The art of navigating a ship the shortest way from port to port is called navigation. In other words, navigation is a way of laying the course of a vessel from the place of departure to the destination, controlling the course, and, if necessary, correcting it.
On the navigation bridge there are instruments and devices necessary to control the vessel. Navigational instruments - compasses, gyroazimuths, autoplotters, logs, lots, echo sounders, sextants and other devices designed to determine the position of the vessel and measure individual elements his movements of the ship.
compasses
A compass is the main navigational instrument used to determine the course of a vessel, to determine directions (bearings) to various objects. On ships, magnetic and gyroscopic compasses are used.
Magnetic compasses are used as backup and control devices. According to their purpose, magnetic compasses are divided into main and travel compasses.
The main compass is installed on the upper bridge in the center plane of the ship, so as to provide good review over the entire horizon (Fig. 3.1). The image of the scale of the card with the help of an optical system is projected onto a mirror reflector installed in front of the helmsman (Fig. 3.2).
Rice. 3.1. Master magnetic compass
A traveling magnetic compass is installed in the wheelhouse. If the main compass has a telescopic reference transmission to the helmsman's station, then the steering compass is not installed.
Rice. 3.2. Mirror reflector magnetic compass
The magnetic needle on the ship is affected by the ship's magnetic field. It is a combination of two magnetic fields: the Earth's field and the ship's iron field. This explains that the axis of the magnetic needle is located not along the magnetic meridian, but in the plane of the compass meridian. The angle between the planes of the magnetic and compass meridians is called deviation.
The compass kit includes: a bowler hat with a card, a binnacle, a deviation device, an optical system and a direction finder.
Lifeboats use a light, small compass that is not permanently fixed (Fig. 3.3).
Rice. 3.3. Boat magnetic compass
Gyrocompass - a mechanical indicator of the direction of the true (geographical) meridian, designed to determine the course of an object, as well as the azimuth (bearing) of the oriented direction (Fig. 3.4 - 3.5). The principle of operation of the gyrocompass is based on the use of the properties of the gyroscope and the daily rotation of the Earth.
Rice. 3.4. Modern gyrocompass
Gyro compasses have two advantages over magnetic compasses:
- they show the direction to the true pole, i.e. to the point through which the axis of rotation of the Earth passes, while the magnetic compass indicates the direction to the magnetic pole;
- they are much less sensitive to external magnetic fields, such as those generated by the ferromagnetic parts of a ship's hull.
The simplest gyrocompass consists of a gyroscope suspended inside a hollow ball that floats in a fluid; 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.
Rice. 3.5. Gyrocompass repeater with direction finder mounted on a pelorus
The gyrocompass may give measurement errors. For example, a sharp change in course or speed causes deviation, and it will exist until the gyroscope has worked out such a change. Most modern ships have satellite navigation systems (such as GPS) and/or other navigation aids that feed corrections into the gyrocompass's built-in computer. Modern designs of laser gyroscopes do not produce such errors, since they use the principle of optical path difference instead of mechanical elements.
The electronic compass is built on the principle of determining coordinates through satellite navigation systems (Fig. 3.6). The principle of the compass:
- based on signals from satellites, the coordinates of the receiver of the satellite navigation system are determined;
- the moment of time at which the determination of the coordinates was made is detected;
- a certain time interval is expected;
- the location of the object is re-determined;
- based on the coordinates of two points and the size of the time interval, the velocity vector is calculated:
- direction of movement;
- movement speed.
Rice. 3.6. Electronic compasses
echo sounder
The navigation echo sounder is designed for reliable measurement, visualization, registration and transmission to other systems of data on the depth under the keel of the vessel (Fig. 3.7). The echo sounder must function at all vessel speeds from 0 to 30 knots, in conditions of strong aeration of water, ice and snow slush, chipped and broken ice, in areas with a sharply changing bottom topography, rocky, sandy or silty soil.
Rice. 3.7. Sonar Pointer
Hydroacoustic echo sounders are installed on ships. The principle of their work is as follows: mechanical vibrations, excited in the vibrator-emitter, propagate in the form of a short ultrasonic pulse, reach the bottom and, reflected from it, are received by the vibrator-receiver.
Echo sounders automatically indicate the depth of the sea, which is determined by the speed of sound propagation in water and the time interval from the moment the impulse is sent to the moment it is received (Fig. 3.8).
Rice. 3.8. The principle of operation of the echo sounder
The echo sounder should provide measurement of depths under the keel in the range from 1 to 200 meters. The depth indicator must be installed in the wheelhouse, and the recorder - in the wheelhouse or chart house.
To measure the depths, a hand lot is also used in cases of running the vessel aground, measuring the depths at the side while moored at the berth, etc.
