Any navigator, both in ancient times and now, finding himself on the open sea out of sight of the shores, first of all wants to know in which direction his ship is moving. The device by which you can determine the course of a ship is well known - it is a compass. According to most historians, the magnetic needle - the ancestor of the modern compass - appeared about three thousand years ago. Communication between peoples in those days was difficult, and until the wonderful direction indicator reached the shores of the Mediterranean Sea, many centuries passed. As a result, this invention came to Europe only at the beginning of the 2nd millennium AD. e., and then spread widely.
As soon as it arrived in Europe, the device underwent a number of improvements and was called a compass, playing a huge role in the development of civilization. Only a magnetic compass gave people confidence in the sea and helped them overcome their fear of the ocean. Great geographical discoveries would be simply unthinkable without a compass.
History has not preserved the name of the inventor of the compass. And even the country that gave humanity this wonderful device cannot be precisely named by people of science. Some attribute its invention to the Phoenicians, others claim that the first who paid attention to the wonderful property of a magnet to be installed in the plane of the magnetic meridian were the Chinese, others give preference to the Arabs, others mention the French, Italians, Normans and even the ancient Mayans, the latter on the basis that once upon a time a magnetic rod was found in Ecuador, which (with a fervent imagination) could be considered a prototype of a magnetic needle.
At first, the device for determining the cardinal points was very simple: a magnetic needle was stuck into a piece of cork and lowered into a cup of water, which later became known as a compass pot. Sometimes, instead of a cork, they took a piece of reed or simply inserted a needle into a straw. Even this simple device brought invaluable convenience to the sailors; with it they could go out to the open sea and not be afraid that they would not find their way back to their native shore. But the sailors wanted more. They vaguely felt that the wonderful floating arrow, the accuracy of which was, of course, very low, had not yet revealed all its magnificent capabilities. And the water often splashed out of the pot, sometimes even along with the arrow. Only in the 13th century did a compass with a dry pot appear, and most importantly, with a card attached to the needle. The card was simple at first glance, but a truly remarkable invention: a small circle of non-magnetic material, together with a magnetic needle rigidly attached to it, is freely suspended on the tip of a vertical needle. Four main directions were applied on top of the card: Nord, Ost, Zuid and West, so that Nord exactly coincided with the northern end of the arrow. The arcs between the main points were divided into several equal parts.
Doesn't seem like anything special? But before that, the old compass with a fixed card had to be turned in a horizontal plane each time until the northern end of the arrow coincided with North. Only then was it possible to determine the course on which the ship was traveling. This, of course, was very inconvenient. But if the card itself rotated along with the arrow and was itself installed in the plane of the meridian, it was enough to just glance at it to determine any direction.
And yet, despite the improvements made, the compass for a long time remained a rather primitive device. In Russia in the 17th - early 18th centuries, it was most skillfully made by Pomors in the cities and villages of our North. It was a round box with a diameter of 4-5 centimeters made of walrus bone, which the Pomors kept at their belts in a leather bag. In the center of the box, on a bone pin, there was a card with magnetized metal arrow needles attached to the bottom. If the compass (or mark, as the Pomors called it) was not used, a blank cover was placed on top of it. About such a device it is written in the Naval Regulations of Peter I: “Compasses must be made with good skill and care so that the needles on which the compass rotates are sharp and strong and do not break quickly. Also, so that the wire (meaning the arrow - V.D) on the compass to Nord and Zuid should be firmly rubbed with a magnet, so that the compass can be correct, in which one must have a strong eye, for the progress and integrity of the ship depends on this.”
Nowadays, the compass bowl is tightly closed with a thick glass lid, tightly pressed to it with a copper ring. On top of the ring, divisions are applied from O to 360° - clockwise from Nord. Inside the pot, two black copper vertical wires are stretched so that one of them is exactly at 0°, and the other at 180°. These delays are called course lines.
The compass on the ship is installed so that the line drawn between the heading lines exactly coincides with the line bow - middle of the stern (or, as they say in the navy, with the center plane of the ship).
History also does not answer who exactly invented the compass with a rotating card. True, there is a widespread version that in 1302 the Italian Flavio Gioia (according to other sources, Gioia) attached a card divided into 32 points to a magnetic needle, and placed the arrow on the tip of a pin. Grateful fellow countrymen even erected a bronze monument to Joya in his homeland - in the city of Amalfi. But if someone really should have erected a monument, it would be our compatriot Peter Peregrin. His work “Epistle on Magnets,” dated 1269 and dedicated to describing the properties of a magnet, contains reliable information about his improvement of the compass. This compass did not have a card. A magnetic needle was mounted on a vertical pin, and the azimuthal circle on the top of the pot was divided into four parts, each of which was divided in degrees from 0 to 90. A movable sight for direction finding was put on the azimuthal circle, using which it was possible to determine directions to the coastal objects and luminaries located low above the horizon. This sight was very similar to a modern direction finder, which still serves the fleet regularly.
About a century and a half passed before a new invention appeared after Peregrine, making it even easier to work with the compass.
The sea is very rarely calm, and any ship experiences rolling, and this, naturally, negatively affects the operation of the compass. Sometimes the sea swell is so strong that it completely disables the compass. Therefore, there was a need for a device that would allow the compass bowl to remain calm during any motion.
Like most ingenious inventions, the new compass pendant was extremely simple. The compass bowl, somewhat weighted at the bottom, was suspended on two horizontal axles resting on a ring. This ring, in turn, was attached to two horizontal semi-axes, perpendicular to the first, and suspended inside the second ring, fixedly attached to the ship. Thus, no matter how steeply and often the ship tilted, and in any direction, the card always remained horizontal. After the Italian mathematician D. Cardano, who proposed this remarkable device, the suspension was called cardan.
The Portuguese proposed dividing the compass card into 32 points. They have remained on the cards of marine compasses to this day. Each got its own name, and until relatively recently, about fifty years ago, you could find a sailor somewhere in the cockpit cramming a compass with shadows: “Nord Nord shadow Ost, Nord Nord Ost, Nord Ost shadow Ost, Nord Ost, Nord Ost shadow Zuid" and so on. Shadow in this case in Russian means: to the side. Now, although all 32 points remain on many modern compasses, divisions in degrees (and sometimes even fractions of a degree) have also been added to them. And in our time, when communicating the course that the helmsman needs to keep, they prefer to say, for example: “Course 327°!” (instead of the former “North West shadow Nord”, which is essentially the same thing - the difference of 1/4° is rounded off).
Since the magnetic compass acquired its modern design in the 19th century, it has improved very little. But the idea of terrestrial magnetism and magnetism in general has advanced far ahead. This led to a number of new discoveries and inventions, which, even if they do not relate to the compass itself, are directly related to navigation.
The more complex the tasks that fell on the military and merchant (commercial) fleets, the greater the demands made by sailors on compass readings. The observations became more accurate, and suddenly, quite unexpectedly for themselves, the sailors noticed that their main assistant, the compass, which they had trusted endlessly for so many centuries, very rarely gave correct readings. Any magnetic compass is lying by two or three degrees, and sometimes much more, to put it mildly. We noticed that compass errors are not the same in different places on Earth, that over the years they increase at some points and decrease at others, and that the closer to the pole, the greater these errors.
But at the beginning of the 19th century, science came to the aid of sailors and by the middle of it had dealt with this disaster. The German scientist Carl Gauss created a general theory of terrestrial magnetism. Hundreds of thousands of precise measurements were made, and now on all navigation charts the deviation of the compass needle from the true meridian (the so-called declination) is indicated directly on the map with an accuracy of a quarter of a degree. It also indicates to which year the declination is given, the sign and magnitude of its annual change.
The work of navigators has increased - now it becomes necessary to calculate the correction for changes in declination. This was true only for mid-latitudes. In high latitudes, that is, in the areas from 70° northern and southern latitudes to the poles, the magnetic compass could not be trusted at all. The fact is that in these latitudes there are very large anomalies of magnetic declination, as the proximity of the magnetic poles, which do not coincide with the geographical ones, affects it. The magnetic needle tends to take a vertical position here. In this case, science does not help, and the compass lies without a twinge of conscience, and sometimes even begins to change its readings every now and then. It was not for nothing that when preparing to fly to the North Pole in 1925, the famous Amundsen did not dare to trust the magnetic compass and came up with a special device called the solar heading indicator. In it, an accurate clock turned a small mirror following the sun, and while the plane flew above the clouds without deviating from the course, the “bunny” did not change its position.
