A floating test method for testing the performance of a ship's stern ramp

Abstract

The present invention relates to the technical field of performance testing of a ro-ro passenger ship stern ramp, and more specifically to a floating test method for testing the performance of a ship stern ramp. The performance testing floating test method comprises the following steps: (1) determining the lifting capacity of a crane according to the load lifted by the stern ramp; (2) selecting a crane; (3) determining the position of the crane and installing and moving the crane to a dock; (4) the crane lifts the stern ramp and tests it; (5) drawing a test conclusion and verifying it; and (6) ending the floating test. The above method has the advantages of being simple, having a high test accuracy, and being able to correct the stern ramp in time.

Description

Technical Field

[0001] The invention relates to the technical field of ro-ro passenger ship stern ramp performance test, in particular to a ship stern ramp performance test floating test method which has simple method, high test accuracy and can correct the stern ramp in time. Background Art

[0002] As we all know, for the ro-ro equipment installed on the passenger ro-ro ship, various functions need to be debugged and inspected in the shipyard. The stern ramp is the transition bridge between the dock and the ship, and it is also the most commonly used ro-ro equipment. When the stern ramp is placed on the dock, it is affected by the waves and needs to be in a free state to float up and down with the waves. For the stern ramp controlled by the winch and the wire rope, as long as the wire rope is in a relaxed state, the stern ramp is only connected to the hull through the hinge, and other places are not restricted, then the stern ramp can be free floating. For the stern ramp that is retracted and released by the hydraulic cylinder, in addition to the hinge connection, there is also a hydraulic cylinder connection. If the stern ramp needs to be in a free floating state, the hydraulic system needs to be adjusted to the free mode. The so-called free mode means that the hydraulic oil in the rod chamber and the rodless chamber of the hydraulic cylinder is not restricted. The valve group control can directly lead to the oil tank. At present, affected by the construction and installation of the stern ramp, especially the production, installation and cleaning of the hydraulic pipeline system, the hydraulic cylinder often cannot achieve the ideal design effect during the oil inlet and oil return process, especially when the stern ramp is required to be in the large floating mode. Therefore, during the dock commissioning stage, the stern ramp needs to be tested in floating mode to verify the performance of the floating function of the stern ramp. During the installation process, even if the hydraulic pipeline and solenoid valve are installed according to the preliminary design, therefore, when verifying the performance of the floating function of the stern ramp in the later stage, if the preset performance is not achieved, there will be problems such as damage to the solenoid valve, blockage of the hydraulic pipeline or too many bends in the hydraulic pipeline. Most domestic shipyards do not have the ability to conduct actual large floating inspections of the stern ramp at the dock. Summary of the invention

[0003] The purpose of the present invention is to solve the above-mentioned deficiencies of the prior art and provide a floating test method for testing the performance of a ship's stern ramp, which has a simple method, high test accuracy and can correct the stern ramp in time.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A floating test method for testing the performance of a ship's stern ramp, characterized in that the performance test floating test method comprises the following steps:

[0006] (1) Determine the crane's lifting capacity based on the load lifted by the stern ramp:

[0007] (2) Select a crane:

[0008] (3) Determine the location of the crane and install and move the crane to the dock:

[0009] (4) The stern ramp is hoisted by crane and tested;

[0010] (5) Test conclusion and inspection: The crane is tested at a preset lifting speed and the flow meter reading on the hydraulic pipeline is observed. If the flow meter reading on the hydraulic pipeline is greater than or equal to the theoretical value, the stern ramp meets the requirements. If the flow meter reading on the hydraulic pipeline is less than the theoretical value, it is necessary to determine whether the solenoid valve is blocked or damaged, whether the hydraulic pipeline is blocked, or whether there are too many bends in the hydraulic pipeline, and correct them one by one until the flow meter reading on the hydraulic pipeline is greater than or equal to the theoretical value.

