Calculation of circulation elements. Quantitative estimates of the vessel's circulation Radius of circulation

The agility of the vessel is the ability to change the direction of movement under the influence of the rudder (controls) and move along the trajectory of a given curvature. The movement of a vessel with a shifted rudder along a curved trajectory is called circulation.
The vessel's circulation is divided into three periods:
- maneuverable, equal to the rudder shift time;
- evolutionary - from the end of the rudder shift until the moment when the linear and angular velocity of the vessel acquire steady-state values;
- steady-state - from the end of the evolutionary period and until the steering wheel remains in the shifted position.
It is impossible to define a clear boundary between the evolutionary period and the established circulation, since the change in the elements of motion fades out gradually. It can be conventionally considered that after a turn by 160-180 °, the movement acquires a character close to the steady-state one. Thus, the practical maneuvering of the vessel always occurs in an unsteady mode.
The trajectory of the curvilinear movement of the ship's center of gravity, that is, its circulation is characterized by the following elements (Fig. 1):

1. The diameter of the circulation is the main characteristic of the ship's (vessel's) turnability. Distinguish between the diameter of the tactical circulation and the diameter of the established circulation. The value of the circulation diameter depends on the ratio of length to width, rudder area and rudder angle, as well as the speed of the ship and the absence of the influence of external forces such as wind, waves and current. The circulation diameter is measured in meters, cable lengths or ship hull lengths (on average, it ranges from 4 to 8 hull lengths).
Tactical circulation diameter (Dt) is the normal distance between the return heading lines after turning the ship through the first 180 °. Determined at 15 ° and 25 ° rudder angles.
The diameter of the steady circulation (Dust) is the diameter of the circle along which the ship's center of mass moves after the angular velocity and roll on the circulation become constant, usually after the ship turns 180 °.
2. Extension (l1) - the distance by which the center of gravity of the vessel is shifted in the direction of the original heading from the point of the beginning of the circulation to the point corresponding to the change in the vessel’s heading by 90 °.
3. Forward displacement (l2) - the distance from the initial course of the vessel to the point of the center of gravity at the moment the vessel turns 90 °;
4. Reverse displacement (l3) - the greatest distance by which the center of gravity of the vessel is displaced from the line of the initial heading in the direction opposite to the turn.
The values of the circulation elements, expressed in fractions of the circulation diameter Dust, lie within relatively narrow limits and for vessels of various types change as follows:
Dt = (0.9 ± 1.2) × Dust;
l1 = (0.6 ± 1.3) × Dust;
l2 = (0.25 ± 0.5) × Dust;
l3 = (0 ± 0.1) × Dset.
For sea transport vessels, Dust is 4-6 vessel lengths. In addition to these elements, circulation characteristics include:
- period of steady circulation:
T is the time of the ship's turn by 360 °;
— angular velocity rotation of the vessel at steady circulation:
ω = 2π / T.
With an error of 5%, we can assume that the speed of transport vessels in circulation with a rudder on board when turning 60 ° is 80%, 90 ° - 73%, 180 ° - 58% of the original.
It is more convenient to express the elements of circulation during maneuvering in dimensionless form - in hull lengths: in this form it is easier to compare the turnability of different vessels. The smaller the dimensionless value, the better the agility. Circulation elements of a conventional transport vessel for a given rudder angle are practically independent of the initial speed at steady state engine operation. If, when shifting the rudder, the propeller speed is increased, the vessel will make a turn more abruptly than with the unchanged mode of the main engine.
When performing the circulation, you can determine its elements if you make successive determinations of the ship's position by some landmarks at short time intervals (15-30 s.). At the time of each observation, the measured navigation parameters and the ship's heading are recorded. By putting the points on the tablet and connecting them with a smooth curve, the trajectory of the vessel is obtained, from which the circulation elements are removed on the accepted scale. The position of the vessel can be determined 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 excluded, and a special polygon is not required.

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

With this movement, the bow of the ship (Fig. 1) is directed inward of the circulation, and the angle a0 between the tangent to the trajectory of the CG and the diametrical plane (DP) is called angledrift on circulation.