But the misadventures of the magnetic compass did not end there. Shipbuilding developed rapidly. At the beginning of the 19th century, steamships appeared, followed by metal ships. Iron ships quickly began to displace wooden ones, and suddenly... One after another, several large steamships sank under mysterious circumstances. Analyzing the circumstances of the crash of one of them, in which about 300 people died, experts determined that the cause of the accident was incorrect readings of magnetic compasses.
Scientists and sailors gathered in England to figure out what was happening here. And they came to the conclusion that the ship’s iron has such a strong influence on the compass that errors in its readings are simply inevitable. Doctor of Divinity Scoresby, who was once a famous captain, spoke at this meeting and demonstrated to those present the influence of iron on the needle of a magnetic compass and concluded: the greater the mass of iron, the more it deflects the compass needle from the meridian. “We,” said Scoresby, “sail the old-fashioned way, as on wooden ships, that is, without taking into account the influence of the ship’s iron on the compass. I’m afraid that it will never be possible to achieve correct compass readings on a steel ship...” The deviation of the magnetic compass needle under the influence of the ship’s iron was called deviation.
Opponents of iron shipbuilding were emboldened. But this time, science came to the aid of the magnetic compass. Scientists have found a way to reduce this deviation to a minimum by placing special destroyer magnets next to the magnetic compass. The palm in this, of course, belongs to Captain Matthew Flinders, after whom the first destroyer, the Flindersbar, was named. They began to be placed in binnacles next to the compass pot.
Previously, a binnacle was a wooden box in which a compass was placed at night along with a lantern. The English sailors called it that way: night house - night house. Nowadays, a binnacle is a wooden four- or hexagonal cabinet on which the compass pot is mounted. To the left and right of him on the binnacle are massive iron balls the size of a small melon. They can be moved and secured closer and further away from the compass. Hidden inside the cabinet is a whole set of magnets that can also be moved and fixed. Changing the relative position of these balls and magnets almost completely eliminates the deviation.
Now, before leaving for a voyage, when the cargo has already been loaded and secured, a deviator is lifted onto the ship and, in a specially designated area of the sea, carries out the destruction of the deviation for an hour and a half. According to his commands, the ship moves in different courses, and the deviator moves the balls and magnets, reducing the influence of the ship's iron on the compass readings. When leaving on board, he leaves a small table of residual deviation, which the navigators have to take into account every time the ship changes course, as a correction for deviation. Let us recall Jules Verne’s novel “The Fifteen-Year-Old Captain,” where the scoundrel Negoro placed an ax under the compass binnacle, dramatically changing its readings. As a result, the ship sailed to Africa instead of America.
The need to periodically destroy and determine residual deviation made us think about the problem of creating a non-magnetic compass. By the beginning of the 20th century, the properties of the gyroscope were well studied, and on this basis a gyroscopic compass was designed. The principle of operation of the gyrocompass, created by the German scientist Anschutz, is that the axis of a rapidly rotating top remains unchanged in its position in space and can be set along the north-south line. Modern gyrocompasses are enclosed in a hermetically sealed sphere (hydrosphere), which, in turn, is placed in an outer casing. The hydrosphere floats suspended in a liquid. Its position is adjusted using an electromagnetic blast coil. The electric motor increases the rotation speed of the gyroscopes to 20 thousand revolutions per minute.
To ensure comfortable working conditions, the gyrocompass (the main device) is placed in the very quiet place ship (closer to its center of gravity). Using electrical cables, gyrocompass readings are transmitted to repeaters located on the wings of the bridge, in the central control room, in the chart room and other rooms where it is necessary.
Nowadays, industry produces various types of these devices. Using them is not particularly difficult. Amendments to their testimony are usually instrumental. They are small and permanent. But the devices themselves are complex and require qualified specialists to service them. There are other difficulties in operation. The gyrocompass must be turned on in advance, before going to sea, so that it has time, as sailors say, to “arrive at the meridian.” Needless to say, the gyrocompass provides incomparably higher heading accuracy and stability of operation at high latitudes, but this has not diminished the authority of the magnetic compass. The combat operations of the fleet during the Great Patriotic War showed that it was still needed on ships. In July 1943, during a combat operation, the gyrocompass on the destroyer Soobrazitelny failed. The navigator switched to a magnetic compass and at night, in stormy weather, out of sight of the coast, having traveled about 180 miles (333 kilometers), he reached the base with a discrepancy of 55 cables (10.2 kilometers). The leader of the Kharkov destroyers, which participated in the same operation, under the same conditions, but with a working gyrocompass, had a discrepancy of 35 cables (6.5 kilometers). In August of the same year, due to a fire on board, the gyrocompass on the gunboat “Red Adzharistan” failed. During combat operations, the ship's navigator successfully conducted precise navigation using only magnetic compasses.
That is why even today, even on the most modern ships equipped with navigation systems, radio engineering and space systems, which include several course indicators that do not depend on either deviation or declination, there is always a magnetic compass.
But no matter how accurately we measure the course, it can only be plotted graphically on a map. The map is a flat model of the globe. Sailors use only specially made, so-called navigation charts, the distances of which are measured in miles. To understand how such maps were created, you will have to look into the 15th century, to those distant times when people had just learned to plot land and sea on them and to swim using them. Of course, there were cards before. But they looked more like clumsy drawings made by eye, from memory. Maps also appeared, based on the scientific concepts of their time, quite accurately depicting the coasts and seas known to navigators. Of course, there were many errors in these maps, and they were not built in the same way as maps are built in our time, but still they were a help for sailors who set out on voyages across the seas and oceans.
It was a time full of contradictions. On the one hand, “experienced people” swore that they had met terrible monsters, huge sea snakes, beautiful sirens and other miracles in the ocean, and on the other hand, great geographical discoveries were made one after another. On the one hand, the Holy Inquisition stifled every living thought, and on the other, many enlightened people already knew about the spherical shape of the Earth, argued about the size of the globe, and had an idea about latitude and longitude. Moreover, it is known that in the same year 1492, when Christopher Columbus discovered America, the German geographer and traveler Martin Beheim had already built a globe. Of course, it was not at all like modern globes. On Beheim's globe and later, more advanced models of the Earth, there were more white spots than accurately depicted continents; many lands and shores were depicted according to the stories of “experienced people” whose word was dangerous to take. Some continents on the first globes were completely absent. But the main thing was already there - in a large circle, perpendicular to the axis of rotation, the equator, which in Latin means equalizer, encircled the model of the Earth.
The plane in which it lies, as it were, divides the globe in half and equalizes its halves. The circle of the equator from the point taken as zero was divided into 360° longitude - 180° to the east and west. To the south and north of the equator, small circles parallel to the equator were drawn on the globe to the very poles. They were called that - parallels, and the equator began to serve as the starting point geographical latitude. The meridian arcs perpendicular to the equator in the Northern and Southern Hemispheres converge at an angle to each other at the poles. Meridian means "midday" in Latin. This name, of course, is not accidental; it shows that along the entire meridian line, from pole to pole, noon (as well as at any other moment) occurs simultaneously. From the equator to the north and south, the meridian arcs were divided into degrees - from 0 to 90, calling them degrees of northern and southern latitude, respectively.
Now, to find a point on a map or globe, it was enough to indicate its latitude and longitude in degrees.
The geographic coordinate grid was finally constructed.
But it’s one thing to find a point on the map and quite another to find it on the open sea. Imperfect maps, a magnetic compass and a primitive goniometric instrument for determining vertical angles - that’s all the sailor had at his disposal when setting off on a long voyage. With an arsenal of even such navigation devices, arriving at a point that is within sight or even beyond the horizon is not a difficult task. Unless, of course, the peaks of the distant mountains located near this point were visible above the horizon. But as soon as the sailor moved further out to sea, the shores disappeared from sight and monotonous waves surrounded the ship on all sides. Even if the navigator knew the exact direction that should lead him to his goal, even then it was difficult to count on success, since capricious winds and unexplored currents always blow the ship off the intended course. Sailors call this deviation from course drift.
But even in the absence of drift, choosing the desired direction using a regular map and navigating the ship along it is almost impossible. And that's why. Let's assume that, armed with an ordinary map and compass, we plan to sail out of sight of the coast from point A to point B. Let's connect these points with a straight line. Let us now assume that this straight line at point A will lie exactly at a course of 45°. In other words, line AB at point A will be located at an angle of 45° to the plane of the meridian passing through point A. This direction is not difficult to maintain using a compass. And we would arrive at point B, but under one condition: if the meridians were parallel and our course line at point B corresponded to the direction of 45°, as at point A. But the fact of the matter is that the meridians are not parallel, and gradually converge at an angle to each other. This means that the course at point B will not be 45°, but somewhat less. Thus, to get from point A to point B, we would have to constantly turn to the right.