[0011] (6) End of floating test: remove the crane, operate the stern ramp normally to open and close the door three times, and check whether there is any abnormality. If there is no abnormality, the floating mode test is ended.

[0012] The step (1) of the present invention determines the lifting capacity of the crane according to the load of the stern ramp lifting, specifically: calculate the lifting force F2 for lifting the stern ramp, that is, the lifting force of the crane, the hinge fulcrum force of the hinge support point of the stern ramp of the ship to be tested is F1, the center of gravity of the ramp weight is G, the distance between the center of gravity of the ramp and the hinge fulcrum is L1, and the distance between the crane lifting point and the hinge fulcrum is L2. According to the formula F2=G*L1 / L2, the lifting force for lifting the stern ramp is obtained, that is, the lifting force F2 of the lifting capacity that the crane needs to meet, and this force is the minimum lifting force of the crane.

[0013] The step (2) of selecting an appropriate crane in the present invention specifically comprises: selecting a crane according to the lifting force of the crane obtained in step (1); and after the crane is selected, obtaining a corresponding lifting capacity curve of the crane according to the crane.

[0014] The step (3) of determining the position of the crane and installing and moving the crane to the dock position of the present invention is specifically as follows: according to the crane lifting capacity curve obtained in step (2), the boom span that satisfies the lifting capacity is determined, and when the minimum lifting radius R1 and the maximum lifting radius R2 are both greater than the lifting force F2, and then according to the position of the ship docked at the dock, the center distance L4 of the stern ramp lifting point is measured, the fender distance L5 between the dock edge and the ship side is measured, and the distance L6 from the center position of the crane to the dock side is measured. The position range of the crane lifting is determined by the minimum lifting radius R1, the maximum lifting radius R2 and the distance L6 from the center position of the crane to the dock side.

[0015] The step (4) of the present invention, in which the crane lifts and tests the stern ramp, specifically comprises: opening the stern ramp to a horizontal position, connecting the crane to the ramp via a wire rope and a shackle, adjusting the ramp to a floating mode, and lifting and lowering the ramp at a preset speed using the crane.

[0016] The floating test of step (6) described in the present invention is terminated as follows: when the stern ramp is in a horizontal position, the stern ramp mode is adjusted to a control mode, the crane is removed, the wire rope and the shackle are removed, the crane is disconnected from the stern ramp, and the stern ramp is opened and closed three times in a normal manner to check whether there is any abnormality. If there is no abnormality, the floating mode test is terminated.

[0017] In step (2) of the present invention, the maximum lifting capacity of the minimum distance between the crane and the center of the stern ramp is greater than the force on the lifting point of the lifting force F2, and the lifting and lowering speed of the crane is greater than or equal to the speed required when the ship's stern ramp is in floating mode.

[0018] In step (3) of the present invention, there are two lifting positions of the crane, one at the tail of the stern ramp and the other at the bow of the stern ramp.

[0019] The present invention adopts the method, so it has the advantages of simple method, high test accuracy, and the ability to correct the stern ramp in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing the crane being located at the stern of the stern ramp.

[0021] Figure 2 This is the layout of the lifting lugs on the stern ramp.

[0022] Figure 3 This is the force analysis diagram of the stern springboard at an angle of 0°.

[0023] Figure 4 This is the force analysis diagram of the stern springboard at a 45° angle.

[0024] Figure 5 This is the force analysis diagram of the stern ramp when the working angle is +7°~-7° in floating mode.

[0025] Figure 6 This is the relative position diagram of the crane position and the stern ramp.

[0026] Figure 7 It is the lifting capacity curve of the crane.