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

In fig. 1 that different points along the length of the ship move along trajectories with different radii of curvature with a common CC and have different drift angles. For a point located at the aft end, the radius of circulation and the angle of drift are maximum. On DP the vessel has a special point - swing pole(ПП), which the drift angle is equal to zero, The position of the ПП, determined by the perpendicular lowered from the CC to the DP, is displaced 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 LB located on opposite sides of the LB, the drift angles have opposite signs. The angular velocity of the vessel in the process of circulation first rapidly increases, reaches a maximum, and then, as the point of application of the force Yo shifts towards the stern, it slightly decreases. When the moments of forces of RuiYo balance each other, the angular velocity acquires a steady value.

The vessel's circulation is divided into three periods: maneuverable, equal to the rudder shift time; evolutionary - from the end of the rudder shift until the moment when the linear and angular velocities of the vessel acquire steady-state values; steady - from the end of the evolutionary period and as long as the rudder remains in the shifted position. The elements that characterize typical circulation are (Fig. 2):

Extension l1 is the distance by which the ship's CG moves in the direction of the initial heading from the moment the rudder is shifted until the course is changed by 90 °;

Forward displacement l2 is the distance from the initial position of the ship's CG to its position after turning by 90 °, measured along the normal to the initial direction of movement of the ship;

Reverse displacement l3 is the distance by which, under the influence of the lateral rudder force, the ship's CG is displaced from the line of the initial course in the direction opposite to the direction of rotation;

Tactical circulation diameter DT - the shortest distance between the ship's DP at the beginning of the turn and its position at the time of the change in course by 180 °;

The diameter of the steady circulation Dust is the distance between the positions of the ship's DP for two successive courses, differing by 180 °, with a 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 motion fades out gradually. It can be conditionally considered that after a turn of 160-180 °, the movement acquires a character close to the steady-state one. Thus, the practical maneuvering of the vessel always occurs in an unsteady mode.

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

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

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 the propeller speed is increased while shifting the rudder, the ship will make a steeper turn. , than with the unchanged mode of the main engine (MA).

Attached are two drawings.

Fig. 1 Fig. 2

By circulation is called the trajectory described by the ship's CG when moving with the rudder deflected at a constant angle. The circulation is characterized by linear and angular velocities, radius of curvature and drift angle. The angle between the vector of the linear speed of the ship and the DP is called drift angle... These characteristics do not remain constant throughout the entire maneuver.

It is customary to divide circulation into three periods: agile, evolutionary and steady-state.

Maneuverable period- the period during which the rudder is shifted to a certain angle. From the moment the rudder begins to shift, the vessel begins to drift in the direction opposite to the rudder shift, and at the same time begins to turn towards the rudder shift. During this period, the trajectory of the ship's CG from a straight line turns into a curved one with the center of curvature on the side of the side opposite to the side of the rudder stack; there is a drop in the speed of the vessel.

Evolutionary period- the period starting from the end of the rudder shift and continuing until the end of the change in the drift angle, linear and angular velocity. This period is characterized by a further decrease in speed (up to 30 - 50%), a change in the roll to the outer side and a sharp removal of the stern to the outer side.

Period of steady circulation- the period starting after the end of the evolutionary one is characterized by the balance of forces acting on the ship: the propeller stop, hydrodynamic forces on the rudder and hull, centrifugal force. The trajectory of the ship's CG is converted into a trajectory of a regular circle or close to it.

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

Do – diameter of steady circulation- the distance between the diametrical planes of the vessel on two successive courses, differing by 180 ° at steady motion;

Dц – tactical circulation diameter- the distance between the positions of the ship's DP before the start of the turn and at the time of changing the course by 180 °;

l1 – advancing- the distance between the positions of the ship's CG before going into circulation to the point of circulation, at which the ship's heading changes by 90 °;

l2 – forward bias- the distance from the initial position of the ship's CG to its position after a 90 ° turn, measured along the normal to the initial direction of movement of the ship;

l3 – reverse bias- the greatest displacement of the ship's CG as a result of drift in the direction opposite to the rudder shifting side (the reverse displacement usually does not exceed the ship's beam B, and on some ships it is absent at all);

Tts–circulation period- the time of the ship's turn by 360 °.

