One of the skills that often separates the best sailors from the rest of the fleet is the ability to see the wind. This is critical because it enables them to consistently get to the windier side of the course and thus sail faster than their competition. How do they do it? Well, seeing the wind directly is obviously impossible, but there are a number of ways to indirectly see what the wind is doing, particularly what it's doing farther up the course. Keeping an eye out to windward for the behavior of flags and other boats is one important way, but these clues are not always available. Veteran sailors know that the most consistent way to see the wind is by observing how it effects the water.
If you've ever had the opportunity to watch a sailboat race from a high-vantage point, like a bridge or a cliff, you've probably seen puffs move down the course in the form of dark patches on the water. These puffs are usually generated by wind from a higher altitude sinking to the surface of the water. Higher-altitude winds move faster than surface winds and this constitutes the puff. These puffs of wind disturb the surface of the water slightly more than the rest of the air and thus cause the water beneath them to appear darker.
Spotting puffs from a high altitude is easy, and it's one reason why you'll often see America's Cup teams send someone up the mast when the wind gets light. In light wind, the weight aloft is a minor concern with these huge rigs, so hoisting someone to the top of the mast is relatively harmless as long as they're safely attached. However, most sailors are forced to try and spot the puffs from deck level, which is a lot more challenging. The highly contrasting dark and light spots that you may notice from a better vantage point become shades of gray. It's important to remember that those shades of gray are the same dark and light spots that you would see from the top of a tall mast or a cliff and they can point to significant differences in wind velocity and direction. Trusting your eyes is often the hardest part, but like everything else it gets better with practice.
The best way to practice spotting puffs is to spend time trying to predict when you're going to sail into them. This is a great way to improve your sailing because you can do it by yourself in any boat that can be single-handed. To run the drill, just sail upwind and try to spot puffs ahead of you. In the beginning, don't worry about tacking for puffs. When you see a puff, try to predict how many seconds it will be before you sail into it, then start counting down the seconds. If the puff hits when you get to zero you've done it perfectly. After practicing upwind, turn around and do the same thing downwind. After a while, you'll also develop the ability to discern how strong a particular puff will be, which is valuable information because it allows you to anticipate the effect and trim accordingly.
Sailing into more wind can greatly increase your boat's speed, but in order to get to the best puffs you need to get a good look upwind. Standing up on the deck will get your eyes a little higher up off the water, which is a good way to get a better view. On most boats you can't sail the whole race standing on the deck so it becomes especially important to stand up and get a look to windward before the start of a race.
At the 2000 Olympic Regatta in Sydney, Australia, US Star crew Magnus Liljedahl spent a lot of time during the downwind legs standing up on the deck and looking backwards for puffs. The Star is a small boat for a guy as big as Magnus to be standing up on, but clearly he and skipper Mark Reynolds thought that getting a better view of the wind was worthwhile—Liljedahl and Reynolds won the gold medal. On boats with more than one crew member, it's a good idea to have one person dedicated to looking for the wind on the water. This person should be constantly communicating with the rest of the crew. The sail trimmers will use the information to anticipate changes in trim and the tactician will use the input for decision-making.
When you are looking upwind, if you can clearly determine that one side of the course has more wind than the other, the tactics for that leg will be greatly simplified. This isn't to say that you should ignore other variables such as current or wind shifts. However, sailing to the side with more wind is almost always a winning move.
When one side is not clearly favored it becomes even more important to pay constant attention to where the puffs are. The goal is to spend as much time in the puffs as possible without ignoring other important tactical considerations. Sailing to an area of more wind is often the right thing to do, however, a common pitfall is to chase a puff that is too far away. If you have to sail all the way across the course for a puff, chances are that it will be gone before you get there. And remember, Murphy's Law dictates that the next puff will fill on the side you just sailed away from.
Once you've gotten a handle on seeing the wind, you become increasingly valuable as a crew because upwind you can count the puffs down for the trimmers and the person on the helm. And downwind you can help to ensure that the boat stays in the strongest breeze as much as possible. Identifying someone to watch for puffs and lulls downwind is something many crews forget to do, but it can really help you make gains.
Placing a high priority on spotting puffs and getting your boat into more wind is almost always a successful tactic in sailboat racing. Sailboats are after all wind-powered machines. So get that Laser or Sunfish out of the garage and spend some time practicing in the near term, and you'll be sure to improve your results when the next race rolls around.