Purpose and device of a magnetic compass. Magnetic compasses

A compass on a high binnacle is intended to be installed as the main one, and on a low one or on a stove - as a track one. On the tabletop, the compass is installed in control posts where it is not possible to place a binnacle.

The compass consists of a compass itself, a binnacle or tabletop plate, a deviation device, and a protective cap with a lighting device. The compass itself includes a card and a bowler hat (Fig. 18).

Cartushka 7 is a sensitive element of a magnetic compass and consists of a magnetic system, a brass float with a firebox, a brass rim on which mica is fixed and a paper disk with degree divisions is pasted.

The magnetic system of the card is assembled from six magnetic arrows inserted into brass pencil cases 3, which are soldered to the bottom of the float 9 and are arranged in parallel and symmetrical pairs of the same length.

In the center of the bottom part of the float 9 there is a cone, at the top of which a firebox 8 made of agate or sapphire is fixed. Card 7 is placed in a pot filled with compass liquid (a 43% solution of ethyl alcohol in distilled water with a boiling point of plus 83 °, and freezing point - minus 26 °), and its firebox 8 rests on the tip of pin 2, which ensures free rotation of the card.

The stud is made of brass in the form of a rod with a diameter of 1.5 mm and a length of 35 mm, has a hard-faced stainless steel tip.

The weight of the card in the air is about 102 g, and thanks to the compass fluid, its pressure on the tip of the pin is only 4 ± 0.5 g. The presence of a cone in the float allows the card to be freely tilted on the pin up to 12 °.

The edge of the paper disc is divided into 360 ° through 1 °, and the numbers indicate tens of degrees, and in Latin letters - the main and quarter points. Possible accuracy of readings on the card is 0°, 2.

compass bowler(see Fig. 18) is a brass tank with two chambers - the upper main 13 and the lower additional 14.

The main chamber is used to place a card 7 in it, it has a hollow column with a thread for attaching a compass pin 2. The chamber is painted with a special white paint.

The lower chamber 14 of the pot is a compensatory one, allowing thermal expansion of the compass liquid in the pot due to the fact that it is closed from below by an easily deformable diaphragm 15.

In the upper chamber 13, vertical wires 4 are fixed on two opposite sides in the longitudinal plane of the bowler. The wire is called a course thread or course line.

The upper part of the pot is covered with mirror glass 10 on a rubber gasket 12 and is pressed against the pot with a ring 11 attached with screws.

The top section of the ring is called the azimuth circle and is divided into 360°. Reading accuracy on a scale of 0 °, 2.

The lower part of the kettle is closed with a brass cup with a load to give the kettle stability. A tube for a cartridge 17 is mounted in the cup for an electric lamp 18, which illuminates the card through a light window 16 and a reflector 1.

Outside, in the upper part of the bowler, two axles are attached from two opposite sides - trunnions 6, with which the bowler is placed on the ring 5 of the cardan suspension. The ring is also equipped with two axes located perpendicular to the axes of the bowler.

The compass bowler outside is painted with black lacquer.

Binnacle is a stand for a kettle. Inside the binnacle is placed a deviation device with magnets-destroyers.

The body 2 of the binnacle (Fig. 19) is made of siluminium and has a hollow cylindrical shape with a flanged base 1, in which four recesses are made with vertical elliptical holes for bolting the binnacle to the cushion. The pillow is attached to the deck. The upper base 7 has a truncated spherical shape, passing in the upper part into a cylindrical neck. A shock-absorbing suspension is placed inside the neck, on the upper spring ring of which there are sockets for the axes of the cardan ring of the bowler. From above, the binnacle is closed with a protective cap 6.

Rice. 19

At high tide, in the upper part of the binnacle body, a power supply unit 5 for the bottom lighting of the compass bowler is mounted.

To access the deviation device in the middle part of the binnacle there is a large vertical window, which is closed with a removable cover 3. When installed on a ship, this window faces the stern.

On the outside of the cylindrical part of the hull there are ears 4 for fastening the binnacle with backstays to the deck.

The deviation device consists of a brass ruby ​​and two carriages.

The pipe is fixed vertically in the center of the binnacle, so that its axis passes through the fulcrum of the card. The carriages are put on the pipe, they can be moved up and down along it and fixed in any position in height with locking screws.

Magnets designed to destroy the deviation are installed in the carriages and inside the pipe of the deviation device, and special magnetic steel in the form of balls or pipes is fixed in the upper part of the binnacle on special brackets, the bars are installed in the neck holes, and the plates are fixed on a special bridge under the bowler.

tabletop stove consists of a square-shaped plate itself, a neck with a spring suspension and bars of special magnetic steel, a deviation device, and a power supply unit. A deaf cap is put on the neck of the tabletop plate, which protects the compass bowler from damage and pollution.

Lighting of traveling compasses installed indoors can be carried out with the help of a sconce.

75 mm GU magnetic compass. On small ships, boats, boats, 75-mm magnetic compasses are used. They differ from the 127-mm compass in smaller dimensions and a simpler device.

Boat 75 mm compass(Fig. 20) consists of a pot with compass fluid, a card and a case with an oil lantern.

The card, unlike the 127 mm compass, has only two magnetic needles, and the scale is divided into two-degree divisions. Each 10-degree division is indicated by a number, which indicates not the number of units, but ten degrees. For example, the number 4 indicates the division corresponding to 40 °, the number 14 - the division corresponding to 140 °, etc.

The weight of the card in liquid at t = +20° is about 2.2 g. compass.

A case with an oil lantern (brass) is used to store and carry the compass bowler, is part of the binnacle when the compass is installed on the ship, protects the bowler from damage and water ingress.

Rice. twenty

Rice. 21

boat The 75-mm magnetic compass (Fig. 21), unlike the boat magnetic compass, has a binnacle and a direction finder.

The binnacle is a 240x390x680 mm cabinet made of siluminium. At the bottom, the binnacle has a flange for attaching to the deck of the vessel.

The boat compass can also be mounted on a special silumin bracket adapted for fastening it to the wheelhouse wall.

The binnacle and the bracket have a deviation device, which in its design resembles the deviation device of a 127-mm compass.

direction finders

Ordinary and optical direction finders can be mounted on a 127 mm magnetic compass.

An ordinary direction finder (Fig. 22) consists of a solid ring, eye and objective targets.

Since the azimuth circle of the bowler near the eye target is closed by the direction finder, the index on the direction finder, according to which the heading angles are counted, as well as 0 ° of the azimuth circle, are shifted to the left by 30 ° for the convenience of taking readings.

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subject target is a folding frame with a vertical silver-plated wire stretched in the middle (target thread) with a diameter of 0.4 mm. A guide block with a folding black mirror is put on the frame of the subject target, which serves to find the direction of the celestial bodies.

The eye and object targets are installed in such a way that the slot of the eye and the thread of the object targets are located in the same vertical plane passing through the center of the direction finder. This plane is called sighting plane.

Direction finder of Kavraysky (Fig. 23). The base of the direction finder 1 has the form of a ring with a protruding shoulder, three legs and a cross, forming a platform in the center, on which a cup 4 for the deflector is fixed.

