How does a windsurfing sail work?

Windsurfing sails: working with the wind | Photo: NeilPryde

Windsurfing sails use the power of the wind to generate forces, which push and/or pull your board forward. Let's dive into the wonderful world of wind science.

Wind generates power. We know that. All we need is to observe its behavior both on land and in the water.

And a scientific formula adds up an interesting issue: the wind pressure on the sail multiplies by the square of the increase in wind speed.

This means that if winds step up from five to ten knots, the pressure on the sail multiplies four times.

As a result, the lift is created, pulling your windsurf board forward and sideways.

There is always more pressure on the side closest to the wind (windward side) than on the side away from the wind (leeward).

The Bernoulli's Principle

According to Bernoulli's Principle (Daniel Bernoulli, 1738), this will result in a pulling action toward the leeward side.

But if you're simply blocking the wind with the entire sail, you'll feel your board moving forward, too.

This is basically the push effect in downwind mode.

So, with the wind pulling the board forward and sideways through the sail, how will we get lateral resistance to sail away properly?

Fins, centerboards, and drag will counteract the sideways pull of the sail, keeping the board tracking straight.

Simple and easy.

New to sailing? "Start Windsurfing Right!" guided James Coutts, or learn how to windsurf quickly in only two hours.