Corrosion protection device

Abstract

To provide a corrosion prevention device capable of reducing UEP and preventing corrosion of a hull by accurately estimating the UEP at a position separated from the hull by a predetermined distance when a ship sails in a specific sea area.SOLUTION: A corrosion prevention device 1A includes a sacrificial positive electrode 4 attached to a ship body 2 via an insulating body 3, a variable resister 15 electrically connected between the sacrificial positive electrode 4 and the ship body 2, and a controller 10. The controller 10 repeatedly obtains a UEP at a predetermined position away from the hull 2 or UEPs at a plurality of positions while changing the calculated resistance value, using at least one of the navigation speed, the seawater temperature, the ship bottom position in the water depth, and the hull coating state level during navigation, which are measured during navigation, and the calculated resistance value, which is a calculated value of the resistance value of the variable resistor 15, and derives a calculated resistance value when the UEP at the predetermined position or the sum of the UEPs at the plurality of positions is equal to or less than a predetermined value. The variable resistor 15 is controlled so that the resistance value becomes the derived arithmetic resistance value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a corrosion prevention device for preventing corrosion of a ship hull. [Background technology]

[0002] Conventionally, corrosion prevention devices have been used on ships to prevent corrosion of the hull. For example, in corrosion prevention devices using a galvanic anode system, an anticorrosion current flows from a sacrificial anode electrically connected to the hull to the hull through seawater. In other words, the sacrificial anode dissolves in seawater, preventing corrosion of the hull.

[0003] In recent years, technology has been developed to detect the presence of ships using the underwater electric potential (UEP) caused by the anticorrosion current, so it is desirable to control the anticorrosion current.

[0004] For example, Patent Document 1 discloses a corrosion protection device that can change the magnitude of the corrosion protection current. Specifically, in the corrosion protection device of Patent Document 1, a sacrificial anode is attached to the hull via an insulator, and a variable resistor is provided between the sacrificial anode and the hull. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-115694 Summary of the Invention [Problem to be solved by the invention]

[0006] Furthermore, Patent Document 1 describes a method of measuring the underwater electric field near the outer surface of the hull using a sensor unit, predicting the distribution of the underwater electric field far from the hull periphery from the measurement value, and changing the resistance value of a variable resistor as necessary based on the distribution of the underwater electric field. However, there is no specific description of a method of predicting the distribution of the underwater electric field far from the hull periphery.

[0007] The present disclosure aims to provide a corrosion prevention device that can accurately estimate the UEP at a position a specified distance from the hull when a ship is navigating a specific sea area, thereby reducing the UEP and preventing corrosion of the hull. [Means for solving the problem]

[0008] In order to achieve the above object, a corrosion protection device according to one embodiment of the present disclosure comprises a sacrificial anode attached to the hull of a ship via an insulator, a variable resistor interposed between the sacrificial anode and the hull and electrically connected to the sacrificial anode and the hull, and a controller for controlling the variable resistor. When the ship is navigating a specific sea area, the controller uses at least one of four items measured during navigation: navigation speed, seawater temperature, and bottom position in the water depth, and the hull paint condition level during navigation, and a calculated resistance value which is a calculated value of the resistance of the variable resistor, to repeatedly determine a UEP at a predetermined position a predetermined distance from the hull or UEP at multiple positions a predetermined distance from the hull while changing the calculated resistance value, and when the hull potential is within the corrosion protection potential range, derives the calculated resistance value when the UEP at the predetermined position or the sum of the UEPs at the multiple positions is equal to or less than a predetermined value, and controls the variable resistor so that the resistance value of the variable resistor becomes the calculated resistance value.

[0009] A corrosion protection device according to another aspect of the present disclosure comprises a sacrificial anode attached to the hull of a ship via an insulator, a variable resistor interposed between the sacrificial anode and the hull and electrically connected to the sacrificial anode and the hull, and a controller for controlling the variable resistor. When the ship is navigating a specific sea area, the controller uses at least one of four items measured during navigation: navigation speed, seawater temperature, and bottom position in the water depth; and the hull paint condition level during navigation; and a calculated resistance value, which is a calculated value of the resistance of the variable resistor, to repeatedly determine a UEP at a predetermined position a predetermined distance from the hull or UEPs at multiple positions a predetermined distance from the hull, and the hull potential while changing the calculated resistance value. When the hull potential is within the corrosion protection potential range, the controller derives the calculated resistance value when the UEP at the predetermined position or the sum of the UEPs at the multiple positions is equal to or less than a predetermined value, and controls the variable resistor so that the resistance value of the variable resistor becomes the calculated resistance value.

[0010] A corrosion protection device according to another aspect of the present disclosure comprises a sacrificial anode electrically connected to the hull of a ship, a shielding mechanism for changing the exposure amount of the sacrificial anode relative to the outside of the hull, and a controller for controlling the shielding mechanism. When the ship is navigating a specific sea area, the controller uses at least one of four items measured during navigation: navigation speed, seawater temperature, and bottom position in the water depth; and the hull paint condition level during navigation; and a calculated exposure amount, which is a calculated value of the exposure amount of the sacrificial anode, to repeatedly determine the UEP at a predetermined position a predetermined distance from the hull or the UEP at multiple positions a predetermined distance from the hull while changing the calculated exposure amount, derives the calculated exposure amount when the UEP at the predetermined position or the sum of the UEPs at the multiple positions is less than a predetermined value, and controls the shielding mechanism so that the exposure amount of the sacrificial anode becomes the calculated calculated exposure amount.

[0011] A corrosion protection device according to yet another aspect of the present disclosure comprises a sacrificial anode electrically connected to the hull of a ship, a shielding mechanism that changes the exposure amount of the sacrificial anode relative to the outside of the hull, and a controller that controls the shielding mechanism. When the ship is navigating a specific sea area, the controller uses at least one of four items measured during navigation: navigation speed, seawater temperature, and bottom position in the water depth; and the hull paint condition level during navigation; and a calculated exposure amount, which is a calculated value of the exposure amount of the sacrificial anode, to repeatedly determine the UEP at a predetermined position a predetermined distance from the hull or the UEP at multiple positions a predetermined distance from the hull, and the hull potential while changing the calculated exposure amount.When the hull potential is within the corrosion protection potential range, the controller derives the calculated exposure amount when the UEP at the predetermined position or the sum of the UEPs at the multiple positions is equal to or less than a predetermined value, and controls the shielding mechanism so that the exposure amount of the sacrificial anode becomes the calculated calculated exposure amount. [Effects of the Invention]

[0012] The present disclosure has the configuration described above and has the effect of providing a corrosion prevention device that can accurately estimate the UEP at a position a predetermined distance from the hull when a ship is sailing in a specific sea area, thereby reducing the UEP and preventing corrosion of the hull. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing a main part of an example of a corrosion prevention device according to the first embodiment. [Figure 2] FIG. 2 is a block diagram of the corrosion protection device of FIG. [Figure 3] FIG. 3 is a diagram showing the simulation results of UEP depending on the sailing speed of the ship S. [Figure 4] FIG. 4 shows the simulation results of UEP depending on the water depth where the ship is located. [Figure 5] FIG. 5 is a flowchart showing an example of the operation of the corrosion prevention device in the first configuration example of the first embodiment. [Figure 6]FIG. 6 is a schematic diagram showing an example of a three-dimensional analytical region model. [Figure 7] FIG. 7 is a flowchart showing an example of the operation of the corrosion prevention device in the second configuration example of the first embodiment. [Figure 8] FIG. 8 is a block diagram of a corrosion prevention device according to a modified example of the first embodiment. [Figure 9] FIG. 9 is a schematic diagram showing a main part of an example of a corrosion prevention device according to the second embodiment. [Figure 10] FIG. 10 is a block diagram of the corrosion prevention device of FIG. [Figure 11] FIG. 11A is a cross-sectional view of a sacrificial anode and a shielding mechanism of a first specific example of a corrosion prevention device in the second embodiment, and FIG. 11B is a cross-sectional view taken along line AA in FIG. 11A. [Figure 12] 12A and 12B are cross-sectional views of a sacrificial anode and a shielding mechanism of a second specific example of a corrosion protection device according to the second embodiment. [Figure 13] FIG. 13 is a flowchart showing an example of the operation of the corrosion prevention device in the first configuration example of the second embodiment. [Figure 14] FIG. 14 is a flowchart showing an example of the operation of the corrosion prevention device in the second configuration example of the second embodiment. [Figure 15] FIG. 15 is a block diagram of a corrosion prevention device according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present disclosure will be described below with reference to the drawings. Note that, in the following, identical or corresponding elements throughout the drawings will be designated by the same reference numerals, and redundant explanations thereof may be omitted. Furthermore, the drawings are schematic illustrations of the respective components for ease of understanding, and the shapes, dimensional ratios, and the like may not be accurately depicted. Furthermore, the present disclosure is not limited to the following embodiments.

[0015] (First embodiment) FIG. 1 is a schematic diagram showing a main part of an example of a corrosion prevention device according to a first embodiment, and FIG. 2 is a block diagram of the same corrosion prevention device.

[0016] The corrosion protection device 1A is provided on a ship S. The corrosion protection device 1A includes a sacrificial anode 4 attached via an insulator 3 to a submerged portion of a hull 2 ​​of the ship S, and a variable resistor 15 interposed between the sacrificial anode 4 and the hull 2 ​​and electrically connected to the sacrificial anode 4 and the hull 2. The sacrificial anode 4 is made of a metal material that has a lower corrosion potential in seawater than the hull 2. Furthermore, as shown in FIG. 2 , the corrosion protection device 1A includes a controller 10, a memory device 11, a speedometer 12, a water thermometer 13, and a ship's bottom position measuring device 14.

