The movement of a sailboat. Why can a sailboat sail against the wind? Advancing against the wind
The course of a ship relative to the wind is the angle between the direction of the wind and the center line of the ship, that is, the heading angle to the point on the horizon from where the wind is blowing, expressed in angular degrees or bearings.
Depending on the magnitude of this angle, courses relative to the wind have their own names:
1 - steep close-hauled (30° - 45°);
2 - full close-hauled (45° - 75°);
3 - gulfwind (about 90°);
4 - backstay (110° - 160°);
5 - jibe (160° - 200°);
6 - left (30° on each side)
Leventik (French le vent) - a course that forms an angle close to 180 degrees with the wind direction, that is, the wind blows almost exactly in front of the ship. Since a sailing ship cannot follow such a course, they usually say not “course”, but “left-hand position”.
Beidewind (Dutch bij de wind) is a course at which the angle between the direction of the wind and the direction of movement of the vessel is more than 100 degrees (less than 8 points). There are close-hauled winds: full (from 100 to 120 degrees) and steep (more than 120 degrees). The thrust of a sail is entirely determined by its lifting force; with increasing drag, the thrust force decreases, but the drift force increases. Thus, on this course, the sail, installed with a minimum angle of attack to the apparent wind (5-10 °), works like an aerodynamic wing.
The best sailing ships sail at an angle of 30-35° to the direction of the true wind. Due to the addition of the wind speed vectors and the oncoming air flow, the apparent wind speed on a close-hauled course turns out to be maximum, as well as the aerodynamic force on the sail, proportional to the square of the wind speed. The drift force also reaches its maximum value. If you try to sail at a sharper angle to the wind, the speed of the vessel will decrease, the sail will begin to flap, the aerodynamic force will decrease and, finally, a moment will come when the drag of the sail and the resistance of the water to the movement of the boat will far exceed the thrust. The ship will reverse.
Gulfwind (Dutch halve wind), or half wind - a course at which the angle between the direction of the wind and the direction of movement of the vessel is approx. 8 directions (from 80 to 100 degrees). On this course the wind blows perpendicular to the port, and the apparent wind is directed from the bow at an acute angle to the port. Accordingly, the sail is set at a lower angle of attack, its thrust is equal to the lifting force, and the drift force is equal to the drag of the sail. on this course the sail should divide the angle between the DP and the direction of the apparent wind approximately in half.
Backstay (Dutch bakstag) - a course that forms an angle with the direction of the wind of more than 8, but less than 16 points (more than ten and less than eighty degrees), that is, the wind blows from the rear-side in relation to the ship; They are distinguished by a full backstay course, at which the angle is no more than twenty degrees, that is, approaching the gybe; the sail is set at an angle to the wind on the leeward side. Usually on this course a sailing ship develops its highest speed. At the backstay, the sail operates at a high angle of attack, at which drag plays a major role in creating the thrust of the sail. There is virtually no drift force.
Fordewind (Dutch voor de wind) - a course in which the wind is directed towards the stern of the ship.
Fordewind is the same “fair wind” that sailors desire, although in sailing this course is by no means the fastest, as one would expect. In addition, it requires attention and skill from the helmsman to control additional sails (usually a spinnaker). In this case, the sail is placed perpendicular to the direction of the wind, the thrust on it is created due to drag. Light wind on this course is practically not felt, since the speed of the apparent wind is equal to the difference between the speed of the true wind and the speed of the oncoming air flow.
A jibe is one of two turns (a turn is a change of tack) of a sailing vessel, in which the direction of the wind at the moment of the turn passes through the stern. Unlike a tack, a jibe is more complex and, at times, dangerous; it requires clear team actions when working with the sails. It is no coincidence that the command is given with the clarification: “Prepare for a jibe!”, whereas during a tack the commander simply commands, “Prepare for a turn!”
Tacking
Tacking a sailing ship. α - tack angle
A sailboat cannot sail directly against the wind. If it is necessary to get to any point located to windward, then tacking is used - moving towards the target on a close-hauled course on alternating tacks. To change tack you must make a turn.