A manual lot (Fig. 3.9) consists of a lead or cast-iron weight and a lotline. The kettlebell is made in the form of a cone 25 - 30 cm high and weighing 3 to 5 kg. A recess is made in the lower wide base of the weight, which is lubricated with grease before measuring the depth. When the lot touches the seabed, soil particles stick to the grease, and after lifting the lot, one can judge the nature of the soil from them.
Rice. 3.9. hand lot
The breakdown of the lotlin is made in metric units and is indicated according to the following system: flags of various colors are intertwined at tens of meters; each number of meters ending in 5 is marked with a leather stamp with axes.
In each five, the first meter is indicated by a leather stamp with one prong, the second by a stamp with two prongs, the third by three prongs, and the fourth by four.
lag
Around the end of the 15th century. a simple speed meter became famous - a manual log. It consisted of a wooden plank with a lead weight in the shape of 1/1 of a circle, to which a light cable was attached, having knots at regular intervals (most often 7 m). To measure the speed of sailing ships sailing in those days, the log, as an approximately constant mark on the surface of the water, was thrown overboard and the hourglass was turned, measuring a certain length of time (14 s). During the time that the sand was pouring, the sailor counted the number of knots that passed through his hands. The number of knots received during this time was converted into the ship's speed in nautical miles per hour. This way of measuring speed explains the origin of the expression "knot".
Log - a navigational device for measuring the speed of the vessel and the distance traveled by it. Mechanical, geomagnetic, hydroacoustic, induction and radio Doppler logs are used on sea vessels. Distinguish:
- relative lags, measuring speed relative to water; And
- absolute logs that measure speed relative to the bottom.
Hydrodynamic log - a relative log, the action of which is based on the measurement of the pressure difference, which depends on the speed of the vessel. The basis of the hydrodynamic lag is made up of two tubes brought out under the bottom of the vessel: the outlet of one tube is directed to the bow of the vessel; and the outlet of the other tube is flush with the skin. Dynamic pressure is determined by the difference in water heights in the tubes and is converted by the lag mechanisms into indications of the ship's speed in knots. In addition to speed, hydrodynamic logs show the distance traveled by the ship in miles.
The induction lag is a relative lag, the principle of which is based on the relationship between the relative speed of a conductor in a magnetic field and the electromotive force (EMF) induced in this conductor. The magnetic field is created by the lag electromagnet, and sea water is the conductor. When the vessel moves, the magnetic field crosses the stationary sections of the aquatic environment, while an EMF is induced in the water, proportional to the speed of the vessel. From the electrodes, the EMF enters a special device that calculates the speed of the vessel and the distance traveled.
A hydroacoustic log is an absolute log that works on the principle of an echo sounder. There are Doppler and correlation hydroacoustic lags.
Geomagnetic lag - an absolute lag based on the use of the properties of the Earth's magnetic field.
Radio lag - a lag, the principle of which is based on the use of the laws of radio wave propagation.
In practice, the lag readings are noted at the beginning of each hour and, from the difference in readings, the navigation S in miles and the ship's speed V in knots are obtained. Logs have an error, which is taken into account by the lag correction.
Radio navigation instruments
The ship's radar station (RLS) is designed to detect surface objects and the coast, determine the position of the ship, ensure navigation in narrow spaces, and prevent ship collisions (Fig. 3.10).
Rice. 3.10. Radar screen
The radar uses the phenomenon of reflection of radio waves from various objects located on the path of their propagation, thus, the phenomenon of echo is used in radar. The radar contains a transmitter, a receiver, an antenna-waveguide device, an indicator with a screen for visual observation of echo signals.
The principle of operation of the radar is as follows. The transmitter of the station generates powerful high-frequency pulses of electromagnetic energy, which are sent into space with the help of an antenna in a narrow beam. Radio pulses reflected from some object (ship, high bank, etc.) return in the form of echo signals to the antenna and enter the receiver. In the direction of a narrow radar beam, which in this moment reflected from the object, you can determine the bearing or heading angle of the object. By measuring the time interval between sending an impulse and receiving a reflected signal, you can get the distance to the object. Since the antenna rotates during the operation of the radar, the emitted impulse oscillations cover the entire horizon. Therefore, an image of the situation surrounding the vessel is created on the display screen of the ship's radar. The central luminous dot on the radar indicator screen marks the position of the vessel, and the luminous line extending from this point shows the course of the vessel.
The image of various objects on the radar screen can be oriented relative to the center plane of the ship (heading stabilization) or relative to the true meridian (north stabilization). The "visibility" range of the radar reaches several tens of miles and depends on the reflectivity of objects and hydrometeorological factors.
Ship radars make it possible to determine the course and speed of an oncoming vessel in a short period of time and thus avoid a collision.
Rice. 3.11. ARPA screen
All ships must provide radar plotting on the radar screen, for this they are equipped with an automatic radar plotting system (ARPA). ARPA performs the processing of radar information and allows you to perform (Fig. 3.11):
- manual and automatic capture of targets and their tracking;
- display on the screen of the indicator of vectors of relative or true movement of targets;
- identification of dangerously approaching targets;
- indication on the board of movement parameters and elements of target rendezvous;
- playing the maneuver with the course and speed for a safe divergence;
- automated solution of navigation problems;
- display of elements of the content of navigation charts;
- determining the ship's position coordinates based on radar measurements.
