Circulation is usually divided into three periods: maneuverable, evolutionary and steady. Vessel circulation. Circulation elements What is the tactical circulation diameter of a vessel

If, while the ship is moving, the rudder is moved out of the center plane - its zero position, i.e. shift it to any angle to the right or left, then the ship will begin to describe a curve on the surface of the water, called circulation.

Circulation called a curvilinear trajectory, which is described by the center of gravity of the ship when changing course.

To a first approximation, the circulation curve is an arc of a circle with a certain diameter (radius), which for a given vessel depends on the rudder angle, speed and draft of the vessel (its load).

The vessel's circulation is characterized by the following main elements (Fig. 7.4):

1. Tactical circulation diameter.
2. Half-cycle circulation.

Rice. 7.4. Basic elements of a ship's circulation

The tactical circulation diameter is the shortest distance between the ship's initial course line and its course line after a 180° turn, measured in cable lengths.

Denoted as – d C or D C .

Tactical circulation radius- there is half d C (D C) and is denoted as – R C .

Half-life of circulation® time during which the ship makes a 180° turn. It is measured in minutes and denoted - t 180°

Circulation elements are determined within the time limits provided for by the governing documents according to the rules set out in the POMES.

The direction of rotation and steering angle are indicated:

When turning the ship to the right - P-5°, P-10°... P-20°... P-30°;

When turning the ship to the left - L-5°, L-10°... L-20°... L-30°.

7.3.2. Methods for determining the elements of a vessel's circulation

Let's look at some methods for determining the elements of a vessel's circulation.

1. By traverse distances, measured by ship radar(Fig. 7.5).

Rice. 7.5. Determination of vessel circulation elements by abeam distances

In the area of ​​a special buoy with radar, the vessel develops the required speed and sets course ( CC 1) with the expectation of passing abeam the buoy at a distance of 2¸3 kb.

When the buoy is abeam, the command “Zero!” is given, according to which:

® the stopwatch(s) starts – T N;

® the distance to the buoy is measured by radar ( D P1);

® the rudder is shifted a specified number of degrees (P-10° ... P-20°) away from the buoy.

At the moment the ship arrives on the reverse course ( CC 2 = CC 1± 180°) the command “Zero!” is again given, according to which:

T K;

® the distance to the buoy is re-measured by radar ( D P2);

® the steering wheel is moved to “0” (in DP).

Calculated:

(7.12)

2. Along the alignment and horizontal angle(Fig. 7.6).

Rice. 7.6. Determination of vessel circulation elements along the alignment and horizontal angle

The ship develops a given speed and sets course ( CC 1), perpendicular to the target line WITH.

At the moment of crossing the target line, the command “Zero!” is given, according to which:

1) ® stopwatch(s) starts ® T N;

2) ® the steering wheel is shifted to a specified number of degrees (P-…° or L-…°);

3) ® the navigation sextant measures the horizontal angle ( a 1) between the target line WITH and landmark ( A).

At the moment of crossing the target line and the vessel arrives on the return course ( CC 2 = CC 1± 180°) a command is issued again, according to which:

1) ® stopwatch(es) stops – T K;

2) ® the rudder is moved to “0” (in the vessel’s DP);

3) ® the horizontal angle ( a 2) between the target line WITH and landmark ( A).

Calculated:

Where d– the length of the perpendicular dropped from the point. A to the target line.

3. By ship length(Fig. 7.7).

Rice. 7.7. Determination of circulation elements by vessel lengths

This method is based on measuring the distance between the wake before the start of circulation ( CC 1) and the wake after the vessel turns 180° ( CC 2 = CC 1± 180°).

There are other ways to determine the elements of agility:

Ø method of direct synchronous intersections (2 coastal theodolite posts);

Ø using aerial photography;

Ø using an auto-layer (at the largest scale);

Ø by gyrocompass and log ( S L = K L × (OL 2 – OL 1 ) And

(7.16)

a– the angle of rotation of the vessel.

