Ship rudder system center line variation monitoring method and tool

Abstract

The application discloses a ship rudder system center line variation monitoring method and tool, which comprises the following steps: after the upper reference point is calibrated, the upper reference point is transferred to a ship body process hole sleeve pipe to serve as an upper fixed reference point; a fixed centering plate is arranged at the lower reference point; a steel wire is pulled between the upper fixed reference point and the lower reference point; the offset of the upper opening of the rudder stock upper bearing seat, the process hole sleeve pipe and the lower opening of the rudder stock lower bearing seat is measured respectively relative to the steel wire, and initial data is recorded; during the construction process, each offset is repeatedly measured periodically; whether the steel wire reference point is offset is determined according to the change of the offset of the process hole sleeve pipe and the lower opening of the rudder stock lower bearing seat; the rudder system center line variation is determined according to the change of the offset of the upper opening of the rudder stock upper bearing seat; when the steel wire is broken, a new steel wire can be pulled again, and the reference point remains unchanged.

Description

Technical Field

[0001] This invention relates to the field of ship repair technology, specifically to a method and tooling for monitoring changes in the centerline of a ship's steering system. Background Technology

[0002] In ship repair and conversion projects, the positional accuracy of the rudder system centerline directly affects the installation quality of the rudder equipment and navigational safety. The rudder system centerline refers to the theoretical axis of rotation of the rudder stock, and the coaxiality of the upper and lower rudder bearings on the rudder stock is the core indicator of the rudder system centerline positional accuracy. During large-area plate replacement and other repair work in the rudder gear area, the welding heat input can cause local deformation of the hull structure, which in turn causes the center position of the rudder bearing on the rudder stock to shift. If this shift is not monitored and controlled in time, it may lead to serious consequences such as eccentric friction between the rudder stock and the rudder bearing, rudder stock bending, or even rudder system jamming.

[0003] Taking a dry-docking project as an example, the steering gear deck and lower cavity require large-scale plate replacement. During construction, the center of the rudder bearing seat on the rudder stock needs to be monitored for changes in order to adjust the welding sequence in a timely manner and control the positional accuracy of the rudder system centerline. However, this monitoring task is limited by the following conditions: the plate replacement work must be completed in a floating state, and the monitoring work is correspondingly carried out in a floating state. The hull is constantly moving slightly with the waves, making it difficult to establish a stable measurement benchmark using traditional measurement methods; the upper level of the steering gear room is the crew's living area, and its normal use cannot be affected during the plate replacement process; the confined space on site makes laser inspection equipment unsuitable. Summary of the Invention

[0004] This invention provides a method and tooling for monitoring changes in the centerline of a ship's steering system, comprising the following steps: S1. Set the lower rudder bearing of the rudder stock as the lower reference point and the upper rudder bearing seat of the rudder stock as the upper reference point. S2. After the upper reference point is calibrated, it is transferred to the process hole sleeve of the hull as the upper fixed reference point. A fixed centering plate is provided at the lower reference point. S3. Stretch a steel wire between the upper fixed reference point and the lower reference point, so that the steel wire passes through the upper opening of the upper rudder bearing seat of the rudder stock at the same time. Measure the first offset of the upper opening of the upper rudder bearing seat of the rudder stock relative to the steel wire, the second offset of the process hole sleeve relative to the steel wire, and the third offset of the lower opening of the lower rudder bearing seat of the rudder stock relative to the steel wire, and record the initial data. S4. During construction, if the steel wire breaks, a new steel wire shall be re-stretched between the upper fixed reference point and the lower reference point. S5. Periodically repeat the measurement of the first offset, the second offset, and the third offset, compare each actual offset with the corresponding initial data, determine whether the wire reference has shifted based on the changes in the second offset and the third offset, and determine the amount of change in the center line of the rudder bearing seat on the rudder stock based on the change in the first offset.