The Automatic Information System (AIS) is a maritime navigation system, which uses mutual exchange between ships, as well as between the ship and the coast service to transmit information about the call sign and name of the ship for its identification, coordinates, information about the ship (size, cargo, draft, etc.) and its voyage, movement parameters (course, speed, etc.) in order to solve the problems of preventing collisions of ships, monitoring compliance with the navigation regime and monitoring ships at sea.
Electronic chart navigation Information Systems(ECDIS) are an effective means of navigation, significantly reducing the workload on the watch officer and allowing you to devote maximum time to observing the environment and making informed decisions on ship management (Fig. 3.12).
Rice. 3.12. ECDIS
Main features and properties of ECDIS:
- carrying out preliminary laying;
- checking the route for safety;
- maintenance of executive laying;
- automatic ship control;
- display of "dangerous isobath" and "dangerous depth";
- recording information in an electronic journal with the possibility of further playback;
- manual and automatic (via the Internet) proofreading;
- alarm when approaching a given isobath or depth;
- day, night, morning and twilight palettes;
- electronic ruler and fixed marks;
- basic, standard and full load display;
- an extensive and complementary base of marine objects;
- base of tides in more than 3000 points of the World Ocean.
A satellite navigation system is a system consisting of ground and space equipment designed to determine the location (geographical coordinates), as well as movement parameters (speed and direction of movement, etc.) for land, water and air objects (Fig. 3.13) .
Rice. 3.13. GPS indicator
GPS is the Global Positioning System, a global navigation satellite positioning system. The system includes a constellation of low-orbit navigation satellites, ground-based tracking and control facilities, and a wide variety of those used to determine coordinates. The principle of determining one's place on the earth's surface in global system positioning is to simultaneously measure the distance to several navigation satellites (at least three) - with known parameters of their orbits at each moment of time, and calculate their coordinates from the changed distances.
Navigation tools
Navigational sextant is a goniometric tool (Fig. 3.14), which serves:
- in nautical astronomy - to measure the heights of luminaries above the visible horizon;
- in navigation - to measure the angles between terrestrial objects.
Rice. 3.14. sextant
The word "sextant" comes from the Latin word "sextans" - the sixth part of the circle.
A marine chronometer is a high-precision portable watch that allows you to get a fairly accurate GMT at any time (Fig. 3.15).
Rice. 3.15. Chronometer
Ship time is determined by the meridian of the vessel's location and is most often corrected at night by the watch officer. So, for example, when the longitude changes by 15 ° to the east, the clock is moved forward 1 hour, and when the longitude changes by 15 ° to the west - 1 hour ago.
In order to have an accurate and uniform time indication in the engine room, crew mess, cabins, saloons, bars, galley, an electric clock is installed, corrected from the main clock located on the bridge.
Rice. 3.16. Interlining tool
Gasketing tools include (Fig. 3.16):
- measuring compass - for measuring and postponing distances on the map;
- parallel ruler - for drawing straight lines on the map, as well as lines parallel to a given direction;
- navigational protractor - for plotting and measuring angles, courses and bearings on the map.
In addition, there are magazines, folders with documentation, navigation maps, mandatory reference books and manuals, etc. on the bridge (Fig. 3.17).
Rice. 3.17. Documentation
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So was the information contained in the portolans reliable? I think that it depended on the tasks assigned to them. For solving "local" applied problems - getting from point A to point B - they were quite suitable. Navigation in the Mediterranean was fairly well understood, as it was constantly supported by major pilot schools, such as the Genoese, Venetian or Lagos. For the knowledge of the whole world, portolans were completely unsuitable, more confusing researchers than helping them.
Only from the end of the 13th century, the first attempts at ocean navigation, as well as the wider use of the compass, revealed the need for a real display on a flat sheet of paper of the relief of the coast, indicating the winds and the main coordinates.
After the 14th century, portolans are often accompanied by rough contour drawings of the Mediterranean coast and the Atlantic coasts of Western Europe. Gradually, ships leaving for ocean voyages begin to be included in the work of compiling more accurate portolans and drawings.
Somewhere by the beginning of the 15th century, real navigation charts. They already represent a complete set of information for the pilot: coast relief, a list of distances, indications of latitude and longitude, landmarks, names of ports and local inhabitants, winds, currents and sea depths are indicated.
The map, the successor to the mathematical knowledge acquired by the ancients, the ever more accurate knowledge of astronomy, and thousands of years of experience in navigating from port to port, becomes one of the main fruits of the scientific thought of the pioneers: from now on, during long voyages, it is required to draw up reports necessary for a complete display of knowledge about the world. Moreover, the first ship's logs! Of course, sea voyages have been described before, but now it is starting to become a regular occurrence. He was the first to introduce a mandatory log book for the captains of his caravels. The captains had to record daily information about the coast with the indication of coordinates - a matter extremely useful for compiling reliable maps.