Rice. 1.8. Trajectory of the vessel in circulation

The characteristics of circulation listed above in sea transport vessels of medium tonnage with full rudder shifting on board can be expressed in fractions of the ship's length and in terms of the diameter of the established circulation by the following ratios:

Dо = (3 ÷ 6) L; Dc = (0.9 ÷ 1.2) Dy; l1 = (0.6 ÷ 1.2) Dо;

l2 = (0.5 ÷ 0.6) Dо; l3 = (0.05 ÷ 0.1) Dо; Tts = πDо / Vts.

Usually the values Do; Dts; l1; l2; l3 expressed in relative form (divided by the length of the ship L) - it is easier to compare the agility of different vessels. The smaller the dimensionless ratio, the better the agility.

Circulation speed for large vessels is reduced ° with rudder shifting on board by 30%, and with a 180 ° turn - by half.

The following provisions should be noted:

a) the initial speed has an effect not so much on Do, how many for its time and advance, and only high-speed vessels are noticeable Do v big side;

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

c) if, during the circulation, the number of revolutions of the main engine is increased, the vessel will make a steeper turn;

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

By circulation call the trajectory describedCT when moving with the rudder deflected at a constant angle. The circulation is characterized by linear and angular velocities, radius of curvature and drift angle. The angle between the vector of the linear speed of the vessel andDP are calleddrift angle ... These characteristics do not remain constant throughout the entire maneuver.

It is customary to divide circulation into three periods: agile, evolutionary and steady-state.

First period (maneuverable) - the period during which the rudder is shifted to a certain angle. From the moment the rudder begins to shift, the vessel 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 rudder shift. During this period, the trajectory of movementCT the vessel from rectilinear turns into curved with the center of curvature on the side of the side opposite to the side of the rudder; there is a drop in the speed of the vessel.

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

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

Circulation elements

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

Do - diameter of steady circulation - the distance between the diametrical planes of the vessel on two successive courses, differing by 180º at steady motion;

D c - tactical circulation diameter - distance between positionsDP the vessel before the start of the turn and at the moment when the course is changed by 180º;

l 1 - advance (gait) - ra
distance between positionsCT before turning the vessel up to the turning point at which the vessel's heading changes by 90º;

l 2 - forward displacement - distance from the original positionCT the vessel to its position after turning by 90º, measured along the normal to the initial direction of movement of the vessel;

l 3 - reverse bias - greatest displacementCT due to drift in the direction opposite to the rudder position (the reverse offset usually does not exceed the ship's breadthV , and on some ships is absent at all);

T c - circulation period - time of the ship's turn by 360º.

Dо = (3 ÷ 6) L ; Dц = (0.9 ÷ 1.2) D at ; l 1 = (0.6 ÷ 1.2) Dо ;

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

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

Turning speed for large vessels is reduced when turning 90º with rudder on board≈ on the⅓ , and when turning 180º - twice.

For arbitrary length su
bottom of the point "a The drift angle is determined from the well-known trigonometry formulas:

wherel a - distance of the point "a "FromCT (into the nose - "+ "; in the stern - "- »).

The following provisions should be noted:

a) the initial speed has an effect not so much onD O how much for her time and nominated; and only high-speed vessels show some changesD O upward;

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

c) if during circulation to increase the number of revolutionsDG , the ship will make a steeper turn;

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

whereR c.w. - the average radius of curvature of the circulation in the section from the initial to the course changed by 90º;

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

β is the drift angle.

The roll angle at steady circulation can be determined by the formula of G.A. Firsov:

(in degrees),

where V 0 - ship speed on a straight course (in m / s);

h - initial transverse metacentric height (m);

L - length of the vessel (m);

z g - ordinate CT vessel;

d - average draft ship.