On the base ring there are two indexes for setting the direction finder on the azimuthal scale, which are located in a vertical plane making an angle of 30 ° with the sighting plane. The feature that distinguishes the Kavraysky direction finder from an ordinary direction finder is that it does not have an object target, but there is a special prism 6 with a lens and a collimator.

The prism of the direction finder has edges that transmit the image of divisions on the compass card in direct form, which is very convenient when taking a reading during direction finding. In addition, the bearing reading is noted directly by the alignment of the object with the image of the card in the prism, as a result of which, when the ship is yaw, the bearing reading does not depend on the accuracy of aiming the sighting plane at the object. This is a great advantage of this direction finder.

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In the upper rounded edge of the prism, when the light rays of the sun are reflected in it, a bright vertical column is formed, called a flare, which is used to take the bearings of the Sun, i.e., it acts as a folding mirror of a conventional direction finder.

The metal frame of the prism has special handwheels, with the help of which the direction finder prism can be rotated around the horizontal axis to improve the image of the card reading and bring it to the desired position.

To find the direction of the Sun and brightly lit objects, a screen 3 and two light filters 5 are installed in front of the prism.

On the base ring of the direction finder opposite the prism, a metal counterweight is fixed with a bubble level 2 located at an angle of 90° to the sighting plane, which serves to set the direction finder in a horizontal position.

The direction finder of Kavraisky gives an image of a card at 20 ° in the field of view; prism lens focal length 66 mm ±1 mm at 3.5 magnification. Sensitivity level 20 to 2 mm. Direction finder weight 0.9 kg.

Boat compass direction finder(Fig. 24) consists of base 1 (brass ring) mounted on the compass bowler. On the basis of the direction finder, subject 2 and eye 3 targets are hinged.

A movable trihedral prism 4 in a frame is put on the eye target bar, which serves to take bearing readings from a card. The prism gives an increase of 2-2.5 times.

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A magnetic compass is a device that points to the Earth's magnetic poles and thus makes it easier to navigate the terrain.

Classical magnetic compass with scale and arethir.

The word "compass" is borrowed from the Italian language, where "compasso" in translation means "compass". In the word "compass" it is customary to put stress on the first syllable, but in the professional speech of sailors, pronunciation is used with stress on the last syllable.

The purpose of modern compasses is not only to show the main directions of the world: they also serve to determine the azimuth, as well as the direction of the known azimuth.

At the heart of a modern magnetic compass is a magnetic needle, which is located along the lines of force of the Earth's magnetic field, which is essentially a permanent magnet. The lines of the Earth's magnetic field, in turn, stretch from one magnetic pole to another. In this case, the magnetic poles are at a distance from the geographic poles. In addition, they are in constant motion, changing their location over time. All this leads to some errors in the readings.

The arrow of a magnetic compass does not point strictly to the North Pole, but a little past. For orientation purposes, this is not critical, but in general it is useful to know.

It is for this reason that for accurate measurements made with a magnetic compass, the difference between the north direction indicated by the arrow and the direction to the geographic north pole of the Earth should be taken into account. We talked about how this is done in a separate article.

History

It is believed that the first compass was invented in China during the Song Dynasty. This is evidenced by the mention of him, made in a Chinese book written in 1044 AD.

Installation in the form of the world's oldest compass.

This compass was a spoon made of a natural magnetic mineral - magnetite (magnetic iron ore), which freely rotated on a metal board under the influence of the Earth's magnetic field.

After some time, the Chinese improved the device by immersing the magnetized element in water, where it could rotate freely without experiencing such resistance as its predecessor. This is how the first water compass appeared.

A little later, the magnetic compass was invented in Europe. His device was a magnetic needle attached to a cork of light material floating in water. The video shows how to repeat this:

The compass, invented in Europe, was improved by the Italian Flavio Gioia, who attached a magnetic needle to a disk with markings (card) and planted this design on a vertical pin to reduce resistance.

Freed from water, the compass has become much lighter and more reliable.

Over the following centuries, the magnetic compass has been improved and today it is a fairly accurate and easy-to-use device.

Classification of magnetic compasses

There are many different types of magnetic compass. It's hard to list all the options, so let's look at some of the distinguishing features, the combinations of which make the choice of these devices so wide.

Compass with maximum scale markings.

Liquid inside the flask

Compasses with a sealed flask filled with a special liquid are called liquid compasses.

The liquid inside the bulb is designed to dampen the fluctuations of the arrow, which contributes to operational work with this compass. However, a violation of the tightness of the flask can lead to air bubbles getting under the glass, which in some cases affects the readings of the device.

Rectangular tablet

Compasses, in which the bulb is placed on a rectangular base, are called tablet compasses.

Such compasses are most convenient for working both with a map and for navigating the terrain. On the “tablet” itself, a ruler is most often drawn for the convenience of working with the map. Sometimes a lens is placed on it, and sometimes there may be cutouts of various geometric shapes and additional markings, for example, for quickly converting distances measured on a map into distances corresponding to them on the ground.

Rear sight and front sight

The presence of a rear sight and a front sight on the compass allows you to measure the azimuth to the object more accurately and more accurately find the direction according to the known azimuth.

Mirror

Compasses equipped with a mirror allow the person taking the measurements to simultaneously control the position of the arrow. This reduces the possibility of error associated with involuntary rotation of the device about the vertical axis.

Arrow fixed on the disc

An arrow fixed on a movable disk with a scale in some situations simplifies the process of orientation. In this case, you do not need to ensure that the north end of the arrow coincides with the north direction on the scale, since the arrow is already fixed in this position.

However, models with an arrow fixed on the disk have two big minuses. Due to the greater friction on the liquid in the flask, the arrow, together with the disk, turns much longer. And if even a small amount of air (literally a few bubbles) gets into the flask, the compass may not work well: the air, being under the movable disk, presses it against the upper glass of the flask and does not allow it to rotate normally.

Glowing markings

Some compasses have luminous markings, which is very convenient for using this tool at night.

Concerns that such compasses are radioactive are myths.

Impact-resistant housing

This case provides additional protection to the compass from damage caused by accidental impacts or falling to the ground.

However, this does not mean at all that such a compass can be used with impunity as a sling: after all, the body is just additional protection, and not a guarantee of indestructibility of the device.

Mounting options

For convenience of work in different models of compasses are provided various options mounts.

For orienteering, where measurement accuracy is not very important, compasses are available with a mount on thumb arms.

Models with a wrist strap can be considered classics of the genre. Many tourists of the older generation, and the military too, know an example of a "wrist" compass - Adrianov's compass. Wrist models, like finger-mounted devices, are always in sight, which is very convenient for fast work with them.

Tablet models tend to be too bulky to mount on the arm, so they usually have a thin string to hang the compass around your neck. Since they require a little more time to work with (the additional time costs are mainly associated with getting the device out from under clothes), these compasses are most convenient for orienting on long hikes, where time does not play a big role, and the requirements for working with a map can be above.

Lately I've seen little Chinese compasses built into the fastex of so-called survival bracelets. However, as far as I can tell, a flint and flint mounted in the same fastex will affect the readings of such an instrument, causing magnetic deviations in it. So such a compass will give incorrect readings. The same applies to survival knives, in which someone thought to mount the compass in the handle. Personally, I would not recommend such "multi-tools" to replace a conventional compass.