Circulation elements are determined for different steering wheel positions (R or L 5°, 10°, 20°, 30°).

Circulation table (training)

Table 7.1.

V L, nodes	Steering angle
R (L) – 10°	R (L) – 20°	R (L) – 30°
R C, kb.	t 180°,min.	d 180°,miles	R C, kb.	t 180°,min.	d 180°,miles	R C, kb.	t 180°,min.	d 180°,miles
			2,5			2,2			1,9
			2,5			2,2			1,9
			2,5			2,2			1,6
			2,2			1,9			1,6
			2,2			1,9			1,6
			2,2			1,9			1,3
			1,9			1,6			1,3
			1,9			1,6			1,3
			1,9			1,6			0,9

Based on certain values ​​of agility elements ( d C or R C And t 180°) for different values ​​of vessel speed and rudder angle RTS circulation tables are filled in and the vessel's log (Table 7.1)

Circulation call the trajectory describedDH vessel, when moving with the rudder deflected to a constant angle. Circulation is characterized by linear and angular velocities, radius of curvature and drift angle. The angle between the linear speed vector of the ship andDP calleddrift angle . These characteristics do not remain constant throughout the maneuver.

Circulation is usually divided into three periods: maneuverable, evolutionary and steady.

First period (maneuverable) - the period during which the steering wheel is shifted to a certain angle. From the moment the rudder begins to shift, the ship begins to drift in the direction opposite to the rudder shift, and at the same time under the influence of forces Y p AndY p " begins to turn towards the steering wheel. During this period, the trajectory of movementDH the vessel turns from rectilinear to curved with the center of curvature on the side opposite to the side of the rudder; the ship's speed drops.

Second period (evolutionary) - the period starting from the moment the rudder is shifted and continuing until the moment when all forces acting on the ship reach equilibrium, and the drift angle(β ) stops growing and the speed of the vessel along the trajectory also becomes constant. During this period, hydrodynamic pressure forces on the ship's hull increase, the drift angle increases, the curvature of the trajectory changes sign, and the center of curvature of the trajectory moves into the circulation. The speed of the vessel along the trajectory, which began to fall during the maneuvering period, continues to decrease. The radius of the trajectory during the evolutionary period is a variable value.

Third period (steady) - the period that begins at the end of the evolutionary period is characterized by the balance of forces acting on the ship: the thrust of the propeller, hydrodynamic forces on the rudder and hull, centrifugal force. The trajectory of the ship's CG turns into the trajectory of a regular circle or close to it.

Circulation elements

Geometrically, the circulation trajectory is characterized by the following elements:

Do - steady circulation diameter - the distance between the center planes of the vessel on two consecutive courses, differing by 180º during steady motion;

D ts - tactical circulation diameter - distance between positionsDP the vessel before the start of the turn and at the moment of changing course by 180º;

l 1 - extension (gait) - ra
distance between positionsDH the vessel before entering the circulation to the circulation point at which the ship's course changes by 90º;

l 2 - forward bias - distance from the original positionDH the vessel to its position after a turn of 90º, measured normal to the original direction of movement of the vessel;

l 3 - reverse bias - greatest displacementDH of the vessel as a result of drifting in the direction opposite to the side of the rudder (reverse displacement usually does not exceed the width of the vesselIN , and on some ships it is completely absent);

T ts - circulation period - time to turn the vessel 360º.

The above-listed characteristics of the circulation of medium-tonnage sea transport vessels with the rudder fully on board can be expressed in fractions of the length of the vessel and through the diameter of the established circulation by the following relations:

Do = (3 ÷ 6)L ; Dts = (0.9 ÷ 1.2)D at ; l 1 = (0.6 ÷ 1.2)Do ;

l 2 = (0.5 ÷ 0.6)D O ; l 3 = (0.05 ÷ 0.1)D O ; T ts = πD O /V ts .

Usually values D O ; D ts ; l 1 ; l 2 ; l 3 expressed in relative form (divided by the length of the vesselL ) - it is easier to compare the agility of different vessels. The smaller the dimensionless ratio, the better the agility.