Despite the desire to clarify and verify that moved the most famous cartographers (Fra Mauro in 1457 claimed that he could not fit into his map all the information that he managed to collect), fantasies, legends, fiction surrounded any cartographic work with a kind of “folklore” halo : on most maps dated before the 17th century, we see how, in place of little-known or insufficiently explored regions, images of various monsters appear, drawn from ancient and early Christian mythologies.
Quite often, the compiler, describing the inhabitants of remote corners, resorted to speculation. Areas that were explored and fell under the rule of European kings were marked with coats of arms and flags. However, the magnificently painted vast wind roses could not be useful if they were incorrectly oriented or marked in the wrong lines of "diamonds" (a primitive system of orientation that preceded the system of meridians and parallels). Often the work of a cartographer became a real work of art. At the courts of kings, planispheres were looked at like canvases, navigators set off on long journeys were guessed behind them, monsters caused shivers, the distances traveled and intriguing names fascinated. It took a long time before the custom of making a map decorative gave way to really useful cartography, devoid of any fiction.
This explains the incredulity with which the great navigators, and above all Christopher Columbus, belonged to the decorated maps of the 15th century. Most sailors preferred to rely on their knowledge of the winds, bottom topography, currents and observations of the celestial sphere, or tracking the movement of schools of fish or flocks of birds, in order to navigate the vast expanses of the ocean.
Undoubtedly, it was in the 15th century, thanks to the Portuguese navigators, and then the voyage of Columbus and, finally, the round-the-world voyage of Magellan in 1522, that humanity was able to test the calculations of the ancient Greeks and ideas about the sphericity of the Earth in practice. Many navigators now in practice received specific knowledge testifying to the sphericity of our planet. The curved line of the horizon, the shifting of the relative heights of the stars, the rise in temperature as we approached the equator, the change of constellations in the southern hemisphere - all this made obvious the truth that contradicted Christian dogma: the Earth is a ball! It remained only to measure the distances that had to be covered on the high seas in order to reach India, in a southerly direction, as the Portuguese did in 1498, or in a western direction, as it seemed to Columbus, when in 1492 he met an insurmountable obstacle in his path in face of the Americas.
Columbus was well acquainted with the cosmographic literature of that time. His brother was a cartographer in Lisbon, and he himself tried to build a globe on the basis of available atlases, modern and ancient treatises on cosmography. True, he made, following his Imago Mundi (1410), a gross mistake in estimating the distance between Portugal and Asia, underestimating it (there is a hypothesis that he did this deliberately). However, he heeded the advice of eminent cartographers such as (who believed in the sea route to the west), (the future Pope Pius II) and (later the author of a fairly accurate globe).
Beginning in 1435, Portuguese and Italian sailors made it a habit to sail at a distance from the African coast to avoid dangerous areas and changeable winds. The coastal zone, replete with reefs and shoals, indeed presented an obvious danger of shipwreck.
However, such a significant distance from the coast that it is lost from sight presupposes the ability to navigate the open sea in a flat, uniform space without lighthouses, limited only by the horizon line. And the sailors of the 15th century lacked the theoretical knowledge of mathematics and geometry necessary to accurately determine their location. As for measuring instruments, things were even worse with them. Until the 16th and 17th centuries, none of them were really good at what they did. The maps, although constantly updated, had significant gaps.
To appreciate the extraordinary courage of the navigators who explored the near and then the far Atlantic, one must remember what miserable means they had at their disposal to determine their location on the high seas. The list will be short: the sailors of the 15th century, including Christopher Columbus, had practically nothing that would help them solve the three main tasks of any navigator going on a long voyage: to keep a course, measure the distance traveled, know with accuracy their present location.
The 15th-century sailor had only a primitive compass (in various variations), a crude hourglass, buggy charts, approximate declination tables, and, in most cases, erroneous ideas about the size and shape of the Earth! In those days, any expedition across the ocean became a dangerous adventure, often fatal.
In 1569 Mercator made the first map conformal cylindrical projection, and the Dutch Luca Wagener brought into use atlas. This was a major step in the science of navigation and cartography, because even today, in the twenty-first century, modern nautical charts are compiled in atlases and made in the Mercator projection!
In 1530 a Dutch astronomer Gemma Frisia(1508-1555) in his work “Principles of Astronomical Cosmography” proposed a method for determining longitude using a chronometer, but the lack of sufficiently accurate and compact clocks left this method purely theoretical for a long time. This method has been named chronometric. Why did the method remain theoretical, because the clock appeared much earlier?