If, having left point A, we constantly keep a course of 45° according to our map, then point B will remain to our right, we, continuing to follow this course, will cross all the meridians at the same angle and approach in a complex spiral at the end ends to the pole.
This spiral is called rhoxodrome. In Greek it means "oblique path." We can always choose a rhoxodrome that will take us to any point. 14, using a regular map, one would have to make a lot of complex calculations and constructions. This is what the sailors were not happy with. For decades they have been waiting for such a map, which would be convenient for plotting any courses and sailing across any seas.
And so in 1589, the famous mathematician and cartographer Flemish Gerardus Mercator came up with a map that finally satisfied the sailors and turned out to be so successful that no one has yet proposed anything better. Sailors all over the world still use this card today. That’s what it’s called: a Mercator map, or a map of a conformal cylindrical Mercator projection.
The principles underlying the construction of this map are ingeniously simple. It is impossible, of course, to reconstruct the course of G. Mercator’s reasoning, but let’s assume that he reasoned like this.
Let's assume that all the meridians on the globe (which quite accurately conveys the relative positions of the oceans, seas and land on Earth) are made of wire, and the parallels are made of elastic threads that easily stretch (rubber was not yet known at that time). Let's straighten the meridians so that they turn from arcs into parallel straight lines attached to the equator. The surface of the globe will turn into a cylinder of straight meridians intersected by stretched parallels. Let's cut this cylinder along one of the meridians and spread it on a plane. The result will be a geographic grid, but the meridians on this grid will not converge, as on the globe, at the pole points. They will run in straight parallel lines up and down from the equator, and parallels will intersect them everywhere at the same right angle.
A round island near the equator, just as it was round on the globe, will remain round on this map; in the middle latitudes, the same island will stretch significantly in latitude, and in the area of the pole it will generally look like a long straight strip. The relative position of land, seas, the configuration of continents, seas, and oceans on such a map will change beyond recognition. After all, the meridians remained the same as they were, but the parallels stretched.
Swimming, guided by such a map, of course, was impossible, but it turned out to be fixable - you just had to increase the distance between the parallels. But, of course, not just increase, but in exact accordance with how much the parallels stretched during the transition to the Mercator map. On a map constructed using such a grid, the round island at the equator and in any other part of the map remained round. But the closer it was to the pole, the more space it occupied on the map. In other words, the scale on such a map increased from the equator to the poles, but the outlines of objects plotted on the map appeared almost unchanged.
But how to take into account the change in scale towards the poles? Of course, you can calculate the scale separately for each latitude. Only such a voyage would be a very troublesome task, in which, after each movement to the north or south, one would have to make rather complex calculations. But it turns out that such calculations do not have to be made on a Mercator map. The map is enclosed in a frame, on the vertical sides of which are the degrees and minutes of the meridian. At the equator they are shorter, and the closer to the pole, the longer. The frame is used like this: the distance to be measured is taken with a compass, brought to that part of the frame that is located at the latitude of the segment being measured and see how many minutes are included in it. And since the minute and degree on such a map change in value depending on the latitude, but in fact always remain the same, they became the basis for the choice of linear measures with which sailors measured their path.
France had its own measure - league, equal to 1/20 of a degree of meridian, which is 5537 meters. The British measured their sea roads in leagues, which are also a fractional part of a degree and are 4828 meters in size. But gradually sailors all over the world agreed that it was most convenient to use the arc value corresponding to one angular minute of the meridian to measure distances at sea. This is how sailors still measure their paths and distances in minutes of the arc of the meridian. And in order to give this measure a name similar to the names of other travel measures, they dubbed the meridian minute a mile. Its length is 1852 meters.
The word “mile” is not Russian, so let’s look at the Dictionary of Foreign Words. It says there that the word is English. Then it is reported that miles are different: a geographical mile (7420 m), land miles vary in size in different countries, and finally, a nautical mile - 1852.3 meters.
Everything is true about the mile, except for the English origin of the word; it's actually Latin. In ancient books, a mile was found quite often and meant a thousand double steps. It was from Rome, and not from England, that this word first came to us. So there is an error in the dictionary. But this error can be understood and forgiven, since the compiler of the dictionary entry had in mind, of course, the international nautical mile, or, as the British call it, the admiralty mile. In the times of Peter the Great, it came to us from England. That's what we called it - the English mile. Sometimes today it is called the same.
Using the mile is very convenient. Therefore, the sailors are not yet going to replace the mile with some other measure.
Having made his way on a Mercator map along a ruler, having calculated and remembered which course should be followed, the sailor can safely set sail without thinking about the fact that his path, straight as an arrow, on the map is not a straight line at all, but just the same curve that was mentioned a little earlier - rhoxodrome.
This is, of course, not the shortest path between two points. But if these points do not lie very far from each other, then the sailors are not upset and put up with the fact that they will burn excess fuel and spend extra time on the transition. But on this map the rhoxodrome looks straight, which costs nothing to build, and you can be sure that it will lead exactly where you need it. What if there is a long voyage ahead, such as, for example, an ocean crossing, during which the additional costs for the curvature of the path will result in a significant amount and time? In this case, the sailors learned to build another curve on the Mercator map - orthodrome, which means “straight path” in Greek. The orthodrome on the map coincides with the so-called great circle arc, which is the shortest distance at sea between two points.
These two concepts do not fit well in the mind: the shortest distance and the arc, standing next to each other. This is all the more difficult to reconcile if you look at the Mercator map: the orthodrome looks much longer than the loxodrome. If on a Mercator map both of these curves are laid between two points, the orthodrome will bend like a bow, and the loxodrome will stretch out like a bowstring, tightening its ends. But we must not forget that ships sail not on a flat map, but on the surface of a ball. And on the surface of the ball, a segment of the arc of a great circle will be the shortest distance.
The unit of measurement of distances at sea - the mile - is closely related to the unit of speed adopted in navigation - the knot, which we will discuss further.
If the distances traveled by the ship are periodically plotted on the course line laid out on the map, then the navigator will always know where his ship is located, that is, the coordinates of his place in the sea. This method of determining coordinates is called dead reckoning and is widely used in navigation. But a necessary condition for this is the ability to determine the speed of the ship and measure time, only then can the distance traveled be calculated.
Ship speed indicators. 2. Flasks. 2. Manual log. 3. Mechanical log
We have already said above that on ships of the sailing fleet, hourglasses were used to measure time, designed for half an hour (flasks), one hour and four hours (watch). But there were also another hourglass on the ships - flasks. These hours were designed for just half a minute, and in some cases even for fifteen seconds. One can only be amazed at the art of glassblowers who managed to produce such accurate instruments for those times. No matter how small these watches were, no matter how short the period of time that they measured, the service that these watches provided to sailors in their time is invaluable, and they, like the flasks, are remembered every time they talk about determining the speed of a ship , as well as when measuring the distance traveled.
The problem of determining the path traveled and the path ahead has always been and is facing sailors.
The first methods of measuring speed were perhaps the most primitive of navigational definitions: they simply threw a piece of wood, bark, bird feather or other floating object overboard from the bow of the ship and at the same time noted the time. Walking along the side from the bow to the stern of the ship, they did not let the floating object out of their eyes and, when it passed the cut of the stern, they again noticed the time. Knowing the length of the ship and the time it took the object to travel through it, the speed was calculated. And knowing the total travel time, they got an approximate idea of the distance traveled.
On sailing ships in very light winds this ancient method is used to determine the speed of a ship even today. But already in the 16th century the first lag appeared. A sector of 65-70 degrees was made from a thick board, with a radius of about 60-70 centimeters. Along the arc delimiting the sector, as a rule, a lead weight was strengthened in the form of a strip, designed in such a way that the sector, thrown into the water, was immersed two-thirds upright and a small corner remained visible above the water. A thin, strong cable, called a laglin, was attached to the top of this corner. In the sector, approximately in the geometric center of the immersed part, a conical hole of 1.5-2 centimeters in diameter was drilled and a wooden plug was tightly fitted to it, to which a lag line was firmly tied eight to ten centimeters from the end attached to the corner of the lag. This plug was held quite firmly in the hole of the submerged joist, but with a sharp tug it could be pulled out.