If, while maintaining the tack, you need to go at a sharper angle to the direction of the wind, then they say that you need to “bring to the wind.” If, on the contrary, you need to increase the angle between the direction of the wind and the boat’s DP, then they say that it is necessary to “fall into the wind.” (It should, however, be remembered that “the wind blows in the compass,” that is, its directions are given not by where the wind is blowing, but from where. This means that if the ship’s course is, for example, north and the wind is from north, it is not blowing along the way, but towards the ship.)
In order to set the sail at the optimal angle of attack during these maneuvers, it must be pulled towards the DP - “select”, or released - “hauled”. Yachtsmen use these terms for all manipulations with gear - sheets, guys, etc.
Depending on the side from which the wind is blowing, courses relative to the wind can be starboard or port tack.
With a heading wind angle of 26 points, the close-hauled starboard tack in the sailing fleet was sometimes called starboard, and the left tack (wind heading angle of 6 points) was called a backboard. To clarify the course relative to the wind, the following expressions were used: “the ship is sailing on a starboard tack of 7 points to the wind” (that is, close-hauled at a heading wind angle of 78°); “The ship is sailing backstay on a starboard tack of 10 points” (that is, the heading angle of the wind is 112°); “The ship is heading fuller than 6 points” (that is, the backstay at a heading angle of 12 points, or 135°). The concept of “close-hauled” is also used as the sharpest course relative to the wind, at which a sailing ship can move forward (it ranges from 3 to 6 points 33.3/4° to 67.1/2°); steep and full backstay (up to 12 points and more than 12 points, or up to 135 ° and more than 135 °, respectively).
Calculation of the ship's path using known compass values. wind direction, course relative to the wind, compass corrections and drift called. in the sailing fleet by correcting bearings.
Rumbas | Degrees | Ship's heading relative to the wind |
0 | 0 | Leventik |
1 | 11,25 | Close-hauled, steep, port tack |
2 | 22,5 | Close-hauled, steep, port tack |
3 | 33,75 | Close-hauled, steep, port tack |
4 | 45 | Close-hauled, steep, port tack |
5 | 56,25 | Closed wind, port tack |
6 | 67,5 | Closed wind, port tack |
7 | 78,75 | Closed wind, port tack |
8 | 90 | Gulfwind, port tack |
9 | 101,25 | Gulfwind, port tack |
10 | 112,5 | Backstay, port tack |
11 | 123,75 | Backstay, port tack |
12 | 135 | Backstay, port tack |
13 | 146,25 | Backstay, port tack |
14 | 157,5 | Backstay, port tack |
15 | 168,75 | Backstay, port tack |
16 | 180 | Fordewind |
17 | 191,25 | Backstay, starboard tack |
18 | 202,5 | Backstay, starboard tack |
19 | 213,75 | Backstay, starboard tack |
20 | 225 | Backstay, starboard tack |
21 | 236,25 | Backstay, starboard tack |
22 | 247,5 | Backstay, starboard tack |
23 | 258,75 | Gulfwind, starboard tack |
24 | 270 | Gulfwind, starboard tack |
25 | 281,25 | |
26 | 292,5 | Closed wind, starboard tack |
27 | 303,75 | Closed wind, starboard tack |
28 | 315 | |
29 | 326,25 | Close-hauled, steep, starboard tack |
30 | 337,5 | Close-hauled, steep, starboard tack |
31 | 348,75 | Close-hauled, steep, starboard tack |
32 | 360 | Leventik |
Yachting: The Complete Guide Toghill Jeff
Yacht's course relative to the wind (Rumb of sailing)
Yacht's course relative to the wind: A - close-hauled, B - close-hauled, C - halfwind, D - backstay, E - favorable direction, F - jibe
Steep close-hauled (tacking). When a boat sails on a course close (as much as possible) to the direction against the wind without lapping the luff, it is said to be moving on a close-hauled course. Sails should be chosen as strong as possible.
Full close-hauled. With this course, the yacht tacks less. The wind does not blow straight towards or towards the stern, but into the side of the boat, so the sails should be slightly trimmed compared to a steep close-hauled wind. as much as possible until they begin to rinse.