The fact is that watches in those days could rarely go without stopping during the day, and their accuracy did not exceed 12-15 minutes a day. And the clock mechanisms of that time were not adapted to work in conditions of sea rolling, high humidity and sudden changes in temperature. Of course, in addition to mechanical ones, sand and sundials were used in maritime practice for a long time, but the accuracy of the sundial, the winding time of the hourglass were completely insufficient for the implementation of the chronometric method for determining longitude.
Today it is believed that the first accurate clock was assembled in 1735 by an Englishman John Harrison(1693-1776). Their accuracy was 4-6 seconds per day! At that time it was simply fantastic accuracy! And what's more, the watch was adapted for sea travel!
Ancestors naively believed that the Earth rotated uniformly, lunar tables were inaccurate, quadrants and astrolabes introduced their own error, so the final errors in calculating coordinates were up to 2.5 degrees, which is about 150 nautical miles, i.e. almost 250 km!
In 1731, an English optician improved the astrolabe. The new device, called octant, made it possible to solve the problem of measuring latitude on a moving ship, since now two mirrors made it possible to simultaneously see both the horizon line and the sun. But the octant did not get the glory of the astrolabe: a year earlier, Hadley had designed sextant- a device that made it possible to measure the position of the vessel with very high accuracy.
The fundamental device of a sextant, i.e. a device that uses the principle of double reflection of an object in mirrors, was developed back in Newton, but was forgotten and only in 1730 was reinvented by Hadley independently of Newton.
The marine sextant consists of two mirrors: an index mirror and a stationary translucent horizon mirror. Light from a luminary (star or planet) falls on a movable mirror, is reflected on the horizon mirror, on which both the luminary and the horizon are visible at the same time. The angle of inclination of the pointing mirror is the height of the luminary.
Since this site is about history and not about navigation, I will not go into details and features of various navigational instruments, but I want to say a few words about two more instruments. These are lot() and lag().
In conclusion, I would like to briefly dwell on some historical dates in the history of the development of navigation in Russia.
One thousand seven hundred and first year is perhaps the most significant date in domestic navigation, since this year the emperor Peter I issued a decree on the establishment of "Mathematical and Navigational, that is, nautical cunning sciences of learning." Year of birth of the first national navigation school.
Two years later, in 1703, the teacher of this school compiled the textbook Arithmetic. The third part of the book is entitled "Generally about the earthly dimension, and even belongs to navigation."
In 1715, the senior classes of the school were transformed into the Naval Academy.
1725 is the year of birth of the St. Petersburg Academy of Sciences, where such luminaries of science taught as, Mikhail Lomonosov(1711-1765). For example, astronomical observations and mathematical description Euler's planetary movements formed the basis of highly accurate lunar tables for determining longitude. Bernoulli's hydrodynamic studies made it possible to create perfect logs for accurate measurement ship speed. Lomonosov's works dealt with the creation of a number of new navigation instruments, which served as prototypes for instruments that are still in use today: course plotters, recorders, logs, inclinometers, barometers, binoculars...
In the wheelhouse of each merchant ship, a variety of navigational equipment, instruments, devices and tools are installed, with the help of which the captain and navigator ensure the safe management of the vessel.
Navigation equipment- these are ship technical means with which the ship is equipped to solve navigation problems.
Navigation- the process of making a decision and managing the course and speed of a vessel when moving from one point to another, taking into account the surrounding conditions and the intensity of navigation.
navigation device- this is a ship's technical tool designed to solve one or more navigation tasks.
navigation tool is a ship navigation device designed to perform manual work in solving navigation problems.
navigation device is a device designed to perform certain functions of measuring navigational parameters, processing, storing, transmitting, displaying and recording data when solving problems of navigation on a ship.
For better view All photos are clickable.
Ship clock.The ship's clock records the time of all events. The ship's clock must be checked daily against the exact time signals and must have an accuracy of not more than one minute. All ship clocks must be set to the same time zone. One ship's clock must be set to Greenwich Mean Time or Coordinated Universal Time (UTC).
magnetic compass (magnetic compass).
The most reliable and irreplaceable device. Unless, of course, it is serviceable and regularly checked in the coastal workshop. At least once every two years, the magnetic compass must be destroyed, the residual deviation determined and a deviation table (Deviation card) compiled. On some ships, a main magnetic compass and a directional compass are installed. If only one compass is fitted on board, one spare compass should normally be available. The magnetic compass is a backup source of guidance for the autopilot and ECDIS. A separate article on the magnetic compass is located. Lifeboats and rescue boats must have magnetic compasses for heading guidance.
gyrocompass (Gyro compass). Gyro-compass. The main source of guidance. Heading guidance from the gyrocompass is sent to radars, ARPA, ECDIS, autopilot, digital indicator heading, gyrocompass repeaters in the wheelhouse, chart house, bridge wings, tiller compartment.
Repeater gyrocompass from
(Gyro repeater with bearing device).