[0005] Furthermore, each of the first offset, the second offset, and the third offset includes a horizontal offset and a vertical offset. The horizontal offset is the radial distance of the measuring point relative to the steel wire in a plane perpendicular to the steel wire axis, and the vertical offset is the axial distance of the measuring point relative to the horizontal plane where the steel wire is located.

[0006] Furthermore, the horizontal offset includes at least three component values ​​that are not in the same straight line direction. These three component values ​​are used to determine the two-dimensional position coordinates of the measuring point in a plane perpendicular to the wire axis and its trajectory relative to the initial position.

[0007] Furthermore, the vertical offset is used to determine the change in the amount of sag of the steel wire caused by changes in the tension of the load or the temperature. When the vertical offset in the second offset or the vertical offset in the third offset changes, it is determined that the amount of sag of the steel wire has changed.

[0008] Furthermore, in step S3, the lower end of the steel wire is connected to a hanging weight, which is immersed in the oil damper.

[0009] Furthermore, in step S3, a torsion indicator is provided on the steel wire. The torsion angle data of the torsion indicator is recorded synchronously each time the offset is measured. The first offset, the second offset, and the third offset are corrected based on the torsion angle data to eliminate the influence of steel wire torsion on the offset measurement results.

[0010] Furthermore, the corrected actual offset is compared with the initial data. When the corrected second offset or the corrected third offset changes relative to the initial data, it is determined that the wire reference has shifted, the wire is re-stretched, and the initial data is re-recorded. When both the corrected second offset and the corrected third offset do not change relative to the initial data, it is determined that the wire reference is stable, and the change in the corrected first offset is the actual change in the center line of the rudder bearing seat on the rudder stock.

[0011] This invention also provides a tooling for monitoring changes in the centerline of the rudder system, comprising: an upper reference assembly disposed at the process hole sleeve on the top of the rudder gear room, the upper reference assembly including a stop plate fixedly installed at the lower part of the process hole sleeve, the stop plate having a first through hole for a steel wire to pass through; a lower reference assembly disposed at the lower opening of the rudder bearing on the rudder stock, the lower reference assembly including a fixed centering plate, the fixed centering plate having a second through hole for a steel wire to pass through at its center; an intermediate measuring assembly disposed at the upper opening of the rudder bearing seat on the rudder stock, the intermediate measuring assembly including a measuring plate, the measuring plate having at least three measuring reference surfaces or measuring reference points not on the same straight line; and a wire guide frame disposed on the front of the second deck of the hull for fixing the upper end of the steel wire.

[0012] Furthermore, the stop plate includes a sleeve body and a stop plate, the stop plate being fixedly connected to the lower end of the sleeve body, and the first through hole being opened at the center of the stop plate.

[0013] Furthermore, the fixed centering plate is provided with multiple hand holes and a detachable center plug, and the second through hole is opened at the center of the center plug.

[0014] This invention establishes two permanently fixed reference points by setting an upper reference component at the process hole sleeve on the top of the rudder gear room and a lower reference component at the lower rudder bearing opening on the rudder stock. Even if the steel wire breaks, it can be restored to the original reference position after a new steel wire is installed. By simultaneously measuring the offset of three points—the upper rudder bearing housing opening on the rudder stock, and the lower rudder bearing opening on the rudder stock—relative to the steel wire, the two endpoints of these three points are used as verification points for the steel wire reference. Only when neither of the two endpoints has shifted is the offset of the midpoint considered as the true change in the rudder system centerline, thus eliminating the contamination of measurement data by the steel wire reference's own offset. By decomposing the offset into horizontal and vertical offsets, centerline changes in three-dimensional space are monitored.

[0015] This invention eliminates the influence of wire torsion on measurement results by setting a torsion indicator on the steel wire and simultaneously recording the torsion angle to correct the offset. By installing an oil damper at the lower end to suppress the swaying of the suspended load, the stability of the steel wire in a floating state is improved. By integrating a process plate and seals into the tooling, the construction area and living area are isolated, meeting the practical needs of ship repair sites for enclosed construction and protection against rain and smoke. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the tooling shown in this invention.

