GRAPHIC CALCULATION OF THE WAY OF THE SHIP. In order to judge the safety of navigation, navigate the environment and choose the right courses for further movement, the navigator must at any time know the position of his ship. To do this, he maintains a navigation pad. Before the ship goes on a voyage, under the guidance of the captain, they study the navigation conditions for the entire upcoming passage using maps and navigational aids. Based on these data, preliminary laying is performed. However, it only gives a general idea of ​​the transition conditions. From the moment you embark on a voyage, the final choice of courses and all factors taken into account are determined by the specific sailing situation. Therefore, the flight is carried out by the executive laying. It includes dead reckoning, calculations and charting, maneuvering calculations to avoid other ships.

Dead reckoning is the continuous accounting of the elements of the vessel's movement (speed and direction) and the effects of external forces in order to determine the coordinates of the vessel (countable place) without observing coastal landmarks and celestial bodies (observations). This accounting is carried out on the basis of the values ​​of the course, speed and drift vector of the vessel. The starting point for dead reckoning on the map is determined by the captain. For such a point, the exact position of the vessel, obtained immediately after leaving the port water area, a floating lighthouse, a receiving buoy, etc., can be taken. Its coordinates are recorded in the ship's log. By the time the executive laying begins, you should turn on the log, determine the compass correction by alignment or in another way.

KEEPING NUMBER WHEN SWIMMING WITHOUT DRIFT AND CURRENT. When sailing without drift and current, the ship's path on the map coincides with the IC line, therefore, the ship's movement on the map is taken into account along the IC lines, along which the distances traveled by the ship along the log are plotted, taking into account its coefficient Kl. From the starting point on the map, a line of the first course is laid. The IC taken from the card is transferred to the CC, on which they are placed according to the magnetic compass. On the map above the IR line, the compass course and its correction are inscribed. The distance Sl traveled along the course is determined by the lag: Sl = Cl (ol 2 - ol 1); (Where ol 2 is the lag reading at the vessel's location, ol 1 is the lag reading at the starting point, Kl is the lag coefficient).

On the lines of the IC, in the cases indicated below, the reckoning of the ship's revenge is applied, i.e., the place calculated according to the course and navigation. If navigation is performed near the coast, countable points are marked every hour, in the open sea - at the end of the watch. In addition, a reckonable place is applied at the points of the beginning and end of turns, when changing speed, when receiving observations. Near the ship's position, in the form of a fraction, the moment is recorded according to the ship's clock with an accuracy of 1 min (T) and the lag reading with an accuracy of 0.1 miles (ol). (See Figure 31).

In real conditions of sea navigation, three main options are possible, which determine the appropriate practical methods of dead reckoning of the yacht's way: sailing in conditions of a stable full wind; sailing in conditions of stable opposite wind; sailing in winds that are unstable in strength and direction.

In the first case, the yacht is usually driven along the line of the path laid during the preliminary laying. The terms of calculation are favorable here. In the second case, tacking is performed relative to the general course, while the actual path laid on each tack does not coincide with the preliminary laying. If the tack is not too steep, then the helmsman accurately maintains a given course, which simplifies the reckoning and increases its accuracy. Under such conditions, the duration of the tacks depends on the angle of the tack (the angle between the general course and the path of the yacht). If the angles of the right and left tacks are equal, their duration is the same, and the tacking can be symmetrical. If not, dead reckoning and laying the track are performed on each private tack according to the instrument data. If there is no lag, it is recommended to evaluate the speed on each tack.