[0017] The speedometer 12 measures the sailing speed of the ship S. The water thermometer 13 measures the seawater temperature. The ship bottom position measuring device 14 measures the ship bottom position in the water depth. For example, the ship bottom position measuring device 14 may be attached to a predetermined position on the ship S and include a depth sounder that measures the distance to the seabed and a depth meter that measures the distance to the water surface, and may be configured to calculate the ship bottom position in the water depth from these measurement values. The ship position measuring device 14 may also be configured to include a depth sounder, derive the water depth using the position of the ship S based on data received by a GPS receiver installed on the ship S and a nautical chart, and calculate the ship bottom position in the water depth from this water depth and the measurement value of the depth sounder. The ship position measuring device 14 may also be configured to include a depth meter, derive the water depth using the position of the ship S based on data received by a GPS receiver installed on the ship S and a nautical chart, and calculate the ship bottom position in the water depth from this water depth and the measurement value of the depth meter. Measurement values ​​from the speedometer 12, water temperature gauge 13 and bottom position measuring device 14 are transmitted to the controller 10.

[0018] The controller 10 is configured, for example, by a microcontroller, and is capable of receiving measurement values ​​from the speedometer 12, the water temperature gauge 13, and the bottom position measuring device 14 and controlling the variable resistor 15. The controller 10 controls the variable resistor 15 to change its resistance value. Changing the resistance value of the variable resistor 15 makes it possible to change the magnitude of the anticorrosion current flowing between the sacrificial anode 4 and the hull 2. Specifically, increasing the resistance value of the variable resistor 15 reduces the anticorrosion current, and decreasing the resistance value of the variable resistor 15 increases the anticorrosion current. Changing the magnitude of the anticorrosion current changes the magnitude of the underwater electric potential (UEP), which is the underwater electric field caused by the anticorrosion current.

[0019] The memory 11 is connected to the controller 10 and stores information necessary for the controller 10 to realize the functions of the corrosion prevention device 1A.

[0020] The controller 10 may be configured by a single controller or by multiple controllers that cooperate with each other to perform distributed control. The memory 11 may be configured by one memory or by multiple memory devices.

[0021] It should be noted that the functions of the controller 10 disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0022] In this embodiment, the traveling speed of the ship S and the position of the ship bottom in the water depth of the ship S are used to determine the UEP at a predetermined distance from the hull 2. Hereinafter, a UEP at a position at a predetermined distance from the hull 2 ​​may be referred to as a "distant UEP." A distant UEP is a UEP that is so far from the hull 2 ​​that it cannot be measured by a UEP sensor, even if the ship S is equipped with a UEP sensor that can measure the UEP around the hull 2.

[0023] Figure 3 shows the simulation results of UEP depending on the sailing speed of ship S. Figure 3 shows the UEP in a horizontal cross section several meters below the sea surface. The area surrounded by curve L1 is the area where the UEP is equal to or greater than a predetermined value α when the ship 2 is stationary, i.e., when the sailing speed is 0, and the area surrounded by curve L2 is the area where the UEP is equal to or greater than the predetermined value α when the ship 2 is sailing at a predetermined speed. The conditions other than the sailing speed when calculating curves L1 and L2 are the same. Figure 3 shows that the UEP varies depending on the sailing speed of ship S.

[0024] Figure 4 shows the simulation results of UEP depending on the water depth at which ship S is located. Figure 4 shows the UEP in a horizontal cross section a few meters below the sea surface. The area surrounded by curve L3 is the area where the UEP is equal to or greater than a predetermined value α when the water depth is 235 m, and the area surrounded by curve L4 is the area where the UEP is equal to or greater than a predetermined value α when the water depth is 25 m. The conditions other than the water depth when calculating curves L3 and L4 are the same. Figure 4 shows that the UEP varies depending on the water depth at which ship S is located. Note that the hull 2 ​​in Figures 3 and 4 shows the position of the hull 2 ​​in a plan view.

[0025] The magnitude of the protection current also depends on the conductivity of seawater, which in turn changes with seawater temperature. In other words, the UEP caused by the protection current also changes with seawater temperature.

[0026] In this embodiment, the distant UEP is calculated taking into consideration the sailing speed, water depth, and seawater temperature of the ship S.

[0027] <First Configuration Example of First Embodiment> 5 is a flowchart showing an example of the operation of the corrosion prevention device 1A in the first configuration example. This operation is realized by the processing of the controller 10.

[0028] The memory 11 stores a polarization curve database consisting of a large number of polarization curves determined for a plurality of sailing speeds and a plurality of seawater temperatures for the constituent materials of the hull 2, the sacrificial anode 4, etc. The polarization curve database is also stored in the memory 11. The polarization curve database is composed of a large number of polarization curves determined for a plurality of sailing speeds and a plurality of seawater temperatures for the constituent materials of the hull 2, the sacrificial anode 4, etc. The polarization curve database is also stored in the memory 11. The hull specification data is data on the shape, material, etc. of the hull 2, the sacrificial anode 4, etc. For example, if the hull 2 ​​is made of carbon steel and copper alloy and the sacrificial anode 4 is made of zinc, the polarization curve database will include a large number of polarization curves for carbon steel determined for a plurality of sailing speeds and a plurality of seawater temperatures, a large number of polarization curves for copper alloy determined for a plurality of sailing speeds and a plurality of seawater temperatures, and a large number of polarization curves for zinc determined for a plurality of sailing speeds and a plurality of seawater temperatures.

[0029] When the ship S is navigating a specific sea area where mines and the like have been laid, the controller 10 repeatedly performs the process shown in Fig. 5 at predetermined time intervals. Here, the controller 10 may determine that the ship S has entered the specific sea area based on data received by a GPS receiver provided on the ship S, or the ship operator may determine and input to the controller 10 that the ship has entered the specific sea area.

[0030] While the ship S is sailing in a specific sea area, first, in step S11, the controller 10 acquires the sailing speed of the ship S measured by the speedometer 12, the seawater temperature measured by the water thermometer 13, and the ship bottom position of the ship S in the water depth measured by the ship bottom position measuring device 14. By performing this step S11 at predetermined time intervals, the processing of steps S11 to S14 is repeatedly performed at predetermined time intervals.

[0031] In the next step S12, the controller 10 refers to the conductivity database stored in the memory 11 and derives the seawater conductivity corresponding to the measured seawater temperature. The controller 10 also refers to the polarization curve database stored in the memory 11 and derives the polarization curves of the metals used in the hull 2 ​​and the sacrificial anode 4, etc., corresponding to the measured sailing speed and seawater temperature. Furthermore, the controller 10 creates a three-dimensional analysis region model that simulates the three-dimensional UEP distribution analysis region, which is the water area surrounding the hull 2, based on the position of the bottom of the ship in the measured water depth and the hull specification data.

[0032] 6 is a schematic diagram showing an example of a three-dimensional analytical domain model M1. The three-dimensional analytical domain model M1 is a three-dimensional model obtained by excluding a portion 2a of the hull 2 ​​below the sea surface from a rectangular parallelepiped domain in which height z is the water depth of the current position of the ship S calculated from the ship bottom position in the water depth measured by the ship bottom position measurement device 14, length x parallel to the width direction of the ship S is a predetermined length, and length y parallel to the propulsion direction of the ship S is a predetermined length. Positions within this three-dimensional analytical domain model M1 are indicated by three-dimensional coordinates.

[0033] In the next step S13, the controller 10 uses the seawater conductivity, polarization curve, and three-dimensional analytical domain model M1 derived in step S12, as well as the calculated resistance value of the variable resistor 15. While repeatedly changing the calculated resistance value, the controller 10 repeatedly calculates the far-field UEP at a predetermined position, deriving the calculated resistance value at which the far-field UEP is equal to or less than a predetermined value. Here, the controller 10 first uses, for example, the currently set resistance value of the variable resistor 15 as the calculated resistance value, and calculates the UEP distribution within the three-dimensional analytical domain model M1 by cathodic protection analysis using, for example, the boundary element method or the finite element method, based on the calculated resistance value, the seawater conductivity, the polarization curve, and the three-dimensional analytical domain model M1. Then, the controller 10 selects a UEP at a predetermined coordinate from the UEP distribution, and designates the selected UEP as the far-field UEP. For example, in FIG. 6, the UEP at position P1 is determined as the far-field UEP. Then, it is determined whether the calculated far UEP is equal to or less than a predetermined value, and if it is not equal to or less than the predetermined value (v1), the UEP distribution is calculated in the same manner as above using a new calculated resistance value obtained by changing the calculated resistance value used in calculating the UEP distribution so as to reduce the far UEP, for example, a calculated resistance value that is a predetermined amount larger than the previous calculated resistance value, and the far UEP is calculated. In this way, the far UEP is repeatedly calculated, and the calculated resistance value when the far UEP is equal to or less than the predetermined value is derived.

[0034] In the next step S14, the controller 10 controls the variable resistor 15 so that the resistance value of the variable resistor 15 becomes the calculated resistance value derived in step S13.