Models with various combinations of the above nuances are widely used by tourists and other outdoor enthusiasts. However, there are models tailored for a different kind of activity.

For example, special magnetic compasses are installed on ships, equipped with a system of magnets that destroys magnetic deviations caused by structural elements the ship itself. The residual deviation is calculated using special tables.

This entire ship structure weighs several kilograms and is definitely unsuitable for orientation in tourism.

Modern magnetic compasses for ships must comply with ISO 11606 “Ships and marine technology. Marine electromagnetic compasses”, according to which the error in compass measurements should not be more than 0.5 °. Such devices, despite their accuracy, as a rule, are much larger and heavier than the "tourist" options, and they are much more expensive.

It is believed that some animals, such as birds, use an internal geomagnetic compass to navigate in space. To date, it has not yet been possible to find out exactly how such a mechanism works. It is suspected that some protein structures can respond to the Earth's magnetic field, but which receptors pick up signals from these proteins remains a mystery to this day.

The so-called mountain (geological) compass is not quite suitable for tourism. Unlike tourist models, the mountain compass scale is marked not clockwise, but against it. Such a device is needed to determine the directions of strike and fall of a rock layer. But if there is no other option, and it’s impossible to make a compact compass from improvised materials, then you can use what you have.

Homemade compass from improvised means

If there is a needle or a fishing hook available, then you can make a primitive compass by putting them on a piece of paper or fixing them on a thin branch, and lowering the entire structure into the water. With a high probability, they will already be magnetized and turn in the north-south direction. If the needle or hook was not magnetized, they can be put on a knife, saw, mobile phone for a few seconds - everything that has a magnetic field - and then lowered into the water again.

Larger objects, such as a knife, can also be used as the arrow of an impromptu magnetic compass. But in this case, you will have to build a device that can hold the knife on the surface of the water. Yes, and the design itself will be quite inertial, and it will take more time for the “arrow” to calm down.

It is important to ensure the isolation of such a compass from the wind, otherwise it will be problematic to determine the cardinal points using such a device. Insulation can be done with a karimat, or using a natural shelter - a recess in the ground, a rock, and the like.

Magnetic compass device

In view of great variety compasses, consider the structure of this device using the example of just one model - the Soviet military wrist compass Adrianov. It is shown in the photo:

Inside the compass case there is a magnetic needle. It is the main part of the device. In working condition, the arrow can freely rotate on the axis, lining up along the lines of force of the magnetic field.

The part of the arrow that points in the direction of magnetic north in Adrianov's compass is painted with luminous paint, which emits light after preliminary "charging" in the light. Some of the marks on the flask itself are painted with the same paint.

Charging during daylight hours, the paint on the arrows of such a compass glows in the dark.

To prevent the arrow from shaking while a person is moving, this compass is equipped with a special brake. Pressing the brake lever causes the arrow to lock, depriving it of the ability to move.

Inside the case, under the flask, a double circular scale is applied: the outer one is marked counterclockwise, the inner one is clockwise.

Outside the case there is a movable ring with the whole, front sight and division indicator.

This compass is equipped with a wrist strap, not very comfortable, but sufficient to securely fasten it to your hand. This can be seen in the video:

How to use the compass

Modern models of compasses allow not only to find out the direction to the north and south, but also to measure the azimuth to an object or determine the direction on the ground using a known azimuth.

In order to determine the directions of the cardinal points, you need to place the compass horizontally, bring the arrows to the working position (if it was fixed by the brake) and wait until the fluctuations of the arrow calm down. The north end of the arrow will point north, the south end south. Knowing these cardinal points, you can easily determine others, which we talked about in this article.

In fact, from the point of view of physics, the north magnetic pole of the Earth is actually the south magnetic pole, because it is to it that the northern part of the magnetic compass needle stretches (opposite poles of magnets are attracted). The same "trouble" with the south magnetic pole, which is essentially the north pole of the magnet. This "twisting" was done for convenience, because otherwise the north geographic pole would correspond to the south magnetic, and the south geographic to the north magnetic, which is not very convenient from a practical point of view.

If you need to measure the azimuth to an object (landmark) using a compass, then the algorithm of actions will depend on which model we use. Let's consider two main options and ways of orienting with their help.

Option number 1. Azimuth measurement with a fixed-scale compass with a movable needle:

1. The compass is located in a horizontal plane.
2. The rear sight and front sight are sighted at the desired landmark.
3. When the compass is in a fixed position, its scale (limb) rotates until the northern part of the magnetic needle points to 0°/360° on the scale. Now the compass pointer shows the value on the scale corresponding to the magnetic bearing to the landmark. You can read about how to translate the magnetic azimuth into the true one in a separate article.

Option number 2. Bearing measurement using a compass with an arrow attached to the scale:

1. The rear sight and front sight are aimed at the object to which the azimuth is measured.
2. Wait for the time until the scale and arrow turn and stop. The pointer will show the number on the scale corresponding to the measured magnetic azimuth.

Now consider how to determine the direction of the known azimuth. We will also consider for two models.

Option number 1. Determination of direction using a compass with a fixed scale and a movable arrow:

1. The compass is horizontal.
2. The limb is rotated until the pointer points to the number on the scale corresponding to the given azimuth, along which the direction is determined.
3. The compass rotates horizontally until the north end of the magnetic needle points to 0°/360° on the scale.
4. The compass is held in this position. Now the front sight and rear sight will indicate the desired direction.

Option number 2. Determination of direction using a compass with an arrow attached to the scale:

1. The compass is held in a horizontal plane.
2. The device rotates in the horizontal plane until the pointer indicates on the dial scale the number corresponding to the given azimuth.
3. The compass is fixedly fixed, and the desired direction is tracked through the front sight and rear sight.

We looked at how to work with a compass on the ground, and how to take measurements with a compass on a map and how to use this tool to walk in azimuths can be found in a separate article.

In addition to working with a compass, it is also worth mentioning general rules operation of it, which will help to maintain the performance of the device for a longer period.

General rules for using a magnetic compass

During storage and operation, the magnetic compass should not be near objects with magnetic properties - metal products, iron-bearing rocks, magnets, electronic devices.

If the magnetic compass is equipped with a brake for the pointer, then the pointer must be fixed during the transition.

The compass must be protected from drops and bumps. This is especially important for liquid models, the violation of the integrity of the flask of which can lead to the failure of the entire device.

And of course, before going out on the route, you need to check the serviceability of the compass and, if possible, take a spare one. And we talked about how exactly the malfunction of the compass is determined in a separate article.

Magnetic compass error

The accuracy of measurements performed using a magnetic compass depends on several factors - the price of division of the compass scale, magnetic declination in the area where the measurement is made, as well as the presence of magnetic anomalies and magnetic deviations. Let's look briefly at each of these factors.

The compass division value shows the angular distance between adjacent serifs on the scale. Thus, the smaller the “step” between two serifs, the more accurately you can take readings from the device.

Ideally, the entire scale should be divided into 360 sectors by serifs. In this case, the compass division value will be equal to 1 °. However, most often, due to the small diameter of the disk on which the scale is applied, it is not possible to make such a large number of marks, and if it does, it will not be very convenient to use such a scale due to the small thickness of the serifs. I suppose that is why very often the price of a compass division is not 1 °, but increases to 2–5 °.