[0027] Reference numerals: stern ramp 1, lifting eye 2. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with the accompanying drawings:

[0029] As shown in the attached drawings, a floating test method for testing the performance of a ship's stern ramp is characterized in that the steps of the floating test method for testing the performance are as follows:

[0030] (1) Determine the crane's lifting capacity based on the load lifted by the stern ramp:

[0031] (2) Select a crane:

[0032] (3) Determine the location of the crane and install and move the crane to the dock:

[0033] (4) The stern ramp is hoisted by crane and tested;

[0034] (5) Test conclusion and inspection: The crane is tested at a preset lifting speed and the flow meter reading on the hydraulic pipeline is observed. If the flow meter reading on the hydraulic pipeline is greater than or equal to the theoretical value, the stern ramp meets the requirements. If the flow meter reading on the hydraulic pipeline is less than the theoretical value, it is necessary to determine whether the solenoid valve is blocked or damaged, whether the hydraulic pipeline is blocked, or whether there are too many bends in the hydraulic pipeline, and correct them one by one until the flow meter reading on the hydraulic pipeline is greater than or equal to the theoretical value.

[0035] (6) End of floating test: remove the crane, operate the stern ramp normally to open and close the door three times, and check whether there is any abnormality. If there is no abnormality, the floating mode test is ended.

[0036] Furthermore, the step (1) of determining the lifting capacity of the crane according to the load of the stern ramp is specifically as follows: calculating the lifting force F2 for lifting the stern ramp, that is, the lifting force of the crane, the hinge support force of the hinge support point of the stern ramp of the ship to be tested is F1, the center of gravity of the ramp weight is G, the distance between the center of gravity of the ramp and the hinge support is L1, and the distance between the crane lifting point and the hinge support is L2. According to the formula F2=G*L1 / L2, the load for lifting the stern ramp is obtained, that is, the lifting force F2 of the lifting capacity that the crane needs to meet, and this force is the minimum lifting force of the crane.

[0037] Furthermore, the step (2) of selecting an appropriate crane specifically comprises: selecting a crane according to the lifting force of the crane obtained in step (1), and after the crane selection is completed, obtaining a corresponding crane lifting capacity curve according to the crane.

[0038] Furthermore, the step (3) of determining the position of the crane and installing and moving the crane to the position of the dock is specifically as follows: according to the crane lifting capacity curve obtained in step (2), the boom span that satisfies the lifting capacity is determined, and when the minimum lifting radius R1 and the maximum lifting radius R2 are both greater than the lifting force F2, and then according to the position of the ship docked at the dock, the center distance L4 of the stern ramp lifting point is measured, the fender distance L5 between the dock edge and the ship side is measured, and the distance L6 from the center position of the crane to the dock side is measured. The position range of the crane lifting is determined by the minimum lifting radius R1, the maximum lifting radius R2 and the distance L6 from the center position of the crane to the dock side.

[0039] Furthermore, the step (4) of lifting and testing the stern ramp by a crane specifically comprises: opening the stern ramp to a horizontal position, connecting the crane to the ramp via a wire rope and a shackle, adjusting the ramp to a floating mode, and lifting and lowering the ramp by the crane at a preset speed.

[0040] Furthermore, the floating test of step (6) is terminated as follows: when the stern ramp is in a horizontal position, the stern ramp mode is adjusted to a control mode, the crane is removed, the wire rope and the shackle are removed, the crane is disconnected from the stern ramp, and the stern ramp is opened and closed three times under normal operation to check whether there is any abnormality. If there is no abnormality, the floating mode test is terminated.

[0041] Furthermore, in the step (2), the maximum lifting capacity of the minimum distance between the crane and the center of the stern ramp is greater than the force on the lifting point F2, and the lifting and lowering speed of the crane is greater than or equal to the speed required when the ship's stern ramp is in floating mode.

[0042] Furthermore, in the step (3), the lifting position range of the crane is two, one is at the tail of the stern ramp, and the other is at the bow of the stern ramp.

[0043] The present invention adopts the method, so it has the advantages of simple method, high test accuracy, and the ability to correct the stern ramp in time.