Why was it so difficult to attach the lagline to the lag sector? The fact is that a flat body moving in a liquid medium is located perpendicular to the direction of movement if the force moving this body is applied to its center of sail (similarly kite). It is worth, however, moving the point of application of forces to the edge of this body or to its corner, and it, like a flag, will be located parallel to the direction of movement.
Likewise, the log, when thrown overboard of a moving ship, is held perpendicular to the direction of its motion, since the log is attached to a plug standing in the center of the sail of the sector plane. When the ship moves, the sector experiences great water resistance. But as soon as you sharply pull the laglin, the cork jumps out of the socket, the point of application of force is transferred to the corner of the sector, and it begins to glide and slide along the surface of the water. It experiences virtually no resistance, and in this form it was not at all difficult to pull the sector out of the water.
Short shkertiks (thin ends) were woven into the laglin at a distance of approximately 15 meters from each other (more precisely, 14.4 m), on which one, two, three, four, and so on knots were tied. Sometimes the segments between two adjacent shkertiks were also called knots. The laglin, together with the shkertiks, was wound onto a small view (like a reel), which was convenient to hold in your hands.
Two sailors stood at the stern of the ship. One of them threw a section of the log overboard and held a view in his hands. The log, having fallen into the water, rested and unwound the log from the view after the moving ship. The sailor, having raised the view above his head, carefully watched the laglin unwinding from the view and, as soon as the first kerf approached close to the edge of the stern cut, he shouted: “Here you go!” (this means “Get ready!”). And almost immediately after this: “Turn!” (“Turn it over!”).
The second sailor held bottles in his hands, designed for 30 seconds, but the team of the first one turned them over and, when all the sand poured into the lower tank, shouted: “Stop!”
The first sailor sharply pulled the lagline, the wooden plug popped out of the hole, the section of the lag lay flat on the water and stopped reeling in the lagline.
Having noticed how many small knots went overboard when winding up the lagline, the sailor determined the ship's speed in miles per hour. It was not at all difficult to do this: the kerchiefs were woven into the lagline at a distance of 1/120 of a mile, and the clock showed 30 seconds, that is, 1/120 of an hour. Consequently, how many knots of lagline were unwound from the view in half a minute, the number of miles the ship traveled in an hour. This is where the expression comes from: “The ship moves at a speed of so many knots” or “The ship makes so many knots.” Thus, a knot at sea is not a linear measure of travel, but a measure of speed. This must be firmly understood, because when talking about speed, we are so accustomed to adding “per hour” that it happens that we read “knots per hour” in the most authoritative publications. This, of course, is wrong, because a knot is a mile/hour.
Nowadays no one uses manual logs anymore. Also M.V. Lomonosov, in his work “On Greater Accuracy of the Sea Route,” proposed a mechanical log. Described by M.V. Lomonosov's lag consisted of a turntable, similar to a large cigar, along which wings and blades were located at an angle to the axis, like on the rotor of a modern hydraulic turbine. A turntable tied into a laglina made of a cable that almost did not twist, M.V. Lomonosov proposed lowering the stern of a moving ship. Naturally, it rotated the faster the faster the ship moved. It was proposed to tie the front end of the lagline to the shaft of a mechanical counter, which was supposed to be attached to the stern of the ship and count the miles traveled.
Lomonosov proposed, described, but did not have time to build and test his mechanical log. After him, several inventors of mechanical lag appeared: Walker, Messon, Clintock and others. Their lags are somewhat different from each other, but the principle of their operation is the same, which was proposed by M.V. Lomonosov.
More recently, as soon as a ship or ship went to sea, the navigator and sailor carried a log turntable, a logline and a counter, which was usually called a machine, onto the upper deck. The turntable with the laglin was thrown overboard, and the machine was mounted on the gunwale of the stern section, and the navigator wrote down in the navigation log the readings that appeared on its dial at the time of the start of work. At any moment, by looking at the dial of such a log, one could quite accurately find out about the path traveled by the ship. There are lags that simultaneously show the speed in knots.
Nowadays, many ships have more advanced and accurate logs installed. Their action is based on the property of water and any other liquid to exert pressure on an object moving in it, which increases as the speed of movement of this object increases. A not very complex electronic device transmits the value of this pressure (dynamic water pressure) to a device installed on the bridge or at the ship’s navigational command post, having, of course, previously converted this value into miles and knots.
These are so-called hydrodynamic logs. There are also more advanced logs for determining the speed of a ship relative to the seabed, that is, absolute speed. Such a log works on the principle of a sonar station and is called hydroacoustic.
In conclusion, the word lag comes from the Dutch log, which means distance.
So, having received at his disposal a compass, a navigation map and units of distance and speed - miles and knots, the navigator can calmly conduct navigational plots, periodically marking on the map the distances traveled by the ship. But the presence of numerable coordinates of one’s place in the sea does not at all reject the observed ones, that is, determined instrumentally by celestial bodies, radio beacons or coastal landmarks plotted on the map, but, on the contrary, necessarily implies them. The difference between the calculated coordinates and the observed ones is called the discrepancy by sailors. The smaller the discrepancy, the more skillful the navigator. When sailing within sight of the coast, it is best to determine the observed place by lighthouses, which are clearly visible during the day and emit light at night.
There are few engineering structures in the world about which there are so many legends and tales as about lighthouses. Already in the poem “Odyssey” by the ancient Greek poet Homer, dating back to the 8th-7th centuries BC, it is said that the inhabitants of Ithaca lit fires so that Odysseus, who was expected home, could recognize his native harbor.
Suddenly on the tenth day he appeared to us
shore of the fatherland.
He howled already close; there are all the lights on it
We could already tell the difference.
These are, in fact, the first mentions of sailors using the lights of ordinary fires for navigational purposes when sailing near the coast at night.
Centuries have passed since those distant times before lighthouses became familiar to everyone. appearance - high tower, topped with a lantern. And once upon a time, tar barrels or braziers with coal, which served as the first lighthouses, burned right on the ground or. on high poles. Over time, to increase the visibility range of light sources, they were installed on artificial structures, sometimes reaching enormous proportions. The lighthouses of the Mediterranean Sea have the most venerable age.
One of the seven wonders ancient world- Alexandria, or Pharos, lighthouse, 143 meters high, built of white marble in 283 BC. The construction of this tallest structure of antiquity lasted 20 years. A huge and massive lighthouse, surrounded by a spiral staircase, served as a guiding star for sailors, showing them the way during the day with smoke from the oil burned on its top, and at night with the help of fire, as the ancients said, “more brilliant and inextinguishable than the stars.” Thanks to a special light reflection system, the visibility range of the fire on a clear night reached 20 miles. The lighthouse was built on the island of Pharos at the entrance to the Egyptian port of Alexandria and served simultaneously as an observation post, fortress and weather station.
No less famous in ancient times was the famous Colossus of Rhodes - a giant bronze figure of Helios, the sun god, installed on the island of Rhodes in the Aegean Sea in 280 BC. Its construction lasted 12 years. This 32-meter-tall statue, also considered one of the seven wonders of the world, stood in the Rhodes harbor and served as a lighthouse until it was destroyed by an earthquake in 224 BC. e.
In addition to the lighthouses mentioned above, about 20 more were known at that time. Today, only one of them has survived - the lighthouse tower near the Spanish port city of La Coruña. It is possible that this lighthouse was built by the Phoenicians. Over its long life, it was renovated more than once by the Romans, but on the whole it retained its original appearance.
The construction of lighthouses developed extremely slowly, and by the beginning of the 19th century there were no more than a hundred of them on all the seas and oceans of the globe. This is explained primarily by the fact that precisely in those places where lighthouses were most needed, their construction turned out to be very expensive and labor-intensive.
Light sources for lighthouses have been continuously improved. In the 17th-18th centuries, several dozen candles weighing 2-3 pounds (about 0.9-1.4 kg) burned simultaneously in lighthouse lanterns. In 1784, Argand oil lamps appeared, in which the wick received oil under constant pressure, the flame stopped smoking and became brighter. At the beginning of the 19th century, gas lighting began to be installed in lighthouses. At the end of 1858, electric lighting equipment appeared at the Upper Foreland Lighthouse (English coast of the English Channel).