[0035] In this first configuration example, when the ship S navigates a specific sea area, the far-field UEP is calculated using the navigation speed, seawater temperature, and bottom position of the ship in the water depth measured during navigation, and the calculated resistance value, which is the calculated value of the resistance of the variable resistor 15. This allows for accurate estimation of the far-field UEP when the resistance value of the variable resistor 15 is the calculated resistance value. The far-field UEP is then repeatedly calculated while changing the calculated resistance value, and the calculated resistance value when the far-field UEP is equal to or less than a predetermined value (v1) is derived. The variable resistor 15 is then controlled so that the resistance value of the variable resistor 15 becomes the calculated resistance value. This reduces the far-field UEP and prevents corrosion of the hull 2. Note that by deriving the minimum calculated resistance value when the far-field UEP is equal to or less than the predetermined value (v1) as the calculated resistance value when the far-field UEP is equal to or less than the predetermined value (v1), the anticorrosion current can be increased, thereby further preventing corrosion of the hull 2.

[0036] In the first configuration example described above, the case where the far UEP at one predetermined position P1 is calculated in step S13 is illustrated, but this is not limiting. That is, in step S13, the far UEP at multiple predetermined positions, for example, the far UEP at multiple positions P1 to P4 in FIG. 6, may be calculated, and the calculated resistance value when the sum of these multiple far UEPs is equal to or less than a predetermined value (v2) may be derived. In this case, the smallest calculated resistance value when the sum of the multiple far UEPs is equal to or less than the predetermined value (v2) is calculated as the calculated resistance value when the sum of the multiple far UEPs is equal to or less than the predetermined value (v2), thereby increasing the anticorrosive current and further preventing corrosion of the hull 2.

[0037] The predetermined value (v1) and the predetermined value (v2) are preset as values ​​at which the presence of a ship is not detected by equipment that detects UEP caused by anticorrosive current and detects the presence of a ship.

[0038] <Second configuration example of first embodiment> 7 is a flowchart showing an example of the operation of the corrosion prevention device 1A in the second configuration example. This operation is realized by the processing of the controller 10.

[0039] Steps S21 and S22 are similar to steps S11 and S12 in FIG.

[0040] In step S23, the controller 10 uses the seawater conductivity, polarization curve, and three-dimensional analytical domain model M1 derived in step S22, and a calculated resistance value, which is the calculated value of the resistance of the variable resistor 15, and repeatedly determines the far UEP and hull potential at a predetermined position while changing the calculated resistance value, and derives the calculated resistance value when the far UEP is equal to or less than a predetermined value (v1) when the hull potential is within the corrosion protection potential range. Here, the far UEP can be repeatedly determined in the same manner as in step S13 of the first configuration example, and the hull potential is also repeatedly determined using the seawater conductivity, polarization curve, three-dimensional analytical domain model M1, and the calculated resistance value while changing the calculated resistance value.

[0041] In the next step S24, the controller 10 controls the variable resistor 15 so that the resistance value of the variable resistor 15 becomes the calculated resistance value derived in step S23.

[0042] The corrosion protection potential range is a range of hull potential that can prevent corrosion of the hull 2, and is predetermined depending on the material of which the hull 2 ​​is made. Some examples of corrosion protection potential ranges based on the potential of a reference electrode (Ag / AgCl seawater) include: if the hull 2 ​​is made of carbon steel with a yield strength of less than 550 MPa or an alloy steel with a yield strength of less than 550 MPa, the corrosion protection potential range can be −0.80 to −1.10 V (vs. Ag / AgCl seawater); or if the hull 2 ​​is made of carbon steel with a yield strength of 550 MPa or more or an alloy steel with a yield strength of 550 MPa or more, the corrosion protection potential range can be −0.80 to −0.95 V (vs. Ag / AgCl seawater). Furthermore, when the hull 2 ​​is formed of a copper alloy containing aluminum, the corrosion protection potential range can be set to a range of −0.45 to −1.10 V (vs. Ag / AgCl seawater).

[0043] In this second configuration example, when the ship S navigates a specific sea area, the far UEP and hull potential are calculated using the navigation speed, seawater temperature, and bottom position of the ship in the water depth measured during navigation, and the calculated resistance value, which is the calculated value of the resistance of the variable resistor 15. This makes it possible to accurately estimate the far UEP when the resistance value of the variable resistor 15 is the calculated resistance value. Then, the far UEP and hull potential are repeatedly calculated while changing the calculated resistance value, and when the hull potential is within the corrosion protection potential range, the calculated resistance value when the far UEP is equal to or less than a predetermined value (v1) is derived, and the variable resistor 15 is controlled so that its resistance value becomes the derived calculated resistance value. This reduces the far UEP and more reliably prevents corrosion of the hull 2.

[0044] Furthermore, when deriving the calculated resistance value when the distant UEP is below a predetermined value (v1) when the hull potential is within the corrosion protection potential range, the presence of the ship can be made less likely to be detected by UEP by deriving the calculated resistance value when the distant UEP is minimum when the hull potential is within the corrosion protection potential range.

[0045] In the second configuration example described above, the case where the far UEP at one predetermined position P1 is obtained in step S23 is exemplified, but this is not limiting. That is, in step S23, the far UEP at a plurality of predetermined positions, for example, the far UEP at a plurality of positions P1 to P4 in Fig. 6, may be obtained, and an operational resistance value may be derived when the sum of the obtained far UEPs is equal to or less than a predetermined value (v2) when the hull potential is within the corrosion protection potential range.

[0046] In this case, when deriving the calculated resistance value when the sum of multiple distant UEPs is less than a predetermined value (v2) when the hull potential is within the corrosion protection potential range, the calculated resistance value when the sum of multiple distant UEPs is smallest when the hull potential is within the corrosion protection potential range can be derived, making it more difficult for the presence of a ship to be detected by UEPs.

[0047] Furthermore, in the first and second configuration examples described above, the polarization curve may be derived in steps S12 and S22, taking into consideration that the polarization curve changes depending on the condition of the coating on the outer surface of the hull 2. In this case, for example, a polarization curve database may be stored in memory 11, which stores a large number of polarization curves determined for the constituent materials of the hull 2, sacrificial anode 4, etc., according to a plurality of sailing speeds, a plurality of seawater temperatures, and a plurality of hull coating condition levels. The hull coating condition level indicates the coating condition of the hull 2. In other words, the hull coating condition level indicates which of a plurality of levels into which the coating condition of the hull 2 ​​is classified. For example, the plurality of hull coating condition levels may be determined as levels 1, 2, 3, 4, etc., in order of best coating condition of the hull 2. Then, for example, before the ship S sails through a specific sea area, the operator may input the current hull coating condition level into controller 10. Alternatively, the relationship between the accumulated sailing time of the ship S and the hull coating condition level may be determined in advance, and the controller 10 may determine the current hull coating condition level in accordance with the accumulated sailing time of the ship S. In this case, when deriving the polarization curves in steps S12 and S22, the controller 10 refers to the polarization curve database stored in the memory 11, and derives polarization curves for the hull 2, sacrificial anode 4, etc. in accordance with the measured sailing speed and seawater temperature and the current hull coating condition level.

[0048] <Modification of the first embodiment> Fig. 8 is a block diagram of a corrosion prevention device according to a modification of the first embodiment. Compared to the corrosion prevention device 1A shown in Fig. 2, this corrosion prevention device 1B does not include a memory 11 that stores a conductivity database, a polarization curve database, etc., and instead includes a machine learning model 10A in a controller 10.

[0049] The machine learning model 10A is trained in advance to use the ship's sailing speed, seawater temperature, the ship's bottom position in the water depth, and the resistance value of the variable resistor 15 as input data, and to use the distant UEP at a predetermined position or distant UEPs at a plurality of predetermined positions and the hull potential as output data. The machine learning model 10A can be configured using a known learning model such as a neural network.

[0050] The controller 10 repeatedly obtains the far UEP at a predetermined position or the far UEP at a plurality of predetermined positions and the hull potential as the output of the machine learning model 10A by inputting the measured current sailing speed, seawater temperature, bottom position in the water depth, and the calculated resistance value while changing the calculated resistance value, which is the calculated value of the resistance of the variable resistor 15. Here, when obtaining the far UEP at one predetermined position, the controller 10 derives the calculated resistance value when the far UEP at the predetermined position is equal to or less than a predetermined value (v1) when the hull potential is within the corrosion protection potential range. In this case, the controller 10 may also derive the calculated resistance value when the far UEP at the predetermined position is minimum when the hull potential is within the corrosion protection potential range.

[0051] Furthermore, when determining the far UEP at multiple positions, the controller 10 derives the calculated resistance value when the sum of the far UEP at multiple positions is equal to or less than a predetermined value (v2) when the hull potential is within the corrosion protection potential range. At this time, the calculated resistance value when the sum of the far UEP at multiple positions is minimum when the hull potential is within the corrosion protection potential range may be derived.

[0052] Next, the controller 10 controls the variable resistor 15 so that the resistance value of the variable resistor 15 becomes the calculated resistance value derived above.

[0053] In the case of this modification, the same effects as in the case of the second configuration example can be obtained.

[0054] In the above-described modified example, the machine learning model 10A may be configured not to output the hull potential. That is, the machine learning model 10A may be a model that has been trained in advance to use the ship's sailing speed, seawater temperature, the bottom position in the water depth, and the resistance value of the variable resistor 15 as input data, and to use the far UEP at a predetermined position or the far UEP at a predetermined plurality of positions as output data. In this case, when the machine learning model 10A outputs the far UEP at a predetermined position, the controller 10 derives a calculated resistance value when the far UEP at the predetermined position is equal to or less than a predetermined value (v1), as in the first configuration example. Furthermore, when the machine learning model 10A outputs the far UEP at a plurality of positions, the controller 10 derives a calculated resistance value when the sum of the plurality of far UEPs is equal to or less than a predetermined value (v2).