[0017] Figure label: 1. Lower reference point, 2. Upper reference point, 3. Process hole sleeve, 4. Stop plate, 5. Centering plate, 6. Steel wire, 7. Measuring plate, 8. Pull wire frame, 9. Hand hole, 10. Center end cap, 11. Oil damper. Detailed Implementation

[0018] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of this application and not intended to limit it. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0019] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0020] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0021] Figure 1 This is a schematic diagram of the structure of the ship's rudder system centerline change monitoring fixture of the present invention. Figure 1 As shown, the present invention provides a method and tooling for monitoring changes in the centerline of a ship's rudder system, which is mainly used for monitoring changes in the center position of the rudder bearing seat on the rudder stock during large-area plate replacement construction in the rudder gear area under floating conditions.

[0022] The rudder system centerline change monitoring fixture of the present invention mainly includes an upper reference component, a lower reference component, an intermediate measuring component, and a cable puller 8.

[0023] The upper reference component is located at the process hole sleeve 3 on the top of the steering gear room. The process hole sleeve 3 is an existing structure on the hull, penetrating the top deck of the steering gear room, and is typically used for pipe installation or process passages. This invention utilizes this existing structure, fixing a stop plate 4 to the lower part of the process hole sleeve 3. The stop plate 4 is a flat plate component with a first through hole in the center for the steel wire 6 to pass through. The fixing connection between the stop plate 4 and the process hole sleeve 3 can be welding or bolting. Since the process hole sleeve 3 is fixedly connected to the hull structure, the stop plate 4 becomes part of the hull structure after installation, and its position will not change during construction, forming a permanent fixed reference point for the upper end of the steel wire 6.

[0024] The lower reference assembly is located at the lower rudder bearing opening of the rudder stock. The lower rudder bearing opening is located at the bottom of the steering gear compartment, where it is not directly disturbed by the plate replacement work. The lower reference assembly includes a fixed centering plate 5. A second through hole for the steel wire 6 to pass through is provided in the center of the centering plate 5. The centering plate 5 is fixedly installed on the hull structure near the lower rudder bearing opening of the rudder stock, forming another permanent fixed reference point for the lower end of the steel wire 6. The centering plate 5 also has multiple handholes 9 and a detachable center plug 10. The handholes 9 are used by operators to reach in for threading the steel wire 6 and lifting the load. The center plug 10 is detachably installed in the center of the centering plate 5, and the second through hole is located in the center of the center plug 10. When it is necessary to thread or replace the steel wire 6, the center plug 10 can be removed for operation; after the steel wire 6 is threaded, the center plug 10 can be installed to position the steel wire 6 in the center position. The centering plate 5 is also provided with a fixing screw seat, which is used to detachably fix the center plug 10 to the centering plate 5.

[0025] The intermediate measuring component is located at the upper opening of the rudder bearing seat on the rudder stock. The upper opening of the rudder bearing seat is located inside the rudder gear room, at the upper bearing position of the rudder stock, and is a critical area requiring monitoring of its center position during plate replacement. The intermediate measuring component includes a measuring plate 7, which is fixedly installed on the upper edge or circumferential side of the rudder bearing seat on the rudder stock. The measuring plate 7 has at least three non-collinear measuring reference surfaces or points, used in conjunction with measuring tools to read the offset of the upper opening of the rudder bearing seat on the rudder stock relative to the steel wire 6.

[0026] The cable holder 8 is located on the front of the second deck of the ship and is used to fix the upper end of the steel wire 6. The cable holder 8 has an adjustable fixing hole through which the steel wire 6 passes and is connected to the hanging weight.

[0027] The tooling of this invention also includes a process plate and a sealing element. The process plate is installed on each deck level to seal the passageway between the construction area and non-construction areas. Sealing rings and sealing plates are installed corresponding to the process plate to prevent welding fumes from entering non-construction areas (such as crew living quarters) and to prevent rainwater from entering the steering gear room. The sealing element creates a physical isolation between the construction area and the living quarters, while the steel wire 6 can pass through pre-drilled holes in the sealing element, ensuring that the sealing does not affect the normal operation of monitoring work.