In Russia, the first lighthouses were built in 1702 at the mouth of the Don and in 1704 at the Peter and Paul Fortress in St. Petersburg. The construction of the oldest lighthouse on the Baltic - Tolbukhin near Kronstadt - lasted almost 100 years. Construction of the building began on the orders of Peter I. His own sketch has been preserved, indicating the main dimensions of the tower and a note: “The rest will be left to the architect.” The construction of a stone building required significant funds and a large number of skilled masons. Construction was delayed, and the king ordered the urgent construction of a temporary wooden tower. His order was carried out young, and in 1719 a light flashed on the Kotlin lighthouse (the name comes from the spit on which it was installed). In 1736, another attempt was made to erect a stone building, but it was completed only in 1810. The project was developed with the participation of the talented Russian architect AD. Zakharov, the creator of the Main Admiralty building in St. Petersburg. Since 1736, the lighthouse has been named after Colonel Fyodor Semenovich Tolbukhin, who defeated the Swedish naval landing on the Kotlin Spit in 1705, and then the military commandant of Kronstadt
The oldest lighthouses in the world. 1, 2. Ancient lighthouses with open fire. 3. Faros (Alexandria) lighthouse. 4. Lighthouse of A Coruña
The round, low, steep tower of the Tolbukhin lighthouse is known to dozens of generations of Russian sailors. In the early 70s of the 20th century, the lighthouse was reconstructed. The shore around the artificial island was reinforced with reinforced concrete slabs. The tower is now equipped with modern optical equipment, which allows increasing the visibility range of fire, and the country's first automatic wind power plant, ensuring its uninterrupted operation.
In 1724 in Gulf of Finland The Kern (Kokshere) lighthouse began operating on the island of the same name. By the beginning of the 19th century, there were 15 lighthouses operating on the Baltic Sea. These are the oldest lighthouses in Russia. Their service life exceeds 260 years or more, and the Kõpu lighthouse on Dago Island has existed for more than 445 years.
At some of these structures, new lighthouse technology was introduced for the first time. So, on Keri, which turned 250 years old in 1974, an octagonal lantern with oil lamps and copper reflectors was installed in 1803 -? Russia's first light-optical system. In 1858, this lighthouse was equipped (also the first in Russia) with a Fresnel lighting system (named after the inventor, French physicist Augustin Jean Fresnel). This system was an optical device consisting of two flat mirrors (bimirrors) located at a small (several minutes of arc) angle to each other.
Thus, Carey twice became the founder of various lighting systems: capitric - a mirror reflective system, and dioptric - a system based on the refraction of light when passing through individual refractive surfaces. The transition to these optical systems has greatly improved the quality characteristics of the lighthouse and increased the efficiency of ensuring navigation safety.
The role of lighthouses was also played by the famous 34-meter Rostral Columns, built in 1806 to commemorate the glorious victories of Russia at sea. They pointed to the branching of the Neva into the Bolshaya and Malaya Neva and were installed on both sides of the Spit of Vasilyevsky Island.
One of oldest lighthouses on the Black Sea - Tarkhankutsky with a tower 30 meters high. It entered service on June 16, 1817. On one of the lighthouse buildings the words are inscribed: “Lighthouses are the shrine of the seas. They belong to everyone and are inviolable, like ambassadors of powers.” Today its white light is visible for 17 miles. In addition, it is equipped with a radio beacon and sound alarm.
In 1843, at the very tip of the Quarantine Pier of the Odessa Bay, a fire guard post was erected with a mast on which two oil lanterns were raised using a winch. Thus, this year should be considered the year of birth of the Vorontsov lighthouse. However, the real lighthouse on the Quarantine Mole was opened only in 1863. It is a 30-foot (over 9 m) cast iron tower topped with a special lantern.
In 1867, the Odessa lighthouse became the first in Russia and the fourth in the world to be switched to electric lighting. In general, the transition to a new energy source occurred extremely slowly. In 1883, out of five thousand lighthouses in the world, only 14 had electric light sources. The rest were still working on kerosene, acetylene and gas lamps and burners.
After the raid pier was significantly lengthened, a new Vorontsov lighthouse was built in 1888, which stood until 1941. It was a cast iron tower 17 meters high. During the defense of Odessa, the lighthouse had to be blown up. But it is he who is depicted on the medal “For the Defense of Odessa.” The new lighthouse, the one we see today, was built in early 1954. The tower, which has a cylindrical shape, has become much taller - 30 meters, not counting the 12-meter base. In a small house on the second pier, remote control of all mechanisms is installed. The austere white tower, standing at the very edge of the raid pier, is depicted on stamps and postcards and has become one of the symbols of the city.
By 1917, 163 light beacons had been built on all Russian seas. The seas had the most underdeveloped network of lighthouses Far East(a total of 24 with a coastline of several thousand kilometers). On the Sea of Okhotsk, for example, there was only one lighthouse - Elizaveta (on the island of Sakhalin), and on the Pacific coast there was also one - Petropavlovsky on the approach to the port of Petropavlovsk-Kamchatsky.
During the war, a significant part of the lighthouses was destroyed. Of the 69 lighthouses on the Black and Seas of Azov 42 were completely destroyed, out of 45 on the Baltic Sea - 16. In total, 69 lighthouse towers, 12 radio beacons, 20 sound signaling installations and more than a hundred luminous navigation signs were destroyed and destroyed. Almost all surviving objects of navigation equipment were in unsatisfactory condition. Therefore, after the end of the war, the Hydrographic Service of the Navy began restoration work. According to data as of January 1, 1987, there were 527 light beacons operating on the seas of our country, of which 174 were on the seas of the Far East, 83 on the Barents and White Seas, 30 on the coast of the Arctic Ocean and 240 on other seas.
At the beginning of 1982, the lights of another Far Eastern lighthouse - Eastern Doom - lit up on the coast of the Sea of Okhotsk. In the desert area between Okhotsk and Magadan, a 34-meter red cast iron tower rose on the slope of a hill.
In 1970, construction of a stationary lighthouse was completed in the Gulf of Tallinn, 26 kilometers northwest of the port of Tallinn (Estonia).
Modern decoys. 1. Peschany Lighthouse (Caspian Sea). 2. Chibuyiy lighthouse (Shumshu island). 3. Lighthouse Peredniy Siversov (Black Sea). 4. Piltun Lighthouse (Sakhalin Island). 5. Shventoy Lighthouse (Baltic Sea). 6. Thallia Lighthouse
The Tallinn lighthouse was the first automatic lighthouse in the USSR, all of whose systems are powered by atomic isotopes. The lighthouse is installed at a depth of 7.5-10.5 meters in the area of Tallinmadal Bank on a hydraulic foundation (a stone bed with a diameter of 64 meters and a giant reinforced concrete conical mass with a base diameter of 26 meters). The conical shape of the base (45°) significantly reduces ice loads on the structure. The lighthouse encloses the bank and provides access to the port. The reinforced concrete monolithic cylindrical tower of the lighthouse, 24.4 meters high, ends in a glazed circular steel lantern structure. The total height of the lighthouse from sea level is 31.2 meters, from the bottom - 41 meters. The tower is lined with cast iron tubes, painted black (lower widened part), orange (middle part) and white (upper part). It has eight floors, which house technical and service premises (the isotope power plant is on the ground floor). The light-optical device provides a range of white light of 28 kilometers. The Tallinn lighthouse is equipped with a radio beacon with a range of 55 kilometers, a radar transponder beacon and telecontrol system equipment for all navigation aids of the lighthouse. At a height of 24.2 meters there is a heavy bronze memorial plaque on which the names of destroyers, patrol ships, submarines and auxiliary vessels are cast - a total of 72 ships that perished during the Great Patriotic War in the Tallinn area.
Lighthouses like the one in Tallinn do not require maintenance personnel. Therefore, the course is currently set for the construction of just such lighthouses.
Among the lighthouses built and put into operation in recent years, a special place belongs to the Irbensky automatic lighthouse. It was built in the open sea on a hydraulic foundation. All technical means of the lighthouse operate automatically. The lighthouse is equipped with a helipad.
Pulsed lighting equipment has begun to occupy a significant place in navigation equipment, especially recently, with the introduction of which there is no need for complex optical systems. Pulse lighting systems with enormous luminous power are especially effective against highly illuminated backgrounds of ports and cities.
To warn about dangerous places located far from the coast, or as receiving stations when approaching ports, lightships are used, which are specially designed vessels anchored and equipped with lighthouse equipment.
To confidently identify lighthouses during the day, they are given different architectural shapes and colors. At night and in conditions of poor visibility, ship crews are helped by the fact that each of the lighthouses is assigned radio light and acoustic signals of a certain nature, as well as lights of various colors - all these are elements of the code by which sailors determine the “name” of the lighthouse.
