A stiff breeze blows off San Francisco Bay. A boy's acrobatic kite plummets, soars, and spins in a crazed loop-the-loop. A little girl barely old enough to walk flies a tiny butterfly-shaped kite with the help of her mom and dad. A purple teddy-bear kite and a green-frog kite make a little aerial zoo overhead.
The Berkeley Marina is one of the best city kite-flying spots in the United States. Winds from the Pacific sweep past the Golden Gate Bridge and the San Francisco skyline, sending kites soaring over this grassy park. The marina even has a resident expert, kite designer Tom McAlister. He sells kites from a recreational vehicle here. He also gives advice, answering questions like: What if a vicious kite-eating tree captures my kite?
"Try to find a better place to fly," Mr. McAlister says. "The ideal kite site would be absolutely flat. No obstructions, particularly upwind."
Wind flows straight and steadily over flat areas. Obstructions, like trees or houses, break up the wind just as boulders in a river break up flowing water. Kites fly best where the wind is steady and straight.
McAlister says the best kite-flying wind is about 5 to 12 miles per hour. At those wind speeds, tree leaves move and bushes rustle. If a wind is strong enough to make small trees bend and sway, the wind is too strong for most types of kites.
A kite flies in much the same way as an airplane does. Both depend on a flow of air to create enough aerodynamic lift (upward force) to overcome the downward force of gravity. The difference in pressure between the air beneath the kite and the air above it produces this lift.
Getting a kite up should be easy, McAlister says. "You should be able to just hold a kite up and let the wind take it." If it doesn't go up, you may need to adjust the "bridle point." The bridle is a short string attached to the top and bottom of the kite. The control string is tied to the bridle at the bridle point. The bridle point determines the angle of the kite to the wind. Finding the right angle gives the kite balance in the air. "Adjust the bridle [point] toward the top of the kite for light winds," he says, "and closer to the tail for stronger winds."
So you don't need to run with a kite to launch it? "If you have to run to get a kite started, you don't have enough wind," McAlister says. But there is a simple way of launching a kite in light wind that has the same effect as running - only safer. It's called "longlining." The kite flyer unwinds about 100 feet of string while a helper holds the kite downwind. The helper lets go of the kite, and the flyer, with the spool of string on the ground, quickly pulls the line hand over hand. It "does the same thing as running - it creates wind," McAlister says. "It will get the kite up where the winds are stronger."
But what if your kite nosedives right back down? Again, adjust the bridle point. If it's too high, the kite will go up easily, but then its nose will dip and the kite will fall. Don't move the bridle point down too far, or you may never get the kite airborne! You must find the right balance.
What if your kite stays up, but wobbles, rocks, and rolls? "If the kite isn't stable, add a tail," McAlister says. "A tail will keep the kite from spinning and wobbling. One long tail is the most stable."
Not far away, a boy flies a kite with a rainbow-striped, 100-foot-long tail. The kite dives, rolls, and goes into a spinning curlicue. That's stable?
McAlister looks at the kite and laughs. "Sometimes a kite is just an excuse to pull a tail," he says. It's an acrobatic, dual-line kite. "They are made to be unstable."
An acrobatic kite inspired McAlister to embark on a life of kite flying. As a boy, he loved kites. "I flew kites with friends, and we heard stories about Indian fighting kites. But we never got our kites to do all the things we wanted them to do."
McAlister had just graduated from college when he saw someone flying an acrobatic kite. "I said, 'Wow! That's what I want to do with a kite,'" he says. He had very little money, but finally "broke down" and spent $59 to buy one.
McAlister advises kids to look for durable kites. "You can get a $2 or $3 plastic kite," he says, "and if the winds are light, that is OK. But you can get a good, easy-to-fly kite for $15 to $40 that will last." Good kites are made of ripstop nylon or polyester, with a frame of fiberglass, wood, or graphite. You can also make one: Simple designs are available online or in kite books at the library.
The right kite string and spool are also important. McAlister says braided Dacron lines are best for single-line kites. Most small- to medium-size single-line kites are best flown on string with a strength rating of 20 to 80 pounds, depending on kite size and wind speed. McAlister's favorite type of spool for winding string is called a figure eight - "it's the most foolproof," he says. Many beginners buy "Indian-style spinners" (they look like a spool with a stick through the middle), but end up with tangles because they don't know how to use them properly. The staff at a kite store can instruct you.
Surprisingly, traditional diamond kites are not the easiest to fly. McAlister suggests single-line dragon kites, delta kites, or parafoils to start. Dragon kites are long and flat. Delta kites look like stretched-out triangles. Parafoils are frameless kites with "pockets" inflated by the wind.
McAlister is flying a parafoil kite today. This one is definitely not for beginners - it is 33 feet long, a monstrous pair of running shorts with two kicking legs attached. "It's a 'Half Man,' " he says. "And, yes, there is another kite that is made like his top half!" He brings "Half Man" down a bit - the end of the line is staked to the grass - and hands me the line. The pull is manageable, but strong. It's easy to imagine how a large kite in a stiff wind could lift a person off the ground. (Flight pioneers Wilbur and Orville Wright were kite flyers, and flew some of their aircraft as kites before adding an engine and pilot.)
The Chinese invented kites about 3,000 years ago, and new kinds are still being created. "Half Man's" parafoil design dates from the 1960s. In the 1980s, a four-line kite was invented. It can fly backward!
McAlister enjoys designing and making kites. He recently won a kite design competition at the American Kitefliers Association's Grand Nationals. (See photo.)
And new kinds of "traction" kites are popping up all over. Kites (usually parafoils) pull in-line skaters, skateboarders, wakeboarders, snowboarders, and even special three-wheeled "kite buggies."
At the Berkeley Marina, a skateboarder skims by in the distance. He's towed by a U-shaped kite high overhead. I expect the skateboarder to be a teenager, but as he zooms past I can see his gray beard. I guess no one's ever too young - or too old - to have fun with a kite!
• Go to www.nationalkitemonth.org, to the 'Teacher' section, for more kite plans.
Last summer, I spotted a wakeboarder skimming across the San Francisco Delta. A boat pulling a wakeboarder is a common sight, but this guy was powered by a kite.
"Any wakeboard moves that you've ever seen - skateboarding moves, windsurfing moves - a kiteboarder can do," says Sandy Parker, a kiteboarding instructor. "But instead of doing those moves 10 feet in the air, a kiteboarder is doing them 40 feet in the air."
Kiteboarders strap their feet into a board similar to a wakeboard. They wear a waist harness. A control bar is attached to the harness, with a quick-release for emergencies. Attached to the bar by a 100-foot line is a large, U-shaped kite. When winds are strong, they use kites 23 to 26 feet across. Lighter winds mean larger kites.
Ms. Parker stresses safety in her kiteboarding lessons. She teaches students to fly kites on land before they get into the water. They launch their kites on land and fly them above their heads so they don't have much "pull." A kiteboarder wades into the water, straps on the board, and crouches down. When the kite is brought into position, off goes the boarder. Experienced kiteboarders can launch a kite while on the water.
Parker's favorite kiteboarding moments are a perfect combination of air and water. "I love a nice wind where you can jump really high, just big soft jumps. You float for a few seconds, but it seems like you are up there forever!"