[0028] The upper rudder bearing seat on the rudder stock (upper reference point 2) was originally the ideal monitoring location, but it is directly located within the plate replacement construction area. During construction, it is subject to interference from various factors such as welding heat input, structural deformation, and personnel activity, making it unsuitable as a long-term stable measurement reference. Therefore, this invention calibrates and transfers upper reference point 2 to the hull process hole sleeve 3 on the top of the steering gear room. This location is outside the construction heat-affected zone and is not affected by personnel activity, thus remaining relatively fixed. Lower reference point 1 is also located in an area undisturbed by construction and is kept in place by a fixed centering plate 5.

[0029] Both the upper fixed reference point (process hole sleeve 3) and the lower reference point (at the lower end of the rudder bearing on the rudder stock) are set on a fixed structure undisturbed by construction. A steel wire 6 is stretched between the two, forming a reference line connecting the two permanent fixed reference points. The steel wire 6 itself may break during construction due to accidental collision or fatigue, but because the positions of its two ends remain unchanged, the newly stretched steel wire 6 will automatically be positioned on the same reference line as the original wire. This means that after the steel wire 6 breaks, there is no need to re-establish the reference; simply re-threading a new steel wire is sufficient to restore monitoring, ensuring the continuity of monitoring work during construction.

[0030] As a flexible body, steel wire 6 may shift due to external disturbances during construction. To determine whether steel wire 6 is in the correct position, this invention simultaneously measures the offset of three points relative to steel wire 6: the process hole sleeve 3, the upper opening of the rudder bearing seat on the rudder stock (i.e., the monitored point), and the lower opening of the rudder bearing on the rudder stock. The upper and lower endpoints are the two endpoints of steel wire 6. If the offset of either endpoint relative to steel wire 6 remains unchanged, it indicates that the positions of both endpoints of steel wire 6 have not changed, meaning that steel wire 6 itself is in a stable reference position. In this case, the change in the offset of the monitored point represents the actual change in the rudder system centerline. If the offset of either endpoint changes, it indicates that the endpoint of steel wire 6 has shifted, meaning that the steel wire reference itself has shifted. In this case, the measurement data of the monitored point is unreliable, and steel wire 6 needs to be readjusted to the correct position.

[0031] Traditional wire-pulling methods only measure offsets in the horizontal plane, while the movement of the rudder system's centerline is a three-dimensional change. This invention decomposes the offset into horizontal and vertical offsets. The horizontal offset is the radial distance of the measuring point relative to the wire in a plane perpendicular to the wire's axis, used to determine the positional change of the measuring point in the horizontal plane. The vertical offset is the axial distance of the measuring point relative to the horizontal plane containing the wire, used to determine the positional change of the measuring point in the vertical direction. The horizontal offset includes at least three components that are not in the same straight direction. These three components are used to determine the two-dimensional position coordinates of the measuring point in a plane perpendicular to the wire's axis and its trajectory relative to the initial position. The vertical offset is also used to monitor changes in the wire's sag. When the vertical offsets at the upper and lower endpoints change, it indicates a change in the wire's sag, requiring readjustment of the load or re-laying of the wire.

[0032] When floating, the steel wire 6 may twist due to the swaying of the hanging weight or the effect of wind. This twisting causes a change in the azimuth angle of the steel wire 6 at the measuring point, thus affecting the accuracy of the offset measurement. This invention provides a twist indicator (such as a lightweight pointer, reflective mark, or graduated ring) on ​​the steel wire 6. The twist angle data of the twist indicator is recorded synchronously each time the offset is measured. The first, second, and third offsets are corrected based on the twist angle data, eliminating the influence of steel wire twisting on the offset measurement results.

