A method for benchmarking and base installation of an ultra-long shaft system

Abstract

The present application provides a method for benchmarking and base installation of an ultra-long shaft system, comprising: S1, locating and surveying the bow and stern reference points of the shaft system in the hull; S2, surveying a coordinate system in the hull with the bow and stern reference points as references, and surveying the position of the intermediate light target in the surveyed coordinate system; S3, pulling the axis steel wire with the surveyed bow and stern reference points and the intermediate light target as references; S4, calculating the three-dimensional coordinates of the shaft system base in the surveyed coordinate system, locating the longitudinal coordinates of the shaft system base with the intermediate light target as reference, and locating the transverse and vertical coordinates of the shaft system base with the axis steel wire as reference; S5, according to the calculated transverse, longitudinal, and vertical coordinate values, cutting a preset margin at the bottom of the shaft system base, and then positioning and installing the shaft system base. This method solves the problem that traditional laser theodolites cannot meet the accuracy requirements within an ultra-long range and the problem that the base positioning is difficult due to the longitudinal inclination angle and flared angle of the ultra-long shaft system.

Description

Technical Field

[0001] The present application relates to the technical field of ship shafting installation, and in particular to a method for benchmarking and base installation of an ultra-long shafting. Background Art

[0002] The quality of ship shafting installation is directly related to the reliability of the ship's power system, the safety of the ship's navigation, and the personal safety of passengers. The installation of ship shafting is mainly carried out through the base, which is positioned by the reference.

[0003] During traditional installation, shafting benchmark surveys typically use a laser theodolite to locate the datum. This involves illuminating the fore and aft datum points with the laser theodolite. Once the benchmark is complete, the main transverse bulkhead and the ship's centerline are typically used as the positioning reference during the base installation process.

[0004] However, with the development of new ships, ultra-long shafting (lengths greater than 80m) has been developed to meet the navigation requirements of these new ships. To further meet high-speed requirements and reduce the mutual influence between shafts during operation, ultra-long shafting will be installed inside the hull with flared and pitch angles. For such ultra-long shafting, if the traditional shafting base installation method is continued, on the one hand, the theodolite laser beam will scatter after exceeding a range of 80m, and the laser beam cannot be focused on a single point, resulting in low accuracy in the shafting benchmark survey. The accuracy deviation of the benchmark will bring great quality risks to the entire shafting base and equipment installation. On the other hand, because the ultra-long shafting has two installation angles (flared and pitch), if the base is still installed with reference to the main transverse bulkhead and the hull centerline, it will be difficult to monitor the positioning data, affecting the accuracy of the base installation and failing to meet the accuracy requirements of the axis's pitch and flared angles.

[0005] Therefore, there is an urgent need to provide a new shafting benchmark survey and base installation method to solve the above technical problems. Summary of the Invention

[0006] The purpose of the embodiments of the present application is to provide a method for benchmarking and base installation of an ultra-long axis system, which solves the problem that traditional laser theodolites cannot meet the accuracy requirements within an ultra-long range and the problem that the base positioning is difficult due to the longitudinal inclination angle and outward angle of the ultra-long axis system.

[0007] In a first aspect, a method for benchmarking and base installation of an ultra-long shaft system is provided, comprising:

[0008] S1. Locate and mark the fore and aft reference points of the shafting system within the hull;

[0009] S2. Using the bow reference point and the stern reference point as references, draw a coordinate system inside the hull, and draw the position of the intermediate light target in the drawn coordinate system;

[0010] S3. Pull the axis wire based on the surveyed bow reference point, stern reference point and intermediate light target;

[0011] S4. Calculate the three-dimensional coordinates of the shafting base in the surveyed coordinate system, locate the longitudinal coordinates of the shafting base using the intermediate optical target as a reference, and locate the transverse and vertical coordinates of the shafting base using the axis steel wire as a reference;

[0012] S5. According to the calculated values of the transverse coordinate, longitudinal coordinate and vertical coordinate, cut the lower opening of the shaft system base to a preset margin and then position and install the shaft system base.

[0013] In one embodiment, in S2, the drawing of a coordinate system within the hull based on the bow reference point and the stern reference point includes:

[0014] The line connecting the bow reference point and the stern reference point on the bottom of the ship is marked as the longitudinal coordinate axis, the intersection of the rib line of the main transverse bulkhead of the hull and the longitudinal coordinate axis is used as the reference point to mark the transverse coordinate axis, and the vertical coordinate axis is used as the reference point to mark the bottom baseline.

