The sails always seems to be somewhat parallel to the direction of the boat, but if the wind is blowing sideways, should that push the boat off course?
In: 9
First, the sails.
[Wikipedia has a picture that can help with the explanation](https://commons.wikimedia.org/wiki/File:Points_of_sail.svg).
There are several ways to set the sails. If the wind is directly behind the way the boat wants to go, or up to about 45 degrees on either side, the wind can blow directly into the sail. Going straight on is generally called running. As you start to reach farther angles it is a reach, a broad or beam reach. Turning the sail a bit can compensate for the direction change and that can get you to nearly a 90 degree on either side, or “blowing sideways” as you put it.
Once it goes even farther, you can use a sail to beat upwind if that’s the direction you need to go. You can set the sails so they work more like an airplane wing providing lift, except they’re doing it at an angle. That’s close hauled. Depending on the boat and the sail, you can do that to about 35 degrees or 45 degrees against the wind. You can zig-zag, or tack, to go back and forth to compensate for the direction it pushes the boat.
So using nothing but the wind you can move in almost any direction, except for directly upwind. With tacking you can travel upwind, it’s just somewhat slower.
Second, the rudder.
A boat has a big movable blade either on the hull or behind the hull that steers the water. There’s a wheel that lets you turn the rudder. As the boat cuts through the water, the rudder pushes the water to either side forcing the boat to turn. This also changes the direction the boat will travel.
Putting them together:
Let’s say the wind is blowing directly from the north, so heading due south, but you want to head due west. You would set your sails to a beam reach, at about a 45 degree angle to the wind. This makes the wind push the boat in a southwest direction. Next, you would turn your rudder to turn you starboard, or to the left, to make up for the other 45 degrees to finish pushing you to the west. You’ll end up traveling somewhat slower at this angle, but still pick up plenty of speed over time.
Let’s say you wanted to beat upwind, say the wind was still heading due south but you wanted to travel north. You would set the sails close hauled so it pulls to one side like a wing lifts an airplane wing up, and turn the rudder so instead of just a 45 degree angle on the sail and the rudder, the sail would be almost straight in line along the boat on the port side, and the rudder turned to starboard. Now your ship would be heading northwest. It won’t have the same force as heading downwind, but will pick up speed over time. Then you would tack, turning from facing northwest to facing northeast, reset your sail so the sail would be along the boat on the starboard side, and turning hard to port. Now your boat is heading northeast, making up for the westward movement. By tacking, alternating between northeast and northwest, your boat will average out to a north direction.
You’re also no limited by the wind speed, since the sail is operating more like lift on an airplane wing. You can gain more and more speed even when traveling directly upwind, losing very little when you tack.
Surprisingly to many people running directly downwind is often the slowest way to sail. As you may have learned in math class, the hypotenuse of a triangle is always longer than either leg. If you’re traveling diagonally with the wind, the wind is pushing you at a certain speed (perhaps 15 knots) in one direction, but your direction is a diagonal line, and may reach 20 knots or more. If you’re looking for speed and running downwind, a racing sailboat will still tack downwind with a broad reach sail. By tacking in a zig-zag downwind they can travel quite a bit faster than windspeed, some racing sailboats can hit 3x the windspeed, and even beating upwind racing sailboats can exceed windspeed.
The sails always seems to be somewhat parallel to the direction of the boat, but if the wind is blowing sideways, should that push the boat off course?
In: 9
First, the sails.
[Wikipedia has a picture that can help with the explanation](https://commons.wikimedia.org/wiki/File:Points_of_sail.svg).
There are several ways to set the sails. If the wind is directly behind the way the boat wants to go, or up to about 45 degrees on either side, the wind can blow directly into the sail. Going straight on is generally called running. As you start to reach farther angles it is a reach, a broad or beam reach. Turning the sail a bit can compensate for the direction change and that can get you to nearly a 90 degree on either side, or “blowing sideways” as you put it.
Once it goes even farther, you can use a sail to beat upwind if that’s the direction you need to go. You can set the sails so they work more like an airplane wing providing lift, except they’re doing it at an angle. That’s close hauled. Depending on the boat and the sail, you can do that to about 35 degrees or 45 degrees against the wind. You can zig-zag, or tack, to go back and forth to compensate for the direction it pushes the boat.
So using nothing but the wind you can move in almost any direction, except for directly upwind. With tacking you can travel upwind, it’s just somewhat slower.
Second, the rudder.
A boat has a big movable blade either on the hull or behind the hull that steers the water. There’s a wheel that lets you turn the rudder. As the boat cuts through the water, the rudder pushes the water to either side forcing the boat to turn. This also changes the direction the boat will travel.
Putting them together:
Let’s say the wind is blowing directly from the north, so heading due south, but you want to head due west. You would set your sails to a beam reach, at about a 45 degree angle to the wind. This makes the wind push the boat in a southwest direction. Next, you would turn your rudder to turn you starboard, or to the left, to make up for the other 45 degrees to finish pushing you to the west. You’ll end up traveling somewhat slower at this angle, but still pick up plenty of speed over time.
Let’s say you wanted to beat upwind, say the wind was still heading due south but you wanted to travel north. You would set the sails close hauled so it pulls to one side like a wing lifts an airplane wing up, and turn the rudder so instead of just a 45 degree angle on the sail and the rudder, the sail would be almost straight in line along the boat on the port side, and the rudder turned to starboard. Now your ship would be heading northwest. It won’t have the same force as heading downwind, but will pick up speed over time. Then you would tack, turning from facing northwest to facing northeast, reset your sail so the sail would be along the boat on the starboard side, and turning hard to port. Now your boat is heading northeast, making up for the westward movement. By tacking, alternating between northeast and northwest, your boat will average out to a north direction.
You’re also no limited by the wind speed, since the sail is operating more like lift on an airplane wing. You can gain more and more speed even when traveling directly upwind, losing very little when you tack.
Surprisingly to many people running directly downwind is often the slowest way to sail. As you may have learned in math class, the hypotenuse of a triangle is always longer than either leg. If you’re traveling diagonally with the wind, the wind is pushing you at a certain speed (perhaps 15 knots) in one direction, but your direction is a diagonal line, and may reach 20 knots or more. If you’re looking for speed and running downwind, a racing sailboat will still tack downwind with a broad reach sail. By tacking in a zig-zag downwind they can travel quite a bit faster than windspeed, some racing sailboats can hit 3x the windspeed, and even beating upwind racing sailboats can exceed windspeed.
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