A system and method for preventing ship grounding

Abstract

The application discloses a system and method for preventing ship grounding, which is arranged on a ship body having a ship bottom, and comprises a water depth measuring sensor array arranged on the side of the ship body, each group of the water depth measuring sensor array comprising a first depth measuring sensor and a second depth measuring sensor arranged close to each other, the first depth measuring sensor being arranged perpendicularly to the water bottom to measure the vertical water depth from the ship bottom to a first position of the water bottom, and the second depth measuring sensor being arranged at a preset angle with the vertical direction to measure the oblique distance from the ship bottom to a second position of the water bottom in the detection direction of the second depth measuring sensor, so as to obtain the third distance between the first position and the second position of the water bottom through the vertical water depth and the oblique distance. The application solves the problems of the traditional anti-grounding means, such as early warning lag and insufficient precision, at a low cost, forms a 360-degree non-blind area detection network, and effectively reduces the risk of inland ship grounding accidents.

Description

Technical Field

[0001] This invention relates to the field of ship navigation safety technology, and in particular to a system and method for preventing ships from running aground. Background Technology

[0002] Currently, most small and medium-sized inland waterway vessels rely on a combination of basic equipment and human experience to prevent grounding. Most vessels are equipped with basic equipment such as single-beam echo sounders, GPS positioning, and simple electronic nautical charts to monitor the water depth and the vessel's horizontal position directly below the hull in real time. This, combined with the crew's experience, helps to prevent grounding. Some small inland waterway vessels also use human-aided methods such as "water probes" to compensate for the lack of equipment functionality.

[0003] However, the existing anti-grounding methods mentioned above can only measure the water depth directly below the ship's current position vertically, and cannot detect changes in underwater topography in front of or to the side of the ship. When the depth sounder shows insufficient water depth, the ship has often already entered the edge of the shoal. GPS positioning can only provide the ship's planar coordinates and cannot reflect the actual underwater water depth. The human-based method of "water-finding bamboo" has a low degree of automation, relies entirely on the personal experience of the crew, and is greatly affected by environmental factors such as night, fog, and rapid currents. It has low detection accuracy, limited detection distance, and cannot achieve continuous monitoring.

[0004] In summary, existing anti-stranding technologies have drawbacks such as delayed early warning, large detection blind spots, insufficient accuracy, reliance on human experience, poor reliability, and high overall cost. Summary of the Invention

[0005] The purpose of this invention is to provide a system and method for preventing ships from running aground, thereby solving the aforementioned technical problems in the prior art. The specific technical solution is as follows: A system for preventing ships from running aground is installed on the hull, which has a bottom. The system includes an array of depth sensors installed on the side of the hull. Each array of depth sensors includes a first depth sensor and a second depth sensor installed close to each other. The first depth sensor is installed perpendicular to the bottom of the water and is used to measure the vertical water depth from the bottom of the hull to a first position on the bottom of the water. The second depth sensor is installed at a preset angle to the vertical direction and is used to measure the oblique distance from the bottom of the hull to a second position on the bottom of the water in its detection direction. A third distance between the first and second positions on the bottom of the water is obtained by measuring the vertical water depth and the oblique distance.

[0006] Furthermore, it also includes an attitude sensor and a data processing unit. The attitude sensor is mounted on the hull and is used to collect the hull's roll and pitch attitude data. The data processing unit is electrically connected to the first depth sounder, the second depth sounder, and the attitude sensor, respectively. The data processing unit is configured to correct the vertical water depth obtained by the first depth sounder and the oblique distance obtained by the second depth sounder based on the attitude data.

[0007] Furthermore, at least one set of depth sensor arrays is installed at the bow of the hull, and at least two sets of depth sensor arrays are installed on each side of the hull to form a blind-spot-free underwater detection network.

[0008] Furthermore, the preset angle between the second depth sensor and the vertical direction is set to 15° to 45°.

[0009] Furthermore, the system also includes an alarm unit and a display unit. The alarm unit is electrically connected to the data processing unit and is used to issue corresponding warning signals according to different grounding risk levels. The display unit is electrically connected to the data processing unit and is used to display the underwater oblique distance, vertical water depth, underwater slope change trend, and grounding risk warning information in real time in all directions around the hull.

