A sailboat depends on the wind for propulsion. So, the wind direction plays a very important role in sailing. A sailboat wouldn't be much use if it were simply blown around by the wind. The sailboat needs to be able to control it's course. So let's take a look at some of the aspects of sailing the wind:

Sailing downwind

It is quite natural to think of going downwind, when sailing. Most objects would, after all, move downwind if the wind blows hard enough. But with modern sailboats, sailing downwind is not the only way to sail. In fact, sailing downwind is the least effective way to sail!

When sailing downwind, the wind will try to blow past the sail, and the sail would then capture some wind to push the boat forward. But the friction of the water on the sailboat's hull will slow the boat down, so the downwind speed of sailing can never equal the wind speed.

Because the sailboat moves slower than the wind, the sail will cause some turbulence, when the air rushes past. The wind will spill in behind the sail, before continuing on its way. This creates "dirty air" ahead of the sail, which can cause the movement of the sail and mast to become erratic.

Another aspect to keep in mind, when sailing downwind, is the fact that the boat becomes harder to steer when sailing with the wind coming from astern. The helmsman will get much less feedback from the tiller, so keeping the boat on course while sailing downwind requires much more effort and care.

When sailing downwind, the sailboat will tend to lean forward, just as it might heel to the leeward side, if the wind was blowing accross the boat. Coupled with the bubbles of wind turbulence, the natural motion of the boat in the water, and the difficult steering, the boat can potentially build up a rolling motion, which can result in a violent capsize!

Think about it: When stuff gets blown downwind, they tend to tumble and roll to their eventual destination. A sailboat can potentially also tumble downwind, if the sailing crew does not stay at the ready to prevent it!

Sailing across the wind

Sailboats are also able to sail in a direction across the wind. Because the sailboat has a hull shaped to prevent "leeway" (sideways drift), the boat can steer across the wind.

When the wind blows across the sails, the shape of the sails will cause it to act as airfoils, much like the wings on an aeroplane. The air flows faster over the front of the sail than the back. This creates a low pressure area ahead of the sail, and the wind therefore effectively "pulls" the boat forward.

Modern sailboats can reach speeds that exceed the wind speed, when sailing across the wind.

Something to keep in mind when sailing across the wind, is the tilting force the wind will excert on the boat. We say that the boat "heels" to leeward, or tilts over at an angle away from the wind.

The sailboat will be less effective, if the boat heels over too much. Some sailboats also tend to capsise, if the crew does not take action to counteract the wind's tilting action. To counteract heeling, the crew would typically move their body weight over to the windward side of the boat. This way, they can shift the sailboat's centre of gravity towards the wind to sail flatter, with the mast in an upright position.

When the crew lean over the side of the boat to counter the heel, they are said to be "hiking".

Sailing upwind

If sailboats were only able to sail downwind and across the wind, it would be impossible to sail to a destination anywhere upwind from the starting point. The crew would have to wait until the wind changed direction before setting off - and then hope and pray that the wind does not change direction again before they reach their destination!

Luckily sailboats can sail upwind, although not straight into the wind. Most modern sailboats can sail a course approximately 45° away from windward. This area of approximately 90 degrees toward windward is known as the "no-sail-zone", where the sailboat cannot generate enough forward motion to sail a course.

When a sailboat is sailing an upwind course, we say that the boat is sailing "on the wind", whereas sailing downwind or across the wind would be called sailing "off the wind".

By sailing a succession of such upwind courses, a sailboat can zig-zag towards an upwind destination. The boat will have to alternate its course between the left and right of the wind direction. This sailing manoeuvre is called "tacking".

A sailboat is said to be on a "starboard tack" when sailing with the wind blowing from the starboard side (the right side of the boat), with the boom and sail to the port side (the left side) of the boat. The sailboat would be on a "port tack", if the wind is coming from the port side, with the boom and sail set on the starboard side.

Sailing the wind

A sailboat cannot sail without wind. But when the wind is blowing, the crew needs to understand how to sail the wind towards the intended destination. After rading this article, you should know a little more about sailing the wind.