Kitesurfing Simulator

Everything a kite does, it does because of where it sits in the wind window. Get this one concept and half of kitesurfing stops being mysterious. Miss it and you will spend your first hours wondering why the kite is sometimes gentle and sometimes tries to take you to Italy.

Fly the wind window

The kite only pulls hard when it flies through the middle of the window. That single fact is most of lesson one, and it is easier to feel than to read.

Drag sideways to steer the kite around the clock. Drag down to pull the bar in: the kite dives deeper and the power builds. Park it back at 12 o’clock and everything goes quiet. Arrow keys work too.

The four power bands

From the outer edge of the window inward, the same wind gets a very different grip on the kite. The colours above follow this scale, and so does every diagram on this site.

What the wind window actually is

Stand with your back to the wind. Stretch your arms out to the sides.

Everything in front of you, from the water on your left, up over your head, and back down to the water on your right, is the area your kite can fly in. It is a quarter of a sphere, and its radius is the length of your lines, usually 20 to 24 metres.

Your kite cannot fly outside it. Behind you there is no window at all, because a kite needs wind flowing over it, and behind you the wind is coming from, not going to. A kite that ends up back there falls out of the sky.

The clock face

Kiters describe positions in the window as a clock, seen from where you stand. It is how every instructor in the world will talk to you, so learn it now. It is also the scale printed around the window above.

Position	Where	What the kite does there
12 o’clock	Straight overhead	Almost no pull. The parking spot.
11 and 1	Slightly to either side of overhead	A little pull. Where you hold it while sorting yourself out.
10 and 2	Halfway down, either side	Steady, usable pull. Where you ride.
9 and 3	Down at the water, at the far edges	Very little pull. Launching and landing.
The middle, low	Straight downwind, near the water	Maximum pull. The danger zone.

Why the power changes so much

Two things stack up.

The angle to the wind. At the edge of the window the kite is nearly parallel to the airflow and generates little lift. In the middle it sits square to the wind, working at full efficiency.

Speed. A kite flown through the middle travels much faster than the wind itself, and the force it makes rises with the square of that speed. This is why a kite sitting still at 12 o’clock in 20 knots is calm, and the same kite dived through the middle is not. Try it above: park at 12 with the bar in, then dive the same kite across the window and watch the pull gauge.

That squared relationship is also why gusts matter so much. Wind rising from 15 to 21 knots does not add 40 percent of pull. It roughly doubles it.

Why the kite tows you sideways

The kite pulls you toward the side it sits on, and the angle decides how well. Straight overhead at 12 there is nothing to tow you, only lift. Right down at 9 or 3 the kite parks at the edge and makes almost nothing.

The cruising sweet spot sits between 10 and 11, or between 1 and 2, with the bar part in. Strong sideways pull, and the kite keeps flying instead of stalling. That is the position you will spend most of your riding life in, and it is marked on the window above.

The window moves with you

Here is the part that catches people out on day one. The window is defined by your position and the wind direction. Turn around and it turns with you. Walk down the beach and it walks with you. Start riding across the wind, and the whole thing rotates.

Once you are moving, the wind you feel is a combination of the real wind and the wind created by your own speed. That combined wind, the apparent wind, comes from further forward, so the window shifts forward too. The practical effect: a kite that felt right while you stood still feels more powerful once you are riding, and you can fly it further forward than you expected.

What changes the size of the window

Factor	Effect
Line length	Longer lines make a bigger window: more power, slower steering. Shorter lines make a smaller window: less power, faster steering.
Depower	Pushing the bar away reduces the kite’s angle of attack. It behaves as though it has moved toward the edge, even when it has not.
Kite type	High aspect kites sit further at the edge and are less forgiving in the middle. Low aspect kites are more even across the window.
Wind strength	The shape does not change. Everything in it gets stronger.

This is why schools teach on short lines. A smaller window means a slower, gentler kite, and gentle is what learning needs. You move to full length lines once your steering is calm.

Reading the window in practice

• Launching: the kite goes up at the edge, at 9 or 3, where it has almost no power. Never launch from the middle.
• Parking: 12 o’clock, or just off it. If anything goes wrong, or you need to think, the kite goes to 12 first.
• Making power on purpose: one smooth dive from 11 down through the middle and back up to 1, or the mirror of it. One stroke, not a saw. Sawing the bar builds power on top of power and is the classic way beginners get overpowered.
• Losing power on purpose: push the bar away and steer the kite back toward the edge or up to 12. Both work. Doing both at once works fastest.
• Landing: kite down to 9 or 3, slowly, into an assistant’s hands.
• The emergency: let go of the bar. A modern kite depowers when you release it. If that is not enough, fire the quick release. Both are covered on the safety page.

Drills that build the feel

The first three are built into the window above, so you can run them right now. Ask your instructor for all five, and practise them long after you think you have them.

1. Park and hold. Kite at 12, both hands off the bar for five seconds, then ten. Sounds trivial, builds everything.
2. Edge to edge. Move the kite slowly from 9 to 12 to 3 and back, staying at the edge the whole way, without dipping into the middle.
3. One power stroke. A single dive into the working band and back out, parked between 1 and 2. One stroke, then stop.
4. Figures of eight, low. The kite tracing a sideways eight through the lower half of the window. This is what generates the pull for body dragging.
5. Eyes off. Fly the kite at 12 while looking at the horizon. You will need this the moment the board comes into the picture.

The five mistakes the window explains

1. Being dragged on the beach.
   The kite generated too much power while you were still on land – often because it moved through the power zone or was flown too aggressively & fast.
   
   Fix: Keep the kite controlled near the edge of the wind window, avoid sending it through the power zone on land, and get into the water before making larger kite movements.
2. Nothing happens on the water start.
   The dive was too shallow or too slow. The kite needs to actually cross the middle and point your board slightly downwind.
3. Too much power, every time.
   Avoid repeatedly pulling the bar in and pushing it out. Make one controlled adjustment, then hold the bar steady and let the kite settle.
4. The kite falls out of the sky at 12. In light wind, the zenith is the weakest part of the window. Fly it slightly to one side instead.
5. Everything feels stronger once riding. That is the apparent wind rotating the window, and it is normal.

Questions people ask

What is the wind window in kitesurfing?

The quarter sphere of sky downwind of you where the kite can fly, with a radius equal to your line length. Where the kite sits inside it decides how much pull it makes.

Where is the power zone?

Straight downwind of you, low, near the water. The kite makes several times more pull there than at the edges. It is the red band on the window above.

Why does the kite usually pull less at 12 o’clock?

Because at 12 o’clock most of the kite’s force is directed upward rather than sideways, and a stationary kite generates less force than one moving quickly through the wind window. However, it can still produce significant lift in strong wind or gusts (20+ knots).

Does the wind window move?

Yes. The wind window moves with you, and once you start riding, apparent wind causes it to rotate forward in your direction of travel.

Why do schools use short lines?

Shorter lines make a smaller window, which means a slower kite with less power. Easier to learn on, and easier for an instructor to talk you through.

Can the kite fly behind me?

No. Behind you is where the wind comes from, so there is no window there. A kite that ends up there falls out of the sky, which can happen if you jump and don’t steer the kite.

Is the window above a simulator?

No. Real kites have inertia, gusts, and a sky that answers back. This is the concept, and the concept is what saves you an hour on the beach.

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