[0010] Furthermore, it also includes a BeiDou time synchronization module, which is electrically connected to the data processing unit and is used to provide a unified time reference for all the first depth sounder, the second depth sounder, and the attitude sensor, so as to synchronize the data collected by the attitude sensor and all the first depth sounder and the second depth sounder.

[0011] A method for preventing a ship from running aground, implemented using the aforementioned system for preventing ship grounding, includes the following steps: S1: Water depth data is collected by multiple sets of depth sensor arrays installed on the side of the hull. Each set of depth sensor arrays includes a first depth sensor and a second depth sensor installed close to each other. The first depth sensor is installed perpendicular to the bottom of the water and collects the vertical water depth from the bottom of the hull to a first position on the bottom of the water. The second depth sensor is installed at a preset angle to the vertical direction and collects the oblique distance from the bottom of the hull to a second position on the bottom of the water in its detection direction. S2: Calculate the third distance between the first position and the second position based on the vertical water depth and oblique distance collected by each group of water depth sensor arrays; S3: Monitor the continuous changing trend of the third distance, judge the change of underwater slope based on the changing trend, and determine the risk of grounding when the underwater slope is continuously steepened.

[0012] 8. The method for preventing a ship from running aground according to claim 7, wherein step S1 further includes: collecting roll and pitch attitude data of the ship by means of attitude sensors installed on the ship hull.

[0013] 9. The method for preventing ship grounding according to claim 8, characterized in that, before step S2, it further includes: correcting the vertical water depth at the first position collected by the first depth sounder and the oblique distance at the second position collected by the second depth sounder based on attitude data, so as to obtain the true vertical water depth and the true oblique distance under the stable state of the ship.

[0014] 10. The method for preventing a ship from running aground according to any one of claims 7 to 9, characterized in that step S3 specifically includes: S31: When the third distance continuously decreases to the first warning threshold within the preset continuous acquisition period, it is determined that there is a risk of long-distance gradual grounding, and the alarm unit is controlled to issue a first-level audible and visual warning signal. S32: When the vertical water depth at the first position collected by the first depth sounder is less than the second safety threshold, it is determined that there is a risk of emergency grounding at close range, and the control alarm unit issues a level two audible and visual warning signal.

[0015] The system and method for preventing ships from running aground according to the present invention have the following advantages: 1. By setting up a water depth sensor array on the side of the hull, which includes a first depth sounder and a second depth sounder that are close to each other, and adopting a dual-angle detection architecture at the same position, the third distance between the two points is calculated using the geometric relationship of triangles to directly reflect the changes in underwater topography and slope. This solves the problems of delayed early warning and large-area detection blind spots in traditional anti-grounding methods, and provides an economical and feasible active anti-grounding hardware foundation for the vast majority of small and medium-sized transport ships and fishing boats that make up the majority of inland waterway vessels.

[0016] 2. By adding attitude sensors and a data processing unit, the interference of roll and pitch on depth measurement data during ship navigation is effectively eliminated. The data processing unit dynamically corrects the vertical water depth and oblique distance based on real-time attitude data, restoring the true measurement values ​​under stable ship conditions. This ensures the accuracy of the system under complex conditions such as wind, waves, and currents, reduces the probability of false alarms and missed alarms caused by ship rolling, and improves the system's environmental adaptability.

[0017] 3. Through the deployment of a distributed sensor array, a 360° blind-spot-free underwater detection network covering the hull has been formed. This significantly enhances the detection capability of the bow area, where ships are most prone to grounding, while also considering lateral safety on both sides. It comprehensively monitors changes in the underwater topography around the ship, avoiding the blind spots present in traditional single-point depth sounding, and providing all-around protection against grounding.

[0018] 4. The preset angle of the second depth sounder is limited to the range of 15° to 45°, balancing the requirements for long-distance detection with the requirements for measurement accuracy. This angle range can be flexibly adjusted according to the average water depth and speed of the waterway in which the ship is navigating, ensuring sufficient early warning distance while avoiding a decrease in measurement accuracy due to an excessively large angle. This allows the system to adapt to different inland waterway conditions and improves its versatility.

[0019] 5. By setting up tiered alarm units and visual display units, differentiated early warning and intuitive presentation of grounding risks are achieved. Level 1 warnings provide advance notice of risks at a distance, allowing crew sufficient time to avoid them; Level 2 warnings address emergencies at close range, urging immediate action. The display units graphically represent complex underwater data, reducing the information processing burden on crew members and effectively improving emergency response speed and decision-making efficiency.