[0015] In one embodiment, in S2, mapping out the position of the intermediate light target in the mapped coordinate system includes:

[0016] On the longitudinal coordinate axis of the surveyed coordinate system, the longitudinal coordinate is surveyed at the theoretical longitudinal distance between the intermediate light target and the bow reference point or the stern reference point, and the vertical coordinate is surveyed at the theoretical height distance from the bow reference point or the stern reference point. A channel steel benchmark is installed at the surveyed position, and a steel stylus is used to mark the cross line of the three-dimensional coordinate point of the intermediate light target on the channel steel.

[0017] In one embodiment, in said S4, positioning the longitudinal coordinate of the shafting base based on the intermediate optical target and positioning the transverse coordinate and vertical coordinate of the shafting base based on the axis steel wire include:

[0018] Mark a cross center line on the panel of the shafting base, locate the longitudinal coordinate of the shafting base according to the theoretical distance between the cross center point of the panel of the shafting base and the intermediate light target in the axial direction, locate the transverse coordinate of the shafting base according to the coincidence of the vertical projection line of the axis steel wire and the longitudinal line of the cross center line of the panel of the shafting base, and locate the vertical coordinate of the shafting base according to the theoretical distance between the axis steel wire and the vertical normal line of the panel of the shafting base.

[0019] In one embodiment, in S5, the step of cutting the lower opening of the shafting base to a preset margin and then positioning and installing the shafting base according to the calculated values of the transverse coordinate, the longitudinal coordinate, and the vertical coordinate comprises:

[0020] Cut the preset allowance L at the bottom of the shafting base, L = (h2-h1) / cosa, h1 is the distance between the axis steel wire and the vertical normal of the panel of the shafting base at the preliminary position, h2 is the distance between the panel of the shafting base at the theoretical position and the vertical normal of the axis steel wire, a is the longitudinal inclination angle of the axis, and the preset allowance calculated is marked at the bottom of the base through two-dimensional measurement and the shafting base is installed after cutting the preset allowance.

[0021] In one embodiment, in S1, positioning the bow reference point and the stern reference point of the shafting system in the hull includes:

[0022] The bow reference point and the stern reference point are longitudinally positioned with the rib line of the main transverse bulkhead of the hull as the reference, and the bottom centerline and the bottom baseline are obtained. The bow reference point and the stern reference point are transversely positioned with the obtained hull centerline as the reference, and the bow reference point and the stern reference point are vertically positioned with the obtained bottom baseline as the reference.

[0023] In one embodiment, obtaining the ship bottom centerline includes measuring the fit data between the ship bottom centerline and the centerline of the dock bottom hull for three consecutive days, correcting the ship bottom centerline, and obtaining the corrected ship bottom centerline; obtaining the ship bottom baseline includes measuring the deflection values of the line connecting each rib point intersecting with the ship bottom centerline for three consecutive days, calculating the average deflection value, correcting the ship bottom baseline, and obtaining the corrected ship bottom baseline.

[0024] In one embodiment, in said S3, pulling the axis line steel wire based on the surveyed bow reference point, stern reference point and intermediate light target includes pulling the axis line steel wire between the bow reference point and the intermediate light target, between every two intermediate light targets, and between the intermediate light target and the stern reference point.

[0025] In one embodiment, the bow reference point, the stern reference point, the intermediate optical target and the shafting base are all positioned by total station measurement, and the position of the total station can be adjusted according to the on-site measurement environment.

[0026] In one embodiment, the process of determining the hull datum of the hull main transverse bulkhead rib line, the hull centerline and the bottom baseline includes marking the location where the benchmark is to be erected, and also includes surveying the hull datum in advance to the conspicuous structure of each compartment through which the shafting passes.