Magnetic declination, which we discussed in detail in a separate article, in some cases can have a significant impact on the measurement results due to the deviation of the magnetic needle of the compass. If the magnetic declination is not taken into account, then the measurement error can reach ten degrees, and in some cases even more.

Near the poles of the Earth, a magnetic compass is practically unusable due to the fact that the location of the magnetic pole of the Earth, which the device points to, can be in the diametrically opposite direction from the location of the geographic pole.

If the magnetic declination is not indicated or the indicated value is outdated, which means that it is most likely incorrect, then in some cases you can find it yourself by measuring the azimuth to a linear landmark on the map and on the ground using a magnetic compass and calculating the difference in readings.

A magnetic anomaly is a territory in which the direction of the magnetic field has a significant difference from the directions of the magnetic field in nearby territories. This may be due, for example, to the occurrence of magnetic ore. Accordingly, in areas with magnetic anomalies, the readings of the magnetic compass will also be distorted.

On some maps, areas with magnetic anomalies are marked on the frame in the same place where magnetic declination is usually indicated. In this case, they usually write about the boundaries within which the magnetic needle can deviate from the direction to the true meridian.

Magnetic deviations are deviations of the compass magnetic needle from the direction of the Earth's magnetic field vector, which occur when magnetized objects or a conductor through which an electric current flows near the device. So, the arrow can deviate when a walkie-talkie is nearby, mobile phone, knife, axe, saw, transport, power line and even other magnetic compass. Therefore, when performing measurements, they try to remove tools and electrical appliances away, and carry out the measurements themselves away from transport, railways and high-voltage wires.

Due to magnetic deviations, you should not buy a knife with a compass built into the handle and a survival bracelet, which were discussed earlier. In them, the compass is immediately built into the instrument, which itself can cause deviation, and therefore it is not necessary to rely on the accuracy of the compass.

What other compasses are

To complete the picture, I consider it necessary to briefly talk about other types of compasses, including non-magnetic ones, whose work is based on slightly different principles.

These compasses are different in their structure and have different magnetic characteristics, which in some cases ensures their superiority over the classic "tourist" model.

Let's start with the gyrocompass. The principle of operation of this device is based on the operation of a gyroscope. In some cases, the gyrocompass may include more than one gyroscope, but several.

Unlike a magnetic compass, a gyrocompass shows true north. Its essential difference is its low sensitivity to magnetic fields, which cause magnetic deviations in the magnetic compass.

However, deviations in the gyrocompass still occur. This can happen if there is a sudden change in speed or heading of the vessel on which the instrument is installed, or a quick change in latitude. Due to the relatively large mass, gyrocompasses are not used in tourism. Their use is mainly associated with maritime navigation and rocket technology.

The next navigation device that I would like to talk about is an electromagnetic compass.

In fact, this is an electric generator in which the Earth's magnetic field plays the role of a stator, and the frame with the winding of the device itself plays the role of a rotor. Movement in a magnetic field leads to the appearance of currents, the ratio of which is used to judge the correctness of the course of movement.

The electromagnetic compass has found application in aviation and maritime affairs. It can be installed in a certain position on an airplane or ship in order to make it easier for the navigator to maintain a certain course. Any deviation from the course will result in a deviation in the readings of the instruments, and the person will be able to correct the direction and return to the correct course.

The main advantage of an electromagnetic compass over a magnetic one is insensitivity to nearby magnetized objects, unless they are stationary relative to the electromagnetic compass.

And one more means of navigation, which I would like to mention, is a satellite compass.

This device cannot work without an energy source, but it is very accurate and points exactly to the North Pole.

A satellite compass, like a gyrocompass, shows true north. It works by receiving signals from satellites, similar to modern navigators. In view of this, such a compass is not afraid of either magnetic deviations, or magnetic anomalies, or even a change in the position of the magnetic pole.

A program that uses satellite communication to orientate a virtual compass can be installed on a modern smartphone or tablet that works without a magnetic sensor.

However, you should not rely on a satellite compass in places where there is no satellite connection. So, for example, it will be useless for lovers of caving.

In addition, do not forget that this compass is dependent on power supply: no battery charge - no instrument readings.

In general, speaking of navigation aids, it is worth noting current trend transition from compasses to navigators. Unfortunately, more and more outdoor enthusiasts are forgetting the skills of working with a simple and reliable magnetic compass, completely replacing them with fast, convenient and comfortable work with modern navigation devices.

Nevertheless, you need to understand the danger of such a situation, because a breakdown of the navigator, a dead battery, or a lack of communication with satellites can cause an emergency. With a compass, this is unlikely, and it is much easier to repair or make it from improvised materials.

Speaking of choosing a compass, I would recommend a tablet magnetic liquid compass. According to me, this the best way: it is quite easy to use, lightweight, does not take up much space and is completely independent of power supplies, which makes it an indispensable device for almost any traveler. In addition, it is usually not difficult to buy such a compass, because budget options at a low cost today in a large assortment are presented in specialized stores, and the quality of their work does not differ much from the quality of work of expensive counterparts.

Useful video: rules for working with a magnetic compass

There are compasses that use one ring magnet instead of bar magnets. This makes it possible to improve the dynamics of the MC card and reduce the level of higher-order deviation. In addition, the complexity of manufacturing a compass is reduced by simplifying the operations of balancing the card and eliminating the need to check the magnets-arrows.

The card is installed on a hairpin 10 in such a way that the fulcrum is above its center of mass, which makes the suspension stable in the presence of external disturbing influences generated, for example, by the ship's rolling. In some MKs, for example, KM-145, an inverted suspension scheme is used, in which the pin is connected to the card, and the firebox against which it abuts is connected to the pot. This is a less successful design, as it complicates the process of replacing the stud in shipboard conditions. In the upgraded version of the KM 145 compass, they returned to the diagram shown in fig. 2.4.

To reduce the pressure of the card on the support pin, it is equipped with a float 7 . An exchange rate scale is placed on the upper plane of the card. 5 .

In a bowler hat 9 where the potato is placed, a frost-resistant liquid is poured. This liquid should completely fill its volume. However, due to various reasons, air bubbles may form under the glass of the bowler hat, making it difficult to read information from the compass. To remove these bubbles, a partition is installed around the perimeter of the pot. 2 , allocating some volume 3 , filled with air, into which the bubbles move when the compass bowler is swaying. The same cavity is used to compensate for changes in the volume of liquid when its temperature changes. There are other constructive options for solving this problem.

The compass bowl is mounted using bearings in the suspension ring 4 , which is also mounted in the MK binnacle with the help of bearings. As a result, a cardan suspension is formed. A load is attached to the bottom of the kettle 12 , due to which its center of mass is shifted down relative to the suspension axis, thereby providing its increased stability in the presence of the ship's motion. This is where the induction sensor is installed. 11 , which measures the angles of rotation of the card, if the MK

has a remote information transmission system. There is an azimuth scale on the top of the bowl. 8 , with which the heading angles of landmarks are measured.