[0020] 6. By setting up a BeiDou time synchronization module, a unified high-precision time reference is provided for all sensors, solving the problem of asynchronous data acquisition from multiple sensors. This ensures precise time matching between attitude data and water depth data, avoiding errors in third distance calculation and slope judgment caused by data time misalignment, and further improving the accuracy and reliability of the system's early warning from a data perspective. Attached Figure Description

[0021] Figure 1 This is a three-dimensional schematic diagram of the rear side of the hull in the system for preventing ships from running aground, which is the subject of this invention.

[0022] Figure 2 This is a three-dimensional schematic diagram of the front side of the hull in the system for preventing ships from running aground, which is the subject of this invention.

[0023] Figure 3 This is a side view of the hull of the system used in this invention to prevent ships from running aground.

[0024] Figure 4 This is a top view of the hull of the system used in this invention to prevent ships from running aground.

[0025] Figure 5 This is a front view of the hull in the system for preventing ships from running aground, as described in this invention.

[0026] Figure 6 This is a flowchart of the signal acquisition and output process in the system for preventing ships from running aground, as described in this invention.

[0027] Figure 7 This is a schematic diagram of the third distance in the method for preventing ships from running aground, when the seabed in front of the hull is flat.

[0028] Figure 8 This is a schematic diagram of the third distance in the method for preventing ships from running aground in this invention when the seabed in front of the hull is in a gentle slope state.

[0029] Figure 9 This is a schematic diagram of the third distance in the method for preventing ships from running aground in this invention when the seabed in front of the hull is in a steep slope state. Detailed Implementation

[0030] To better understand the purpose, structure, and function of the present invention, the system and method for preventing ships from running aground are described in detail below with reference to the accompanying drawings.

[0031] This invention provides a system for preventing ships from running aground, which is mainly applicable to small and medium-sized inland waterway transport vessels, fishing boats and operating vessels. The system achieves early detection and risk warning of the underwater terrain around the ship at low cost through sensor architecture and early warning algorithm.

[0032] like Figures 1 to 9 As shown, the system is mounted on hull 1, which has a bottom. Its core detection component is a depth sounding sensor array 2 distributed along the sides of hull 1. Each array 2 contains two depth sounding sensors positioned close to each other: a first depth sounding sensor 3 and a second depth sounding sensor 4. Since these sensors are close together, their detection beams can be approximated as originating from the same point and lying in the same vertical plane. The two sensors are configured with different accuracy levels. The first depth sounding sensor 3 uses a high-precision module to ensure the accuracy of close-range vertical depth A measurements. The second depth sounding sensor 4 can use a slightly lower-precision module to meet long-distance detection requirements while controlling overall cost. The first depth sounding sensor 3 is positioned perpendicular to the seabed 5, with its detection beam pointing vertically downwards. This allows for direct measurement of the distance from the sensor to the seabed 5. This data can be converted into the actual vertical depth A from the bottom of the hull to the seabed 5, reflecting the ship's current draft safety margin. The second depth sensor 4 is set at a preset angle α with the vertical direction, and its detection beam is obliquely pointed in front of or to the side of the ship's navigation. It is used to measure the distance from the sensor to the bottom 5 in the oblique direction, which can also be converted into the actual oblique distance B from the bottom of the ship to the bottom 5.

[0033] By detecting the first position 'a' of the wave at the bottom 5 using the first depth sounder 3 and the second position 'b' of the wave at the bottom 5 using the second depth sounder 4, the system can use the geometric relationship of a triangle to calculate the third distance 'C' between the first position 'a' and the second position 'b'. Based on the change of the third distance 'C', it can obtain underwater topographic information at a certain distance in front of or to the side of the ship. This dual-angle sensor architecture at the same position overcomes the limitation of only measuring the water depth directly below the ship, providing a foundation for long-distance early warning.