When tacking, it may happen that the helmsman, at the direction of the captain of the yacht, when getting out into the wind, does not pay attention to the compass. Here, at small but equal time intervals (15 - 30 minutes), the average QC and the corresponding IC are determined and recorded, according to which the data obtained by the lag or speed are put aside. In unstable winds, the helmsman does not set the course, but sets the task of guiding the sail in search of the wind, adhering as close as possible to the general course. Sometimes in such a situation, depending on local indications and the weather forecast, it may be beneficial to deviate from the general course in order to get a full steady wind sooner (for example, a breeze offshore). In all these cases, in the interests of dead reckoning, all turns are recorded on the yacht and on each tack (at the beginning and end of the tack, it is obligatory) with a certain frequency (1-2 times per hour, depending on conditions), data on the movement of the vessel (time, course , speed, lag reading). These records are processed by averaging the course and speed of each tack, and then plotted on the chart.

Practice shows that the accuracy of the calculation in such conditions increases with increasing discreteness of observations. Approximation errors of curved sections of navigation by straight lines will be insignificant compared to other errors.

SHIP DRIFT. In navigation, drift ("a") refers to the drift of a vessel from the course line under the combined action of the wind and the waves caused by it. When drifting, the ship moves relative to the water under the combined action of the ship's machinery and wind. The line of its actual movement (OV), called the line of the ship's track during drift, does not coincide with the course of the ship (OA). (See Figure 33). When the track line is shifted to the right of the ship's DP (the wind blows to the port side), a plus sign (+) is assigned to a, and when the track is shifted to the left (the wind blows to the starboard side), a minus sign (-) is assigned. Relationship between track angle with drift (PUa), IC and a: PUa = IC + a ; IR \u003d PUa - a; a = PUa - IR

The drift angle can be determined by comparing the actual path of the vessel obtained from the observations with the IR. When following in sight of the coast, a number of reliable navigational observations are made. By connecting the observed points, we get the line of the actual movement of the vessel, i.e., the track line during the drift of the launcher (Fig. 34). The angle between the track line and the IR line plotted on the map corresponds to the drift angle. The found drift angle with its sign is taken into account in the further calculation. If there is a current in the navigation area, then the resulting drift angle will be the result of the impact on the ship not only of the wind, but also of the current.

ACCOUNTING FOR DRIFT IN CALCULATION. If the ship is drifting, then when plotting, the line of the ship's track during the drift is plotted on the map. It is inscribed with KK, the compass correction and the drift angle a taken into account with its sign. Along the path line, the distances Sl traveled along the lag are laid off. It is believed that for a

If the navigator is not sure of the accuracy of the drift angle, then in order to control the safety of navigation, in addition to the drift track, it is recommended to plot the IR line on the map. Both of these lines must be clear of underwater obstacles. The calculation is carried out only along the track line, along which the vessel moves.

SEA CURRENTS. Sea currents are the horizontal movements of large masses of water. The flow is characterized by its elements: direction and speed. The direction of the current Kt is indicated in degrees in a circular count or rhumbs and is set according to the point on the horizon to which the current is directed. The current velocity Vt is measured in knots, and its small speeds are measured in miles per day. According to the nature of the flow, they are classified into constants, the elements of which almost do not change from year to year, periodic, the elements of which change according to a certain law, and temporary (random), the elements of which can change dramatically. In practice, the navigator most often has to deal with constant and periodic (tidal) currents. Information about the elements of constant and tidal currents is placed in sailing directions, atlases of currents and on maps. At the same time, the average values ​​of the flow elements are indicated, which can differ significantly from the actual ones. The movement of the vessel relative to the ground when swimming in the current is determined by the following factors (Fig. 36).

Under the action of ship engines, the ship moves relative to the water in the direction of its DP, i.e., the line of the true course OA. The speed of the ship in relation to the water is the speed Vl indicated by the log. At the same time, together with the entire mass of water, the ship is carried away relative to the ground in the direction of the flow of the OD with the speed of the flow Vt. As a result, relative to the ground, the ship moves along the resultant OB at a speed called the true speed of the ship V. In this case, the ship's DP remains parallel to the IR line. The line OB, along which the ship moves under the combined action of the ship's machinery and the current, is called the line of the ship's track on the current. The position of the track line relative to the true meridian is determined by the angle NOB, which is called the track angle on the PU current. The angle " " between the ship's true heading OA and the track OB is called the drift angle. When the vessel is drifting to the right of its DP (the current is directed to the port side), a "+" sign is attributed, and when drifting to the left, a "-" sign is assigned. Relationship between (PU), IR and:

PU \u003d IR +; IR \u003d PU -; = PU - IR

NUMBER WHEN FLOATING ON THE CURRENT. When sailing in a constant current, the ship's path line is plotted on the map, along which it actually moves relative to the ground. Above the track line, they inscribe KK, the compass correction and the drift angle with their own sign. For auxiliary calculations, an IR line is also applied with a thin line, along which the distances Sl are plotted, passed by the ship relative to the water according to the lag readings. The points obtained on the IC line are transferred in the direction of the current to the track line (Fig. 37). Countable points on the track line are marked with time and lag readings, and at the corresponding points on the course line - only lag readings. Points of traverse, opening and hiding of landmarks are applied to the path line (Fig. 38).

CALCULATION WITH JOINT ACCOUNTING FOR DRIFT AND CURRENT. Let us consider the case when the ship moves relative to the ground under the combined action of ship engines, wind and current. To maintain the reckoning on the map, lay the line of the ship's path during drift and current and inscribe KK, the compass correction and the total drift angle c \u003d a +.

In addition, for auxiliary calculations, a drift track is also laid on the map, along which the vessel’s navigation along the Sl log is postponed. Each point on the drift track corresponds to a point on the line of the actual movement of the ship. These points are interconnected by the flow vector. Graphically, tasks related to finding the track line on the map during drift and current, the true speed V and the total drift angle c for the given KK, Vl, a, and flow elements, plotting a countable place, precalculating time and ol at the time of arrival at a given point, finding a traverse of the reference point is solved in the same way as when swimming in the current, but all auxiliary constructions are made on the track line during drift, replacing the IR line.

ESTIMATES OF THE ACCURACY OF THE NUMBER. As a result of the effect of unaccounted errors, the actual path of the vessel and the distance traveled by it (voyage) will not correspond to those taken into account when calculating on the map, and the actual position of the vessel will not correspond to the calculated one. For an approximate judgment about the errors in the calculation, you can use the following data, which reflect the accumulated generalized experience of navigation and the studies carried out. Duration of navigation (hours) corresponds to the radial root mean square error, % of S: Up to 3 hours - 10%; 3-6 hours - 9%; 6-10 hours - 8%; 10 -14 h - 7%; 14-18 hours - 6%; 18-23 h - 5%; 23-25 ​​h - 4%; more than 35 hours - 3%. When laying the ship's route on the chart at a certain distance from navigational hazards, it is necessary to take into account the possibility of the ship's deviation from the route line, and the deviation value will increase with increasing distance traveled, especially when sailing with drift and current. The insufficient accuracy of the reckoning necessitates additional control over the position of the vessel, i.e., determining its location not only by reckoning, but also by observations: navigational, astronomical or using GPS.

Dead reckoning - finding the current coordinates of the vessel in direction and distance traveled - is the basis of the navigational (instrumental) method of navigation and allows you to get the position of the vessel (its reckonable coordinates) at any time.

dead reckoning is carried out continuously during the entire time of the vessel's voyage.

dead reckoning allows at any time to assess the position of the vessel relative to the intended path, as well as to detect inaccuracies (misses) in observations.

Graphic reckoning of the ship's track is performed on track MNCs according to the main heading indicator and speed meter (passed S), corrected by their corrections, taking into account drift from the wind ( a°), drift of the vessel by the current ( b°) and maneuvering elements of the ship.

Written (analytical) reckoning by hand is practically not used (only during ocean crossings).

With graphic reckoning, the following is laid on the route map:

[ true heading line (TR) - when sailing without taking into account drift from wind and current;

[ track line – when taking into account drift from wind, current or total drift.