Gulfwind. A yacht moving under sail at right angles to the wind is said to be tacking. Since the wind blows against the side, the sails are trimmed by about half.
Backstay. When the wind is blowing from behind, but not directly astern, the yacht heads backstay. The sails are etched until the luff begins to rinse. and then select enough for it to disappear. In this position the wind is blowing from the stern and the spinnaker can be raised.
Fordewind. With a fair wind, the sails are completely trimmed. They are spread out to catch as much wind as possible, the yacht goes with the wind. When the wind blows directly into the stern, the jib can flutter because the sail overlaps the trot. In this case, you can either put it on the other side, where it will fill with wind again, or lower it and install a spinnaker instead. (Large spinnakers, shaped like a parachute, can only be used when the wind is following.)
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Today we will turn our attention to the following fact: The yacht, regardless of the direction of the wind, moves where the captain and his crew lead it. This happens even when the wind is blowing in the opposite direction. Why is this happening? What is the secret of this phenomenon?
The boat with a sail appeared long before the advent of airplanes. But the principle of operation of sails and wings is the same. The basis of the work is the lifting force. But if in airplanes, the lifting force of the wing, cutting through the wind, pushes the car upward, then the sail, located vertically, pushes the yacht forward.
The headwind hitting the sail creates a pushing force. The secret is that on the windward side, the one that is internal, the wind speed is less than on the leeward side. Therefore, a vacuum is formed, and the sail is literally sucked in by air. All this is possible thanks to the features of the sail design. In other words, we can say the following: it doesn’t matter how the sail is located on the ship, because it just converts the wind energy. That is why the yacht is able to sail against the wind current.
Even in those moments when it seems to the viewer’s eye that the sail must certainly slow down the yacht, since the wind is blowing into it from outside, this does not happen. But this does not happen also because the center of application of forces is at the bow of the ship, and the wind easily provides a “pushing” movement.
But let's ask real yachtsmen about how and why a yacht moves, and is it true that you can sail against the wind?
Andrey Volkhov has considerable experience in managing yachts, and therefore you can trust him unconditionally. “In fact, the yacht will not be able to move against a strong wind. If you place it perpendicular to the wind flow. You can only move at a certain angle. The operation of a sail is identical to that of an airplane wing. The lift created by the wind pushes the ship forward.”
But not only lifting force occurs under wind load. Roll is another phenomenon that needs to be taken into account when steering a boat. This phenomenon not only slows down the yacht, but is also very dangerous for the entire crew. In cases where the boat is heeling, the crew must create a counterweight as quickly as possible.
Let's look at everything in more detail using the example of a sports yacht.
- Option one: the wind blows in a favorable direction. Everything here is clear and simple. The yacht moves forward without difficulty, and the crew is not burdened with significant actions.
The sail has several shapes. The Arabian shape is when the sail has an “oblique” appearance. This form is effective for side wind flows, as well as those close to oncoming ones. However, it will certainly be behind a straight sail, with a fair wind. In this case, to the main sail (mainsail), a “staysail” would be added - an additional sail. These two sails are capable of accelerating a light yacht to 30 km/h.
- The second situation is that the wind flows hit the side of the ship. Now the crew has perked up and unfurls the sail. An important part of the spar (rigid equipment of the yacht) is the boom. Rope gear is called rigging. All this serves to control the spar. Moving the ship forward is the art of yachtsmen. The main task of the crew is to turn the sail to the desired angle in time. Thus, the crew pursues one goal - to get maximum energy from the wind.
- The next situation is that the wind is blowing at an angle of 20 degrees, and this is against the movement of the boat. Beidewind - calls a move against the wind. This is what seasoned sailors called it back in ancient times. In this case, the team is as tense as possible, because it needs to catch the wind. And after some time this succeeds, and the yacht begins to move forward again. We have already examined the secret of this phenomenon. But the yacht has another sail! He is invisible!
Many have already guessed that this sail is located under the bottom of the ship. It's called a keel. Sailors usually call it a centerboard. This element is necessary in order to resist heeling, as well as restrain the force of the wind on the sail. Another ability of the centerboard is to convert heeling force into propulsion energy. The laws of physics work as precisely as possible in yacht sports.