Circulation speed for large-tonnage vessels is reduced when turning 90º with the rudder on board≈ on⅓ , and when turning 180º - twice.

For any length of su
bottom of the point "A » the drift angle is determined from the well-known trigonometry formulas:

,

Wherel a - point distance "A » fromDH (into the nose - "+ "; aft - "- »).

The following points should also be noted:

a) the initial speed affects not so muchD O , how much for her time and nomination; and only high-speed ships have some noticeable changesD O upward;

b) when the vessel enters the circulation path, it acquires a list on the outer side, the value of which, according to the Register rules, should not exceed 12º;

c) if you increase the speed during circulationGD , then the ship will make a sharper turn;

d) when performing circulation in cramped conditions, it should be taken into account that the stern and bow ends of the vessel describe a strip of considerable width, which becomes commensurate with the width of the fairway.

Safe turning is ensured provided that the lane width in meters is:

WhereR ts.sr - the average radius of curvature of the circulation in the section from the initial to the course changed by 90º;

β k - angle of change of the ship's course;

β - drift angle.

The roll angle in a steady circulation can be determined using the formula of G.A. Firsov:

(in degrees),

Where V 0 - speed of the vessel on a straight course (in m/s);

h - initial transverse metacentric height (m);

L - length of the vessel (m);

z g - ordinate DH vessels;

d - average draft of the vessel.

TABLE OF MANEUVERABLE ELEMENTS

The maneuverable elements of the vessel are initially determined whenwater and full-scale tests for two displacement vessels #000000">fully loaded and empty. Based on completed testsand additional calculations provide information about the maneuverable elements of the vessel(IMO Resolution No. A.601(15)“Requirements for displaying maneuvering information on ships”) . The information consists of two parts:table of maneuvering elements posted on the chassistick; additional information taking into account the specifics of thisth vessel and the dynamics of the influence of various factors on maneuverablequality of the vessel under various sailing conditions.

Can be used to define maneuverable elementsany full-scale and full-scale calculation methods that provide accurateaccuracy of the final results within ±10% of the measured valueus. Full-scale tests are carried out under favorable weather conditions: wind up to 4 points, waves up to 3 points, sufficient depthbinet and without noticeable current.

The table of maneuverable elements includes inertialcharacteristics of the vessel, elements of maneuverability, changes in draftvessels, elements of propulsion, elements of maneuver to save peopleka, who fell overboard,

Inertial characteristics are presented as lineargraphs constructed on a constant distance scale and havedefining the scale of time and speed values. Braking distance from the frontof moves to “Stop” are limited to the moment of loss of controllablespeed of the vessel or a final speed equal to 20% of the initial speed. On the graphicthey show with an arrow the most probable side of the deviationof the vessel from the initial path in the process of reducing speed.

Information about agility is given in the form of a graph andblitzes. The circulation graph shows the ship's position every 30°on the trajectory to the right and left with the steering wheel position “on board” and “onhalf a side." Similar information is presented in tabular form, but every 10° changes in the initial course in the rangenot 0-90°, for every 30° - in the range of 90-180°, for every 90° - inrange 180-360°. At the bottom of the table there is data aboutlargest circulation diameter.

Elements of marketability are reflected in the form of a graphical dependenceship speed from the propeller speed and complementtable, where the hour is indicated for each constant speed valuethe rotation of the propeller.

The increase in vessel draft is taken into account during heeling and subsidence, when the vessel moves at a limited depth with a certain speed.height.

Elements of maneuver for rescuing a person who has fallen overboard,
font> performed by receiving coordinates on the starboard or left side. In informationmations indicate the following data to perform the correct maneuver: angle of turn from the initial course; operational timeshifting the rudder to the opposite side, entering a counter course andto the starting point of the maneuver; actions of the skipper at each stageevolution.

IN

all distances in information about maneuverable drive elementsThey are in cable lengths, time is in minutes, speed is in knots.