[0034] To eliminate the impact of ship rolling on measurement accuracy during navigation, the system is also equipped with attitude sensors and a data processing unit, which is essentially an intelligent hardware acquisition terminal. The attitude sensors are fixedly installed at stable locations such as near the center of gravity of the hull 1, enabling real-time acquisition of the hull 1's roll and pitch attitude data. The data processing unit can be implemented using a low-cost embedded microcontroller (MCU). The digital signals output by the sensors are directly connected to the MCU for acquisition and processing, eliminating the need for an additional high-performance computer and further reducing the overall system cost. As the core control component of the system, the data processing unit is electrically connected to the first depth sounder 3, the second depth sounder 4, and the attitude sensor, respectively, and is responsible for receiving and processing the data acquired by all sensors. When the ship tilts due to water currents or waves, the actual detection angles of the two depth sounders will deviate from the preset angles, resulting in errors in the measured water depth and oblique distance B. At this point, the data processing unit corrects the original measurements using trigonometric transformations based on the real-time roll and pitch angles collected by the attitude sensors. This correction process considers both the initial installation angle deviation of the sensors and the dynamic tilt angle of hull 1, restoring the true vertical water depth A and the true oblique distance B of hull 1 when it is in a stable state. This design ensures the accuracy of the system's measurements under complex hydrological and meteorological conditions, effectively avoiding false alarms or missed alarms caused by the rolling of hull 1.

[0035] To achieve full coverage detection of the underwater environment surrounding the hull 1, the depth sounding sensor array 2 adopts a distributed layout. Specifically, at least one set of depth sounding sensor array 2 is installed at the bow of the hull 1, because the bow is the part most prone to grounding during navigation, and priority needs to be given to ensuring forward detection capabilities; at least two sets of depth sounding sensor array 2 are installed on each of the port and starboard sides of the hull 1, respectively covering the lateral areas of the port and starboard sides of the hull. In this embodiment, a total of five sets of depth sounding sensor array 2 are set, with one set at the bow of the hull 1 and two sets on each of the port and starboard sides of the hull 1. Through this layout, the detection ranges of each set of depth sounding sensor array 2 are superimposed, forming a 360° blind-spot-free underwater detection network at low cost, comprehensively monitoring changes in the underwater topography around the ship. For ease of installation and maintenance, the first depth sounder 3 and the second depth sounder 4 in each set of depth sounding sensor array 2 are integrated into the same waterproof housing, which can adapt to the harsh environment of long-term underwater operation. The waterproof housing is installed on the outside of the hull 1 via a detachable bracket. The installation height is higher than the lowest draft of the ship, which ensures that the sensor can always be below the water surface for effective detection, and also avoids the sensor from colliding with the seabed 5 when the ship is unloaded or in shallow draft.

[0036] The second depth sounder 4 has a preset angle α with the vertical direction set to 15°–45°, pointing towards the area outside the vertical projection plane of the hull 1. This angle range is determined after comprehensively considering the detection distance and measurement accuracy. When the preset angle α is too small, the third distance C obtained by oblique detection is limited, making effective long-range early warning impossible. When the preset angle α is too large, the oblique detection distance is too long, leading to a significant decrease in measurement accuracy, while also increasing the power consumption and cost of the sensor. In practical applications, the preset angle α can be pre-adjusted according to the average water depth and ship speed in the navigation area. For example, in waters with greater depth and higher ship speed, the preset angle α can be appropriately increased to obtain a longer detection distance, allowing the crew more reaction time; in waters with less depth and lower ship speed, the preset angle α can be appropriately decreased to improve measurement accuracy.

[0037] The system also includes an alarm unit and a display unit, both electrically connected to the data processing unit. The alarm unit issues corresponding warning signals based on different grounding risk levels, alerting the crew to take timely action. The display unit shows in real-time the underwater oblique distance B, vertical water depth A, calculated underwater slope distribution, and grounding risk warning information in all directions around the hull, presenting complex underwater topography data to the crew in an intuitive graphical format, helping them quickly grasp the safety situation around the vessel. Through tiered warnings and visual displays, the system effectively reduces the crew's workload and improves emergency response speed.

[0038] To ensure time consistency of data collected by multiple sensors, the system also includes a BeiDou time synchronization module, which is electrically connected to the data processing unit. This module receives time signals from BeiDou satellites, providing a unified, high-precision time reference for all the first depth sounder 3, the second depth sounder 4, and the attitude sensor, ensuring that all sensors acquire data at the same time. Without a unified time reference, time differences would exist in the data collected by different sensors, causing errors in the data processing unit's calculation of the third distance C and underwater slope, affecting the accuracy of the warning. The synchronization accuracy meets the requirements of multi-sensor data fusion, avoiding false warnings due to data time misalignment. The BeiDou time synchronization module fundamentally solves the problem of multi-sensor data synchronization, further improving the system's reliability and accuracy.