[0027] The method for benchmarking and base installation of the ultra-long shaft system in this application has the following beneficial effects:

[0028] Locating the shafting's bow and stern datum points, establishing a coordinate system based on these points, and marking intermediate optical targets within this established coordinate system address the inability of traditional laser theodolites to meet accuracy requirements over extended ranges. This method of establishing a coordinate system based on the bow and stern datum points for positioning and installing the shafting base addresses the difficulty in locating the base due to the extremely long shafting's pitch and flare angles. This improves the installation accuracy of the entire shafting system and reduces installation quality issues caused by precision errors. Furthermore, intermediate optical targets are placed at the front and rear of each base, forming a localized optical target coordinate system, facilitating the monitoring of shafting base accuracy data during construction. The calculation of the cutting allowance at the bottom of the shafting base has also been optimized, reducing construction errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 This is a flow chart of a method for benchmarking and base installation of an ultra-long shaft system according to an embodiment of the present application;

[0031] Figure 2 Schematic diagram of the arrangement of bow and stern reference points and intermediate light targets according to an embodiment of the present application;

[0032] Figure 3 for Figure 1 A top view showing the arrangement of bow and stern reference points and intermediate light targets;

[0033] Figure 4 This is a schematic diagram of positioning a shafting base according to an embodiment of the present application;

[0034] Figure 5 This is a schematic diagram of a preset margin at the bottom of a cutting shaft base according to an embodiment of the present application.

[0035] 110. Bow reference point; 120. Stern reference point; 200. Intermediate light target; 210. First intermediate light target; 220. Second intermediate light target; 230. Third intermediate light target; 300. Axis wire; 400. Shaft system base; 410. First shaft system base; 411. Cross center line; 420. Second shaft system base; 430. Third shaft system base; 500. Total station. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0038] Figure 1 This is a flow chart of a method for benchmarking and base installation of an ultra-long shaft system according to an embodiment of the present application. Figure 1-Figure 3 ,include,

[0039] S1. Locate and mark the bow reference point 110 and stern reference point 120 of the shaft system inside the hull; the bow reference point 110 is generally set between the output rear flange of the second stage gear shaft of the main reduction gear unit and the input flange of the main thrust bearing, and the stern reference point 120 is generally set at the center of the propeller disk.

[0040] S2. Using the bow reference point 110 and the stern reference point 120 as references, a coordinate system is drawn inside the hull, and the position of the intermediate light target 200 is drawn in the drawn coordinate system;

[0041] Drawing a coordinate system within the hull using the bow reference point 110 and the stern reference point 120 as references includes drawing a line connecting the bow reference point 110 and the stern reference point 120 on the bottom of the ship as the longitudinal coordinate axis, drawing a transverse coordinate axis using the intersection of the main transverse bulkhead rib line of the hull and the longitudinal coordinate axis as the reference point, and drawing a vertical coordinate axis using the bottom baseline as the reference point (either the bow or stern reference point, whichever is closest). On the longitudinal coordinate axis of the drawn coordinate system, i.e., the transverse coordinate value is drawn on the same straight line as the bow reference point and the stern reference point, i.e., the transverse coordinate value of the intermediate light target 200 in the drawn coordinate system is 0. The longitudinal coordinates of the intermediate optical target 200 are measured using the theoretical longitudinal distance from the bow reference point 110 or the stern reference point 120. The vertical coordinates are measured using the theoretical height distance from the bow reference point or the stern reference point (whichever is closest). A channel steel pole is installed at the measured location. A steel stylus is used to mark the three-dimensional coordinates of the intermediate optical target 200 on the pole. A crosshair can be used, and a punch is used to mark the location. The intermediate optical target 200 is placed at the center rib position to facilitate measurement and positioning of the shafting base 400.

[0042] S3. Pull the axis wire based on the bow reference point 110, stern reference point 120 and the middle light target 200. Pull the wire by measuring the bow and stern reference points and the middle light target. The axis wire is 19# piano wire, with a diameter of d=1mm and a theoretical weight of W=6.17*10 -3 g / mm, calculation formula for steel wire deflection In the formula, Y is the deflection value, see Figure 4 and Figure 5 , L is the distance between the two ends of the steel wire, X is the distance from the calculation point to the end point, and the commonly used tension P = 90Kg or 75Kg.