Additional information may include materially, taking into account the specific features of specific typesvessels, information on the influence of various factors on the maneuvering data of the vessel, etc.

The table of maneuvering elements represents a mandatory minimum operational data for each ship, which can be supplemented at the discretion of the ship’s captain or the maritime service.

The table should include:

Inertial characteristics.

(PPKH - stop; PMPH - stop; SPH - stop; MPH - stop; PPH - PZH; PMPH - PZH; SPH - PZH; MPH - PZH; acceleration from the “stop” position to full forward travel).

Inertial characteristics are presented in the form of graphs constructed on a constant distance scale and having a scale of time and speed values.

Braking distances from forward to “stop” must be limited to the moment of loss of control of the vessel or the final speed equal to 20% of the full speed, depending on which speed is greater.

Above the graphs of inertial and braking paths the possible direction (arrow) and magnitude (in kbt) of the vessel's lateral deviation from the line of the initial path and course change at the end of the maneuver (in degrees) are indicated. The listed characteristics are presented for two displacements of the vessel - loaded and in ballast.

Agility elements.

In the form of a graph and a table when the PPH circulates on the right and left side in cargo and in ballast with the rudder position “on board” (35 degrees) and “half on board” (15 - 20 degrees).

The information should contain time intervals for every 10 degrees, in the range of changes in the initial course of 0 - 90 degrees (on the graph, every 30 degrees is sufficient), for every 30 degrees in the range of 90 - 180 degrees, for every 90 degrees in the range of 180 - 360 degrees; largest circulation diameter; extension of the vessel along the line of the original course and displacement along the normal to it; initial, intermediate (90 degrees) and final speeds; the angle of drift of the vessel in circulation.

Mobility elements. (Cargo and ballast).

The dependence of the ship's speed on the propeller revolutions (position of the propeller) in the form of a graph and table at a constant interval in revolutions. On the graphs, the zone of critical revolutions is highlighted with a symbol (color).

Change in vessel draft under the influence of roll and subsidence.

Left: 0.75cm; margin-bottom: 0cm" class="western" align="justify"> Elements of maneuver to rescue a person who has fallen overboard. (For right and left sides); angle of rotation from the initial course; operational time for shifting the rudder to the opposite side; entering a counter course and arriving at the starting point of the maneuver; appropriate actions(resetting the circle, giving a command to the helmsman, announcing an alarm, monitoring the fallen person and the circle).

2 DEPARTURE OF THE SHIP ABROAD

p/p	Title of the document
	VMP certificate (for port supervision at the fishing port for fishing vessels)
	Ship's roles (certified by the harbor master)
	General Declaration
	Cargo declaration
	Port clearance
	Certificate for currency
	Ship Supply Declaration
	Copy of crew insurance policy
	Crew's effects declaration
	Receipt general declaration with customs mark
	Cargo declaration with a customs mark “release permitted”

DEPARTURE OF THE VESSEL FOR COASTERING

COMING FROM ABROAD

	Ship's role
	Application for arrival
	General Declaration
	Cargo declaration
	Certificate for currency
	Declaration of ship's stores
	Cargo manifest
	Crew's effects declaration
	Cargo information for port supervision

COMING FROM COASTERING

Ship documents

Issued by the Harbor Master

Certificate of right to sail under National flag Russia

Certificate of ownership of the vessel (perpetual)

Minimum Crew Certificate

Certificate of civil liability for damage caused by oil pollution

Ship documents issued by the technical supervision authority:

Passenger certificate

Permission to use a ship's radio station

Cargo Ship Safety Certificate by Radiotelegraphy

Certificate of load line (lowest freeboard)

Regional cargo certificate

Ship documents required by international conventions.