Each ship or vessel has a directory “Lights and Signs”, which contains information about the type of construction of each lighthouse and its color, the height of its tower, the height of the light above sea level, the nature (constant, flashing, eclipsing) and color of the lighthouse light. In addition, data on all means of navigational equipment of the seas are included in the corresponding directions and are indicated on navigation maps at their locations.
The range of luminous beacons is 20-50 kilometers, radio beacons - 30-500 or more, beacons with airborne acoustic signals - from 5 to 15, with hydroacoustic signals - up to 25 kilometers. Acoustic air signals are now given by nautofons - howlers, and previously a bell buzzed at lighthouses, warning about dangerous place- about shoals, reefs and other navigational hazards.
Nowadays it is difficult to imagine navigation without lighthouses. To extinguish their light is the same as somehow removing the stars from the sky, which sailors use to determine the location of the ship astronomically.
The selection of locations, installation, and ensuring the continuous operation of the lighthouse are carried out by people of a special specialty - hydrographs. IN war time their work takes on special significance. When on the morning of December 26, 1941, the ships of the Black Sea Fleet and the ships that were part of the Azov flotilla and the Kerch naval base began landing on the northeastern coast of the Kerch Peninsula, well-organized hydrographic support contributed to the successful landing operations. On the eve of the landing, targets of two illuminated portable buoys were installed near the shore on the approaches to Feodosia, and orientation lights were also installed, including on the Elchan-Kaya rock.
In the dead of night on December 26, lieutenants Dmitry Vyzhull and Vladimir Mospan secretly disembarked from the submarine Shch-203, reached an icy cliff in a rubber boat, with great difficulty climbed with equipment to its top and installed an acetylene lantern there. This fire reliably ensured the approach of our ships with landing forces to the shore, and also served as a good reference point for landing ships approaching Feodosia. The submarine from which the brave souls landed was forced to move away from the rock and dive due to the appearance of an enemy aircraft. At the appointed time, the boat did not approach the meeting place with the hydrographs, and the search for them, carried out a little later, ended in failure. The names of lieutenants Dmitry Gerasimovich Vyzhull and Vladimir Efimovich Mospan are listed on the memorial plaque of the victims installed in the building of the Hydrographic Department of the Black Sea Fleet, their photographs are placed on the stand of hydrographers who died during the Great Patriotic War, in the Main Directorate of Navigation and Oceanography.
During the heroic defense of Sevastopol, the Chersonesos lighthouse continued to operate under continuous bombing and artillery shelling, ensuring the entry and exit of ships.
During the third assault on the city, June 2 - July 4, 1942, Chersonesos was attacked by more than 60 enemy bombers. All residential and service premises of the lighthouse were destroyed, the optics were broken.
The head of the lighthouse, who gave more than 50 years of his life to the fleet, Andrei Ilyich Dudar, despite being seriously wounded, remained at his combat post until the end. Here are the lines from the petition to name the passenger ship “Andrei Dudar”: “... a hereditary sailor of the Black Sea Fleet - his grandfather was a participant in the first defense of Sevastopol, his father served as a keeper of the Chersonesos lighthouse for 30 years. Andrei Ilyich was born at a lighthouse and served as a sailor on the destroyer Kerch. At the end of the civil war he worked to restore the fleet. He began the Great Patriotic War as the head of a lighthouse...” Work at a lighthouse requires special training from people. The life of lighthouse workers cannot be called settled, especially in winter. This people for the most part stern, unspoiled.
Lighthouses have a surprisingly sharp sense of duty and responsibility. Once Alexander Blok wrote to his mother from the small port of Abervrak in Brittany: “Recently, a watchman died at one of the revolving lighthouses without having time to prepare the car for the evening. Then his wife forced the children to turn the car with their hands all night. For this she was given the Order of the Legion of Honor.” The American romantic poet G. Longfellow, the author of the wonderful epic about the Indian folk hero “The Song of Hiawatha,” wrote about the eternal connection between the lighthouse and the ship:
Like Prometheus, chained to a rock, Holding the light stolen from Zeus, Meeting the storm with his chest in the roaring darkness, He sends greetings to the sailors: “Sail on, majestic ships!”
The ocean forced hydrographers to create a whole system of protection against sea dangers, which was improved along with navigation. It will develop and improve as long as the ocean and ships exist.
Thus, when sailing near the coast, lighthouses, mountain peaks, and individual noticeable places on the coast have long served as landmarks for sailors. Having determined the directions (bearings) for two or three such objects using a compass, sailors receive a point on the map - the place where their ship is located. But what if there are no noticeable places or the shore has disappeared beyond the horizon? It was this circumstance that for a long time was an insurmountable obstacle to the development of navigation. Even the invention of the compass - after all, it only shows the direction of the ship's movement - did not solve the problem.
When it became known that it was possible to determine longitude from a chronometer, and latitude from the altitudes of luminaries, a reliable goniometric instrument was needed to determine altitudes.
Before the goniometric instrument that suited sailors appeared and established its superiority, the sextant, and many other instruments, its predecessors, were on ships. The very first among them, perhaps, was the naval astrolabe - a bronze ring with divisions into degrees. An alidade (ruler) passed through the center, both halves of which were offset relative to each other. Moreover, the edge of one was a continuation of the opposite edge of the other, so that the ruler passed through the center as accurately as possible. There were two holes on the alidade: a large one for searching for the luminary, and a small one for fixing it. During measurements, it was held or suspended by the ring.
Goniometer instruments and chronometer. 1. Astrolabe. 2. Quadrant. 3. Chronometer. 4. Sextant
Such an instrument was suitable only for rough observations: it oscillated not only during rolling and in windy weather, but also from the simple touch of hands. Nevertheless, the very first long-distance voyages were made with a similar device.
Subsequently, the astronomical ring came into use. The ring also had to be suspended, but during measurements there was no need to touch it with your hands. A tiny sunbeam, penetrating through the hole onto the inner surface of the ring, fell on the graduated scale. But the astronomical ring was also a primitive device.
Until the 18th century, Jacob's staff, also known as an astronomical ray, arrow, golden rod, but most of all as a city rod, served as a navigational tool for measuring angles. It consisted of two slats. A movable transverse one was mounted on a long rail perpendicular to it. The long staff has degrees marked on it.
To measure the height of a star, the observer placed a long rod with one end near the eye, and moved the short one so that it touched the star with one end and the horizon line with the other. The same short rod could not be used to measure any heights of stars, so several of them were included with the device. Despite its imperfections, the city pole existed for about a hundred years, until at the end of the 17th century the famous English navigator John Davis proposed his quadrant. It consisted of two sectors with an arc of 65 and 25° with two movable diopters and one fixed one at the common top of the sectors. The observer, looking through the narrow slit of the eye diopter, projected the thread of the object diopter onto the object being sighted. After this, the count along the arcs of both sectors was summed up. But the quadrant was far from perfect. Standing on the swaying deck, combining the thread, the horizon and the sunbeam was not an easy task. In calm weather this was possible, but in rough weather the heights were measured very roughly. If the sun shone through the darkness, its image on the diopter blurred, and the stars were completely invisible.
To measure altitudes, a device was needed that would allow the luminary to be aligned with the horizon line once and regardless of the movement of the ship and the position of the observer. The idea of constructing such a device belongs to I. Newton (1699), but it was designed by J. Hadley in England and T. Godfrey in America (1730-1731) independently of each other. This marine goniometer had a scale (dial) that was one-eighth of the circle, and therefore it was called octane. In 1757, Captain Campell improved this navigational instrument by making the dial one-sixth of a circle, the device was called a sextant. It can measure angles up to 120°. The sextant, like its predecessor octane, belongs to a large group of instruments that use the principle of double reflection. By turning the large mirror of the device, you can send a reflection of the luminary to the small mirror, align the edge of the reflected luminary, for example the sun, with the horizon line and at this moment take a reading.
Over time, the sextant was improved: an optical tube was installed, and a number of colored filters were introduced to protect the eye from the bright sun during observations. But, despite the appearance of this perfect goniometric instrument and the fact that by the middle of the 19th century, nautical astronomy had already become an independent science, methods for determining coordinates were limited and inconvenient. The sailors did not know how to determine latitude and longitude at any time of the day, although scientists proposed a number of cumbersome and difficult mathematical formulas. These formulas have not received practical distribution. Latitude was usually determined only once a day - at true noon; in this case, the formulas were simplified, and the calculations themselves were reduced to a minimum. The chronometer made it possible to determine longitude at any time of the day, but at the same time it was necessary to know the latitude of one’s place and the height of the sun. Only in 1837, the English captain Thomas Somner, thanks to a happy accident, made a discovery that had a significant impact on the development of practical astronomy; he developed rules for obtaining a line of equal heights, the laying of which on a Mercator projection map made it possible to obtain an observed place. These lines were called Somner lines in honor of the captain who discovered them.