And of course, the crew is powerless when there is no wind at all. Although...many yachts have engines, just in case of “no wind”. Therefore, you don’t have to worry about the “unforeseen death” of the wind.
Russian poet Mikhail Yurievich Lermontov loved sea and often mentioned him in his works. He wrote a wonderful poem about the whitening sail, which rushes among the waves in the distant expanses of the sea. You are probably familiar with Lermontov’s poem, because these are the most famous lines of poetry about sailing ships. Reading them, you can imagine a raging sea and beautiful ships among its waves. The wind fills the sails. And, thanks to the power of the wind, the ships move forward. But how do sailboats manage to sail against the wind?
In order to answer this, you will first have to learn an unfamiliar word "tack".Galsom The direction of movement of the ship relative to the wind is called. The tack can be port when the wind is blowing from the left, or starboard when the wind is blowing from the right. It is important to know the second meaning of the word “tack” - this is part of the path, or rather, the segment of it that the sailboat passes when it moves against the wind. Remember?
Now, to understand how sailboats manage to sail against the wind, let's look at the sails. They come in different shapes and sizes on a sailboat - straight and oblique. And everyone does their job. When a headwind blows, the ship is steered using oblique sails, which turn first one way and then the other.
Following them, the ship turns in one direction or another. He turns and walks forward. Sailors call this movement - moving on alternating tacks. Its essence is that the wind presses on the slanting sails and blows the ship slightly to the side and forward. The rudder of a sailboat does not allow it to turn completely, and skilled sailors set the sails in motion in time, changing their position. So, in small zigzags, it moves forward.
Of course, moving on alternating tacks is a very difficult task for the entire crew of a sailboat. But the sailors are seasoned guys. They are not afraid of difficulties and love the sea very much.
It is difficult to imagine how sailing ships can go “against the wind” - or, as sailors say, go “close-hauled”. True, a sailor will tell you that you cannot sail directly against the wind, but you can only move at an acute angle to the direction of the wind. But this angle is small - about a quarter of a right angle - and it seems, perhaps, equally incomprehensible: whether to sail directly against the wind or at an angle to it of 22°.
In reality, however, this is not indifferent, and we will now explain how it is possible to move towards it at a slight angle by the force of the wind. First, let's look at how the wind generally acts on the sail, that is, where it pushes the sail when it blows on it. You probably think that the wind always pushes the sail in the direction it blows. But this is not so: wherever the wind blows, it pushes the sail perpendicular to the plane of the sail. Indeed: let the wind blow in the direction indicated by the arrows in the figure below; line AB denotes a sail.
The wind always pushes the sail at right angles to its plane.
Since the wind presses evenly on the entire surface of the sail, we replace the wind pressure with a force R applied to the middle of the sail. Let's break this force down into two: force Q, perpendicular to the sail, and the force P directed along it (see figure above, right). The last force pushes the sail nowhere, since the friction of the wind on the canvas is negligible. Strength remains Q which pushes the sail at right angles to it.
Knowing this, we can easily understand how a sailing ship can sail at an acute angle towards the wind. Let the line QC depicts the keel line of the ship.
![](https://i1.wp.com/allforchildren.ru/sci/img/perelman2-16-2.gif)
How can you sail against the wind?
The wind blows at an acute angle to this line in the direction indicated by a series of arrows. Line AB depicts a sail; it is placed so that its plane bisects the angle between the direction of the keel and the direction of the wind. Follow the distribution of forces in the figure. We represent the force of the wind on the sail Q, which we know should be perpendicular to the sail. Let's break this force down into two: force R, perpendicular to the keel, and the force S, directed forward, along the keel line of the vessel. Since the ship's movement is in the direction R meets strong water resistance (the keel in sailing ships is made very deep), then the force R almost completely balanced by water resistance. Only strength remains S, which, as you can see, is directed forward and, therefore, moves the ship at an angle, as if towards the wind. [It can be proven that the force S receives the greatest value when the plane of the sail bisects the angle between the keel and wind directions.]. Typically this movement is performed in zigzags, as shown in the figure below. In the language of sailors, such a movement of the ship is called “tacking” in the strict sense of the word.