Passenger Ship Safety Certificate

Cargo ship safety design certificate

Cargo ship safety certificate for equipment and supplies

Cargo ship safety certificate by radiotelegraphy

Cargo Ship Safety Certificate by Radiotelephony

Certificate of seizure

Nuclear Passenger Ship Safety Certificate(nuclear passenger ship) andNuclear Cargo Ship Safety Certificate job@site The curved line that the ship's center of gravity describes when the rudder is shifted to a certain constant angle is called circulation. There are the following three characteristic periods of vessel circulation. Maneuverable, during which the rudder is shifted (10-15 seconds when shifted on board). Evolutionary, during which the coordinate parameters of the vessel change (the angle of the vessel's drift and its angular and linear speeds).

It begins with the end of the rudder shift and ends approximately after the ship's course changes by 90-120°. Steady, during which the coordinate parameters of the vessel remain unchanged. In this case, the curve takes the shape of a regular circle, the diameter of which is called the diameter of the steady circulation Dc (Fig. 41). It is a measure of the maneuverability of the vessel and is expressed in the length of the vessel's hull.

The vessel's circulation is characterized by: tactical diameter DT - the distance in a straight line between the line of the initial course and the center line of the vessel when turning 180°, D = 1.1 Dts; advancement 11 - the distance between the position of the vessel’s center of gravity at the moment the rudder begins to shift and the centerline of the vessel when the course changes by 90°, l1 = 0.6 / 1.20 c; forward bias l2 - the distance by which the ship’s center of gravity shifts from the initial course line when turning 90°, l2 = 0.25 + 0.5 Dts, and reverse bias l³ - the distance by which the vessel’s center of gravity shifts from the line of the initial course during circulation in the direction opposite to the turn, l³ ~ up to 0.1 Dc.

A vessel in circulation always acquires a drift, while its center plane is not located tangentially to the circle (its bow is always located inside the circulation).

The angle between the centerline plane of the vessel and the tangent to the circulation is called drift angle As a result, the vessel in circulation occupies a strip significantly larger than the width of the vessel. The drift angle and reverse displacement must always be taken into account when performing maneuvers in limited water areas.

During circulation, the speed of the vessel decreases to 35% with a constant number of propulsion revolutions and a list appears. In displacement vessels, the roll occurs on the side that is located on the outside of the circulation, and can reach a significant value. The vessel's circulation is also characterized by its period.

This period is the period of time during which the ship describes a complete circulation, i.e., from the moment the turn actually begins until the ship returns to its original course.

During navigation, it is rarely necessary to perform a complete circulation, but its elements must be taken into account when changing course (turning the ship).

When calculating graphically, the value of the tactical circulation diameter Dt or its radius is taken into account

Definition of Circulation Elements

Circulation elements are usually determined during sea acceptance tests at three main forward speeds (full, medium and low) and when the rudder is shifted by 15° and “on board” (to the maximum angle) in both directions for ships with one and three propellers and in one - for ships with two and four propellers.

There are several ways to define circulation elements. The most common of them are: the moving base method; at two horizontal angles; along the alignment and horizontal corners.

Rice. 42

Movable base method is as follows. A buoy is installed in the testing area. On the ship, at a certain distance from each other (let's call it the basis), there are two observers with sextants (one in the bow and the other at the stern). The vessel moves at a certain distance from the buoy at a given speed, and at the command of the test director, usually 20-25 seconds from the moment the rudder is shifted, observers simultaneously measure the angles between the center plane and the buoy, at the same moment the compass course is noted. Then, on the tablet, graphs of changes in angle values ​​(heading and ship course) are plotted over time.

In Fig. Figure 42 shows the construction of the position of the vessel during circulation at the first moment of observation. Point O is the location of the buoy, line N0 is the meridian. In accordance with the course of the vessel KK at the time of the first observation, we draw line I through point O and on this line at point O we construct heading angles KUa1 AND KUv1, measured by observers. Then we plot the OS segment, on a scale equal to the base.