They are mounted on the wings of the bridge and serve to take visual bearings. The bearing of lighthouses and signs are taken to determine the position of the ship in the sea near the coast. The bearing of the celestial bodies is taken to determine the compass correction. The bearing of approaching ships is taken to determine if there is a risk of collision with them. The photo shows a simple direction finder. There are also optical direction finders, in which lenses are installed to approach the direction-finding objects.
Digital indicator course(transmitting heading device). Device for digital display of the ship's heading. Mandatory device.
Binoculars (Binocular).
It serves to recognize objects located at some distance from the vessel and poorly visible to the naked eye. Also used for surveillance under regulation 5 of COLREG 72.
Radar (radar). The radar is used to prevent collisions with other vessels and for navigational purposes - determining the position of the vessel by bearings and distances of coastal landmarks measured using the radar. Serves to monitor the environment in accordance with regulation 5 COLREG-72.
ARPA (ARPA). A device for avoiding collision with other ships and floating objects. Serves to monitor the environment in accordance with regulation 5 COLREG-72. In most modern radars, the ARPA function is implemented and, therefore, ARPA is practically never found as a separate device.
Electronic cartographic navigation and information system - ECDIS (Electronic chart display and information System ECDIS). Electronic cartography devices are used to display a navigation chart, navigation information and the position of the vessel according to the coordinates of the GPS receiver on the displays. Many ships have two sets of ECDIS equipment and paper navigational charts are not available.
Receiver satellite navigation(Global Positioning System - GPS). Serve to determine the coordinates of the vessel using the global satellite system. Displays the boat's speed over the ground. Traveled distance. Serves for entering the coordinates of the waypoints of the transition route, compiling the transition route, transmitting the transition route to the radar. Shows the direction and distance to waypoints, deviation from the route, time of arrival at waypoints.
echo sounder (echo sounder). A device for measuring depth under the keel of a vessel.
lag(Speed and distance Log). The device is used to measure the speed of the vessel and the distance traveled by the vessel. Measures the speed of the vessel both through the water and over the ground. The speed through the water is necessary for transmission to the radar and ARPA to solve problems of divergence from other vessels.
Automatic identification system (Automatic Identification System – AIS ). Serves for receiving and transmitting ship data using a VHF transceiver. Displays data received from other ships on the display of the device and transmits them to the radar and ECDIS. Serves to monitor the environment in accordance with regulation 5 COLREG-72.
Navigation lights panel (Navigation Lights ). Each vessel must display lights in accordance with COLREGs 72. The navigation lights panel provides visual and audible warning in case any light goes out.
ship's whistleship’ s whistle). The ship's whistle is used to give warning and fog signals in accordance with COLREGs-72.
Vessel's Fog Signal Device (Automatic fog signal device). To send fog signals to automatic mode.
Watch officer's capacity control system (Bridge navigational watch Alarm System – BNWAS. Serves to give an audible signal in case of incapacity of the officer in charge of the watch. Should be switched on at all times after the ship has left the berth and before mooring at the berth.
Autopilot (Autopilot). Serves to keep the vessel on course in automatic mode. If the device has a ship-on-track mode, then the autopilot will change the ship's heading itself to bring it to the next waypoint. When approaching a waypoint within a predetermined distance, the device will sound signal, if the officer on watch presses the confirmation button, the device will shift the rudder and take the ship to the next set heading.
Flight data recorder –VDR – Voyage Data recorder . The ship's black box. Data logging device for navigation instruments and devices.
NAVTEX receiver -NAVTEX receiver. Serves for receiving various warnings in automatic mode: navigational, meteorological, distress and others.
Terminal Inmarsat - C (Inmarsat – C). Serves for receiving and sending messages via satellite communication system.
The system of long-range identification and control of the location of ships - OSDR (Long Range Identification and tracking System – LRIT ). Serves for the transmission of vessel data (coordinates, heading, speed, vessel identifier) in automatic mode via a satellite communication system.
Rudder axiometer (Rudder Angle indicator). A device that indicates the direction and angle of the rudder.
Rate of turn indicator (rate of turn indicator). Shows the rate of turn of the vessel.
Sound receiving and playback device (sound reception System). The device serves to reproduce external sounds in closed bridges.