[0055] In the first embodiment described above, the controller 10 uses the sailing speed of the ship S measured by the speedometer 12, the seawater temperature measured by the water thermometer 13, and the ship's bottom position in the water depth measured by the ship's bottom position measuring device 14, but it may also use at least one of these. For example, if it is determined that the ship S will sail at a substantially constant sailing speed when sailing in a specific sea area, in the first and second configuration examples, the measured sailing speed is not used, and the polarization curve database may be constructed with polarization curves corresponding to multiple seawater temperatures at a constant sailing speed.

[0056] Furthermore, in the first and second configuration examples, if the seawater temperature in a specific sea area when ship S is sailing is almost constant, the measured seawater temperature is not used, but the seawater conductivity corresponding to the constant seawater temperature is determined in advance, and the polarization curve database is constructed with polarization curves corresponding to multiple sailing speeds at a constant seawater temperature.

[0057] Furthermore, if the water depth of a specific sea area is substantially constant, in the first and second configuration examples, the three-dimensional analytical domain model M1 may be created based on the constant water depth.

[0058] It is also possible to combine any two of the above cases: when the navigation speed is almost constant, when the seawater temperature is almost constant, and when the water depth of the specific sea area is almost constant.

[0059] Furthermore, in the first and second configuration examples, when a polarization curve is derived using a hull coating condition level, and the ship S navigates a specific sea area at a substantially constant speed, the seawater temperature in the specific sea area is substantially constant, and the water depth in the specific sea area is substantially constant, the following configuration may be adopted. In this case, the polarization curve database is configured with polarization curves corresponding to multiple hull coating condition levels at a constant speed and a constant seawater temperature. The controller 10 then derives a polarization curve from the polarization curve database based on the current hull coating condition level during navigation, and can calculate the far-field UEP, or the far-field UEP and hull potential, using this polarization curve, a seawater conductivity predetermined for a constant seawater temperature, a three-dimensional analytical domain model M1 created based on a constant water depth, and the calculated resistance value. In this case, the current hull coating condition level is either input to the controller 10 as described above or determined by the controller 10 based on the accumulated navigation time of the ship S. In this case, the controller 10 can obtain the far-field UEP, or the far-field UEP and the hull potential, without using the measurement data from the speedometer 12, the water temperature gauge 13, and the ship bottom position measuring device 14.

[0060] Therefore, the controller 10 may determine the distant UEP, or the distant UEP and the hull potential, using at least one of the following four items: the sailing speed of the ship S measured by the speedometer 12, the seawater temperature measured by the water thermometer 13, the bottom position in the water depth measured by the bottom position measuring device 14, and the current hull coating condition level, and the calculated resistance value.

[0061] In addition, in the case of a modified example, a machine learning model 10A may be constructed in advance, which uses at least one of the sailing speed of the ship S, the seawater temperature, and the position of the ship's bottom in the water depth as an input.

[0062] In the first embodiment described above, a plurality of sacrificial anodes 4 and variable resistors 15 may be provided.

[0063] (Second embodiment) FIG. 9 is a schematic diagram showing a main part of an example of a corrosion prevention device according to the second embodiment, and FIG. 10 is a block diagram of the same corrosion prevention device.

[0064] The corrosion prevention device 1C is provided on a ship S. The corrosion prevention device 1C includes a sacrificial anode 4 electrically connected to the hull 2 ​​of the ship S, and a shielding mechanism 16 that changes the amount of exposure of the sacrificial anode 4 to the outside of the hull 2. As shown in FIG. 10 , the corrosion prevention device 1C further includes a controller 10, a memory 11, a speedometer 12, a water thermometer 13, and a ship's bottom position measuring device 14. The speedometer 12, water thermometer 13, and ship's bottom position measuring device 14 are the same as those in the first embodiment shown in FIG. 2, and the measurement values ​​obtained by these devices are transmitted to the controller 10.

[0065] The controller 10 is configured, for example, by a microcontroller or the like, and is able to receive measurement values ​​from the speedometer 12, water temperature gauge 13, and bottom position measurement device 14, and control the shielding mechanism 16. The controller 10 controls the shielding mechanism 16 to change the amount of exposure of the sacrificial anode 4 from the outside of the hull 2. By changing the amount of exposure of the sacrificial anode 4, it is possible to change the magnitude of the anticorrosion current flowing between the sacrificial anode 4 and the hull 2. Specifically, by reducing the amount of exposure of the sacrificial anode 4, the anticorrosion current decreases, and by increasing the amount of exposure of the sacrificial anode 4, the anticorrosion current increases.

[0066] The memory 11 is connected to the controller 10 and stores information necessary for the controller 10 to realize the functions of the corrosion prevention device 1C.

[0067] The controller 10 may be configured by a single controller or by multiple controllers that cooperate with each other to perform distributed control. The memory 11 may be configured by one memory or by multiple memory devices.

[0068] <First Example of Sacrificial Anode and Shielding Mechanism> 11A and 11B show a sacrificial anode 4 and a shielding mechanism 16A of a first specific example of a corrosion protection device 1C. Fig. 11A is a cross-sectional view of the sacrificial anode 4 and the shielding mechanism 16A of the first specific example, and Fig. 11B is a cross-sectional view taken along line AA in Fig. 11A.

[0069] In this example, an opening 21 is provided in the hull 2, and a plate-shaped sacrificial anode 4 is arranged inside the hull 2 ​​so as to face the opening 21. The sacrificial anode 4 is electrically connected to the hull 2 ​​by wiring 41.

[0070] The shielding mechanism 16A includes a shutter 61 interposed between the opening 21 and the sacrificial anode 4, a drive device 63 that moves the shutter 61 via a rod 62, and a pair of guides 64 provided on both sides of the opening 21 that guide the movement of the shutter 61. An enclosure 5 that surrounds the shielding mechanism 16A is attached to the inside of the hull 2. The enclosure 5 serves to separate the seawater inlet that communicates with the opening 21 from the interior space of the ship. However, the enclosure 5 may be omitted depending on the structure of the hull 2.

[0071] The shutter 61 can be moved in the direction of arrow a by the operation of a drive device 63, and moves between an exposure state shown by a solid line in which the opening 21 is opened, and a blocking state shown by a two-dot chain line in which the opening 21 is closed. The drive device 63 is controlled by the controller 10.

[0072] In this example, by controlling the drive device 63 of the shielding mechanism 16A using the controller 10 to change the position of the shutter 61, it is possible to change the area of ​​the sacrificial anode 4 exposed to the outside of the hull 2 ​​through the opening 21 and change the amount of exposure of the sacrificial anode 4 to the outside of the hull 2. Changing the amount of exposure of the sacrificial anode 4 to the outside of the hull 2 ​​using the shielding mechanism 16A changes the magnitude of the anticorrosive current indicated by the arrow in Figures 11A and 11B, and changes the magnitude of the UEP caused by the anticorrosive current.

[0073] In this example, the movement direction of the shutter 61 is a direction parallel to the outer surface of the hull 2, but the movement direction of the shutter 61 may also be a circumferential direction about a rotation axis parallel to the outer surface of the hull 2. In addition, the shutter 61 may be disposed on the outside of the hull 2.

[0074] Alternatively, an opening 21 may not be provided, and a plate-shaped sacrificial anode 4 may be fixed on the outer surface of the hull 2, and a shutter may be arranged on the outside of the hull 2 ​​that changes the amount of exposure of the sacrificial anode 4 by moving between a shielding state that covers the sacrificial anode 4 and an exposure state that exposes the sacrificial anode 4.

[0075] <Second Example of Sacrificial Anode and Shielding Mechanism> 12A and 12B show cross-sectional views of the sacrificial anode 4 and shielding mechanism 16B of a second example of the corrosion protection device 1C. Fig. 12A shows the case where the amount of exposure of the sacrificial anode 4 to the outside of the hull 2 ​​is minimized, and Fig. 12B shows the case where the amount of exposure of the sacrificial anode 4 to the outside of the hull 2 ​​is increased.

[0076] In this example, a hole 22 is provided in the hull 2. The sacrificial anode 4 is in the form of a wire and is inserted through the hole 22.

[0077] The shielding mechanism 16B includes a drum 91 around which the sacrificial anode 4 is wound, a tube 92 attached to the inside surface of the hull 2 ​​so as to extend the hole 22, and a drum drive device that rotates the drum 91. The drum 91 is made of a conductive material and is connected to the hull 2 ​​by wiring 42. In other words, the sacrificial anode 4 is electrically connected to the hull 2 ​​via the drum 91 and wiring 42. The drum drive device, which is the drive device for the shielding mechanism 16B, is controlled by the controller 10.

[0078] In this example, the controller 10 controls the drum drive device and rotates the drum 91 to change the amount of projection of the sacrificial anode 4 outside the hull 2 ​​through the hole 22, thereby changing the amount of exposure of the sacrificial anode 4 from the outside of the hull 2. Changing the amount of exposure of the sacrificial anode 4 from the outside of the hull 2 ​​using the shielding mechanism 16B changes the magnitude of the anticorrosive current indicated by the arrow in Figure 12B, and changes the magnitude of the UEP caused by the anticorrosive current.