Then from point C we draw a line CP parallel to OD. Next, from the point of intersection of lines CF with OE, draw line II, parallel to the course line, until it intersects with OD. The position of the segment AB will correspond to the position of the centerline plane of the vessel in circulation at the first moment of observation. If you make such constructions at every moment of observation - from the beginning of the maneuver to the turn to the opposite course, then you can draw the circulation, determine the size of its diameter, the width of the lane occupied by the vessel on the circulation, the drift angle, etc. The roll angle is determined by the inclinometer.

At two horizontal angles circulation elements can be determined in an area where there are three landmarks clearly visible from the ship. Moreover, their location must be such that the angles measured from the vessel in circulation between the middle and extreme landmarks vary within the range of no less than 30° and no more than 150°.

The ship must move at a given speed. From the moment the rudder is shifted, every 20-25 seconds, two observers on command simultaneously measure horizontal angles with sextants (Fig. 43, a) between objects AB (a) and BC (b). Then, on a large-scale map or plan, all observed points are plotted from the beginning of the circulation until the ship turns to the opposite course (P1, P2, etc.) and a smooth curve is drawn through them, which will be the circulation. Next, the diameter of the circulation and its other elements are determined.

Rice. 43

Along the alignment and horizontal corners it is possible to determine only the value of the tactical circulation diameter DT. To do this, it is necessary to have a target (Fig. 43, b) and another landmark located perpendicular to the target line at a known distance l. The vessel must approach the target line at a steady speed with a course perpendicular to it. At the moment of crossing the target, shift the rudder to the set angle, turn on the stopwatch and measure the angle a1 between the target line and landmark E. When the vessel arrives on a reverse course to the target line, stop the stopwatch, measure the angle a2 between the target line and landmark E.

The calculation of the tactical diameter is obtained from the expression

The accuracy of the calculated DT value will depend on the accuracy of the measured angles and the distance l.

The time counted by a stopwatch will give the duration half cycle of circulation, i.e. the time spent by the ship when turning 180°.

Circulation table

Let us assume that on a ship sailing on course AK1 (Fig. 44), at point B the rudder was shifted to the starboard side and, having described an arc S, at point C it rested on new course CK2 Arc S will be taken as an arc of a circle, the center of which is located at point O. By connecting points B, E and C with the center of circulation O, we obtain two pairs of symmetrically located right triangles EBF = ECF and BOE = COE, from which we obtain

where

and

Rice. 44

When the radius of circulation Rt and the angle of rotation a are known, then using formulas (31) and (32) it is possible to calculate the length d of the intermediate course (IR cp) and the distance d1 to the point of intersection of the new course with the original one.

In addition to these quantities, in practice there is a need to know the length of the turning path (arc) S and the turning time. To calculate S, use the formula

or
Where

To calculate the time of rotation T at a given angle, use the formula
To speed up graphical constructions on the map associated with calculations of the turning path length S, turning time Г, turning angle by

The intermediate course α/2 of the length d of the intermediate course and the distance d1 at turning angles up to 150° are prepared in advance by circulation tables. They are compiled for different rudder angles, travel speeds and vessel loading (laden and empty).

An example of such a table for a rudder angle of 15° at a speed of 10 knots, D T = 3 kbt, T 180 = 4 min is presented in Table 4. For rotation angles of more than 150°, such tables are not compiled, since the value of d1 becomes too large (d1 = RC t g a/2, a tgl80°=~). intermediate course length d intermediate course and distance

Table 4

Table 30 (MT-63) makes it possible to select, based on the values ​​of Rts and T 180, the circulation elements for different angles of rotation on a new course: S, d, d 1 T.

Circulation accounting methods

The moments of the vessel's turn to change course are usually calculated in advance and the turns are performed: abeam any lighthouse or sign; at the intersection of the secant alignment; upon arrival on the line of a pre-selected bearing of any landmark; according to the lag of a pre-calculated countdown or according to a pre-calculated point in time by the clock.

In all cases, the expected lag readings and clock time must be calculated for the intended turning moment. If it turns out that the actual log reading or clock time diverges from the pre-calculated ones, then it is necessary to immediately find an error in the calculations.