sextant (Sextant). Sextant (Sextant) navigational is used to measure the heights of celestial bodies, which are used to calculate the lines of position and determine the position of the vessel by astronomical methods. They also measure the heights of coastal and floating navigation marks, and other objects. In addition, true navigators-navigators measure the horizontal angles between three navigation marks with a navigational sextant and determine the position of the ship in the sea by two horizontal angles. But only very earnest navigators determine the place of the vessel in this way, unfortunately, most modern navigators can be attributed to “GPS navigators”, that is, to those who, except for GPS, are no longer able to determine the position of the vessel in the sea. Professional degradation however. About the navigational sextant separate article
Chronometer (Chronometer). Shows the time on the Greenwich meridian. Before the invention of radio, the chronometer was the only source of accurate time on board. The accuracy of determining the location of a sailing ship in the sea depended on the accuracy of the chronometer and knowledge of its daily course. Chronometers were verified by astronomers in observatories, their daily course was determined with the greatest possible accuracy, and before the ship sailed to the sea, they were brought on board with the greatest care. After a long ocean voyage, at the first opportunity, the chronometers were brought ashore to check them and determine the daily course. Each ship had several chronometers. With the advent of radio receivers, it became possible to receive radio signals of exact time to determine the daily rate of chronometers, and the requirements for their accuracy decreased somewhat. With the advent of satellite navigation and a significant weakening of the role of astronomical observations in navigation, chronometers on almost all merchant ships were replaced by accurate clocks. However, until now, individual accurate watches used to keep time are called chronometers. The navigator responsible for navigational instruments is obliged to keep a chronometer log in which to record the daily course of the chronometer.
Mechanical stopwatch (Stopwatch). Serves for fixing the time at the time of astronomical and navigational observations, for determining the correction of the chronometer, for comparing and setting ship's clocks. To determine the characteristics of lighthouse lights and other navigational signs and buoys. Used to determine the ship's roll and pitch period and wave period.
star globe (star Globe). Used to solve problems of nautical astronomy. You can read more about the device of the star globe
Hand Anemometer (Wind anemometer). Used to measure wind speed.
Automatic device for measuring wind speed and direction (Wind speed and direction indicator
).
Serves for measurement of the direction and speed of a wind in the automatic mode.
ship gongship’ s gong). Serves for giving fog signals in accordance with the rules of COLREG-72. Mandatory for all vessels of 100 meters or more in length. The gong is a brass disc with a rim. It is hit by hand with a beater, which is a handle with a spherical impact part at the end.
Signal flags - MCC (ICS). The flags are used to give signals in accordance with the International Code of Signals - MCC (International Code of Signal - ICS).
Signal figures - balls, cylinder, rhombus (Signaling Shapes). Serve for exhibiting signals in accordance with the rules of COLREG-72.
Chart table. Installed in the holy of holies for each navigator - in the navigator's cabin. On it, a navigation chart with a preliminary plotting is laid out in the sea, and an executive plotting with observations of the ship's position is also being carried out on it. Nautical charts are stored in the drawers of the table. Navigational tools can be stored in the side lockers.
Weights for cards. Serve to hold the navigation chart on the chart table while the ship is rolling. They are usually made from rubber. As a weighting agent, there is lead inside the weight. More information about the use of weights can be found in the article.« ».
Navigator's magnifying glass (magnifier). Enlarges hard-to-see images on the navigation map.
Navigator's parallel ruler (navigational ruler).
Navigation Protractor (Protractor ). Serves for laying, determining the position of the vessel and other navigational tasks on the navigation chart.
Navigation meter (navigational divider). Serves for laying, determining the position of the vessel and other navigational tasks on the navigation chart. Meters are made of brass or chrome-plated steel. They come in various types and sizes.
Pilot compass. As a rule, ordinary drawing compasses of various sizes and types are used for navigational purposes, the main thing is that they are convenient to use on the navigation chart and do not cause significant damage to the chart.
Navigation protractor.A navigational tool that is used to determine the position of the vessel at two horizontal angles.
The procedure for determining the position of the vessel on two horizontal angles.
Inclinometer. Used to determine the ship's heel angle.
barometer (Barometer). Used to determine atmospheric pressure.
barograph (barograph ). Serves to determine the atmospheric pressure and monitor its change. The barometer reading is recorded on paper tape.
Thermometer (thermometer).
Used to measure the ambient temperature.
Hygrometer(Hygrometer ). Serves for measurement of humidity of air.
Computer with satellite internet connection. Used to receive weather maps and plan a safe route based on weather forecasts. It also serves to transmit and receive operational information to ensure the safe operation of the vessel.
Depending on the special purpose, special instruments and devices are installed on the bridge, and the watch officer uses them to solve special problems.
In the other, it is important to choose the most profitable path and stick to it, constantly monitoring your location. This is where navigation helps people.
Ancient sailors tried to navigate near the coast and the location of the vessel was determined by coastal landmarks. The brave Phoenicians and Vikings, sailing far from the coast, were guided by the sun and stars. In the XI century. a compass appeared, but the magnetic needle at high latitudes did not point to the geographical north, but to the magnetic pole, which did not coincide with the north pole. This means that the higher the latitudes in which the ships sailed, the greater the error in the compass readings. The compass was far from a universal means of orientation. In the middle of the XVI century. the outstanding Flemish cartographer G. Mercator calculated the coordinates of the magnetic pole, proposed a new principle for compiling maps in a conformal cylindrical projection. Since then, all nautical charts have been compiled in this projection.