The upper part of the binnacle can rotate relative to its lower part along with the bowler. In addition, the bowler itself can be rotated relative to the top of the binnacle. As an example, in fig. 2.5 shows the upper part of the binnacle MK Sektor. Here, bowler hat 1 together with a gimbal installed in a binnacle 2 using springs 6 protecting it from the effects of vibration and shock. The kettle is equipped with a direction finder 3 . With the help of scales 4 And 5 the course of the ship and the heading angles of landmarks are measured, respectively. As mentioned above, bars 7 And 8 are used to compensate for the deviation of the MC.

In the compasses “Hals” mentioned earlier (Fig. 2.7) for small boats, the card 2 containing two magnets 1 , has no float. Scales with a division value of 5 0 are marked on its outer horizontal 3 and lateral cylindrical 4 surfaces. The elements of the support device included in the card include a corundum thrust bearing and a conical part 2, which protects it from lateral movements. An emphasis pointer is inserted into the body of the card 5 , with a ball at the free end, which serves to prevent its vertical movement and at the same time acts as an indicator of the roll and trim of the vessel. The latter is possible because the card has the properties of a physical pendulum.

The working chamber of the pot is closed on top with a hemispherical transparent lid 3 and completely filled with liquid PMS-5. As a result, an increase in the image of the scale occurs and its visible diameter increases to 160 mm.

There is a hole in the bottom wall of the case. 7 connecting the working and compensation chambers. In the compensation chamber, the air volume is separated from the liquid by an elastic diaphragm 5. Fluctuations in the liquid caused by mechanical effects on the compass are damped by the cup 9 and screen 10 . In the center of the bottom of the pot there is a hole closed with a cork 8 , to fill the kettle with liquid. A deviation device can be attached to the bottom of the pot.

On fig. 2.10 presented general form device KMS-160. Here 1 - spherical glass, 2 - deviation compensators, 3 - binnacle.

The quality of the MC operation significantly depends on the dynamic characteristics of its card, which are determined by the parameters of its own and forced movements. Let's consider the main of these parameters.

A compass is a navigation device designed to determine the course of the vessel and directions to various coastal or floating objects that are in the navigator's field of view. The compass is also used to determine the direction of the wind and the drift of the ship. According to the indication of the magnetic compass, the ship is controlled, with its help, bearings are determined for coastal objects. Typically, a magnetic compass is installed in a high open place in the center plane of the vessel.

The magnetic compass uses the property of a magnetic needle to be set with its ends in the direction of the magnetic field acting on it. In addition to the magnetic field of the earth, the arrow of the ship's compass is also affected by the magnetic field created on the ship by the iron hull and iron pieces of equipment. Under the influence of these two forces, the magnetic needle is set in the plane of the compass meridian. The magnetic compass is also affected by other external forces that occur during the roll, turns of the vessel, which take the arrow out of a stable position. The compass needle is also affected by the vibration of the case from the operation of the engine.

For marine magnetic compasses, the role of the arrow is performed by a system of four, six or more thin magnets placed in a pot with a liquid that provides rapid damping of the magnetic system oscillations.

For compasses that are used on land, including tourist compasses, a scale with degree divisions is applied to the compass case. Such a compass, mounted on a ship, will rotate with the ship and the reference scale. - WHY ALL THIS??????????????????????????

The air float keeps the magnet system afloat, ensuring minimal friction at the suspension point. The marine magnetic compass is equipped with a special device - a deviation device, which reduces the effect on the magnetic system of the compass of the magnetic field of the iron hull of the ship. With the help of a gimbal suspension, the horizontal position of the bowler is ensured during pitching, roll and trim. NO BASIC FORMULA

3.2. Methods for determining the compass correction. MEAN GYROCOMPASS

The compass correction is the value of the parameter (course or bearing), which compensates for the systematic error of its measurement.

To determine the correction of any compass, it is necessary to compare the true and compass directions to the same landmark, i.e.:

∆MK = IP - KP.

Determination of the compass correction on the alignment. IP of the target is removed from the map. KP is taken at the moment of crossing the leading line. Determination of the compass correction by coastal natural alignments (for example, sections of two capes). At the moment of crossing the line of natural alignments, the compass bearing is taken and compared with the direction of the line taken from the map passing through the sections of the two capes.

Determining the compass correction from the bearing of a distant landmark. This method is used when the vessel is anchored, when the place of reference and parking is precisely known.

Determining the correction of a compass by comparison with another compass whose correction is known. The method is used to determine the correction of the main and traveling magnetic compasses by comparing the readings with a gyrocompass, the correction of which is known. On command, two observers simultaneously notice the course on both compasses. Determine:

∆MK = (GKK + ∆GK) - KK.

Determining the compass correction when determining the ship's position using three bearings. When determining the ship's position using three bearings, the so-called error triangle may appear, i.e. the laid position lines do not intersect at one point. When there is confidence in the correct identification of landmarks and in the absence of gross errors in bearings, and the triangle turns out to be large, this indicates an error in the accepted compass correction. To eliminate such an error, and at the same time to determine the current compass correction,

in the following way:

- all bearings are changed by 3-5 0 in one direction or another, and after laying a new triangle of errors is obtained;

- lines are drawn through similar vertices of the old and new triangles of errors, and the point M of their intersection is taken as the observed position of the vessel, free from the influence of a systematic error in the compass correction ∆K;

- point M is connected to landmarks on the map and the obtained true bearings are measured with a protractor. Comparing them with the compass bearings of the same landmarks, they find three values ​​of the compass correction ∆K = IP - KP. The arithmetic mean of the results obtained is taken as the actual correction for this course.

When determining the compass correction in an astronomical way, the bearing to the luminary, measured using a direction finder, is used as the compass direction, and the calculable azimuth of the given luminary, calculated at the time of measurement in a tabular or machine way, is used as the true direction.

The following conditions must be observed:

1. Use to clarify ∆K the luminaries located at a low altitude (h< 30°) и вблизи диаметральной плоскости судна (КУ< 30°);

2. Measurements should be made in series of 3-5 bearings with direction finder refixation;

3. The bearing is measured with an accuracy of 0.1 °, the moments of measurements are recorded with an accuracy of no worse than 2-3 s;

4. The calculated azimuth must be converted into a circular account, i.e. IP \u003d A to.

There are several ways to determine AK by luminaries:

1. Determination of ∆K by a luminary located at an arbitrary azimuth;

2. Determination of ∆K by the Sun at the time of its true sunrise and sunset;

3. Determination of ∆K from the observations of the Polar Star.

The first method is the main and most common, the other two are its special cases. It is executed in the following sequence:

Example: August 24, 2006, Mediterranean Sea. At T c \u003d 20:46′; N=1E; Measured a series of compass bearings: α Scorpio

– CP cf = 219.5°; T gr.av. = 19:45′ 07″, ϕ с = 33°19.0′ N; λ c = 21°43.0′ E; KK = 196.0°, determine ∆K.