TABLE OF MANEUVERABLE ELEMENTS

The maneuverable elements of the vessel are initially determined whenwater and full-scale tests for two displacement - a vessel #000000">with a full load and empty. Based on tests performedand additional calculations make up information about the maneuverable elements of the vessel(IMO Resolution No. A.601 (15)"Requirements for the display of maneuverable information on ships") ... The information consists of two parts:table of maneuverable elements, posted on the chassistic; additional information, taking into account the specifics of thisof the vessel and the dynamics of the influence of various factors on the maneuverablethe quality of the vessel under various sailing conditions.

To determine the maneuverable elements,any full-scale and full-scale calculation methods that provide accuratefinal 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 a noticeable current.

The table of maneuverable elements includes inertialcharacteristics of the vessel, elements of turnability, change in draftship, elements of propulsion, elements of maneuver for rescuing peopleka who fell overboard

Inertial characteristics are presented as lineargraphs built on a constant scale of distances and havethe scale of time and speed values. Braking distance from fronttheir moves to "Stop" are limited by the moment of loss of controllableship or final speed equal to 20% of the original. On the graphkax show with an arrow the most probable side of deviationfrom the initial track in the process of decreasing the speed.

Information about the agility is given in the form of a graph andblitz. The circulation graph reflects the position of the vessel after 30 °to the trajectory to the right and to the left with the rudder position "on board" and "onhalf board ". Similar information is presented in tabular form, but every 10 ° change 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, data aboutthe largest diameter of the circulation.

Movement elements are reflected in the form of a graphical dependencespeed of the vessel from the speed of the propeller and complementthe table, where the hour is indicated for each constant speed value.the rotation of the propeller.

The increase in the ship's draft is taken into account when heeling and sagging, when the ship moves at a limited depth with a certaingrowth.

Elements of a maneuver to rescue a person who has fallen overboard,
font> performed by receiving coordinates to the starboard or port side. In the informationMats indicate the following data for performing the correct maneuver: angle of turn from the initial course; operational timeshifting the rudder to the opposite side, entering the countercourse andto the starting point of the maneuver; actions of the boatmaster at every stageevolution.

V

all distances in the information on the maneuverable elements of the drivefire in cables, time in minutes, speed in knots.

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

The table of maneuverable elements is an operational minimum of data that is mandatory for each ship, which can be supplemented at the discretion of the ship's master or the maritime service.

The table should include:

Inertial characteristics.

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

The inertial characteristics are presented in the form of graphs built on a constant scale of distances and having a scale of values of time and speed.

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

Possible direction (arrow) and value (in kbt) of the vessel's lateral deviation from the initial track line and course change at the end of the maneuver (in deg.) Are indicated above the inertial and stopping distance charts. The listed characteristics are presented for two displacement of the vessel - in cargo and in ballast.

Agility elements.

In the form of a graph and a table during the circulation of the PPH to the right and left sides in cargo and in ballast with the rudder position "on board" (35 degrees) and "half board" (15 - 20 degrees).

The information should contain time intervals for every 10 degrees, in the range of changes in the initial rate of 0 - 90 degrees (on the graph, it is enough after 30 degrees), 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; the extension of the vessel along the line of the initial heading and displacement along the normal to it; initial, intermediate (90 degrees) and final speeds; the drift angle of the vessel in circulation.

Elements of travel. (Loaded and Ballast).

Dependence of the ship's speed on the propeller speed (CPP position) in the form of a graph and a table at a constant interval in revolutions. The zone of critical revolutions is highlighted on the graphs with a conventional sign (color).

Change in ship draft under the influence of heel and subsidence.