If, without constructing a navigation triangle of speeds, a large error in calculating the ship's path is allowed, then this triangle is built on the map.

Along the way, as a rule, they sign from above GKK…(+1.0°) QC a (or β or C).

Calculating position of the vessel with graphic laying on MNC designate a notch perpendicular to the track (course) in the following cases:

1. ¨ every hour when sailing near the coast;
2. ¨ at the time of shift change every 4 hours (on the high seas);
3. ¨ when moving from map to map (in the absence of observations);
4. ¨ at each location of the vessel;
5. ¨ in other cases at the direction of the captain or at the discretion of the military-industrial complex.

A horizontal line is drawn next to the notch of the vessel's reckonable place - parallel to the parallel and the ship's time (17.32) is put down above it, and the lag reading (28.3) is below it. If the lag does not work, then put a dash under the line.

When moving from map to map, at the transfer points on both maps put down:, No. MNC from which the point is transferred.

If there is an auto-calculator of coordinates (in the PI SNS), the current reckonable position of the vessel is calculated automatically according to the entered heading and speed (automatically from the compass and log or manually) and is displayed on the display. Turning points, as well as waypoints, with the frequency specified by the captain, are manually applied to the track MNC and marked with a conventional sign. These points can be connected by track lines to form a performance pad. With automatic heading and (or) speed input, such calculation is always more accurate than manual calculation due to taking into account small changes in heading and (or) speed, including the ship's yaw.

When leaving the area of ​​frequent maneuvering, the captain indicates the waypoint to the military-industrial complex, which should be taken as the starting point of the executive laying on the map.

If the final laying almost coincides with the preliminary laying, countable turning points and waypoints are marked on the line of the selected track.

The reliability and accuracy of the calculation is ensured by the correct operation of the ship's instruments, the reliability of their corrections taken into account, the accuracy of keeping the ship on course, and the correct consideration of the influence of wind and current on the ship's path.

Dead reckoning is controlled by the equality of segments between waypoints laid at regular intervals (30 minutes, 60 minutes, etc.).

The angle of the wind drift and the change in the ship's speed due to the influence of the wind (in the absence of a lag) are determined on the basis of the accumulated information and taken into account in graphical reckoning.

The flow elements are selected from navigational aids or determined by residual analysis.

It should be kept in mind that the actual drift values ​​( a°) and drift of the vessel by the current ( b°) may differ from those taken into account. Wind drift and drift are re-evaluated with each change in the course and (or) speed of the ship and are taken into account with a word depth of up to whole degrees.

When using the coordinate calculator, you should:

1) ® timely manually enter a new course and (or) speed of the vessel after the completion of the maneuver (if there is no automatic input of data from the log and (or) compass);

2) ® turn on drift auto-input only in areas of relatively stable currents, turn it off near the coast with significant changes in the elements of the vessel's motion (EMF) and a spread of residuals.

When using automated recording devices navigation systems, the frequency of data recording is set depending on the area of ​​navigation, the speed of the vessel and the frequency of its maneuvers.

Graphic reckoning of the ship's path

The essence of graphic calculus

The safety of navigation in terms of navigation is ensured by the correct choice of the route between the points and following the chosen path.

Choosing a path is one of the most important tasks in navigation, the decision of which is based on a thorough analysis of the entire situation during the transition.

The selected route of the vessel is put on the maps - preliminary laying is performed. Preliminary laying is carried out before the vessel enters the voyage by the captain. She is she is the result of work on the choice of the safest and most profitable way of the vessel. To ensure navigational safety of navigation, the places of course change are marked on the map, for which such turning points are chosen so that the moments of arrival of the vessel at these points can be quickly determined, for example, the moments of arrival at the traverse, at the target, etc.

They plan how far capes, lighthouses, and other landmarks will pass.

Declension leads to the year of navigation and inscribes its value in pencil along the entire path of the ship.

Above the path lines, the values ​​​​of true courses are inscribed.