1. Calculate by MAE δ and t m of the star α Scorpio on T gr.av. \u003d 19: 45′ 07 ″

2. Calculate the true bearing of the star in one of the ways: - according to the TVA tables:

Using the PT formula calculator: THE SIGNS OF THE SHIPS WILL NOT UNDERSTAND

Ctg A = cosϕ tgδ cosec tm - sinϕ ctg tm

Сtg A \u003d 0.8356 ∗ - 0.4975 ∗ 1.4525 - 0.5493 ​​1.0547 \u003d -1.1825

A \u003d arcctg - 1.1825 \u003d 40.22 °; A k \u003d 220.2 °

on a computer using the program "Electronic almanac" A k \u003d 220.2 °

3. Calculate the compass correction:

∆K = IP - KP = 220.2° - 219.5° = + 0.7°. - symbols in the formulas are UNCLEAR

Determination of ∆K by the Sun at the time of its rising and setting:

If at the time of sunrise or sunset (at the moment of touching the horizon with its lower edge) to measure its compass bearing, then you can quickly and fairly accurately determine the compass correction. The specificity of this method lies in the fact that at the moment of sunrise (sunset) of the Sun, the height of its center is equal to a very specific value (-24.4 ′ cm. MT-2000), therefore the desired Azimuth is a function of two parameters - latitude and declination. Therefore, A c is easier to calculate and easier to tabulate. Table 3.37 MT-2000 is used to calculate the azimuth of the Sun. The input arguments in Table 3.37 are the decimal latitude - ϕ s, taken from the gasket at the time the compass bearing was measured, and the declination of the Sun - δ o, which is selected from the MAE at the Greenwich moment of sunrise (sunset). Tabular azimuth is given in a semi-circular account; the first letter of the name is of the same name with the denumerable latitude, and the second at sunrise - E, and at sunset - W.

It should be remembered that the instantaneous compass correction obtained in this way is less accurate and reliable than that obtained by the main method, therefore it is more often used only for control.

Example: April 12, 2006; Black Sea. ϕ s = 44°25.0′ N; λ c = 34°12.0′ E; KK = 92.0°; T c = 06:08′; N=3E; We measured the compass bearing of the Sun at the moment of its rising: KPO = 77.2°; determine ∆K.

1. Determine the Greenwich time of sunrise and for the moment obtained, the declination of the Sun is selected from MAE:

T gr \u003d T s ± N W / E \u003d 06:08 ′ - 3 \u003d 03: 08′

At Tgr = 03:08′ 12.04.02 from MAE - δо = 08°36.0′ N

2. Included in the table. 3.37 МТ-2000 with ϕ с = 44°25.0′ N and δ о = 08°36.0′ N and receive on April 12 А t = N 77.7° Е, taking into account

interpolation over ϕ and δ about get A to = IP = 77.5 °.

3. Calculate ∆K = IP - KP = 77.5 ° - 77.2 ° = + 0.3 °. THE SAME THING - IT IS UNCLEAR WHAT'S WHAT

3.3. Practical methods for determining the deviation of a magnetic compass.

Usually the residual deviation is determined after it is destroyed, but sometimes the determination of the deviation can be performed as independent work. Such a need arises if a noticeable discrepancy between the observed deviation is found on individual courses with its tabular values, as well as when transporting metal cargo, after sailing in ice, with a significant change in latitude by the vessel.

There is a full definition of deviation for compiling a deviation table and a partial one, on separate courses, in order to control the operation of a magnetic compass.

To compile the table, the deviation is most often determined on eight main and quarter compass courses, then the deviation coefficients A, B, C, D and E are calculated from the observed deviation values. Then, using the known coefficients, the deviation table is calculated for any number of courses using formula (1) . Depending on the value of the coefficients, the deviation table is calculated for 24 or 36 courses. If any coefficient exceeds 3 °, the table is compiled after 10 °, and for smaller coefficients - after 15 °. The input argument to the table is the compass heading.

The deviation table is signed by the person who made its determination. The calculated values ​​of the deviation coefficients are also entered in the table.

The determination of the deviation is carried out on a pale or at a low speed of the vessel, and before proceeding with the determination of the deviation on a new course, it is necessary to wait 3-5 minutes, which is necessary for the remagnetization of the vessel. On each course, if possible, determine the deviation from 3 - 5 observations, and average the result. The bearing or heading readout accuracy must be at least 0.2°.

All the main methods for determining deviation come down to comparing magnetic directions (bearings, courses) with directions measured by a compass. The following formulas are used to calculate the deviation:

δ = MP - KP,

δ \u003d OMP - OKP, (1)

δ = MK - KK

All methods for determining the deviation differ only in the method of obtaining the magnitude of the magnetic bearing or heading. The main ways to determine the deviation are:

- Determination of deviation along the alignment or by the fan of alignments - is the most accurate way. The essence of the method lies in the fact that at the moment of crossing the alignment notice the bearing on the compass.

The magnetic direction of the alignment is calculated from the true direction and magnitude

The alignment fan (Fig. 24) allows you to determine the deviation several times on the same course. The magnetic directions of the alignment fan are given in the sailing directions or in the descriptions of the deviation polygons. If there are no alignments marked on the map in the area where the deviation is determined, then you can use the alignment of any objects (conspicuous towers, buildings, masts, capes, etc.). The magnetic direction of such an alignment is approximately calculated as the average of eight directions measured by compass on the main and quarter courses,

- Determining the deviation from the bearing of a distant object produced when there are no targets in the area of ​​work. More often this method is performed when the place of the vessel does not change or changes slightly, i.e. when the vessel is parked on a deviation board, barrels, etc. The value of the magnetic bearing can be obtained from the chart if the ship's position is known with high accuracy. If this is not possible, the magnetic bearing is again calculated as the average of the eight measured compass bearings on the main and quarter points according to the formula (2). When the ship turns to a new course, its place on the ground does not remain constant, and the value of the MP changes. Obviously, the method can be applied only when the change in bearing Δ from the average value does not exceed a certain allowable value. From fig. 25 it can be seen that between the distance to the landmark D, the radius of the circle within which the position of the ship (compass) changes, r and the angle Δ, there is a relationship:

if we set Δ = 0.2°, then D = 300r. (3)

Thus, for example, at r = 100 m, the distance to the landmark should be at least 16.2 miles.

The method can also be used while the vessel is moving, but in this case, the bearing to a distant object is taken at the moment when the vessel passes in close proximity to a pre-installed buoy or pole. An exemplary scheme of maneuvering when determining the deviation in this way is shown in fig. 26.

Determination of deviation by comparison with the main magnetic compass usually produced by a traveling compass, since there is no possibility of measuring the bearing from it. Eight main and quarter courses are laid down according to the directional compass, and the magnetic course is calculated according to the QC of the main compass. The deviation of the steering compass δp is obtained by the following formulas:

MK=KKgl+δgl. δp=MK - KKp (4)

or according to the working formula obtained after substituting the first equation into the second,

δp \u003d KKgl - KKp + δgl. (five)

Comparison of compass readings, i.e., simultaneous fixing of the course, is carried out 3-5 times and the average value is displayed.

Determination of deviation by mutual bearings can be performed when there are no alignments and distant objects in visibility, but it is possible to bring the compass to the shore and install it on a tripod. The location of the compass should provide mutual visibility of the compass and the vessel.

When determining deviation by any signal(descent of a specified signal flag, radio command, etc.) simultaneously measure the bearing from the shore and the ship. The bearing from the coastal compass is MP + 180°, so it is easy to calculate the deviation value.