Currently, the direction of the vessel's movement is determined by a magnetic compass (taking into account magnetic declination) or by a gyrocompass. The gyrocompass is arranged according to the principle of a top and is rotated by an engine with a frequency of 300,000 revolutions per minute. Like any top, it has the property of maintaining a given position of the axis in space, for example, the direction from north to south.
When a ship is on the high seas, its course and distance traveled are constantly plotted on the map. Such accounting of the rate is called reckoning, and the rate is reckonable. The result of the navigator's work is called laying (the ship's course on the map).
Only close to the coast using a lighthouse or a direction finder (a device for determining the angular directions to external landmarks: coastal or floating objects, celestial bodies, etc.) can the navigator accurately name the ship's coordinates. It determines the direction to two landmarks, the position of which is known from the map. Lines are drawn from these landmarks on the map, and the point of their intersection will be the location of the vessel at sea.
Away from the coast, the navigator uses navigational instruments. Vessel speed and distance traveled are measured using a log. Logs are hydrodynamic and hydrostatic. A hydrodynamic lag is a turntable (screw) that is pulled on a cable behind the stern of the vessel. Usually the log is connected to a rev counter installed on the bottom of the vessel. The faster the ship goes, the faster the log rotates, and the counter shows more revolutions, and on its dial the value of the speed of the vessel is indicated.
The hydrostatic log perceives the force of water pressure. A tube is lowered into the water, bent at the end. The tube opening faces forward. The flow of water running on the ship creates pressure. The greater the speed, the greater the pressure. The pressure value is used to determine the speed of the vessel.
Measuring the ship's speed in knots is associated with the use of the first simple log, similar to a float. He was thrown from the ship on a rope, divided into parts by knots. The number of knots that “ran out” from the ship in half a minute corresponded to the number of nautical miles (1111.852 km) covered by the ship per hour.
However, the log does not give a very accurate idea of the ship's speed, because it cannot take into account the speed and direction of currents, wind, and factors that affect the ship's drift. Sailors need not a reckonable, but a true course of the ship, so the reckonable course is corrected by astronomical observations using a sextant (or sextant) - a goniometric reflective instrument for measuring the heights of celestial bodies above the horizon or the angles between objects visible on the shore. The device of the sextant is as follows: a telescope and two mirrors are attached to the bronze sector, which is approximately 1/6 of the circle (the name of the device comes from the Latin word sextantis - “sixth”), and two mirrors (to reflect the rays of light from the celestial body). The sector has divisions - degrees and minutes - for angular measurements.
When determining the location of a ship or aircraft by the sun or stars, a sextant usually measures the heights of several celestial bodies above the line of the visible horizon. Then a number of corrections are made to the result obtained, taking into account, for example, a decrease in the visible horizon, etc. Finally, corrections to denumerable coordinates are determined (most often graphically) using the formulas of nautical and aviation astronomy.
With the development of radio technology, radio communications came to the aid of ship navigation. Radio beacons, the location of which is precisely known, continuously send radio signals. They are received by a ship direction finder - a special radio receiver, with the help of which the bearing is determined - the angle between the meridian on which the ship is located and the direction to the source of radio waves. When determining the position of the vessel, the bearings of two radio stations (radio beacons) are taken into account.
In the interests of navigation, radar is also used (see Radar), which allows you to "see" in the dark and fog, determine the distance and bearing to the coast or to the ship with which you need to disperse at sea.
The location of the vessel can also be specified by the bottom topography shown on the map. For this, an ultrasonic device is used - an echo sounder (see Acoustics, acoustic technology). By measuring the time of passage of an ultrasonic pulse to the seabed and back, the device determines the depth, and the auto-recorder draws a depth curve - the bottom topography. The navigator compares the image on the map with the readings of echo sounders.
An important role is played by navigation technology in aviation, helping to drive aircraft. In front of the pilot on the dashboard, among the many different instruments, there are also navigational ones. This is an altimeter, the device of which is based on the same principles as a barometer that responds to pressure changes. The pressure decreases with altitude, and the navigator compares the pressure on the ground with the readings of the altimeter. So you can find out the approximate flight altitude. The true flight altitude is determined by a radio altimeter - a small radar. It sends radio pulses to the ground and receives them back. The speed of the radio wave is known - 300,000 km / s, and the device determines the flight altitude in time from the moment of sending and until the return of the pulse. The altitude meter is a manometer that measures the pressure of the oncoming air flow. With altitude, it decreases, and the device shows a lower speed. But the speed indicator automatically takes this change into account, and as a result, its arrow points to the true airspeed. The direction of flight can be judged by the readings of the gyrocompass.
Imagine that the ship is on the high seas. It is surrounded on all sides only by sky and water; no shore or island is visible around. Swim wherever you want! when there were no Earth satellites or radio communications? If the captain of a ship does not know how to make astronomical observations, he will not be able to determine the position of his ship. There is only one way out - to surrender "to the will of the waves." But in this case, the ship is doomed to almost certain death.