[0079] The specific configurations of the sacrificial anode 4 and the shielding mechanism 16 are not limited to the above specific example and can be modified in various ways. Any configuration is possible as long as the sacrificial anode 4 is electrically connected to the hull 2 ​​and the shielding mechanism 16 is controlled by the controller 10 to change the amount of exposure of the sacrificial anode 4 from the outside of the hull 2. In the following, the amount of exposure of the sacrificial anode 4 from the outside of the hull 2 ​​may be simply referred to as the "exposure amount of the sacrificial anode 4." The controller 10 is also configured to be able to control the drive device of the shielding mechanism 16 so that the amount of exposure of the sacrificial anode 4 becomes the desired amount of exposure.

[0080] In this embodiment, as in the first embodiment, the distant UEP is calculated taking into consideration the sailing speed, water depth, and seawater temperature of the ship S.

[0081] <First Configuration Example of Second Embodiment> 13 is a flowchart showing an example of the operation of the corrosion prevention device 1C in the first configuration example. This operation is realized by the processing of the controller 10.

[0082] Steps S31 and S32 are similar to steps S11 and S12 in FIG.

[0083] In step S33, the controller 10 uses the seawater conductivity, polarization curve, and three-dimensional analytical domain model M1 derived in step S32, and the calculated exposure amount, which is the calculated value of the exposure amount of the sacrificial anode 4, and repeatedly determines the far UEP at a predetermined position while changing the calculated exposure amount, to derive the calculated exposure amount when the far UEP is equal to or less than a predetermined value (v1). Here, the method for determining the far UEP is the same as in step S13 of Fig. 5, except that the calculated exposure amount of the sacrificial anode 4 is used instead of the calculated resistance value of the variable resistor 15.

[0084] In the next step S34, the controller 10 sets the calculated exposure amount derived in step S33 to a desired exposure amount, and controls the shielding mechanism 16 so that the exposure amount of the sacrificial anode 4 becomes the calculated exposure amount derived in step S33.

[0085] The first configuration example of the second embodiment also achieves the same effects as the first configuration example of the first embodiment. That is, when the ship S navigates a specific sea area, the far UEP is calculated using the navigation speed, seawater temperature, and bottom position in the water depth measured during navigation, and the calculated exposure amount, which is the calculated value of the exposure amount of the sacrificial anode 4. This allows for accurate estimation of the far UEP when the exposure amount of the sacrificial anode 4 is the calculated exposure amount. The far UEP is then repeatedly calculated while changing the calculated exposure amount, and the calculated exposure amount when the far UEP is equal to or less than a predetermined value (v1) is derived. The shielding mechanism 16 is controlled so that the exposure amount of the sacrificial anode 4 becomes equal to the calculated calculated exposure amount. This reduces the far UEP and prevents corrosion of the hull 2. Note that by deriving the maximum calculated exposure amount when the far UEP is equal to or less than the predetermined value (v1) as the calculated exposure amount when the far UEP is equal to or less than the predetermined value (v1), the anticorrosion current can be increased, thereby further preventing corrosion of the hull 2.

[0086] In the first configuration example described above, the case where the far UEP at one predetermined position is calculated in step S33 is exemplified, but this is not limiting. That is, in step S33, the far UEP at multiple predetermined positions may be calculated, and the calculated exposure amount when the sum of these multiple far UEPs is equal to or less than a predetermined value (v2) may be derived. In this case, the maximum calculated exposure amount when the sum of the multiple far UEPs is equal to or less than the predetermined value (v2) is calculated as the calculated exposure amount when the sum of the multiple far UEPs is equal to or less than the predetermined value (v2), thereby increasing the anticorrosion current and further preventing corrosion of the hull 2.

[0087] <Second Configuration Example of Second Embodiment> 14 is a flowchart showing an example of the operation of the corrosion prevention device 1C in the second configuration example. This operation is realized by the processing of the controller 10.

[0088] Steps S41 and S42 are the same as steps S31 and S32 in FIG. 13, that is, steps S11 and S12 in FIG.

[0089] In step S43, the controller 10 uses the seawater conductivity, polarization curve, and three-dimensional analytical domain model M1 derived in step S42, and a calculated exposure amount, which is a calculated value of the exposure amount of the sacrificial anode 4, and repeatedly determines the far UEP and hull potential at a predetermined position while changing the calculated exposure amount, to derive the calculated exposure amount when the far UEP is equal to or less than a predetermined value (v1) when the hull potential is within the protection potential range. Here, the far UEP can be repeatedly determined in the same manner as in step 33 of the first configuration example, and the hull potential is also repeatedly determined using the seawater conductivity, polarization curve, three-dimensional analytical domain model M1, and the calculated exposure amount while changing the calculated exposure amount.

[0090] In the next step S44, the controller 10 sets the calculated exposure amount derived in step S43 to a desired exposure amount, and controls the shielding mechanism 16 so that the exposure amount of the sacrificial anode 4 becomes the calculated exposure amount derived in step S43.

[0091] The second configuration example of the second embodiment also achieves the same effects as the second configuration example of the first embodiment. That is, when the ship S navigates a specific sea area, the far-field UEP and the hull potential are calculated using the navigation speed, seawater temperature, and bottom position in the water depth measured during navigation, and the calculated exposure amount, which is a calculated value of the exposure amount of the sacrificial anode 4. This allows for accurate estimation of the far-field UEP when the exposure amount of the sacrificial anode 4 is the calculated exposure amount. The far-field UEP and the hull potential are then repeatedly calculated while changing the calculated exposure amount. When the hull potential is within the corrosion protection potential range, the calculated exposure amount when the far-field UEP is equal to or less than a predetermined value (v1) is derived, and the shielding mechanism 16 is controlled so that the exposure amount of the sacrificial anode 4 becomes equal to the calculated exposure amount. This reduces the far-field UEP and more reliably prevents corrosion of the hull 2.

[0092] Furthermore, when deriving the calculated exposure amount when the distant UEP is below a predetermined value (v1) when the hull potential is within the corrosion protection potential range, the presence of the ship can be made less likely to be detected by UEP by deriving the calculated exposure amount when the distant UEP is minimum when the hull potential is within the corrosion protection potential range.

[0093] In the second configuration example described above, the case where the far UEP at one predetermined position is calculated in step S43 is illustrated, but this is not limiting. That is, in step S43, the far UEP at multiple predetermined positions may be calculated, and the calculated exposure amount may be derived when the sum of the multiple calculated far UEPs is equal to or less than a predetermined value (v2) when the hull potential is within the corrosion protection potential range.

[0094] In this case, when deriving the calculated resistance value when the sum of multiple distant UEPs is less than a predetermined value (v2) when the hull potential is within the corrosion protection potential range, the calculated resistance value when the sum of multiple distant UEPs is smallest when the hull potential is within the corrosion protection potential range can be derived, making it more difficult for the presence of a ship to be detected by UEPs.

[0095] Furthermore, in the first and second configuration examples of the second embodiment, as in the first and second configuration examples of the first embodiment, it may be considered that the polarization curve changes depending on the condition of the coating on the outer surface of the hull 2. In this case, a polarization curve database is stored in the memory 11, containing a large number of polarization curves determined for constituent materials such as the hull 2 ​​and the sacrificial anode 4 according to a plurality of sailing speeds, a plurality of seawater temperatures, and a plurality of hull coating condition levels. When deriving the polarization curves in steps S32 and S42, the controller 10 references the polarization curve database and derives polarization curves for the hull 2, the sacrificial anode 4, etc. according to the measured sailing speed and seawater temperature and the current hull coating condition level.

[0096] <Modification of the second embodiment> Fig. 15 is a block diagram of a corrosion prevention device according to a modification of the second embodiment. Compared to the corrosion prevention device 1C shown in Fig. 10, this corrosion prevention device 1D does not include a memory 11 that stores a conductivity database, a polarization curve database, etc., and instead includes a machine learning model 10B in a controller 10.

[0097] The machine learning model 10B is trained in advance to use the ship's sailing speed, seawater temperature, the position of the ship's bottom in the water depth, and the exposure amount of the sacrificial anode 4 as input data, and to use the distant UEP at a predetermined position or distant UEPs at a plurality of predetermined positions and the hull potential as output data. The machine learning model 10B can be configured using a known learning model such as a neural network.

[0098] The controller 10 repeatedly obtains the far UEP at a predetermined position or the far UEP at a plurality of predetermined positions and the hull potential as the output of the machine learning model 10B by inputting the measured current sailing speed, seawater temperature, bottom position in the water depth, and the calculated exposure amount while changing the calculated exposure amount, which is the calculated value of the exposure amount of the sacrificial anode 4. Here, when obtaining the far UEP at one predetermined position, the controller 10 derives the calculated exposure amount when the far UEP at the predetermined position is equal to or less than a predetermined value (v1) when the hull potential is within the corrosion protection potential range. In this case, the controller 10 may also derive the calculated exposure amount when the far UEP at the predetermined position is minimum when the hull potential is within the corrosion protection potential range.

[0099] Furthermore, when determining the far UEP at multiple positions, the controller 10 derives the calculated exposure amount when the sum of the far UEP at multiple positions is equal to or less than a predetermined value when the hull potential is within the corrosion protection potential range. In this case, the calculated exposure amount may be derived when the sum of the far UEP at multiple positions is minimum when the hull potential is within the corrosion protection potential range.