[0043] S4. Calculate the three-dimensional coordinates of the shafting base in the surveyed coordinate system, locate the longitudinal coordinates of the shafting base using the intermediate optical target as a reference, and locate the transverse and vertical coordinates of the shafting base using the axis steel wire as a reference;

[0044] S5. Based on the calculated transverse, longitudinal, and vertical coordinate values, cut the lower opening of the shafting base to a preset margin and then position and install the shafting base. Specifically, during the shafting base positioning process, check the alignment of the shafting base web with the vibration-damping square steel, and the vibration-damping square steel with the anti-roof structure. Ensure that the shafting base web is centered on the vibration-damping square steel, that the web edge is at least 20 mm from the square steel edge, and that the centerline deviation between the square steel and the anti-roof reinforcement structure is at least 10 mm.

[0045] During the above implementation process, the present invention overcomes the influence of the span length of the shaft system on the measurement accuracy by measuring and surveying the bow reference point and the stern reference point of the shaft system, and solves the problem that the traditional laser theodolite cannot meet the accuracy requirements within an ultra-long range. Secondly, a coordinate system is established with the bow reference point and the stern reference point. In the established coordinate system, intermediate light targets are set before and after each base to form a local light target coordinate system, and the shaft system base is positioned and installed, solving the problem of difficulty in positioning the base due to the longitudinal inclination angle and the outward angle of the ultra-long shaft system, and facilitating the monitoring of the accuracy data during the base construction process. In addition, the calculation problem of the cutting allowance of the lower opening of the base is optimized and solved, which reduces construction errors, improves the installation accuracy of the entire shaft system, and reduces installation quality problems caused by precision errors.

[0046] In one embodiment, in S4, positioning the longitudinal coordinate of the shafting base based on the intermediate optical target and positioning the transverse coordinate and vertical coordinate of the shafting base based on the axis steel wire include:

[0047] Mark the cross center line 411 on the panel of the shafting base. Before installing the shafting base 400, check whether the position and thickness of the cross center line 411 of the panel of the shafting base meet the requirements of the drawing to prevent positioning deviation. Locate the longitudinal coordinate of the shafting base according to the theoretical distance between the cross center point of the panel of the shafting base and the axis direction of the intermediate light target 200 (i.e. the direction of the axis steel wire 300). Figure 1 The first and second intermediate optical targets 210 and 220 are used to locate the longitudinal coordinates of the first shafting base 410, the second and third intermediate optical targets 220 and 230 are used to locate the longitudinal coordinates of the second shafting base 420, and the third intermediate optical target 230 is used to locate the longitudinal coordinates of the third shafting base 430. The transverse coordinates of the shafting base are determined by the coincidence of the vertical projection of the axis wire 300 with the longitudinal cross-centerline 411 of the faceplate of the shafting base 400. The vertical coordinates of the shafting base 400 are determined based on the theoretical distance between the axis wire 300 and the faceplate of the shafting base 400. The distance between the faceplate of the shafting base and the normal line of the axis wire can be measured with a right-angled T-square. If this is unavailable, a two-dimensional tape measure can be used to measure the shortest distance between the faceplate of the shafting base and the axis wire. This distance is the normal distance between the faceplate of the shafting base and the axis wire.

[0048] In this implementation, based on the assembly characteristics of the ultra-long shafting system (with pitch and flare angles), the fore and aft reference points and intermediate optical targets were surveyed, and the axis line wire was pulled. The intermediate optical target and axis line wire were then used to locate the transverse, longitudinal, and vertical coordinates of the shafting base. This method can eliminate the construction errors associated with traditional benchmark surveying and base installation, facilitating the positioning and installation of the shafting base.

[0049] In one embodiment, in order to solve the problem of inaccurate positioning of the shaft base of an ultra-long shaft system, in combination with the installation characteristics of the ultra-long shaft system, in S5, according to the calculated values of the transverse coordinate, longitudinal coordinate, and vertical coordinate, the shaft base is positioned and installed after cutting the lower opening of the shaft base to a preset margin, which includes:

[0050] See also Figure 4 and Figure 5 , cut the shafting base's lower opening to a preset allowance, L, where L = (h2-h1) / cosa, where h1 is the distance between the axis steel wire and the faceplate of the shafting base in the initial position, the perpendicular normal, h2 is the distance between the faceplate of the shafting base and the perpendicular normal of the axis steel wire at the theoretical position, and a is the longitudinal inclination angle of the axis. The shafting base is installed after the preset allowance is calculated and cut using two-dimensional measurement. After the base is installed, a total station is used to remeasure the three-dimensional coordinates.