The distance in miles for each course is taken from the map and the number of miles of the entire transition is calculated.

On the track line, the boundaries of the visibility range of beacons and lights for the height of the bridge are marked, the most appropriate ways to determine the position of the vessel in separate sections are outlined. Time is kept from the operational time, counting the time of departure of the vessel at 00 hours 00 minutes.

Before performing the preliminary laying, the card is raised (see § 45).

The calculations made during the pre-laying process are indicative and should be corrected during sailing.

Preliminary laying is carried out, as a rule, on road maps.

The second major challenge- ensuring the movement of the vessel along the selected path, for this, the vessel's movement is continuously recorded - dead reckoning of the vessel's path.

The main elements of the reckoning are the course (according to the compass) and the distance traveled (according to the log).

The ship's graphical reckoning is expressed in reference executive navigation pad. Its beginning coincides with the departure of the vessel from the berth (shooting from the anchor), when leaving the port, the navigator focuses on visual orientation in the environment, based on knowledge of the harbor or roadstead and the correct use of TSS, aids to navigation and natural landmarks.

With access to clean water, the location of the vessel is accurately determined and a laying is carried out from the obtained point.

Before arriving at this point, a lag is turned on, near the starting point, time is recorded as a fraction in the numerator, and the lag count is in the denominator.

From the starting point, an IR line is laid, on which countable points are marked every hour or every four hours, i.e. places obtained without measuring the navigation parameters of external landmarks.

Countable points are marked on the path line with a short transverse line, and the thickness of the path line itself should be approximately equal to the thickness of the meridians and parallels.

All laying and calculations are done with a soft, finely sharpened pencil.

Positions of the ship according to observations, i.e. according to the results of measuring the navigation parameters, external landmarks are applied as often as possible and, if possible, when changing the course.

Observed places are indicated by conventional signs in accordance with RShS-89.

The discrepancy between the observed point and the numeral is called the discrepancy, denoted by the letter "C". Its direction and magnitude are recorded in the ship's log (C = 225º -1.5 ')

The direction of the discrepancy is calculated from the calculated point to the observed one.

Laying ends when the ship enters the port water area or at the point where maneuvers begin when the ship is anchored.

Thus, a laying is a set of measurements, calculations and graphic constructions related to the choice of the path of the vessel, taking into account its movement and determining the location of the vessel.

Maintaining graphic reckoning and solution

tasks in the absence of drift and current

The absence of vessel drift and drift by the current simplifies both graphical constructions on the map and calculations when solving various problems.

Firstly, the ship's track line coincides with the direction of its DP i.e. with IR line.

Secondly, the distance traveled by the ship relative to the water i.e. according to the indications of the lag, corrected by its error, it is also the actual distance traveled relative to the ground (S L \u003d S I).

Direct problem solution

(Course Correction Tasks)

With a given steering KK according to MK						Same for GC

Solution of the inverse problem

(Problems for course translation)

Solving private problems

I.Drawing the reckonable place of the vessel on the map.

Given: T 1, OL 1, T 2, OL 2. Find: S L.

When sailing, the ship is on the border of two environments - air and water, the movement of which affects it, deviating from the course and changing the speed of movement.
The drift of a ship by the wind is called drift. Wind is the forward movement of air masses. Wind direction is the direction (in degrees) from where the wind is blowing. Wind speed is measured in meters per second or in points.