[0039] The present invention also discloses a method for preventing ships from running aground, which is implemented using the above-mentioned system for preventing ships from running aground, and specifically includes the following steps: First, water depth data is collected using multiple depth sounding sensor arrays 2 mounted on the side of the hull 1. In each array, the first depth sounding sensor 3 vertically downwards collects the vertical water depth A from the hull bottom to the seabed 5, while the second depth sounding sensor 4 obliquely collects the oblique distance B from the hull bottom to the seabed 5 at a preset angle α. Simultaneously, attitude sensors mounted on the hull 1 collect roll and pitch attitude data, providing a basis for subsequent measurement corrections.

[0040] Before calculating the third distance C, the data processing unit corrects the original measurements from the first depth sounder 3 and the second depth sounder 4 based on the attitude data collected by the attitude sensor. This eliminates errors caused by the tilting of the hull 1, yielding the true vertical water depth A and the true oblique distance B of the hull 1 in a stable state. This step is crucial for ensuring the accuracy of subsequent calculations, especially in waters with large waves, effectively preventing misjudgments caused by the rolling of the hull 1.

[0041] like Figures 7 to 9 As shown, the data processing unit then calculates the third distance C between the first position a of the sounding wave from the first depth sounder 3 on the seabed 5 and the second position b of the sounding wave from the second depth sounder 4 on the seabed 5, based on the corrected vertical depth A and oblique distance B of each set of depth sounder arrays 2 using the Pythagorean theorem. The variation of this third distance C reflects the slope variation characteristics of the underwater topography. Specifically, in a flat seabed environment 5, the third distance C remains at its maximum value and is basically stable; as the vessel gradually approaches the shore, shoals, or underwater protrusions, the underwater slope gradually becomes steeper, and the third distance C shows a continuous decreasing trend; when the vessel approaches the edge of the shoal with the steepest slope, the third distance C reaches its minimum value, and then gradually increases again as the vessel passes the apex of the slope. By identifying the above-mentioned characteristic variation patterns of the third distance C, the system can accurately distinguish between normal seabed undulations 5 and actual grounding risks, significantly reducing the probability of false alarms.

[0042] It should be noted that the third distance C described in this embodiment is a relative distance based on the local coordinate system of hull 1. Its core function is to reflect the degree of terrain undulation between the first position a and the second position b, rather than the absolute geographical distance in the geodetic coordinate system. Using this definition of relative distance eliminates the need for complex geodetic coordinate transformations and three-dimensional decoupling calculations of hull 1's attitude, significantly simplifying the data processing flow, reducing the performance requirements of the embedded microcontroller, and accurately reflecting the relative degree of danger between hull 1 and underwater obstacles. Even when hull 1 experiences slight roll, pitch, or minor underwater undulations, the trend of the third distance C can still stably and accurately reflect changes in the underwater slope, effectively improving the robustness and reliability of the system.

[0043] Finally, the system continuously monitors the changing trend of the third distance C and judges the changes in underwater slope based on the changing trend. When the third distance C continuously decreases within the preset continuous acquisition period, it indicates that the slope of the underwater terrain ahead is becoming steeper and the water depth is gradually becoming shallower, posing a risk of grounding. Specifically, when the third distance C continuously decreases to the first warning threshold, it is determined that there is a risk of gradual grounding at a long distance. At this time, the data processing unit controls the alarm unit to issue a first-level audible and visual warning signal, reminding the crew to slow down in advance and pay attention to the water ahead. When the vertical water depth A collected by the first depth sounder 3 is less than the second safety threshold, it indicates that the vessel has approached the shoal and there is a risk of emergency grounding at close range. At this time, the control alarm unit issues a second-level audible and visual warning signal, reminding the crew to take immediate evasive or stop measures. Through this graded warning mechanism, the system can issue early warnings when the vessel is far from the shoal, allowing the crew sufficient time to avoid the situation, and can also issue emergency alarms when the vessel approaches the danger zone, effectively preventing grounding accidents.