[0100] Next, the controller 10 controls the shielding mechanism 16 so that the exposure amount of the sacrificial anode 4 becomes the calculated exposure amount derived above.

[0101] In the case of this modified example of the second embodiment, the same effects as in the case of the second configuration example of the second embodiment can be obtained.

[0102] In the above-described modified example, the machine learning model 10B may be configured not to output the hull potential. That is, the machine learning model 10B may be a model that has been trained in advance to use the ship's sailing speed, seawater temperature, the bottom position in the water depth, and the exposure amount of the sacrificial anode 4 as input data, and to use the far UEP at a predetermined position or the far UEP at a predetermined plurality of positions as output data. In this case, when the machine learning model 10B outputs the far UEP at a predetermined position, the controller 10 derives the calculated exposure amount when the far UEP is equal to or less than a predetermined value (v1), as in the first configuration example. Furthermore, when the machine learning model 10B outputs the far UEP at a plurality of positions, the controller 10 derives the calculated exposure amount when the sum of the plurality of far UEPs is equal to or less than a predetermined value (v2).

[0103] In the second embodiment described above, the controller 10 uses the sailing speed of the ship S measured by the speedometer 12, the seawater temperature measured by the water thermometer 13, and the ship's bottom position in the water depth measured by the ship's bottom position measuring device 14, but as in the first embodiment, it may also use at least one of the sailing speed of the ship S, the seawater temperature, and the ship's bottom position in the water depth.

[0104] Furthermore, in the first and second configuration examples of the second embodiment, when a polarization curve is derived using a hull coating condition level, and the ship S navigates a specific sea area at a substantially constant speed, the seawater temperature in the specific sea area is substantially constant, and the water depth in the specific sea area is substantially constant, the following configuration may be adopted. In this case, the polarization curve database is configured with polarization curves corresponding to multiple hull coating condition levels at a constant speed and a constant seawater temperature. The controller 10 then derives a polarization curve from the polarization curve database based on the current hull coating condition level during navigation, and can calculate the far-field UEP, or the far-field UEP and hull potential, using this polarization curve, a seawater conductivity predetermined for a constant seawater temperature, a three-dimensional analytical domain model M1 created based on a constant water depth, and the calculated exposure. In this case, the current hull coating condition level is either input to the controller 10 as described above or determined by the controller 10 based on the accumulated navigation time of the ship S. In this case, the controller 10 can obtain the far-field UEP, or the far-field UEP and the hull potential, without using the measurement data from the speedometer 12, the water temperature gauge 13, and the ship bottom position measuring device 14.

[0105] Therefore, the controller 10 may calculate the far-field UEP, or the far-field UEP and the hull potential, using at least one of the following four items: the sailing speed of the ship S measured by the speedometer 12, the seawater temperature measured by the water thermometer 13, the bottom position in the water depth measured by the bottom position measuring device 14, and the current hull coating condition level, as well as the calculated exposure amount.

[0106] In the second embodiment, a plurality of sacrificial anodes 4 and shielding mechanisms 16 may be provided.

[0107] From the above description, many improvements and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present disclosure. Details of the structure and / or function thereof can be substantially changed without departing from the spirit of the present disclosure.

[0108] Summary of the Disclosure A corrosion protection device according to a first aspect of the present disclosure comprises a sacrificial anode attached to the hull of a ship via an insulator, a variable resistor interposed between the sacrificial anode and the hull and electrically connected to the sacrificial anode and the hull, and a controller for controlling the variable resistor. When the ship is navigating a specific sea area, the controller uses at least one of four items measured during navigation: navigation speed, seawater temperature, and bottom position in the water depth; and the hull paint condition level during navigation; and a calculated resistance value, which is a calculated value of the resistance value of the variable resistor, to repeatedly determine a UEP at a predetermined position a predetermined distance from the hull or UEP at multiple positions a predetermined distance from the hull while changing the calculated resistance value, derives the calculated resistance value when the UEP at the predetermined position or the sum of the UEPs at the multiple positions is equal to or less than a predetermined value, and controls the variable resistor so that the resistance value of the variable resistor becomes the calculated resistance value.

[0109] According to this configuration, when a ship navigates a specific sea area, the UEP at a predetermined position or multiple positions a predetermined distance from the hull is calculated using at least one of the following four parameters measured during navigation: navigation speed, seawater temperature, and bottom position in the water depth; and the hull coating condition level during navigation, along with a calculated resistance value, which is the calculated resistance value of the variable resistor. This allows for accurate estimation of the UEP when the resistance value of the variable resistor is the calculated resistance value. The UEP is then repeatedly calculated while changing the calculated resistance value, and the calculated resistance value is derived when the UEP at the predetermined position or the sum of the UEPs at multiple positions is equal to or less than a predetermined value. The variable resistor is then controlled so that the resistance value of the variable resistor becomes the calculated resistance value. This reduces the UEP at positions a predetermined distance from the hull and prevents corrosion of the hull.

[0110] A corrosion protection device according to a second aspect of the present disclosure comprises a sacrificial anode attached to the hull of a ship via an insulator, a variable resistor interposed between the sacrificial anode and the hull and electrically connected to the sacrificial anode and the hull, and a controller for controlling the variable resistor. When the ship is navigating a specific sea area, the controller uses at least one of four items measured during navigation: navigation speed, seawater temperature, and bottom position in the water depth; and hull paint condition level during navigation; and a calculated resistance value, which is a calculated value of the resistance of the variable resistor, to repeatedly determine a UEP at a predetermined position a predetermined distance from the hull or UEPs at multiple positions a predetermined distance from the hull, and the hull potential while changing the calculated resistance value, and when the hull potential is within the corrosion protection potential range, derives the calculated resistance value when the UEP at the predetermined position or the sum of the UEPs at the multiple positions is equal to or less than a predetermined value, and controls the variable resistor so that the resistance value of the variable resistor becomes the calculated resistance value.

[0111] According to this configuration, when a ship navigates a specific sea area, the UEP and hull potential at a predetermined position or multiple positions a predetermined distance from the hull are calculated using at least one of four measured values ​​during navigation: navigation speed, seawater temperature, and bottom position in water depth; and the hull coating condition level during navigation, along with a calculated resistance value, which is the calculated resistance value of the variable resistor. This allows for accurate estimation of the UEP when the resistance value of the variable resistor is the calculated resistance value. The UEP and hull potential are then repeatedly calculated while changing the calculated resistance value. When the hull potential is within the corrosion protection potential range, the calculated resistance value is derived when the UEP at the predetermined position or the sum of the UEPs at multiple positions is equal to or less than a predetermined value, and the variable resistor is controlled so that the resistance value of the variable resistor becomes the calculated resistance value. This reduces the UEP at positions a predetermined distance from the hull and more reliably prevents corrosion of the hull.

[0112] A corrosion prevention device according to a third aspect of the present disclosure is the corrosion prevention device according to the first or second aspect, and further comprises a memory that stores polarization curves of the constituent materials of the hull and the sacrificial anode corresponding to a plurality of sailing speeds and a plurality of seawater temperatures, wherein the controller acquires the measured sailing speed, seawater temperature, and bottom position of the ship in the water depth, derives seawater conductivity from the acquired seawater temperature, derives a polarization curve corresponding to the acquired sailing speed and seawater temperature from the polarization curves stored in the memory, creates a three-dimensional analysis domain model that simulates a three-dimensional UEP distribution analysis domain in the water area surrounding the hull based on the bottom position of the ship in the water depth, calculates a UEP distribution within the three-dimensional analysis domain model based on the derived seawater conductivity, the derived polarization curve, the created three-dimensional analysis domain model, and the calculated resistance value, and determines the UEP at the specified position or the UEP at the plurality of positions from the UEP distribution. This configuration makes it possible to more accurately estimate the UEP when the resistance value of the variable resistor is a calculated resistance value.

[0113] A corrosion prevention device according to a fourth aspect of the present disclosure is the corrosion prevention device according to the first or second aspect, further comprising a memory that stores polarization curves of the constituent materials of the hull and the sacrificial anode corresponding to a plurality of sailing speeds, a plurality of seawater temperatures, and a plurality of hull coating condition levels, and the controller acquires the measured sailing speed, seawater temperature, and ship bottom position in the water depth, as well as the current hull coating condition level, derives seawater conductivity from the acquired seawater temperature, and selects the acquired sailing speed from the polarization curves stored in the memory. A polarization curve corresponding to the seawater temperature and the hull coating condition level may be derived, a three-dimensional analysis domain model simulating a three-dimensional UEP distribution analysis domain in the water area around the hull may be created based on the position of the bottom of the hull in the water depth, a UEP distribution within the three-dimensional analysis domain model may be calculated based on the derived seawater conductivity, the derived polarization curve, the created three-dimensional analysis domain model, and the calculated resistance value, and the UEP at the specified position or the UEPs at the multiple positions may be obtained from the UEP distribution. This configuration allows for more accurate estimation of the UEP when the resistance value of the variable resistor is the calculated resistance value.

[0114] A corrosion prevention device according to a fifth aspect of the present disclosure is the corrosion prevention device according to the first aspect, wherein the controller has a machine learning model trained in advance using the vessel's sailing speed, seawater temperature, vessel bottom position at water depth, and the resistance value of the variable resistor as input data, and a UEP at a predetermined position a predetermined distance from the vessel or UEPs at multiple positions a predetermined distance from the vessel as output data, and may be configured to repeatedly determine the UEP at the predetermined position or the UEPs at the multiple positions by inputting the measured vessel speed, seawater temperature, vessel bottom position at water depth, and the calculated resistance value into the machine learning model while changing the calculated resistance value. This configuration allows for more accurate estimation of the UEP when the resistance value of the variable resistor is the calculated resistance value.