Fig.1
Let V0 be the speed of the ship relative to the water, due to the work of its own propellers (Fig. 1). The air resistance to the movement of the ship is perceived by the observer on the ship as a counter flow of air, the velocity vector of which is (-V0). Let u be the true wind speed vector. The counter flow of air and the true wind, adding up, form a total flow observed on a moving ship and called the apparent (observed) wind. The apparent wind speed vector is equal to the geometric sum:
W \u003d u + (-V0) \u003d u - V0.
The apparent wind speed is determined automatically using an anemorumbometer or manually using an anemometer, the direction KW is determined by an anemorumbometer or in the direction of a flag or pennant. Seeming wind. Inactive on the ship at a heading angle qW, it causes the total aerodynamic force P applied to the center of the ship's windage. Due to the refractive properties of the superstructure, the direction of the force P in the general case does not coincide with the direction of the apparent wind. Under the action of the force P, the ship is displaced in the direction of this force with a drift velocity VDR.
Let us decompose the velocity VDR into components VDR X along the diametrical plane and VDR Y along the traverse. The speed VDR X, depending on the direction of the apparent wind, is subtracted or added to the speed V0. If the lag works, it takes this speed into account. That's why
Vl \u003d V0 + VDR X.
VDR Y speed deviates the ship from the set course. Having geometrically added the speed of the ship Vl with the speed VDR Y, we get the vector V of the actual, or ground, speed of the ship:
V \u003d Vl + VDR Y.
As you can see, when adding the velocities Vl and VDR Y, the ship moves in the direction of their resultant.
The line along which the ship actually moves relative to the seabed under the action of propulsors and the apparent wind is called the drift track. The diametrical plane of the ship, when moving along the track line, remains parallel to the line of the true course. This is due to the fact that the helmsman constantly maintains a given true course. Consequently, the ship moves along the path forward not with its bow, but with its cheekbone.
The angle in the plane of the true horizon between the northern part of the true meridian and the track line during drift is called the track angle during drift PU?.
The angle in the plane of the true horizon between the lines of the true course and the track when drifting is called the drift angle?. If the wind is blowing to the port side of the ship, the drift angle is positive (the course angle during drift is greater than the true heading). With wind from the starboard side, the drift angle is negative (the course angle during drift is less than the true heading).
The drift angle depends on the speed and heading angle of the apparent wind, on the speed and design features of the ship: the height and architecture of the superstructures, the surface part of the hull and the shape of the hull contours. The drift angle is measured with a driftmeter. In the absence of this instrument, drift angles for various navigation conditions are selected from a drift table compiled from experimental data. From fig. 1 is visible:

Formulas - algebraic, angle? is taken with its sign.
In the practice of ship navigation, it is necessary to solve mainly two problems related to the drift of the ship. Direct task:
Calculate the ground angle when the launcher drifts? (track of the ship when drifting), if the true heading is set.
To solve this problem, you need:
- determine the sign of the drift angle?;
— calculate the heading angle qW of the apparent wind;
— choose the angle value? from the drift table by arguments: by ship speed and qW;
- calculate the track angle during the drift of the launcher ?, lay the track on the map.
KK = 79.0°; Vl = 12.0 knots;
?GK = + 1.0°; wind 5° -12 m/s.
Solution:
The wind is blowing to the port side of the ship - angle? positive:
IR = KK + ?GK = 80.0°;
? = +4.0°; PU? = IR + ? = 84.0°.

2. Laying true radio bearings in case the radio beacon is located outside the eastern or western borders of the map frame.

To find the position of the defining point (point M ') through which the radio bearing will be drawn on the KRMK (point A), it is necessary:
1) ? from "RTSNO" write out the coordinates of KRMKA (? A,? A);
2) ? calculate value? ? = ?Р – ?А, where? Р – longitude of the side frame of the map;
3) ? draw a parallel of KRMKA on the map (? A - from "RTSNO") and set aside the segment;
4) ? through t. A "to draw an additional meridian aa;
5) ? from t. A’ hold Lok. P KRMKA A to the intersection with aa - t. M;
6) ? from t. M along aa, set aside a segment and through the obtained point M 'to draw a radio bearing on KRMK A? this will be the desired line of position (I–I).

To ensure the safety of navigation, the boatmaster must at any time know the position of his vessel, which can be achieved by maintaining navigation pad. Plotting includes dead reckoning, calculations and plotting on a chart to locate a vessel, and maneuvering calculations to avoid other vessels.