Determination of deviation by comparison with a gyrocompass- a common method on ships with a gyrocompass. The essence of the method lies in the fact that the magnetic heading is obtained by determining the true one from the readings of the gyrocompass, and the declination is selected from the map. In the process of determining the deviation, the ship consistently lays down on eight main and quarter courses according to the magnetic compass. On each course, the courses are simultaneously noticed (compared) by the gyrocompass and the magnetic compass.

The deviation is calculated sequentially according to the following formulas:

ik=gkk+Δgk,

MK \u003d IR - d, δ \u003d MK - KK

or according to the working formula derived from them, (6)

δ \u003d GKK-KK + (ΔGK - d),

where GKK n ΔGK - gyrocompass heading and compass correction, respectively.

The comparison is performed 3-5 times, and the resulting deviations are averaged.

The method should be performed at the smallest speed, avoiding large angle turns, as this minimizes errors in the correction of the gyrocompass from the influence of accelerations.

In addition to the methods considered, the deviation determination method is used. along the bearings of heavenly bodies, if it is possible to measure the bearing to the luminary (Sun, Moon, star) and calculate its azimuth.

While sailing, every opportunity should be taken to regularly determine the deviation on individual courses in order to check the accuracy of the deviation table. For this, the definitions of the compass correction by alignments, by bearings of celestial bodies and by comparison with a gyrocompass are most often used.

3.4. The principle of operation of the gyrocompass, accounting for errors in its readings. Methods for determining the gyrocompass correction.

The main heading guidance device is a gyrocompass. The basis of all gyroscopic direction indicators is a gyroscope (a rapidly rotating solid body), and the operation of these direction indicators is based on the property of a gyroscope to keep the direction of the axis of rotation in space unchanged without the action of external force moments.

The principle of operation of a gyrocompass can be described using a simplified diagram shown in Figure 27. The simplest gyrocompass consists of a gyroscope suspended inside a hollow ball that floats in a liquid; the weight of the ball with the gyroscope is such that its center of gravity is located on the axis of the ball in its lower part, when the axis of rotation of the gyroscope is horizontal. Suppose that the gyrocompass is located on the equator, and the axis of rotation of its gyroscope coincides with the direction west - east (position a); it retains its orientation in space in the absence of external forces. But the Earth rotates, making one revolution per day. Since an observer nearby rotates with the planet, he sees the east end (E) of the gyroscope axis rise and the west end (W) fall; in this case, the center of gravity of the ball shifts to the east and upwards (position b). However, the force of gravity prevents such a shift in the center of gravity, and as a result of its influence, the gyroscope axis rotates so as to coincide with the axis of the Earth's daily rotation, i.e., with the north-south direction (this rotational movement of the gyroscope axis under the action of an external force is called precession) . When the axis of the gyroscope coincides with the direction north - south (N - S, position c), the center of gravity will be in the lower position on the vertical and the cause of precession will disappear. Putting the mark "North" (N) on the place of the ball against which the corresponding end of the axis of the gyroscope rests, and correlating the scale with the necessary divisions, a reliable compass is obtained. In a real gyrocompass, compensation for compass deviation and a latitude correction are provided. The action of the gyrocompass depends on the rotation of the Earth and the features of the interaction of the gyroscope rotor with its suspension.

a B C)

Fig.27 Working principle of the gyrocompass

To reduce the time of arrival at the meridian, gyrocompasses have a device for accelerated bringing to the meridian. If using such a device to install and hold the HC SE in the meridian with an accuracy of 2 ÷ 3 °, then the time to reach the equilibrium position is reduced to 1 ÷ 1.5 hours (min 45 min.) dynamic and static errors is located in the direction of the gyroscopic meridian, which does not coincide with the true meridian.

Dynamic errors:

speed error, which occurs due to the angular velocity of rotation of the true horizon plane due to the movement of the ship on the surface of the Earth. This error is eliminated in the GC with the help of a special counting-deciding mechanism-corrector of the GC (by entering IR, V, φ into it); inertial errors of the I and II kind, which arise when the course and speed of the vessel change. At the end of the maneuver, the HA comes to a new equilibrium position in 25-30 minutes. These errors are eliminated in the HA by adjusting the period of undamped oscillations of the SE HA (84.3 min.) and the use of an oil dampener in the SE;

the error from pitching, which is due to the rocking of the SE HA relative to its main axis. It is excluded by the stabilization of the SE in the horizon plane.

Static errors: the presence of friction in the suspensions of gyromotors; inconstancy of the speed of rotation of the rotors of gyro motors; inaccurate installation of the main device in the ship's DP; action of magnetic fields. These errors, which characterize the stability of the HA operation on a fixed base, are determined empirically. If it is possible to eliminate all the indicated errors, then the main axis of the SE GC is set in the direction of the true meridian (NI), and the tracking system allows you to directly record this direction and transmit it to the GC repeaters. The guiding moment of the GC is many times greater than that of the MC, and does not depend on the Earth's magnetic field. However, with increasing latitude (φ), it decreases in proportion to cos φ, and at high

latitudes (> 75°) the HA works less reliably.

The magnetic compass is the simplest of all types of compasses known today. But it continues to be used by many people: tourists, military, fishermen, etc.

The simplest magnetic compass models consist of:

• Arrows - the main element of any such device
• Scales with designations of the main directions of the world
• Housing in which the pointer is fixed in such a way as to be able to rotate
• Protective glass that protects the pointer and scale from mechanical damage

More complex models can be equipped with additional elements, such as:

• Movable dial with pointer for faster and more convenient operation
• Arretir for fixing the arrow
• Liquid for quick stabilization of the arrow
• Rear sight and front sight for more accurate measurements
• Mirror to control the position of the compass needle during measurements on the ground
• Rectangular base with ruler for map measurements
• Clinometer, which allows you to know the slope of the terrain
• Lens for working with fine map details
• Mounting elements for more comfortable work with the compass
• Protective housing that protects the flask from damage

Now let's look at some of these elements in more detail.

compass needle

The compass needle is made of ferromagnetic material and is a permanent magnet that rotates on an axis. This arrow is directed towards the Earth's magnetic poles, unless it is significantly influenced by extraneous magnetic fields. (here are some options) .
Most often, it is located on the capstan to reduce friction during rotation. In some models of compasses, it is one with the disk on which the scale is applied.

Like any other magnet, a magnetic compass needle has a north and south pole, which are located at its two opposite ends. The northern one points towards the north, the southern one points towards the south.

To avoid confusion during measurements, the opposite ends of the arrow must differ in some way. To do this, they are most often painted in different colors, or only the northern end of the arrow is painted.

How to distinguish the north arrow of a magnetic compass

The simplest option is an arrow on a compass with a triangular or other form of an arrow in the north or a point (usually luminous).

Quite often, the arrow is painted in different colors, or only the northern end of the arrow is painted. The color of the north arrow may vary. This is decided by the manufacturer, and often does not coincide with what is written in various sources.

Usually one end of the arrow is marked with color. It could be blue, red, orange, green etc. Regardless of the color, if only one end of the arrow is marked, then this is the northern one. In this case white or black paint on the arrow are the background paints.

If the compass has red and blue arrows, then the red compass needle points to the south, and the blue one to the north. Blue was associated with cold and red with warmth.