[0115] A sixth aspect of the present disclosure provides a corrosion prevention device according to the second aspect, wherein the controller has a machine learning model pre-trained using the vessel's speed, seawater temperature, vessel bottom position at the water depth, and the resistance value of the variable resistor as input data, and the UEP at a predetermined position a predetermined distance from the vessel or UEPs at multiple positions a predetermined distance from the vessel and the vessel potential as output data, and the controller is configured to repeatedly determine the UEP at the predetermined position or the UEPs at the multiple positions and the vessel potential by inputting the measured vessel speed, seawater temperature, vessel bottom position at the water depth, and the calculated resistance value into the machine learning model while changing the calculated resistance value. This configuration allows for more accurate estimation of the UEP when the resistance value of the variable resistor is the calculated resistance value.

[0116] A corrosion protection device according to a seventh aspect of the present disclosure comprises a sacrificial anode electrically connected to the hull of a ship, a shielding mechanism for changing the exposure amount of the sacrificial anode relative to the outside of the hull, and a controller for controlling the shielding mechanism. When the ship is navigating a specific sea area, the controller uses at least one of four items measured during navigation: navigation speed, seawater temperature, and bottom position in the water depth; and the hull paint condition level during navigation; and a calculated exposure amount, which is a calculated value of the exposure amount of the sacrificial anode, to repeatedly determine the UEP at a predetermined position a predetermined distance away from the hull or the UEP at multiple positions a predetermined distance away from the hull while changing the calculated exposure amount, derives the calculated exposure amount when the UEP at the predetermined position or the sum of the UEPs at the multiple positions is less than a predetermined value, and controls the shielding mechanism so that the exposure amount of the sacrificial anode becomes the calculated exposure amount.

[0117] According to this configuration, when a ship navigates a specific sea area, the UEP at a predetermined position or multiple positions a predetermined distance from the hull is calculated using at least one of the following four parameters measured during navigation: navigation speed, seawater temperature, and bottom position in water depth; and the hull coating condition level during navigation, along with a calculated exposure amount, which is a calculated value of the exposure amount of the sacrificial anode. This allows for accurate estimation of the UEP when the exposure amount of the sacrificial anode is the calculated exposure amount. The UEP is then repeatedly calculated while changing the calculated exposure amount, and the calculated exposure amount is derived when the UEP at the predetermined position or the sum of the UEPs at multiple positions is equal to or less than a predetermined value. The shielding mechanism is then controlled so that the exposure amount of the sacrificial anode becomes the calculated exposure amount. This reduces the UEP at positions a predetermined distance from the hull and prevents corrosion of the hull.

[0118] An eighth aspect of the present disclosure provides a corrosion protection device comprising a sacrificial anode electrically connected to the hull of a ship, a shielding mechanism for changing the exposure amount of the sacrificial anode relative to the outside of the hull, and a controller for controlling the shielding mechanism. When the ship is navigating a specific sea area, the controller uses at least one of four items measured during navigation: navigation speed, seawater temperature, and bottom position in the water depth; and the hull paint condition level during navigation; and a calculated exposure amount, which is a calculated value of the exposure amount of the sacrificial anode, to repeatedly determine the UEP at a predetermined position a predetermined distance from the hull or the UEP at multiple positions a predetermined distance from the hull, and the hull potential while changing the calculated exposure amount. When the hull potential is within the corrosion protection potential range, the controller derives the calculated exposure amount when the UEP at the predetermined position or the sum of the UEPs at the multiple positions is below a predetermined value, and controls the shielding mechanism so that the exposure amount of the sacrificial anode becomes the calculated calculated exposure amount.

[0119] According to this configuration, when a ship navigates a specific sea area, the UEP and hull potential at a predetermined position or multiple positions a predetermined distance from the hull are calculated using at least one of four parameters measured during navigation: navigation speed, seawater temperature, and bottom position in water depth; and the hull coating condition level during navigation, along with a calculated exposure amount, which is a calculated value of the exposure amount of the sacrificial anode. This allows for accurate estimation of the UEP when the exposure amount of the sacrificial anode is the calculated exposure amount. The UEP and hull potential are then repeatedly calculated while changing the calculated exposure amount. When the hull potential is within the corrosion protection potential range, the calculated exposure amount is calculated when the UEP at the predetermined position or the sum of the UEPs at multiple positions is equal to or less than a predetermined value. The shielding mechanism is then controlled so that the exposure amount of the sacrificial anode is equal to the calculated exposure amount. This reduces the UEP at positions a predetermined distance from the hull and more reliably prevents corrosion of the hull.

[0120] A corrosion prevention device according to a ninth aspect of the present disclosure is the corrosion prevention device according to the seventh or eighth aspect, and further includes a memory that stores polarization curves of the constituent materials of the hull and the sacrificial anode corresponding to a plurality of sailing speeds and a plurality of seawater temperatures, wherein the controller acquires the measured sailing speed, seawater temperature, and bottom position of the ship in the water depth, derives seawater conductivity from the acquired seawater temperature, derives a polarization curve corresponding to the acquired sailing speed and seawater temperature from the polarization curves stored in the memory, creates a three-dimensional analysis area model that simulates a three-dimensional UEP distribution analysis area in the water area surrounding the hull based on the bottom position of the ship in the water depth, calculates a UEP distribution within the three-dimensional analysis area model based on the derived seawater conductivity, the derived polarization curve, the created three-dimensional analysis area model, and the calculated exposure amount, and determines the UEP at the specified position or the UEP at the plurality of positions from the UEP distribution. This configuration makes it possible to more accurately estimate the UEP when the exposure amount of the sacrificial anode is the calculated exposure amount.

[0121] A corrosion prevention device according to a tenth aspect of the present disclosure is the corrosion prevention device according to the seventh or eighth aspect, further comprising a memory that stores polarization curves of constituent materials of the hull and the sacrificial anode corresponding to a plurality of sailing speeds, a plurality of seawater temperatures, and a plurality of hull coating condition levels, and the controller acquires the measured sailing speed, seawater temperature, and ship bottom position in the water depth, as well as the current hull coating condition level, derives seawater conductivity from the acquired seawater temperature, and selects the acquired sailing speed from the polarization curves stored in the memory. A polarization curve corresponding to the seawater temperature, the seawater temperature, and the hull coating condition level may be derived, a three-dimensional analysis domain model simulating a three-dimensional UEP distribution analysis domain in the water area around the hull may be created based on the ship bottom position in the water depth, a UEP distribution within the three-dimensional analysis domain model may be calculated based on the derived seawater conductivity, the derived polarization curve, the created three-dimensional analysis domain model, and the calculated exposure amount, and the UEP at the specified position or the UEPs at the multiple positions may be obtained from the UEP distribution. This configuration allows for more accurate estimation of the UEP when the exposure amount of the sacrificial anode is the calculated exposure amount.

[0122] In an eleventh aspect of the present disclosure, in the corrosion prevention device of the seventh aspect, the controller may have a machine learning model pre-trained using the vessel's sailing speed, seawater temperature, vessel bottom position at the water depth, and the exposure amount of the sacrificial anode as input data, and the UEP at a predetermined position a predetermined distance from the vessel or UEP at multiple positions a predetermined distance from the vessel as output data, and may be configured to repeatedly determine the UEP at the predetermined position or the UEP at the multiple positions by inputting the measured vessel speed, seawater temperature, vessel bottom position at the water depth, and the calculated exposure amount to the machine learning model while changing the calculated exposure amount. This configuration allows for more accurate estimation of the UEP when the exposure amount of the sacrificial anode is the calculated exposure amount.

[0123] A twelfth aspect of the present disclosure provides a corrosion prevention device according to the eighth aspect, wherein the controller has a machine learning model pre-trained using the vessel's sailing speed, seawater temperature, vessel bottom position at the water depth, and the exposure amount of the sacrificial anode as input data, and the UEP at a predetermined position a predetermined distance from the hull or the UEP at multiple positions a predetermined distance from the hull and the hull potential as output data, and the controller may be configured to repeatedly calculate the UEP at the predetermined position or the UEP at the multiple positions and the hull potential by inputting the measured sailing speed, seawater temperature, vessel bottom position at the water depth, and the calculated exposure amount to the machine learning model while changing the calculated exposure amount. This configuration allows for more accurate estimation of the UEP when the exposure amount of the sacrificial anode is the calculated exposure amount. [Explanation of symbols]

[0124] 1A~1D Corrosion prevention equipment 2. Hull 4 Sacrificial anode 10 Controller 10A, 10B Machine Learning Model 11 Memory device 12 speedometer 13 Water temperature gauge 14. Ship bottom position measurement device 15 Variable resistor 16 Shielding mechanism M1 3D analysis domain model

Claims

1. a sacrificial anode attached to the hull of the vessel via an insulator; a variable resistor interposed between the sacrificial anode and the hull and electrically connected to the sacrificial anode and the hull; a controller for controlling the variable resistor; The controller When the ship is navigating a specific sea area, a UEP at a predetermined position a predetermined distance away from the hull or UEPs at multiple positions a predetermined distance away from the hull is repeatedly obtained while changing the calculated resistance value using at least one of the four items measured during navigation, namely, navigation speed, seawater temperature, and ship bottom position in the water depth, and the hull coating condition level during navigation, and a calculated resistance value which is a calculated value of the resistance value of the variable resistor, and the calculated resistance value is derived when the UEP at the predetermined position or the sum of the UEPs at the multiple positions is equal to or less than a predetermined value, controlling the variable resistor so that the resistance value of the variable resistor becomes the calculated resistance value; Corrosion prevention device.