Having a sextant, chronometer and compass, the navigator can navigate any ship, regardless of whether it has other, even the most modern, electronic navigation systems. With these time-tested instruments, the sailor is free and independent from any vicissitudes on the high seas. A navigator who neglects the sextant risks finding himself in a difficult situation.
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Ship's magnetic compass and other types of ship's compasses
Magnetic compass is an indispensable component of navigation equipment
Magnetic compass is a navigation device that implements the physical principle of the ability of a magnetic needle to orient itself along the magnetic lines of the Earth, with the help of which the ship’s course is determined, as well as directions to objects directly observed by the navigator. Ideal magnetic compass indicates the direction north along the Earth's magnetic meridian, passing through the magnetic poles. Accuracy magnetic compasses decreases as it approaches the magnetic poles.
When determining the direction of movement of the ship, it is taken into account that the magnetic and geographic poles do not coincide, and the angle between the corresponding magnetic and true meridians, called magnetic declination, is non-zero. In addition, vibrations of the Earth’s magnetosphere and the own magnetic field of ships, which contain magnets in their design, contribute to the readings magnetic compass interference called deviation magnetic compass. Direction indicated magnetic compass, corresponds to the compass meridian, therefore the deviation of the magnetic compass is defined as the angle between the magnetic meridian and the compass meridian. To determine the true course, magnetic declination and deviation are taken into account magnetic compass.
Composition of a ship's magnetic compass:
- Pot with card
- Binnacle
- Direction finder
- Deviation device
Bowler magnetic compass is a cylindrical container made of two parts located one below the other. The upper one contains a card that moves freely in a solution of ethyl alcohol - a non-magnetic disk with a printed scale and magnetic arrows, and the lower one - compensates for changes in the volume of the compass liquid, depending on external reasons, for example, temperature environment. The gimbal compensates for ship motion.
Binnacle magnetic compass- in fact, a housing with a protective cap, shock-absorbing suspension and lighting; inside it there is also a deviation device, the purpose of which is to “destroy” deviation magnetic compass. However, even taking into account the “destruction”, the direction calculations take into account the residual deviation, which changes as the ship moves.
Direction finder magnetic compass determines angular directions to visible objects. In a simplified way, the direction finder consists of targets (eye and object) fixed to the base and a deflector cup. The direction finder rotates relative to the azimuthal circle. The object target has a folding mirror to obtain the bearing of celestial objects.
Types of ship's compasses:
Magnetic compass- not the only design option ship's compass. Manufacturers also offer gyroscopic compasses(based on a gyroscope), indicating the direction of the true pole, not the magnetic one, and guaranteeing accuracy of readings at high latitudes, but is sensitive to ship accelerations; electronic compasses, operating through data interfaces, transmitting information to a compatible ship equipment; satellite compasses– devices whose operation is based on satellite positioning information – a common type ship's compasses, offered by a large number of manufacturers and ensuring accurate measurements. Choice structural type ship's compass depends on the type of vessel and equipment, economic feasibility and welfare of the shipowner.
To choose and buy ship's compass, you need to either understand the industry, or contact the company "", whose engineers have implemented dozens of projects for equipping ships of all types with all types of ship equipment, including magnetic compasses, typical for small fleets.
On the pages of the online store catalog "" are presented magnetic compasses world-class manufacturers, as well as Russian devices of equal quality. The company accepts orders for equipping ships magnetic compasses world brands such as:
- Magnetic compasses purchased from " Marinek", tested by practice and time.
Market ship's compasses is wide, so when choosing a specific model it will be useful to listen to the opinions of engineers. When equipping your own ship with equipment, remember that comfort on board depends on the trouble-free operation of all ship systems, including magnetic compass and other “little things” without which it is impossible to imagine a modern ship.
Nautical compass
A marine compass works on the same principle as a regular tourist compass, where the needle always aligns with the north-south line.
The main difference between these two compasses is that a marine compass has several needles attached to the card at the bottom so that when the needles move, the card moves with them, with the "north" mark aligned with the magnetic north pole. This is done for the convenience of taking readings, since in the sea the card rotates more slowly than the needle. In order to slow down the rotation even further, the compass body is filled with a liquid, usually a non-freezing mixture of alcohols.
The globe is surrounded by a magnetic field. Since magnetic north and geographic north are not the same, a magnetic compass does not point to geographic north. The difference between geographic and magnetic north is called declination
Internal structure of a marine compass with card
The Earth's magnetic field is best illustrated by an old school experiment in which a magnet is placed under a sheet of metal filings. The sawdust is aligned along the magnetic lines coming out of the poles of the magnet.
If the needle is placed in the Earth's magnetic field, it will also take a position along the magnetic lines emerging from the poles. So, at any point on the globe, a loose arrow will take a position along the north-south line. The ship can turn in any direction, but the card will always point in the same direction.
There is a mark on the compass body indicating the diametrical (longitudinal) line of the vessel; The direction on the compass card that coincides with this mark indicates the compass direction in which the boat is moving. To steer using a compass, you need to turn the yacht until the desired direction on the compass card coincides with the center line.
Deflection
The geographic north and south poles do not coincide with the magnetic poles, therefore, since all objects on maps correspond to the geographic poles, there is an error in all magnetic compass readings. It's called declination. This value changes when moving along to the globe. Declination is a tabular value; its value for a particular area is indicated in the center of the compass image on the map of this place. Declination is defined as the difference between the compass reading and geographic north caused by the earth's magnetism; it is eastern and western.
Deviation
There is another factor that affects the compass readings on board a ship and causes errors. We are talking about the influence of the magnetic properties of the equipment of the boat itself on the compass needles, for example, steel parts of the motor and some electrical appliances. On wooden and fiberglass yachts this error is relatively small, but on a metal boat it can be significant.
Example of a small boat deviation map
Deviation is defined as the deviation of the compass from geographic north under the influence of the magnetic field of the ship itself; it is also eastern and western.
Deviation changes depending on the direction the boat is moving, so it must be taken into account whenever changing course. To determine the deviation, the yacht must be brought to open place, then walk in a circle through all the points of the compass. Compass readings taken in each direction are compared with the true bearings indicated on sea map, the difference between them is recorded in a table called a deviation map (for an example of such a map, see the figure on the left). The data on this map indicates the deviation of any course that the ship may follow and is taken into account when taking all compass readings.
Main compass
To reduce vibrations of the card and make it easier to control the vessel, most main compasses are covered with convex glass filled with a liquid that softens any vibrations. This also keeps the cartridge level constant when the yacht is heeling.
Sometimes a professional adjuster can reduce the deviation or eliminate it by placing correction magnets around the compass in the cockpit. The ship's main compass is checked regularly to ensure that the deviation remains constant. Usually the yacht is controlled based on its readings. This compass is placed in the cockpit near the steering wheel or tiller.
Compass for taking bearing
This is a small compass used to take bearings of shore features when determining the location of a boat. There are many varieties of such devices, but they all have one common feature– portability, which allows you to determine bearings from any place on board from where a coastal object is clearly visible. Compass readings for bearings do not take deviation into account, so the results must be compared with the readings of the main compass at the point where the bearing is determined, since deviation values can vary from place to place on board. Typically the compass is held at eye level while using the sight to line up coastal features before taking readings.
Compass error
Because every compass reading contains error (magnetic declination and deviation), it must be corrected before being used for navigation. The two errors are combined and, after addition or subtraction, form the compass error:
Declination east 5° + deviation east 2° = compass error east 7°
Eastern declination 5° – western deviation 2° = compass error eastern 3°
This means that when navigation concepts correspond to the names of different cardinal directions (north and south, west and east), values with the same names need to be added, and those with different names need to be subtracted.
If the error is easterly, the compass reading will be less than the true one. If the error is western, the compass reading will be greater than the true one.
Each compass reading contains an error, so it must be corrected to work with a map where only true values are used.
The ship's course plotted on the map is true (does not contain errors), therefore, before using it to control the ship, you need to switch from it to the compass.
Similarly, the bearing of a coastal object taken using a hand compass must be converted to true before marking the map. The transition process can get confusing, so you need to do it carefully.
The two examples below will make it easier to understand.