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

2 MISSING OF THE SHIP ABROAD

p / p	Title of the document
	VMP certificate (for port control in the fishing port for fishing vessels)
	Ship's Lists (certified by the Harbor Master)
	General declaration
	Cargo declaration
	Port clearance
	Currency certificate
	Ship Supply Declaration
	Copy of crew insurance policy
	Crew's effects declaration
	Incoming general declaration with a customs stamp
	Cargo Declaration with Customs Mark "Release Permitted"

SHIP'S DEPARTURE TO CABOTAGE

COMING FROM ABROAD

	Crew list
	Application for arrival
	General declaration
	Cargo declaration
	Currency certificate
	Declaration of Ship's Stores
	Cargo manifest
	Crew's effects declaration
	Information about cargo for port control

COMING FROM CABOTAGE

Ship documents

Issued by the Harbor Master

Certificate of the right to sail under State flag Of Russia

Certificate of ownership of the ship (unlimited)

Minimum Crew Certificate

Certificate of Provision of Civil Liability for Damage from Oil Pollution

Ship documents issued by the technical supervision body:

Passenger certificate

Permit for the right to use a ship radio station

Cargo Ship Safety Radiotelegraphy Certificate

Load line certificate (lowest freeboard)

Regional cargo certificate

Ship documents required by international conventions.

Passenger Ship Safety Certificate

Cargo Ship Safety Certificate of Construction

Cargo Ship Safety Certificate for Equipment and Supplies

Safety Certificate of a cargo ship by radiotelegraphy

Cargo Ship Safety Certificate by Radiotelephony

Withdrawal certificate

Nuclear Passenger Ship Safety Certificate(nuclear passenger ship) andNuclear Cargo Ship Safety Certificate [email protected] site

With this movement, the bow of the ship (Fig. 1) is directed inward of the circulation, and the angle a 0 between the tangent to the trajectory of the CG and the diametrical plane (DP) is called angle drift on circulation.

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

In fig. 1 that different points along the length of the ship move along trajectories with different radii of curvature with a common CC and have different drift angles. For a point located at the aft end, the radius of circulation and the angle of drift are maximum. On DP the vessel has a special point - swing pole (ПП), which the drift angle is equal to zero, The position of the ПП, determined by the perpendicular lowered from the CC to the DP, is displaced 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 LB located on opposite sides of the LB, the drift angles have opposite signs. The angular velocity of the vessel in the process of circulation first rapidly increases, reaches a maximum, and then, as the point of application of the force Y o shifts towards the stern, slightly decreases. When the moments of forces Р у and Y o will balance each other, the angular velocity acquires a steady value.

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

Forward displacement l 2 - the distance from the initial position of the ship's CG to its position after turning by 90 °, measured along the normal to the initial direction of movement of the ship;

Reverse displacement l 3 - the distance by which, under the influence of the lateral rudder force, the ship's CG is displaced from the line of the initial course in the direction opposite to the direction of rotation;

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

The diameter of the steady circulation D mouth is the distance between the positions of the ship's DP for two successive courses differing by 180 °, with 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 motion fades out gradually. Conventionally, we can assume that after turning 160-180 °, the movement takes on a character close to steady state. Thus, the practical maneuvering of the vessel always occurs in an unsteady mode.

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

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

Attached are two drawings.

Fig. 1 Fig. 2

It is customary to divide circulation into three periods: agile, evolutionary and steady-state.

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

D about – diameter of steady circulation- the distance between the diametrical planes of the vessel on two successive courses, differing by 180 ° at steady motion;

D c – tactical circulation diameter- the distance between the positions of the ship's DP before the start of the turn and at the time of changing the course by 180 °;

l 1 – advancing- the distance between the positions of the ship's CG before going into circulation to the point of circulation, at which the ship's heading changes by 90 °;

l 2 – forward bias- the distance from the initial position of the ship's CG to its position after a 90 ° turn, measured along the normal to the initial direction of movement of the ship;

l 3 – reverse bias- the greatest displacement of the ship's CG as a result of drift in the direction opposite to the rudder shifting side (the reverse displacement usually does not exceed the ship's beam B, and on some ships it is absent at all);

T c–circulation period- the time of the ship's turn by 360 °.