Having determined the moment of turning, they give a command to the helmsman, note the countdown of the log and the time on the clock. Then, on a map of scale 1:500,000 and larger, the necessary graphical constructions are made to plot the circulation. When sailing away from the coast, circulation elements are taken into account only with frequent course changes and when turning at an angle of more than 30°.

To calculate the angle of rotation a, use the following formulas: when turning to the right

and when turning left
Circulation elements can be taken into account using tabular or graphical techniques.

Table method. Let the ship follow course IR1 and make a turn at point A (Fig. 45, a). From this point at an angle a/2 to IR1, an intermediate course line is drawn, on which the value d selected from the table is plotted. 30 (MT-63). Point B will indicate the end of the turn. From this point a new course IR2 is carried out.

Rice. 45

In the case when the turning point A (Fig. 45, b) to the new course is unknown, proceed as follows. From point O (the point of intersection of courses), the distance dl9 selected from the table is set aside. 30 (MT-63) in the opposite direction along IK1 and IK2. The resulting points A and B will show the beginning and end of the turn, respectively. If the angle a > 150°, then the intermediate true course is preliminarily calculated using the formula
After this, from an arbitrary point F on the line IR1 (Fig. 45, c), a line IRsr is drawn and a segment FG = d is laid off from the same point on this line. Then the line of the new course is laid at such a distance from the line of the original course that between them above point F a segment equal in size to d can be accommodated. From point G, a parallel IRg is drawn, which, at the intersection with line IR2, will give point B - the end point of the turn to a new course, and a notch from point B with a compass with an opening equal to d, will give on line IR1 the starting point of turn A. In these cases Circulation curves (arcs) are usually not carried out, except in cases of navigation in narrow places, skerries, etc.

Graphic technique. Let us assume that the ship follows IR1 (Fig. 46, a), and from the starting point of the turn A sets a new course. From this point we restore the perpendicular to the line IR1 in the direction of the turn and on the perpendicular we plot the distance RC equal to the radius of circulation on the map scale. From the resulting point O as from the center with radius OA we describe the arc AB". To this arc we draw a tangent corresponding to the line IC2, the point of tangency B will be the end point of the turn.

Rice. 46

In cases where the starting and ending points of the turn are unknown, proceed as follows. Line IR2 is laid in the middle of the fairway or along the line of the target (Fig. 46, b), on which the ship should lie after the turn. Then, at arbitrary points on lines IR1 and IR2 (points A1 and B2), perpendiculars are restored, at which distances equal to the radius of circulation RC are laid. From the obtained points O1 and O2, lines are drawn parallel to the course lines. From the point of intersection of these lines (point O), as from a center with a radius equal to O1A1 (02B1), describe an arc; the points of tangency A and B with the true course lines will indicate the beginning and end of the turn.

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Vessel circulation

Under agility vessel implied his ability change direction movement under influence steering wheel (funds management) And move By trajectories given curvature.

Movement vessel With rearranged driving By curvilinear trajectories called circulation.

Rice. 2.17

The vessel's circulation is divided into three periods: maneuverable , equal to the rudder shift time; evolutionary - from the moment the rudder is shifted until the moment when the linear and angular speed of the vessel acquire steady-state values; steady - from the end of the evolutionary period until the steering wheel remains in the shifted position.

Rice. 2.18

It is impossible to define a clear boundary between the evolutionary period and the established circulation, since the change in the elements of movement fades gradually. Conventionally, we can assume that after a rotation of 160 - 180 O, the movement acquires a character close to steady-state. Thus, practical maneuvering of the vessel always occurs under unsteady conditions.

It is more convenient to express circulation elements during maneuvering in dimensionless form - in body lengths:

circulation ship steering wheel maneuvering

L 1 = L 1 /L; L 2 = L 2 /L; L 3 = L 3 /L; D T = D T /L; D mouth = D mouth /L,

V like this form easier compare between yourself agility various ships. How less dimensionless size, those better agility.