[0033] A weight is attached to the lower end of the steel wire 6, which is used to tighten the steel wire 6 and keep it taut. In a floating state, the hull sways with the waves, causing the weight to swing and the steel wire 6 to sway. In this invention, the weight is immersed in an oil damper 11. The oil damper 11 includes a sealed container and damping oil filled within the sealed container. The weight is completely immersed in the damping oil, and the bottom of the sealed container is fixedly connected to the hull. When the weight tends to sway due to the hull's movement, the viscous resistance of the damping oil consumes the energy of the sway, suppressing the weight's sway and thus preventing the steel wire 6 from being unnecessarily affected by tidal forces or other factors during limited hull movements.

[0034] The method of the present invention includes the following steps: S1. Set the lower rudder bearing of the rudder stock as the lower reference point 1, and set the upper rudder bearing seat of the rudder stock as the upper reference point 2.

[0035] S2. After calibrating the upper reference point 2, transfer it to the process hole sleeve 3 on the top of the steering gear room as the upper fixed reference point. The specific operation is as follows: Set a first positioning target at the upper reference point 2, and a second positioning target at the process hole sleeve 3. Use a plumb bob or spirit level to transfer the center position of the first positioning target to the second positioning target, ensuring that the second and first positioning targets are on the same vertical line. A fixed centering plate 5 is installed at the lower reference point 1; the center position of the centering plate 5 is not adjustable.

[0036] S3. Stretch a steel wire 6 between the upper fixed reference point and the lower reference point 1, so that the steel wire 6 passes through the upper opening of the rudder bearing seat on the rudder stock. The specific operation method is as follows: Open the process access doors of each deck, install the process plate, sealing ring, and sealing plate in sequence, and weld the measuring plate 7 in four directions on the lower outer side of the hull process sleeve on the back of the first deck (i.e., the top of the steering gear room). Pass the upper end of the steel wire 6 through the adjustable fixing hole of the wire guide 8 and fix it. Pass the lower end of the steel wire 6 through the first through hole of the stop plate 4, the upper opening of the rudder bearing seat on the rudder stock, and the second through hole of the centering plate 5, and then connect it to the hanging weight. The hanging weight is immersed in the oil damper 11.

[0037] Measure the first offset of the upper opening of the rudder bearing seat on the rudder stock relative to the steel wire 6, the second offset of the process hole sleeve 3 relative to the steel wire 6, and the third offset of the lower opening of the rudder bearing on the rudder stock relative to the steel wire 6, and record the initial data. Each offset includes a horizontal offset and a vertical offset, and the horizontal offset includes at least three component values ​​that are not in the same straight direction.

[0038] S4. During construction, if steel wire 6 breaks due to accidental collision or fatigue, a new steel wire is re-stretched between the upper fixed reference point and the lower reference point 1. Since the positions of the upper fixed reference point and the lower reference point 1 remain unchanged, the new steel wire and the broken steel wire are located on the same reference line. The specific operation method is as follows: remove the center end cap 10 of the centering plate 5, remove the broken steel wire through the handhole 9, pass the lower end of the new steel wire through the second through hole and connect it to the hanging weight, pass the upper end of the new steel wire through the adjustable fixing hole of the wire frame 8 and fix it, and reinstall the center end cap 10.

[0039] Step S5: Periodically repeat the measurements of the first, second, and third offsets. Use vernier calipers, dial indicators, or specialized measuring tools, positioned perpendicular to the steel wire 6. Simultaneously record the torsion angle data from the torsion indicator on the steel wire 6, and correct the measured offsets for torsion. Compare the corrected actual offset with the corresponding initial data. If the corrected second or third offset changes relative to the initial data, it is determined that the steel wire reference has shifted; the steel wire is then re-stretched, and the initial data is recorded again. If both the corrected second and third offsets remain unchanged relative to the initial data, the steel wire reference is considered stable, and the change in the corrected first offset is the true change in the centerline of the rudder bearing seat on the rudder stock.

[0040] Example 1 Taking a steering gear area plate replacement project as an example, the lower rudder bearing of the rudder stock is located at the bottom of the steering gear compartment, approximately 15m from the process hole sleeve at the top of the steering gear room. The tooling and method of this invention are used to monitor the change in the centerline of the steering system.

