local effects. If you act non-threatening, you can learn quite a bit.
When you're sailing in an area with a dominant thermal breeze, try to find out what I call the "happy" direction for that breeze. In Newport, RI, for example, the happy number is around 230°. In other words, on most days (except those influenced by a frontal situation) the seabreeze will tend to shift toward 230°. Once it gets there it will usually settle in and oscillate around that number until the power (i.e. heat) which is fueling that wind starts to die off for the day.
Once you arrive at the race area, what information do you collect about the wind and weather?
On the way out to the course I like to steer the boat and watch the wind and water, just to keep my head up and out of the boat. Since races are generally won or lost on the first leg, it's important to get into the flow of the day mentally so you can be on top of what's going to happen early in the race.
When we hoist sails, the first thing I do is check my instruments, hopefully in conjunction with another boat, to see if there is any wind sheer or gradient. The clouds will also give you good clues about this. If the low clouds are moving a different direction than the wind you feel, for example, there's a good chance you will have sheer. I look for sheer early in the day because this will give you clues about what the wind may do later on.
Of course, I keep track of wind direction before the start to see trends. If I have instruments and I trust their calibration, I will use the true wind direction readout. But on any boat I rely primarily on the compass heading for each tack. Before the start, I like to check the heading on each tack at least every 5 or 10 minutes.
When the wind is oscillating, do you try to figure out both the range of oscillation and the timing of the shifts?
The range of oscillation is very important, but I very rarely trust the timing of the shifts. In fact, I can't think of any regatta I've sailed where I could tell you what the period of oscillation was. However, I do try to get a handle on the timing of oscillations before the start. That way I can predict where the wind will be at the start or just afterward, which is obviously important for picking the favored end and hitting the first shift.
Do you record your wind observations during a race?
I usually write down the numbers in pencil on the deck. The most important things to me are the farthest left and farthest right numbers that I see for any leg. I basically treat each leg separately as a new situation. Every time I go around a mark I re-evaluate the wind and pick a new median direction if necessary.
During a race, what are you watching to gauge the wind?
I look at two things: the clouds and the water surface. The lower layer of clouds, such as cumulus that may be filling in across the course, can have a big effect on wind velocity and direction. One thing I look for is the shape of the bottom of each cloud. If the underside of the cloud looks linear and chopped-of'f, there will probably be more breeze under it. But if the bottom of the cloud is very puffy and wispy, there will be less breeze under it.
In either case, there is likely to be a change in wind direction around the edges of the clouds. And, more often than not, that change will be consistent from cloud to cloud on any given day.
The other thing I look at for wind is the water surface. In general, more breeze appears darker because the wind ripples break up the surface of the water, allowing more light to go into the water rather than be reflected to your eye.
Can you tell whether a puff is a lift or a header before it gets to you?
Reading the wind on the water depends on subtle reflective differences. It's a lot like reading the grain on a putting green. Sometimes I look at a puff and know instantly whether it's a lift or header. Other times I'm much less sure. I think it depends on the angle of the sun. The key for me is noticing the subtle differences in a puff, experiencing what that puff brings and then expecting the same result the next time I see those subtle effects.Whenever you're not steering the boat, you have a lot of time to watch the water and play some wind games. Look at each puff and try to guess whether it will be a lift or a header. Then see what happens. The next time you notice a similar puff, see if the same thing happens.
When the wind seems irregular, how do you know whether to play it as oscillating or persistent?
First of all, I think it's important to make the distinction between oscillating and persistent because this changes your whole philosophy on how you're going to sail that leg.
The wind pattern depends on the time of day and what you think the wind will do. In most places, I don't look for an oscillating breeze until later in the day. Earlier on, the breeze is still settling in and is more likely to make bigger jumps in one direction. If I expect the wind to shift 40° to the right, I don't really call it oscillating, even if it shifts in jumps. I don't consider a breeze to be oscillating unless it always comes back to the same average direction.
When I'm in doubt about the wind on any particular ieg, I'll play the odds by favoring the side that usually pays off in that area. Here in Galveston Bay, for example, I'd go right. In the ocean off San Diego, a lot of times I'd go left.
In an oscillating breeze, how do you know exactly when to tack?
In a smaller boat, if you have very quick oscillations, you should tack right away. When the oscillating period is longer, you may want to sail into the shift a little just so you don't sail out of it when you tack.
This is also a function of how much breeze you have. When it's lighter, you should probably sail a little further into the new wind. That's because your boatspeed is greater relative to the wind, which increases the chances you will sail out of the new wind after tacking. Also, your wider tacking angles take you further away from the wind.
How much of a header do you need before you're willing to tack?
It's all relative to the situation. If my competition is going the same direction I am, it will have to be a pretty good-sized shift - say 5 or 10 degrees. If I'm not happy with my position or if my boatspeed isn't great, I'll go on a smaller shift. The larger your boat, the bigger the shift must be before you are willing to tack. And the lighter the wind, the bigger the shift you need since you will lose more by tacking.
When sailing upwind, is it more important to go for good windshifts or for increases in velocity?
That's a great question. It mostly depends on the wind velocity you're racing in. In light air, I'd go for better pressure almost every time. That's because in light air, an extra knot or two of wind will produce a relatively large increase in your boatspeed. In 6 knots of wind, for example, an AC boat will go upwind at 7 knots. If the wind increases to 7, your speed will jump to 8.5 knots and you'll point 5 degrees higher. That extra knot of breeze is worth more than a 5° or 10° shift.
On the other hand, if you're sailing in moderate or heavy air, I'd tend to go for/the shift, since an extra knot or two of wind will no longer add much to your VMG. If the wind increases from 11 to 12, for example, an AC boat might gain one tenth of a knot and one degree of pointing. Even a 5° shift at 11 knots would be better.
Basically this choice depends on knowing your boat's performance. If you're close to hull speed you should go for the shift. If you're downspeed, go for velocity.
Any final wind comments?
I'm very much an observer on the race course. What I try to do is compile a history, even if it's very short, to help my decision-making in real time. However, I'm much more interested in "what" happens than "why" it happens. Too much analysis slows down your decision-making. That's why to a certain extent, you have to shoot from the hip. Be a good observer, look for patterns and stick to the most basic information you know. That will help you win races much more than coming up with fancy theories. •
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