Circulation elements of a conventional transport vessel for given angle rudder shifts are practically independent of the initial speed under steady-state engine operation. However, if you increase the propeller speed when shifting the rudder, the ship will make a sharper turn. Than with unchangeable main engine mode.

Determination of circulation elements from natural observations

When performing a circulation, you can determine its elements if you make sequential determinations of the ship’s position using some landmarks at short time intervals (15 - 30 s). At the time of each observation, the measured navigation parameters and the course of the vessel are recorded. By plotting the observed points on the tablet and connecting them with a smooth curve, the ship’s trajectory is obtained. From which circulation elements are removed on an accepted scale.

Determinations of the vessel's position can be obtained from the bearing and distances of a free-floating landmark, such as a raft. With this method, the influence of an unknown current is automatically eliminated, and a special testing ground is not required.

The agility of a vessel means its ability to change the direction of movement under the influence of the rudder (controls) and move along a trajectory of a given curvature. The movement of a vessel with the rudder shifted along a curved trajectory is called. circulation. (Different points of the ship’s hull during circulation move along different trajectories, therefore, unless specifically stated, the ship’s trajectory means the trajectory of its CG.)

With such a movement, the bow of the vessel (Fig. 1) is directed into the circulation, and the angle a 0 between the tangent to the CG trajectory and the center plane (DP) is called. drift angle on circulation.

The center of curvature of this section of the trajectory is called. circulation center (CC), and the distance from CC to CG (point O) - circulation radius.

In Fig. 1 it can be seen that different points along the length of the vessel move along trajectories with different radii of curvature with a common center of gravity and have different drift angles. For a point located at the aft end, the radius of circulation and the drift angle are maximum. On DP the vessel has a special point - turning pole(PP), for which the drift angle is equal to zero, The position of the PP, determined by the perpendicular lowered from the CC to the DP, is shifted from the CG along the DP to the bow by approximately 0.4 of the ship’s length; The magnitude of this displacement varies within small limits on different vessels. For points on the DP located on opposite sides of the PP, the drift angles have opposite signs. The angular velocity of the vessel during circulation first quickly increases, reaches a maximum, and then, as the point of application of force Y o shifts towards the stern, decreases slightly. When the moments of forces P y and Y o balance each other, the angular velocity acquires a steady-state value.

The vessel's circulation is divided into three periods: maneuvering, equal to the time of shifting the rudder; evolutionary - from the moment the rudder is shifted until the moment when the linear and angular velocities of the vessel acquire steady-state values; steady - from the end of the evolutionary period until the steering wheel remains in the shifted position. The elements characterizing a typical circulation are (Fig. 2):

Extension l 1 - the distance by which the ship's center of gravity moves in the direction of the initial course from the moment the rudder is shifted until the course changes by 90°;

Direct displacement l 2 - the distance from the line of the original course to the center of gravity of the vessel at the moment when its course changed by 90°;

Reverse displacement l 3 - the distance by which, under the influence of the lateral force of the rudder, the ship’s center of gravity shifts from the original course line to the side, opposite direction turning;

Tactical circulation diameter D T - the shortest distance between the vessel’s DP at the beginning of the turn and its position at the moment of the course change by 180°;

The diameter of the steady circulation D mouth is the distance between the positions of the vessel's DP for two successive courses, differing by 180°, during steady motion.

It is impossible to define a clear boundary between the evolutionary period and the established circulation, since the change in the elements of movement fades out gradually. Conventionally, we can assume that after a rotation of 160-180°, the movement acquires a character close to the steady state. Thus, practical maneuvering of the vessel always occurs under unsteady conditions.

It is more convenient to express circulation elements during maneuvering in dimensionless form - in body lengths:

in this form it is easier to compare the agility of different vessels. The smaller the dimensionless value, the better the agility.

The circulation elements of a conventional transport vessel for a given rudder angle are practically independent of the initial speed at steady state engine operation. However, if you increase the propeller speed when shifting the rudder, the ship will make a sharper turn. , than with a constant mode of the main engine (MA).

Attached are two drawings.