[0051] In one embodiment, in S1, locating the bow reference point and the stern reference point of the shafting in the hull includes:

[0052] The bow and stern datum points are longitudinally positioned with the rib position line of the main transverse bulkhead as the reference, and the bottom centerline and bottom baseline are obtained. The bow and stern datum points are transversely positioned with the obtained hull centerline as the reference, and the bow and stern datum points are vertically positioned with the obtained bottom baseline as the reference. Obtaining the bottom centerline includes measuring the fit data between the bottom centerline and the dock bottom hull centerline for three consecutive days, correcting the bottom centerline, and obtaining the corrected bottom centerline. Obtaining the bottom baseline includes measuring the deflection values of the line connecting the rib positions that intersect with the bottom centerline for three consecutive days, calculating the average deflection value, correcting the bottom baseline, and obtaining the corrected bottom baseline. After three consecutive days of measurement, the next stage of the procedure can be carried out only when the data is stable and there is no sudden change. That is, the longitudinal coordinate of the bow datum point is based on the rib line of the main transverse bulkhead of the hull, and is surveyed from bow to stern according to the theoretical size. The selected main transverse bulkhead is generally located in the stern tube compartment. The longitudinal coordinates of the bow and stern datums must be surveyed based on the same main transverse bulkhead. The transverse coordinate value is based on the corrected centerline of the bottom of the ship and is surveyed according to the theoretical size. The vertical coordinate is based on the corrected bottom baseline and is surveyed according to the theoretical size. According to the surveyed three-dimensional coordinates, the bow and stern datum poles are installed and erected, and a steel stylus is used to mark the cross lines of the bow and stern datum points, and a strike is made as a conspicuous mark. It is particularly important to note that the survey time should be selected at night when the temperature difference is small to avoid measurement errors. After the bow and stern datum poles are erected, red and white warning flags should be hung around them, and a warning sign should be marked not to move, so as to avoid touching the poles during the cross construction process, which will cause datum deviation.

[0053] Since the extra-long shaft system tensioning wire is too long, it is easy to break in a complex construction environment, causing safety hazards. The wire can be shortened between the two intermediate light targets to reduce the safety hazard. In one implementation scheme, in S3, the axis line wire is pulled based on the surveyed bow reference point, stern reference point and intermediate light target, including pulling the shaft system wire between the bow reference point and the intermediate light target, between every two intermediate light targets, and between the intermediate light target and the stern reference point.

[0054] In one embodiment, the bow reference point, stern reference point, intermediate light target and shafting base are all measured and positioned using a total station 500, and the position of the total station 500 can be adjusted according to the on-site measurement environment. Moving the station for measurement is allowed, but the number of times should not exceed 3. The total station 500 in the present invention is an electronic total station, which is a high-tech measuring instrument integrating optics, mechanics and electronics. It is a surveying and mapping instrument system that integrates horizontal angle, vertical angle, distance and height difference measurement functions. Users can choose which model of total station to use according to actual conditions.

[0055] In one embodiment, the process for determining the hull datums for the main transverse bulkhead rib line, hull centerline, and bottom baseline includes marking the locations where the benchmarks are to be erected. The process also includes pre-marking the hull datums to conspicuous structures in each compartment through which the shafting passes. This prevents subsequent obstructions during line pulling, making datum measurement difficult and preventing the establishment of a coordinate system.

[0056] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for benchmarking and base installation of an ultra-long shaft system, characterized in that: include: S1. Locating and marking the bow reference point and the stern reference point of the shaft system in the hull. Locating the bow reference point and the stern reference point of the shaft system in the hull includes: The bow reference point and the stern reference point are longitudinally positioned with the rib line of the main transverse bulkhead as the reference, and the bottom centerline and the bottom baseline are obtained. The bow reference point and the stern reference point are transversely positioned with the obtained hull centerline as the reference, and the bow reference point and the stern reference point are vertically positioned with the obtained bottom baseline as the reference; S2. Drawing a coordinate system in the hull with the bow reference point and the stern reference point as references, and drawing the position of the intermediate light target in the drawn coordinate system. Drawing a coordinate system in the hull with the bow reference point and the stern reference point as references includes: The line connecting the bow datum point and the stern datum point on the bottom of the ship is marked as the longitudinal coordinate axis, the intersection of the hull main transverse bulkhead frame line and the longitudinal coordinate axis is marked as the datum point, and the vertical coordinate axis is marked with the bottom baseline as the datum. On the longitudinal coordinate axis of the marked coordinate system, the longitudinal coordinate is marked with the theoretical longitudinal distance of the intermediate light target from the bow datum point or the stern datum point, and the vertical coordinate is marked with the theoretical height distance from the intermediate light target to the bow datum point or the stern datum point; S3. Pull the axis wire based on the surveyed bow reference point, stern reference point and intermediate light target; S4. Calculate the three-dimensional coordinates of the shafting base in the surveyed coordinate system, locate the longitudinal coordinates of the shafting base using the intermediate optical target as a reference, and locate the transverse and vertical coordinates of the shafting base using the axis steel wire as a reference; S5. According to the calculated values of the transverse coordinate, longitudinal coordinate and vertical coordinate, cut the lower opening of the shaft system base to a preset margin and then position and install the shaft system base.