[0041] Install the tooling according to the steps described above. Use 1.0mm diameter stainless steel wire, with a hanging weight of 10kg, and immerse it in the oil damper. Before starting the plate replacement work, complete the initial data measurement and record the initial values ​​of the horizontal and vertical offsets at the process hole sleeve, the upper opening of the rudder bearing seat on the rudder stock, and the lower opening of the rudder bearing on the rudder stock.

[0042] On the third day after construction began, the vertical offset at the process hole sleeve changed by 0.5 mm compared to the initial value, the horizontal offset at the upper opening of the rudder bearing seat on the rudder stock changed by 1.2 mm, and the vertical offset at the lower opening of the rudder bearing on the rudder stock changed by 0.6 mm. According to the verification logic, the vertical offsets at both ends changed, indicating that the sag of the steel wire had changed (analyzed to be thermal expansion and elongation of the steel wire due to increased ambient temperature). At this point, it was determined that the steel wire reference had shifted, and the measurement data at the monitored points were temporarily unreliable. The operators readjusted the weight to restore the tension of the steel wire, remeasured the vertical offsets at both ends, confirmed that they had returned to the initial value, and then remeasured the offset at the monitored points and recorded the new initial data.

[0043] On the 15th day of construction, the steel wire broke due to an accidental collision. The operators replaced the wire with a new one through a manhole, re-stretched it, and measured the offset of the upper and lower endpoints. Comparison with the initial data showed no change, confirming that the new wire was on the correct baseline, and monitoring continued. The entire plate replacement construction cycle was approximately 25 days, with continuous monitoring that was not interrupted by the wire breakage or baseline drift.

[0044] Example 2 Ten repeated measurements were performed at the same workstation, and the torsion angle data of the torsion indicator was recorded at each measurement.

[0045] The standard deviation of the uncorrected measurement data was 0.35 mm, while the standard deviation of the measurement data after torsion correction was 0.12 mm, resulting in an improvement in measurement accuracy of approximately 65%.

[0046] A lightweight pointer is fixedly installed on the steel wire approximately 200mm from the top of the rudder bearing seat on the rudder stock as a torsion indicator. The pointer extends outward perpendicular to the axis of the steel wire. Next to the pointer, a protractor scale fixed to the hull structure is installed, with the center of the scale coinciding with the axis of the steel wire. When the steel wire twists, the pointer rotates with the steel wire, and the operator can obtain the torsion angle θ by reading the deflection angle of the pointer on the scale.

[0047] Because the twisting of the steel wire causes a change in the spatial orientation of the measuring point relative to the measurement reference plane, the measured offset R_measurement includes an error component introduced by the twisting. Let the radial distance between the measuring point and the steel wire axis be r, then the error component introduced by the twisting Δ = r × sinθ. The corrected measured value = measured value - error component.

[0048] Each time the offset is measured, the value of the torsion angle θ is recorded simultaneously. The measuring tool is a set of four dial indicators, arranged in the horizontal and vertical directions respectively. The probes of the dial indicators are perpendicular to the steel wire axis and abut against the respective measuring reference surfaces of the measuring plate 7.

[0049] Comparative Example The centerline of the same rudder system was monitored using the traditional wire-stayed method. Two days after the wire was laid, it shifted due to accidental contact by construction workers. Lacking dual-reference calibration, the operators failed to detect the shift in reference in time and continued to measure and record erroneous offset data. Subsequently, during the installation of the rudder bearing on the rudder stock, an excessive positional deviation was discovered. Investigation confirmed that this was caused by incorrect monitoring data, resulting in rework and a delay of approximately three days.