The navigation pad is divided into two types:

- preliminary laying carried out before going on a flight to study the upcoming transition through charts, manuals and swimming guides: it gives a general idea of ​​​​the conditions for the transition.

- executive gasket performed from the moment of departure and up to the end. In this case, the choice of courses and all factors taken into account are determined by the specific sailing situation.

reckoning is called the registration of the movement of the vessel on the sea chart. Depending on the navigation conditions, this accounting is carried out in two ways:

- written reckoning used for ocean voyages, when you have to be guided by small-scale maps . Its essence lies in the calculation of the coordinates of the vessel, which is performed by the navigator according to formulas, followed by drawing the calculated place on the map.

- graphic reckoning it is used when sailing near the coast, when dangerous depths, surface and underwater obstacles, the influence of the wind that creates drift, and currents can be located at relatively short distances from the course. In this case, the reckoning must be carried out especially carefully and continuously.

The starting point for laying the path of the vessel on the map is determined by the captain. The coordinates of the laying start point are recorded in the ship's logbook. By the time you start laying, you should turn on the log and determine the compass correction.

From the starting point on the map, a line of the first course is laid. If navigation is performed near the coast, counting points should be marked every hour, when sailing in the open sea at the end of the watch, at the beginning and end of turns, when changing speed, when receiving observations. Next to the countable place in the form of a fraction, the moment is recorded according to the ship's clock with an accuracy of 1 minute and the lag reading with an accuracy of 0.1 miles. To control and clarify the dead reckoning, the place of the vessel in the voyage is determined by various navigation, radio navigation and astronomical methods. Received at the same time observed points put on the map. Upon receipt of the observed place, further laying is carried out from the observed point, showing on the map the magnitude and direction of the deviation of the ship from the dead reckoning. The curved line connecting the observed and countable points is called inviscid.

Graphical reckoning without drift and current:

When sailing without drift and current, the ship's path on the map coincides with the IC line, therefore, the ship's movement on the map is taken into account along the IC lines, along which the distances traveled by the ship along the log are plotted, taking into account its coefficient Cl. From the starting point on the map, a line of the first course is laid. The IC removed from the card is transferred to the KK (GKK), on which they fall according to the magnetic (gyro) compass. On the map above the IR line, the compass course and its correction are inscribed. Course traveled distance S determined by log:

S = Cl (OL 2 - OL 1);

(Where OL 2- countdown of the lag at the location of the vessel, OL 1- countdown of the lag at the starting point, Cl- lag factor).

On the IC lines in the cases indicated below, the calculated place of the vessel is applied, i.e., the place calculated according to the course and navigation. In addition, a reckonable place is applied at the points of the beginning and end of turns, when changing speed, when receiving observations. Near the ship's position, in the form of a fraction, the moment is recorded according to the ship's clock with an accuracy of 1 min (T) and the lag reading with an accuracy of 0.1 miles (OL).

There are two types of tasks that can be carried out during plotting:

direct task. known QC, v l (v about), the starting point of the reckoning (φ 1, λ 1, T 1, OL 1). Unknown IC, end point of reckoning (φ 2 , λ 2 , T 2 , OL 2).
Solution:

or S = ROL k l

Remove the countable coordinates φ 2 , λ 2 and determine the time of arrival at this point T 2 = T 1 + S/v, note the readings of the lag OL 2 .

Reverse problem. IR, v l (v about), φ 1 , λ 1 , T 1 , ol 1 are known.

Unknown QC, φ 2 , λ 2 , T 2 , OL 2 .
Solution:

• Lay the IC line from the starting point of the reckoning;
• Calculate KK = IR - ΔK and ask it to the helmsman;
• Calculate S l \u003d v l t(if the reckoning point is calculated in advance), or S = ROL k l(if the countable point is calculated for the passed moment) and put it on the IR line;
• Remove φ 2 , λ 2 and determine the time of arrival at this point T 2 = T 1 + S/v, and at this moment read the lag OL 2 .