Rice. 1.8. Trajectory of the vessel in circulation

D about = (3 ÷ 6) L; D c = (0.9 ÷ 1.2) D y; l 1 = (0.6 ÷ 1.2) D about;

l 2 = (0.5 ÷ 0.6) D about; l 3 = (0.05 ÷ 0.1) D about; T c = πD o / V c.

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

Circulation speed for large vessels is reduced ° with rudder shifting on board by 30%, and with a 180 ° turn - by half.

The following provisions should be noted:

a) the initial speed has an effect not so much on D about, how many for its time and advance, and only high-speed vessels are noticeable D about upward;

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

c) if, during the circulation, the number of revolutions of the main engine is increased, the vessel will make a steeper turn;

The curvilinear trajectory, which is described by the center of gravity of the ship when the rudder is shifted to a certain angle and then held in this position, is called circulation.

There are three periods of circulation: maneuverable, evolutionary and the period of steady circulation. Maneuverable circulation period determined by the beginning and end of the rudder shift, i.e. in time coincides with the duration of the rudder shift. During this period, the ship continues to move almost in a straight line. Evolutionary circulation period begins from the moment of the end of the rudder shift and ends when the elements of movement take on a steady character, i.e. stop changing over time. The period of steady circulation begins from the moment of the end of the evolutionary period and lasts all the time while the rudder of the ship is in the shifted position.

The trajectory of the curvilinear movement of the ship's center of gravity, i.e. its circulation is characterized by the following elements:

The diameter of the steady circulation (D c)- the diameter of the circle described by the vessel during the steady circulation period, which begins after the vessel has turned 90-180 °; Tactical circulation diameter (D t)- the shortest distance between the position of the center line of the vessel at the beginning of the turn and after changing the initial course by 180 °. Extension l 1 the distance by which the ship's center of gravity shifts in the direction of the original heading from the point of the beginning of the turn to the point corresponding to the change in the ship's heading by 90 °. Forward displacement l 2- the distance from the initial course of the vessel to the point of the center of gravity at the moment the vessel turns 90 °. Reverse displacement l 3- the greatest distance by which the center of gravity of the vessel is shifted from the line of the initial heading in the direction opposite to the turn.

Also, the characteristics of circulation include: the period of steady circulation T - the time of rotation of the vessel by 360 °; the angular velocity of rotation of the vessel at steady circulation ω = 2π / T.

Steps to prepare the steering gear before leaving the vessel to sea

Gyrocompass directions. Gyro compass correction

Gyrocompass meridian - the direction in which the main axis of the gyrocompass is set

Gyrocompass heading - the direction of the ship's centerline measured by the horizontal angle between the northern part of the gyrocompass meridian and the bow of the ship's centerline.

Gyrocompass bearing - direction to a landmark measured by the horizontal angle between the northern part of the gyrocompass meridian and the bearing line.

Backward gyrocompass bearing - the direction opposite to the direction of the object.

Gyrocompass correction - the angle in the plane of the true horizon between the true and gyrocompass meridians.

Types of ship pitching. Rolling elements

Ship pitching- oscillatory movements that the vessel makes about its equilibrium position. There are three types of rolling of ships: a) vertical- vibrations of the vessel in vertical plane in the form of periodic translational movements; b) onboard(or lateral) -vibrations of the vessel in the plane of the frames in the form of angular displacements; v) keel(or longitudinal) roll - oscillations of the vessel in the center plane, also in the form of angular displacements. When a vessel is sailing on rough water surface, often all three types of pitching occur simultaneously or in different combinations.

Two types of vibrations of the ship while pitching: free(on the calm water), which occur by inertia after the termination of the forces that caused them, and forced which are caused by external periodically applied forces, for example, sea waves.

Rolling elements:

Roll amplitude (a) - the greatest deviation of the vessel from the initial position, measured in degrees. Swing swing(b) - the sum of two successive amplitudes (inclination of the vessel on both sides).

Movement period (in)- the time between two successive inclinations or the time during which the ship makes full cycle fluctuations, returning to the position at which the countdown began.

28 (10.1) Name the features of the steering modes: "simple", "tracking", "automatic"