2. The method for benchmarking and base installation of an ultra-long shaft system according to claim 1, characterized in that: In S2, mapping out the position of the intermediate light target in the mapped coordinate system includes: Install the channel steel pole at the surveyed position, and use a steel stylus to mark the cross lines of the three-dimensional coordinate points of the middle light target on the channel steel.

3. The method for benchmarking and base installation of an ultra-long shaft system according to claim 2, characterized in that: In the above S4, the longitudinal coordinates of the shafting base are positioned based on the intermediate optical target, and the transverse coordinates and vertical coordinates of the shafting base are positioned based on the axis steel wire. Mark a cross center line on the panel of the shafting base, locate the longitudinal coordinate of the shafting base according to the theoretical distance between the cross center point of the panel of the shafting base and the intermediate light target in the axial direction, locate the transverse coordinate of the shafting base according to the coincidence of the vertical projection line of the axis steel wire and the longitudinal line of the cross center line of the panel of the shafting base, and locate the vertical coordinate of the shafting base according to the theoretical distance between the axis steel wire and the vertical normal line of the panel of the shafting base.

4. The method for benchmarking and base installation of an ultra-long shaft system according to claim 3, characterized in that: In S5, the step of positioning and installing the shafting base after cutting a preset margin at the lower opening of the shafting base according to the calculated values of the transverse coordinate, the longitudinal coordinate, and the vertical coordinate includes: Cut the preset allowance L at the bottom of the shafting base, L = (h2-h1) / cos a, h1 is the distance between the axis steel wire and the vertical normal of the face plate of the shafting base at the preliminary position, h2 is the distance between the face plate of the shafting base at the theoretical position and the vertical normal of the axis steel wire, a is the longitudinal inclination angle of the axis, and the preset allowance calculated is marked at the bottom of the base through two-dimensional measurement and the shafting base is installed after cutting the preset allowance.

5. The method for benchmarking and base installation of an ultra-long shaft system according to claim 1, characterized in that: The method of obtaining the centerline of the ship bottom includes measuring the fit data between the centerline of the ship bottom and the centerline of the dock bottom hull for three consecutive days, correcting the centerline of the ship bottom, and obtaining the corrected centerline of the ship bottom; the method of obtaining the bottom baseline includes measuring the deflection values of the line connecting each rib point intersecting with the centerline of the ship bottom for three consecutive days, calculating the average deflection value, correcting the bottom baseline, and obtaining the corrected bottom baseline.

6. The method for benchmarking and base installation of an ultra-long shaft system according to claim 1, characterized in that: In said S3, said pulling the axis steel wire based on the surveyed bow reference point, stern reference point and intermediate light target includes pulling the axis steel wire between the bow reference point and the intermediate light target, between every two intermediate light targets, and between the intermediate light target and the stern reference point.

7. The method for benchmarking and base installation of an ultra-long shaft system according to claim 1, characterized in that: The positioning of the bow reference point, the stern reference point, the intermediate light target and the shafting base are all carried out by measuring and positioning with a total station, and the position of the total station can be adjusted according to the on-site measurement environment.

8. The method for benchmarking and base installation of an ultra-long shaft system according to claim 1, characterized in that: The process of determining the hull datum of the main transverse bulkhead frame line, hull centerline and bottom baseline includes marking the locations where the benchmarks are to be erected, and also includes surveying the hull datum in advance to the conspicuous structures of each compartment through which the shafting passes.

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