[0050] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for monitoring changes in the centerline of a ship's steering system, characterized in that, Includes the following steps: S1. Set the lower rudder bearing of the rudder stock as the lower reference point and the upper rudder bearing seat of the rudder stock as the upper reference point. S2. After the upper reference point is calibrated, it is transferred to the process hole sleeve of the hull as the upper fixed reference point. A fixed centering plate is provided at the lower reference point. S3. Stretch a steel wire between the upper fixed reference point and the lower reference point, so that the steel wire passes through the upper opening of the upper rudder bearing seat of the rudder stock at the same time. Measure the first offset of the upper opening of the upper rudder bearing seat of the rudder stock relative to the steel wire, the second offset of the process hole sleeve relative to the steel wire, and the third offset of the lower opening of the lower rudder bearing of the rudder stock relative to the steel wire, and record the initial data. S4. During construction, if the steel wire breaks, a new steel wire shall be re-stretched between the upper fixed reference point and the lower reference point. S5. Periodically repeat the measurement of the first offset, the second offset, and the third offset, compare each actual offset with the corresponding initial data, determine whether the wire reference has shifted based on the changes in the second offset and the third offset, and determine the amount of change in the center line of the rudder bearing seat on the rudder stock based on the change in the first offset.

2. The method according to claim 1, characterized in that, Each of the first offset, the second offset, and the third offset includes a horizontal offset and a vertical offset. The horizontal offset is the radial distance of the measuring point relative to the steel wire in a plane perpendicular to the steel wire axis, and the vertical offset is the axial distance of the measuring point relative to the horizontal plane where the steel wire is located.

3. The method according to claim 2, characterized in that, The horizontal offset includes at least three component values ​​that are not in the same straight line direction. These three component values ​​are used to determine the two-dimensional position coordinates of the measuring point in a plane perpendicular to the wire axis and its trajectory relative to the initial position.

4. The method according to claim 2, characterized in that, The vertical offset is used to determine the change in the amount of sag of the steel wire caused by changes in the tension of the load or the temperature. When the vertical offset in the second offset or the vertical offset in the third offset changes, it is determined that the amount of sag of the steel wire has changed.

5. The method according to claim 1, characterized in that, In step S3, the lower end of the steel wire is connected to a hanging weight, which is immersed in the oil damper.

6. The method according to claim 1, characterized in that, In step S3, a torsion indicator is provided on the steel wire. The torsion angle data of the torsion indicator is recorded synchronously each time the offset is measured. The first offset, the second offset, and the third offset are corrected based on the torsion angle data to eliminate the influence of steel wire torsion on the offset measurement results.

7. The method according to claim 6, characterized in that, In step S5, the corrected actual offset is compared with the initial data. When the corrected second offset or the corrected third offset changes relative to the initial data, it is determined that the steel wire reference has shifted, the steel wire is re-pulled, and the initial data is re-recorded. When both the corrected second offset and the corrected third offset remain unchanged relative to the initial data, the wire reference is determined to be stable, and the change in the corrected first offset is the actual change in the center line of the rudder bearing seat on the rudder stock.

8. A tooling for monitoring changes in the centerline of a steering system, characterized in that, include: The upper reference assembly is located at the process hole sleeve on the top of the steering gear room. The upper reference assembly includes a stop plate fixedly installed at the lower part of the process hole sleeve. The stop plate has a first through hole for a steel wire to pass through. The lower reference assembly is located at the lower opening of the rudder bearing under the rudder stock. The lower reference assembly includes a fixed centering plate, and the centering plate has a second through hole for a steel wire to pass through. An intermediate measurement component is located at the upper opening of the rudder bearing seat on the rudder stock. The intermediate measurement component includes a measurement plate, and the measurement plate is provided with at least three measurement reference surfaces or measurement reference points that are not on the same straight line. The wire rack is located on the front of the second deck of the ship and is used to fix the upper end of the steel wire.

9. The tooling according to claim 8, characterized in that, The stop plate includes a sleeve body and a stop plate, the stop plate is fixedly connected to the lower end of the sleeve body, and the first through hole is opened at the center of the stop plate.

10. The tooling according to claim 8, characterized in that, The fixed centering plate is provided with multiple hand holes and a detachable center end cap, and the second through hole is opened at the center of the center end cap.

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