[0044] The terms “above,” “below,” and “within” as used above include the number itself; the terms “exceeding” and “excluding” do not include the number itself.

[0045] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific descriptions herein should not be construed as limiting the substance and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention. The various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0046] If the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

Claims

1. A system for preventing ships from running aground, installed on the hull, the hull having a bottom, characterized in that, The system includes an array of depth sensors mounted on the side of the hull. Each array includes a first depth sensor and a second depth sensor positioned close to each other. The first depth sensor is perpendicular to the bottom of the water and is used to measure the vertical water depth from the bottom of the hull to a first position on the bottom. The second depth sensor is set at a preset angle to the vertical direction and is used to measure the oblique distance from the bottom of the hull to a second position on the bottom of the water in its detection direction. The system then uses the vertical water depth and the oblique distance to obtain a third distance between the first and second positions on the bottom of the water.

2. The system for preventing ship grounding according to claim 1, characterized in that, It also includes an attitude sensor and a data processing unit. The attitude sensor is mounted on the hull and is used to collect the hull's roll and pitch attitude data. The data processing unit is electrically connected to the first depth sounder, the second depth sounder, and the attitude sensor, respectively. The data processing unit is configured to correct the vertical water depth obtained by the first depth sounder and the oblique distance obtained by the second depth sounder based on the attitude data.

3. The system for preventing ship grounding according to claim 1, characterized in that, At least one set of depth sensor arrays is installed at the bow of the hull, and at least two sets of depth sensor arrays are installed on each side of the hull to form a blind-spot-free underwater detection network.

4. The system for preventing ship grounding according to claim 1, characterized in that, The angle between the second depth sensor and the preset vertical direction is set to 15° to 45°.

5. The system for preventing ship grounding according to claim 2, characterized in that, The system also includes an alarm unit and a display unit. The alarm unit is electrically connected to the data processing unit and is used to issue corresponding warning signals according to different grounding risk levels. The display unit is electrically connected to the data processing unit and is used to display the underwater oblique distance, vertical water depth, underwater slope change trend and grounding risk warning information in real time in all directions around the hull.

6. The system for preventing ship grounding according to any one of claims 2 to 5, characterized in that, It also includes a BeiDou time synchronization module, which is electrically connected to the data processing unit and is used to provide a unified time reference for all the first depth sounder, the second depth sounder and the attitude sensor, so as to synchronize the data collected by the attitude sensor and all the first depth sounder and the second depth sounder.

7. A method for preventing a ship from running aground, implemented using any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Water depth data is collected by multiple sets of depth sensor arrays installed on the side of the hull. Each set of depth sensor arrays includes a first depth sensor and a second depth sensor installed close to each other. The first depth sensor is installed perpendicular to the bottom of the water and collects the vertical water depth from the bottom of the hull to a first position on the bottom of the water. The second depth sensor is installed at a preset angle to the vertical direction and collects the oblique distance from the bottom of the hull to a second position on the bottom of the water in its detection direction. S2: Calculate the third distance between the first position and the second position based on the vertical water depth and the oblique distance collected by each group of water depth sensor arrays; S3: Monitor the continuous change trend of the third distance, judge the change of underwater slope based on the change trend, and determine the risk of grounding when the underwater slope is continuously steepened.

8. The method for preventing ship grounding according to claim 7, characterized in that, Step S1 also includes: collecting the ship's roll and pitch attitude data by using attitude sensors installed on the ship's hull.

9. The method for preventing ship grounding according to claim 8, characterized in that, Before step S2, the method further includes: correcting the vertical water depth at the first position collected by the first depth sounder and the oblique distance at the second position collected by the second depth sounder based on the attitude data, so as to obtain the true vertical water depth and the true oblique distance under the stable state of the ship.

10. The method for preventing a ship from running aground according to any one of claims 7 to 9, characterized in that, Step S3 specifically includes: S31: When the third distance continuously decreases to the first warning threshold within the preset continuous acquisition period, it is determined that there is a risk of long-distance gradual grounding, and the alarm unit is controlled to issue a first-level audible and visual warning signal. S32: When the vertical water depth at the first position collected by the first depth sounder is less than the second safety threshold, it is determined that there is a risk of emergency grounding at close range, and the alarm unit is controlled to issue a level two audible and visual warning signal.

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