What makes a yacht move

How a ship moves depends on its location. If a ship is in a crowded harbour then small slow exact movements are required. All of these were each once the height of technology. But today are normally only used for sport and pleasure craft.

Modern ships normally use some variation of a propeller due to the higher efficiency and performance. For the ship to move, the propeller needs a source of power, or a engine. This is normally placed in the centre of the ship low down as it can be very heavy. To connect the engine to the propeller, a propeller shaft can be used, providing a physical link. Get the series on your phone or tablet and listen whenever you like — at home, in the car or onboard your very own ship!

Since the wind is not blowing across the boat, there is no sideways or heeling force. As you bear off from a beam reach to a run, you ease out the sheets so the sails catch as much wind as possible to push you along. On a run, the boom will be close to a degree angle to the boat, and the mainsail will block the wind to the jib.

You can get more wind by flying the jib wing-and-wing, with the jib pulled to the side opposite the main. The jib fills with wind, and you're off. If your boat has a centerboard, you'll want it raised when you're running.

When you are running straight with the wind, you don't need any help from the centerboard to keep from sliding sideways, but a little board helps reduce side-to-side rocking. As you bear off, begin to raise the centerboard—approximately one-third on a beam reach and up to two-thirds on a run.

Lower the centerboard before you head up. Beware of the unexpected gybe; it can be dangerous. Always be aware of the boat's angle to the wind. When the jib will not fill with wind, or when you are wing-and-wing, an accidental gybe is possible.

Don't bear off further than straight downwind unless you plan to gybe. If you're in doubt, head up toward a broad reach. To steer a sailboat, you use the tiller or wheel to turn the rudder to direct the flow of water passing over its surfaces—which turns the boat. Just as a car won't turn when it's parked, a sailboat must be moving in order for its rudder to be effective.

Steering with a wheel is just like turning a car. You turn the wheel in the direction you want the boat to turn. When you steer with a tiller, though, the boat turns in the direction opposite to the way you move the tiller. Using the rudder alone will cause excess drag in the water, slowing the boat or even stalling out the flow of water and causing a loss of steerage. The most efficient way to steer is to use a combination of the rudder, body weight, and sail trim to turn the boat.

Moving your weight to one side of the boat helps to turn the boat in the opposite direction. The sails also help with steering. When you ease the main, the boat will tend to bear off, and when you trim the main, the boat will tend to head up.

The opposite is true with the jib; trimming the jib helps the boat bear off, and easing the jib helps the boat head up. You can tell whether your boat is on a collision course with another boat by taking a compass bearing on the other boat. If you don't have a compass, sit still and line up the other boat with a fixed part of your boat—a shroud, for example. If your course stays the same but the bearing doesn't change after a little while, you are on a collision course with the other boat and should alter course to stay clear.

Tacking is the process of turning the boat's bow through the wind from an angle at which the sails are full on one tack to one of which they are full on the other tack. When your destination is directly upwind, you can't just head straight there. Instead, you have to zigzag by sailing close-hauled on one tack, then tacking to sail close-hauled on the other tack. By sailing back and forth as close to the wind as possible, you'll make the quickest progress into the wind.

Tacking has three parts: 1 turning the bow through the wind; 2 trimming the jib on the new leeward side, and 3 moving the crew to the new windward side. Before you do anything, though, check that you have a clear path for the tack and that the crew is ready. The helmsman says, "Ready about. Begin the tack by pushing the tiller or turning the wheel , slowly at first, then more rapidly, so the bow heads toward and then passes through the wind.

The crew releases the jibsheet just as the wind begins to fill on the "back" side of the jib, then trims the jib on the new leeward side with the new leeward jibsheet. If your weight is needed for balance, you should cross the boat during the tack. Slow down your turn as the boat approaches a close-hauled course on the new tack, and straighten the course when the sails are filled.

Gybing is the process of turning the boat's stern through the wind from a reach or run on one tack to a reach or run on the other. Gybing is often a faster and more powerful maneuver than tacking because the sails are full of wind and do not luff through the turn. You can sail downwind on a more direct path than you can upwind, but you will have to gybe if you want to change direction.

As with tacking, you will have to adjust the jib when the gybe is completed and make sure that you have a clear path for the gybe. The helmsman says, "Prepare to gybe. Begin the gybe by pulling the tiller or turning the wheel at an even speed; there's no need to worry about getting into irons, as you're sailing away from the wind. Even in a moderate amount of wind, the boom will cross the boat quickly, so be prepared to duck out of its way.

The crew should have a hand on the jibsheet to trim or ease the jib as necessary, although it won't luff very much. Both skipper and crew should switch sides after the gybe is completed. Once you have turned the boat onto the new tack, head the boat downwind enough that the sails fill with wind. As they say, practice makes perfect, and there are many exercises you can perform to improve your sailing skills.

We've thought of several good drills to start with, but if you want to practice a specific skill, simply design your own drill. Go the other way to work on gybing. LAPS : Using the same two buoys, reach back and forth, tacking around one buoy and gybing around the other.

When you are between the buoys, try to sail on a reach with your helm balanced. Use only your rudder at first, then experiment by using your weight and the sails to help steer the boat. Use your rudder, sails, and weight to help the boat turn and see how tight a circle you can sail. These are NOT the sounds you want to hear as you trailer your boat to the launch ramp.

I was about a mile away from the ramp at the time, and looking in the rearview mirror I immediately noticed Betty Jane, my Mystic 20 Catboat, was now riding a good deal The second heat is held in the afternoon, when there is a 10 knot wind from the West. In which heat are the faster times recorded? Answer below.

Sailing downwind parallel to the wind, like the boat at left is easy to understand: the wind blows into the sails and pushes against them. The wind is faster than the boat so the air is decelerated by the sails. The sails push backwards against the wind, so the wind pushes forward on the sails. But for a boat with normal sails, the catch is that, downwind, you can only ever sail more slowly than the wind, even with a spinnaker. Which is comfortable, but not the most interesting sailing.

You know this force: In a strong wind, it is easier to walk, run or bicycle with the wind pushing on your back. Usually, the wind pushes you in the direction it is going. Sailing directly upwind exactly anti-parallel to the wind, like the boat at right is also easy to understand: it's impossible impossible with sails: a boat with a wind turbine driving a propellor could go directly upwind.

You just sit there with your sails flapping. This is also not interesting sailing. So let's think about In this diagram, the quantities force and velocity have arrows, because they have a magnitude as well as a direction.

Try this link for an Introduction to vectors. Note that nowhere in this argument did we need to say that the wind was faster than the boat. Now this force is mainly sideways on the boat, and it gets more and more sideways as you get closer to the wind.

However, part of the force is forward: the direction we want to go. Why doesn't the boat drift sideways? Well it does a little, but when it does, the keel , a large nearly flat area under the boat, has to push a lot of water sideways. The water resists this, and exerts the sideways force F k on the keel. This cancels the sideways component of F w. A little digression: the sideways components of wind and water on the boat make the boat heel tilt away from the wind, as is shown in the diagram below.

These two horizontal components have equal size but opposite direction: as forces they cancel, but they make a torque tending to rotate the boat clockwise. This is cancelled by another pair of forces.

The buoyancy and the weight are also equal and opposite, and they make a torque in the opposite direction. As the boat heels to starboard, the lead on the bottom of the keel, which has a substantial fraction of the weight, moves to port and exerts an anticlockwise torque.

These two torques cancel.