1. The map shows a course from point A to point B, its value (true) is 266° according to the compass card. The compass error is eastern and is 5°. (Since the error is eastern, the compass reading will be less than the true one.) The steering wheel must be turned at a heading of 26 degrees (compass reading) to follow a heading of 266° (true) on the map.
2. The bearing of a coastal feature taken using a hand compass is 266°. The compass error is eastern 5°. The error is eastern, which means that the true bearing for plotting on the map should be less than the compass bearing. The bearing plotted on the map will be 261°.
Electronic compasses
Most yacht owners still use traditional magnetic compasses, but on large ocean-going vessels they prefer electronic compasses.
They are produced in different modifications. There are gyrocompasses, digital and laser compasses. Laser and gyro compasses are very expensive and are rarely found on cruisers. They are distinguished by one advantage: they have no error, that is, the compass reading is true, like on a map.
A more affordable digital compass, it is popular among many yachtsmen, especially during ocean crossings. It eliminates or at least reduces deviation; the digital readings on its screen are much easier to read than on the oscillating card of a magnetic compass. Conveniently, it can be combined with an autopilot device and instruments for measuring wind strength and direction.
From the book Everything about everything. Volume 1 author Likum ArkadyWho invented the compass? The simplest form of compass is a magnetic needle mounted on a rod so that it can rotate freely in all directions. The needle of such a so-called compass points to “north”, by which we mean the North Magnetic Pole
From the book 100 Great Inventions author Ryzhov Konstantin Vladislavovich21. COMPASS The compass, like paper, was invented by the Chinese in ancient times. In the 3rd century BC. Chinese philosopher Hen Fei-tzu described the structure of a contemporary compass this way: it looked like a pouring spoon made of magnetite with a thin handle and spherical, carefully
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From the book 100 Famous Inventions author Pristinsky Vladislav LeonidovichWhich ship owned the stern, keel, sails and compass, which became the constellations of the same name? The constellations Puppis, Carina, Sails and Compass were formed in the 18th century as a result of the “dismemberment” of the constellation Ship Argo by Abbot Lacaille. Described by Claudius Ptolemy in 150
From the book The Newest Book of Facts. Volume 1. Astronomy and astrophysics. Geography and other earth sciences. Biology and medicine author Kondrashov Anatoly Pavlovich From the book How to Write in the 21st Century? author Garber Natalya From the book Who's Who in the World of Discoveries and Inventions author Sitnikov Vitaly PavlovichProfessional reading as the source and compass of your creativity If you want to be a writer, you first need to do two things: read a lot and write a lot. Every book you pick up teaches you a lesson or lessons, and very often a bad book can teach you more.
From the book Always Ready! [Survival course in extreme conditions for modern men] by Green RodWho invented the compass? The simplest form of compass is a magnetic needle mounted on a rod so that it can rotate freely in all directions. The needle of such a primitive compass points to “north,” by which we mean the Earth’s North Magnetic Pole.
From the author's bookHow to make a compass with your own hands If you are lost, expect trouble. Any sane gentleman would double check and double check his camping gear to make sure he has all the maps he could possibly need, as well as a compass to guide him.
compass- a, m. compas (de mer), goal. kompas, it. compasso. 1. A device with a magnetized needle for determining the cardinal points. Sl. 18. A compass has an arrow anointed with a magnet that turns around at midnight. Lex. new vocabulary. // Smorgon Terms 77.… … Historical Dictionary of Gallicisms of the Russian Language
compass- (compass (sea compass); Italian compasso, compassare – adymdap olsheu) bagytty bagdarlap, anyktauga arnalgan aspap. K. kome zhane uzhak zhurgizude, artillery and topography, geodesy zhumystardy zhurgizu ushin, zhergiliktі zherde askerlerdin bagdar... ... Kazakh explanatory terminological dictionary on military affairs
Compass- Seeing a compass in a dream means that you will be forced to fight with limited means, with your hands tied, thus making your success more difficult, but also more honorable. Seeing an ordinary or nautical compass in a dream portends... Miller's Dream Book
- (Compass) a nautical instrument used to continuously indicate the ship’s compass course at sea and, if necessary, to determine directions to various earthly objects or celestial bodies visible from the ship. K. for a sailor... ... Marine Dictionary
Compass (in maritime affairs ≈ compass) (German: Kompass, Italian: compasso, from compassare ≈ to measure in steps), a device for orienteering on the ground. According to the principle of operation, magnets are divided into: magnetic, which uses the property of a direct permanent magnet... Great Soviet Encyclopedia
Compass- The compass is dreamed of by people who are waging a desperate struggle with very limited means. It is quite difficult to achieve success in such a struggle, but it is honorable. Whether you dream of a sea or an ordinary compass is not important. In any case, this dream foreshadows... Large universal dream book
A compass installed in the conning tower of a ship. During the battle, the CB serves at the same time as the main one if the main CBs are moved down behind cover for safety or knocked down by enemy fire. Samoilov K.I. Marine dictionary. M.L.: State Military... ... Naval Dictionary
- (Gyroscopic compass) see Compass. Samoilov K.I. Marine dictionary. M. L.: State Naval Publishing House of the NKVMF of the USSR, 1941 ... Marine Dictionary
- (Standard compass) a compass by which the ship’s course is assigned and its position is determined. On large ships, two main ships are usually installed: the main bow and the main stern on the front and rear bridges. Samoilov K.I. Marine... ...Marine Dictionary
- (Magnetic compass) see Compass. Samoilov K.I. Marine dictionary. M. L.: State Naval Publishing House of the NKVMF of the USSR, 1941 ... Marine Dictionary
- (Steering compass) the compass by which the helmsman steers, i.e., keeps the ship on a given course. K.P. is installed on a ship as many as there are control posts. Samoilov K.I. Marine dictionary. M.L.: State Naval... ... Naval Dictionary
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The technical means used to determine the main directions at sea also include magnetic compasses. Magnetic compasses use the property of a magnetized needle to be located along the magnetic lines of force of the Earth's magnetic field in the north-south direction. On a ship, the magnetic needle, in addition to the Earth's magnetic field, is affected by magnetic fields created by the ship's iron and electrical installations. Therefore, the magnetic needle of a compass installed on a ship will be located in the so-called compass meridian.
Simplicity of the device, autonomy, constant readiness for action and small size are the advantages of a magnetic compass compared to a gyroscopic one.
But the readings of the magnetic compass must be corrected by a correction, the magnitude and sign of which vary depending on the course of the ship, its location on the earth’s surface and other reasons. At high latitudes, the accuracy of the magnetic compass readings decreases, and in the area of the Earth’s magnetic and geographic poles it ceases to function at all.
All naval vessels are equipped with marine magnetic 127 mm (5 inch) compasses (Fig. 131).
The main parts of the compass are: bowl 1 with a card, binnacle 2, direction finder 3 and deviation device 4.
Bowler(Fig. 132) is a brass cylindrical tank divided into two chambers that communicate with each other. The upper chamber 1 houses the compass card, the lower chamber 2 serves to compensate for changes in the volume of the compass fluid when the ambient temperature fluctuates.
A solution of ethyl alcohol (43% by volume) in distilled water, which freezes at a temperature of -26°C, is used as a compass liquid. To reduce the vibrations of the pot during pitching, a brass cup with a lead weight 3 is attached to the lower part of its body.
The bowler is equipped with a cardan ring, which allows you to keep the azimuth ring of the bowler in a horizontal position.
Cartushka(Fig. 133) - the main part of the compass, consists of a system of magnetic needles 1, a float 2, an agate firebox 3, a screw for fastening the firebox 4, six brackets 6 supporting a mica disk 5, onto which a paper disk is glued, divided into rhumbs and degrees .
Rice. 131.
Rice. 132.
Direction finder- a special device for determining directions to visible objects and celestial bodies. It consists of a base, object and eye targets and a deflector cup.
Binnacle made from silumin. The main parts of the binnacle are: body, upper and lower bases, shock-absorbing suspension, deviation device and protective cap.
Rice. 133.
Deviation device is placed inside the binnacle and is a brass pipe with two movable carriages for installing destroyer magnets. A set of magnets for eliminating semicircular deviation is supplied in a special wooden case.
All manufactured 127 mm compasses have a bottom illuminated card. The lighting system includes: a umformer, a power supply and a socket with a light bulb (if powered from the ship's DC network).
The lighting system can operate on ship's alternating current, but in this case, instead of an umformer, a transformer is included in the power circuit, reducing the voltage to 6.12 or 24 V.