2. a sacrificial anode attached to the hull of the vessel via an insulator; a variable resistor interposed between the sacrificial anode and the hull and electrically connected to the sacrificial anode and the hull; a controller for controlling the variable resistor; The controller When the ship is navigating a specific sea area, at least one of four items measured during navigation, namely, navigation speed, seawater temperature, and ship bottom position in the water depth, and the hull coating condition level during navigation, and a calculated resistance value which is a calculated value of the resistance value of the variable resistor, are used to repeatedly determine the UEP at a predetermined position a predetermined distance away from the hull or the UEP at a plurality of positions a predetermined distance away from the hull, and the hull potential while changing the calculated resistance value, and when the hull potential is within a corrosion protection potential range, the calculated resistance value is derived when the UEP at the predetermined position or the sum of the UEPs at the plurality of positions is equal to or less than a predetermined value, controlling the variable resistor so that the resistance value of the variable resistor becomes the calculated resistance value; Corrosion prevention device.

3. a memory that stores polarization curves of the constituent materials of the hull and the sacrificial anode corresponding to a plurality of sailing speeds and a plurality of seawater temperatures; The controller The measured sailing speed, seawater temperature, and ship bottom position in the water depth are acquired, the seawater conductivity is derived from the acquired seawater temperature, a polarization curve corresponding to the acquired sailing speed and seawater temperature is derived from the polarization curves stored in the memory, and a three-dimensional analysis area model is created that simulates a three-dimensional UEP distribution analysis area that is the water area around the ship based on the ship bottom position in the water depth, 3. The corrosion prevention device according to claim 1, wherein a UEP distribution within the three-dimensional analytical domain model is calculated based on the derived seawater conductivity, the derived polarization curve, the created three-dimensional analytical domain model, and the calculated resistance value, and the UEP at the specified position or the UEPs at the multiple positions is determined from the UEP distribution.

4. a memory that stores polarization curves of the constituent materials of the hull and the sacrificial anode corresponding to a plurality of sailing speeds, a plurality of seawater temperatures, and a plurality of hull coating condition levels; The controller the measured sailing speed, seawater temperature, and ship bottom position in the water depth are acquired, and the current hull coating condition level is acquired; the seawater conductivity is derived from the acquired seawater temperature; a polarization curve corresponding to the acquired sailing speed, seawater temperature, and hull coating condition level is derived from the polarization curves stored in the memory; and a three-dimensional analysis region model is created that simulates a three-dimensional UEP distribution analysis region, which is the water area around the hull, based on the ship bottom position in the water depth; 3. The corrosion prevention device according to claim 1, wherein a UEP distribution within the three-dimensional analytical domain model is calculated based on the derived seawater conductivity, the derived polarization curve, the created three-dimensional analytical domain model, and the calculated resistance value, and the UEP at the specified position or the UEPs at the multiple positions is determined from the UEP distribution.

5. The controller a machine learning model that has been trained in advance using the ship's sailing speed, seawater temperature, ship bottom position in the water depth, and the resistance value of the variable resistor as input data, and a UEP at a predetermined position a predetermined distance from the hull or UEPs at multiple positions a predetermined distance from the hull as output data, and the machine learning model is configured to repeatedly calculate the UEP at the predetermined position or the UEPs at the multiple positions by inputting the measured sailing speed, seawater temperature, ship bottom position in the water depth, and the calculated resistance value while changing the calculated resistance value; The corrosion protection device according to claim 1 .

6. The controller a machine learning model that has been trained in advance using the ship's sailing speed, seawater temperature, ship bottom position in the water depth, and the resistance value of the variable resistor as input data, and the UEP at a predetermined position a predetermined distance from the hull or the UEPs at multiple positions a predetermined distance from the hull and the hull potential as output data, and by inputting the measured sailing speed, seawater temperature, ship bottom position in the water depth, and the calculated resistance value into the machine learning model while changing the calculated resistance value, the UEP at the predetermined position or the UEPs at the multiple positions and the hull potential are repeatedly obtained; The corrosion protection device according to claim 2.

7. a sacrificial anode electrically connected to the hull of the vessel; a shielding mechanism for changing the amount of exposure of the sacrificial anode to the outside of the hull; a controller for controlling the shielding mechanism, The controller When the ship is navigating a specific sea area, at least one of the four items measured during navigation, namely, navigation speed, seawater temperature, and ship bottom position in the water depth, and the hull coating condition level during navigation, and a calculated exposure amount which is a calculated value of the exposure amount of the sacrificial anode, is used to repeatedly determine the UEP at a predetermined position a predetermined distance away from the hull or the UEP at a plurality of positions a predetermined distance away from the hull while changing the calculated exposure amount, and derive the calculated exposure amount when the UEP at the predetermined position or the sum of the UEPs at the plurality of positions is equal to or less than a predetermined value; controlling the shielding mechanism so that the exposure amount of the sacrificial anode becomes the calculated exposure amount; Corrosion prevention device.

8. a sacrificial anode electrically connected to the hull of the vessel; a shielding mechanism for changing the amount of exposure of the sacrificial anode to the outside of the hull; a controller for controlling the shielding mechanism, The controller When the ship is navigating a specific sea area, the method uses at least one of the four items measured during navigation, namely, navigation speed, seawater temperature, and ship bottom position in the water depth, and the hull coating condition level during navigation, and a calculated exposure amount which is a calculated value of the exposure amount of the sacrificial anode, to repeatedly determine the UEP at a predetermined position a predetermined distance away from the hull or the UEP at a plurality of positions a predetermined distance away from the hull, and the hull potential while changing the calculated exposure amount, and derives the calculated exposure amount when the UEP at the predetermined position or the sum of the UEPs at the plurality of positions is equal to or less than a predetermined value when the hull potential is within a corrosion protection potential range, controlling the shielding mechanism so that the exposure amount of the sacrificial anode becomes the calculated exposure amount; Corrosion prevention device.

9. a memory that stores polarization curves of the constituent materials of the hull and the sacrificial anode corresponding to a plurality of sailing speeds and a plurality of seawater temperatures; The controller The measured sailing speed, seawater temperature, and ship bottom position in the water depth are acquired, the seawater conductivity is derived from the acquired seawater temperature, a polarization curve corresponding to the acquired sailing speed and seawater temperature is derived from the polarization curves stored in the memory, and a three-dimensional analysis area model is created that simulates a three-dimensional UEP distribution analysis area that is the water area around the ship based on the ship bottom position in the water depth, 9. The corrosion prevention device according to claim 7 or 8, wherein a UEP distribution within the three-dimensional analytical region model is calculated based on the derived seawater conductivity, the derived polarization curve, the created three-dimensional analytical region model, and the calculated exposure amount, and a UEP at the specified position or UEPs at the multiple positions is obtained from the UEP distribution.

10. a memory that stores polarization curves of the constituent materials of the hull and the sacrificial anode corresponding to a plurality of sailing speeds, a plurality of seawater temperatures, and a plurality of hull coating condition levels; The controller the measured sailing speed, seawater temperature, and ship bottom position in the water depth are acquired, and the current hull coating condition level is acquired; the seawater conductivity is derived from the acquired seawater temperature; a polarization curve corresponding to the acquired sailing speed, seawater temperature, and hull coating condition level is derived from the polarization curves stored in the memory; and a three-dimensional analysis region model is created that simulates a three-dimensional UEP distribution analysis region, which is the water area around the hull, based on the ship bottom position in the water depth; 9. The corrosion prevention device according to claim 7 or 8, wherein a UEP distribution within the three-dimensional analytical region model is calculated based on the derived seawater conductivity, the derived polarization curve, the created three-dimensional analytical region model, and the calculated exposure amount, and a UEP at the specified position or UEPs at the multiple positions is obtained from the UEP distribution.

11. The controller a machine learning model that has been trained in advance using the ship's sailing speed, seawater temperature, ship bottom position in the water depth, and the exposure amount of the sacrificial anode as input data, and a UEP at a predetermined position a predetermined distance away from the hull or UEPs at multiple positions a predetermined distance away from the hull as output data, and the measured sailing speed, seawater temperature, ship bottom position in the water depth, and the calculated exposure amount are input to the machine learning model while changing the calculated exposure amount, thereby repeatedly determining the UEP at the predetermined position or the UEPs at the multiple positions; The corrosion protection device according to claim 7.

12. The controller a machine learning model that has been trained in advance using the ship's sailing speed, seawater temperature, ship bottom position in the water depth, and the exposure amount of the sacrificial anode as input data, and the UEP at a predetermined position a predetermined distance from the hull or the UEPs at multiple positions a predetermined distance from the hull and the hull potential as output data, and by inputting the measured sailing speed, seawater temperature, ship bottom position in the water depth, and the calculated exposure amount into the machine learning model while changing the calculated exposure amount, the UEP at the predetermined position or the UEPs at the multiple positions and the hull potential are repeatedly obtained; The corrosion protection device according to claim 8.

Images