Therefore, before using the compass, you must independently check your compass by orienting yourself on the terrain with any accessible way(for example, on a map, stars or the Sun) and comparing the result with the readings of the device.

Card on a magnetic compass

If you look at the examples of compasses above, you will see that they have letters and numbers printed in a circle on a disk located near or below the arrow. They are called a card or sometimes some call it scales.

First of all, they are indicated on the card. There are 32 in total, dividing the compass disk into 32 equal parts, but most often only 8 are used: 4 main and 4 auxiliary:

• N (North) - north.
• NE (North-East) - northeast.
• E (East) - east.
• SE (South-East) - southeast.
• S (South) - south.
• SW (South-West) - southwest.
• W (West) - west.
• NW (North-West) - northwest.

Also on the compass scale there are numbers that, depending on the model of the compass, show or degrees or thousandths. Although there are models simultaneously with two scales.

Degrees are used by tourists to work with azimuths, and thousandths are units for measuring angles used in military affairs.

If this is a degree scale, then the numbers in it are arranged in ascending order clockwise. A full rotation is 360 degrees.

If the scale is given in thousandths, then the numbers here can be located both clockwise and counterclockwise, depending on the compass model.

The values ​​of the scale showing thousandths can lie in different limits. There are three possible options:

• from 0 to 60
• 0 to 63
• 0 to 64

• in the former USSR and some other armies, the thousandth was taken equal to 1/6000
• in the army of Sweden - 1/6300
• in the NATO army - 1/6400

For example, in order to find out the price of division of the internal scale of the Adrianov compass:

1. We take offhand two of its values ​​lying next to each other on the scale - 45 ° and 60 °.
2. We determine the difference between them: 60° - 45° = 15°.
3. We count the number of gaps delimited by strokes between the values ​​​​of 45 ° and 60 ° - there are 5 of them.
4. We calculate the division value of the degree (internal) scale of this model: 15° / 5 = 3°.

Magnetic compass case

Metal cases tend to be stronger. There are even special impact-resistant models that can withstand significant mechanical stress. However, metal-framed compasses tend to be heavier than plastic-framed models.

It is believed that the brass case contributes to faster stabilization of the arrow due to the resulting induction currents. But in most modern models tourist compasses and compasses for orienteering, this problem is solved in a different way - by filling the sealed flask of the device with a special liquid that creates additional resistance for the arrow and instantly dampens any of its fluctuations, which is very convenient, especially if you have to navigate right on the go.

Movable magnetic compass

A movable dial with a pointer is used for faster and more convenient work with the compass.

On the dial of the compass, divisions go from 0 ° to 360 ° in a counter-clockwise direction or thousandths.

One of the most famous compasses with a lock is the Adrianov compass. In this model, the arrow is fixed in a fixed position when the arrester is pressed and is set in motion if the arrester lever is slightly pulled out of the body.

Rear sight and front sight (finder)

The rear sight with the front sight, as a rule, are located on opposite sides of the place where the compass needle is attached, and even when turned, they retain their position relative to the center of the arrow. Although, of course, not all models provide for the mobility of these elements.

There are different versions of rear sights and front sights.

Mirror

In some models, the mirror also allows you to more accurately point the compass to the desired object.

Typically, such a mirror is a flat, smooth metal plate, which makes it invulnerable to falls, because, unlike a glass mirror, metal plate will never break.

In addition to more accurate measurements, the mirror on the compass allows you to use the mirror for its intended purpose, for example, in order to independently remove something that has fallen into the eye foreign body(midge, mote). And in emergency this mirror can reflect Sun rays, send distress signals.

Liquid for quick stabilization of the arrow

This non-freezing liquid slows down the movement of the compass needle and stops it faster than in an air-filled case.

At high altitudes or at low temperatures, the liquid can contract and form bubbles. Bubbles do not affect accuracy. They disappear when the compass is back to normal.

Substrate

The base is a rectangular transparent base on which the compass is placed.

Usually, ruler markings are applied to the substrate, which makes it possible to effectively use it for working with a map.

Very often, instead of one ruler, two scales are applied to the tablet, one of which is drawn in such a way as to measure distances in inches or to automatically convert map centimeters into kilometers on the ground. The second option works only on maps of a certain scale, which is indicated on the ruler with such a scale.

If the substrate is transparent, then additional scales can be applied to it.

Also, cutouts in the form of various geometric shapes of different sizes can be made on the substrate for sketching symbols on the map, and a lens can also be built into it to look at small details of the terrain / map.

Magnetic compass mount

There are three main options for mounting the compass: on the thumb, on the wrist, hanging on the neck.

This compass mount is used for orienteering. It allows you to quickly navigate to the cardinal points without additional manipulations.

However, finger-mounted devices are less accurate than others for two reasons:

• their dimensions are too small to be marked with a scale with a minimum division value
• there is no ruler in their design, which makes it impossible to make accurate measurements on the map

Typically, such compasses are more accurate when measuring on the ground, as they have a more “detailed” scale, and are often equipped with sighting elements.

Mounting a magnetic compass by hanging around the neck

When moving, the compass hides under outerwear, so as not to hang around the neck, not to cling to surrounding objects (for example, tree branches, protruding parts of the relief) and not to beat on them, and if necessary, it is quickly removed and used for its intended purpose, after which it is again hidden under clothing

Luminous scale and pointer

At first, for a luminous compass, special phosphorus substances were applied to the magnetic needle and dial, which have the property of phosphorescence - glow in the dark after they are irradiated (“charged”) sunlight. However, the duration of such a glow was short.

In the 20s. of the last century, substances (usually based on isotopes of thorium or radium) began to be used for these purposes, the glow of which was due to soft and hard radiation (radioluminescence). At the same time, “recharging” with sunlight was not required, and the glow persisted for decades. However, due to harmful influence in the middle of the last century they were replaced by new types of phosphorescent materials, the duration of the glow exceeded 10 hours.

In the 1960s Swiss company "Mb-microtec AG" has developed new technology radioluminescent backlight GTLS (Gaseous Tritium Light Source - gas tritium light sources), which received the trade designation Trigalight (Trigalight). This technology is based on tiny cone tubes filled with tritium (an isotope of hydrogen). Their inner surface was coated with a phosphor that glowed under the influence of soft tritium radiation. Insofar as chemical element tritium has the designation 3 H, sometimes this technology is called "3 H" or "H3" illumination.

Depending on the composition of the phosphor, the glow of tritium tubes can be of different colors - from green and yellow to blue and red. Military compasses usually use phosphors that give a green color (the brightest and most intense glow).
The guaranteed service life of tritium illumination is at least 10 years (depending on the composition of the phosphor and the manufacturing technology, the glow can last for 15–20 years).
The safety of tritium illuminated compasses is confirmed by modern medical research, which found that the annual dose of trigalight radiation is almost 500 times less than from natural background radiation.
Despite many advantages, the tritium illumination technology also has a significant drawback - the high labor intensity of manufacturing trigalight tubes and, as a result, the high cost of products using this technology.

Commonly used in geological and some military compasses.

Ruler on a magnetic compass

If you carefully examined the above compasses, you often saw a ruler on them.

The ruler is needed for laying a route and measuring distances on the map.

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