[0044] Example:

[0045] Ship type: STENA 3100m LANE METER ROPAX project is a high-end luxury ro-ro passenger ship for short-distance international routes, which is classified by DNV-GL and meets the SOLAS "safe return to port" requirements. The ship carries passengers, cars, trucks, general cargo and container trailers, and has four vehicle decks, 7 decks, 5 decks, 3 decks and 1 deck. Among them, decks 1, 3 and 5 are closed ro-ro areas, and the tail of deck 7 is a car deck. The ship is equipped with bow and stern ramps, bow ramps, front bulkhead doors, fixed ramp covers and two two-way movable ramps. In order to meet the normal use of the stern ramp in the case of large waves at the dock where the ship is docked, the shipowner requires the maximum floating speed of the stern ramp to reach 18 meters / minute.

[0046] Stern ramp parameters: The stern ramp is an open structure, consisting of a main structure plus a top wing plate and a transition flap connected to the hull. It is connected to the hull through a hinge at the stern of the 3rd deck and serves as a vehicle ramp and a watertight door. When open, it serves as a passage connecting the ship and the dock for vehicles or personnel to get on and off. When closed, it keeps the cargo hold watertight. The opening and closing of the stern ramp is mainly achieved by the hydraulic cylinders on both sides.

[0047] The parameters of the stern ramp are as follows:

[0048] Clear width for passage: 18.6m, 17.0m (clear width on the end wing);

[0049] Clearance height: 4.9m;

[0050] Total length (including wing): 9.5m + 2.5m (wing);

[0051] Working angle: +7.0°;

[0052] Maximum deck load: 2 x 60t + 1 x 45t;

[0053] Maximum shaft load: 50t / 4W;

[0054] Total weight: about 60 t.

[0055] Arrangement of stern ramp lifting lug 2:

[0056] The total weight of the stern ramp structure and accessories is about 60t. Through calculation, the weight center position of the stern ramp in the horizontal open state is:

[0057] X = -4.98 m ≈ -5.0 m, (4.98 m from the hinge center, stern direction is -, bow direction is +)

[0058] Y = 0

[0059] Since the wing structure at the end of the stern springboard is weak, it is not suitable to arrange the lifting lug 2 on it, so the lifting lug 2 needs to be arranged on the main structure of the stern springboard. The total length of the main structure is 9.5 meters. The center of gravity of the stern springboard is about 5 meters away from the hinge center, so the center of gravity of the stern springboard is biased to the stern, not in the middle of the stern springboard. According to the estimation, the force of the lifting lug 2 is slightly greater than about 1 / 2 of the total weight of the stern springboard. Considering the safety factor, two 30t lifting lugs 2 are selected in the design. In order to reduce the force on the crane during lifting, it is necessary to consider arranging the lifting lug 2 at the most stern end of the main structure of the stern springboard as much as possible during the design. The left and right positions are selected from the longitudinal strong structure position of the stern springboard. The layout diagram is shown in Figure 2 .

[0060] According to the above parameters, a floating test of the ship stern ramp performance test is carried out. The steps of the floating test method of the performance test are as follows:

[0061] (1) Determine the lifting capacity of the crane based on the load of the stern ramp: Calculate the load F2 of the stern ramp, which is the lifting force of the crane. The hinge support force of the hinge support point of the stern ramp of the ship to be tested is F1, the center of gravity of the ramp weight is G, the distance between the center of gravity of the ramp and the hinge support is L1, and the distance between the crane lifting point and the hinge support is L2. According to the formula F2=G*L1 / L2, the load of the stern ramp is obtained, which is the lifting force F2 of the lifting capacity that the crane needs to meet. This force is the minimum lifting force of the crane;

[0062] The structural weight of the stern ramp is about 60 tons. The lifting lug 2 is located at the end of the stern ramp, 9.27 meters away from the center of the main hinge. The force calculation analysis is as follows:

[0063] Assume the support force at the hinge position is F1, the weight of the stern springboard is G, and the lifting force at the lifting lug 2 is F2. When the stern springboard is in a horizontal state, the arm length from the center of gravity of the stern springboard to the F1 fulcrum is L1=5000mm, and the arm length from the center of the lifting lug 2 to the F1 fulcrum is L2=9154mm. According to the calculation formula of force and moment, then:

[0064] F2=G*L1 / L2

[0065] =60*5000 / 9154

[0066] =32.77 t

[0067] When the stern ramp forms an angle of 30° with the plane of deck 3, the arm length from the center of gravity of the stern ramp to the F1 fulcrum is L1=4308mm, and the arm length from the center of the lifting lug 2 to the F1 fulcrum is L2=7723mm. According to the calculation formula of force and moment, then:

[0068] F2=G*L1 / L2

[0069] =60*4308 / 7723

[0070] =33.47 t

[0071] When the stern springboard is at an angle of 45° to the plane of deck 3, the arm length from the center of gravity of the stern springboard to the F1 fulcrum is L1=3502mm, and the arm length from the center of the lifting lug 2 to the F1 fulcrum is L2=6172mm. According to the calculation formula of force and moment, then:

[0072] F2=G*L1 / L2

[0073] =60*3502 / 6172

[0074] =34.04 t

[0075] Through the above calculations, we can see that when the angle between the stern ramp and the 3rd deck plane is 0 degrees, the force on the crane is 32.77 tons, and when the angle increases to 45 degrees, the force on the crane is 34.04 tons. Between 0 and 45 degrees, the force on the stern ramp increases as the angle increases, see Figure 3 and Figure 4 .

[0076] The working angle of the stern ramp in floating mode is +7°~-7°. The force analysis at this time is as follows:

[0077] When the stern ramp is at +7°:

[0078] F2=G*L1 / L2

[0079] =60*4955 / 9043

[0080] =32.88 t

[0081] When the stern ramp is at -7°:

[0082] F2=G*L1 / L2

[0083] =60*4971 / 9165

[0084] =32.54 t;

[0085] Through force calculation, the force on the crane at the lifting point of the stern ramp is about 33t, see Figure 5 .

[0086] (2) Selecting a crane: Selecting a crane according to the lifting capacity of the crane obtained in step (1). After the crane is selected, a corresponding lifting capacity curve of the crane is obtained according to the crane.

[0087] The maximum lifting capacity of the minimum distance between the crane and the center of the stern ramp in step (2) is greater than the force on the F2 lifting point, and the lifting and lowering speed of the crane is greater than or equal to the speed required when the ship's stern ramp is in floating mode;

[0088] Dock conditions: The ship is docked at the shipyard dock. The dock is a straight dock. The ship is docked parallel to the dock. The dock is equipped with two cranes with a lifting capacity of 45 tons and a maximum lifting radius of 90 meters. The center of the crane is 11.5 meters away from the dock. The dock is equipped with a rubber fender with a width of 0.8 meters. When the maximum lifting radius of the crane is 90 meters, the lifting capacity is 10 tons; when the minimum lifting radius is 42 meters, the lifting capacity is 45 tons. The maximum lifting height is 60 meters, the maximum lowering depth is 14 meters, and the maximum lifting speed is 20 meters / minute. The lifting capacity curve of the crane is shown in Figure 7 ;

[0089] The force on the crane at the lifting point of the stern ramp is about 33t, which is less than the maximum safe load of the crane, 45t. The floating mode test plan of the stern ramp is carried out using a 45t crane at the dock;

[0090] (3) Determine the position of the crane and install and move the crane to the dock: According to the crane lifting capacity curve obtained in step (2), determine the boom span that meets the lifting capacity. When the minimum lifting radius R1 and the maximum lifting radius R2 are both greater than the lifting force F2, then measure the center distance L4 of the stern ramp lifting point, the fender distance L5 between the dock edge and the ship side, and the distance L6 from the center of the crane to the dock according to the location of the ship docked at the dock. Determine the crane lifting position range through the minimum lifting radius R1, the maximum lifting radius R2 and the distance L6 from the center of the crane to the dock;

[0091] In the step (3), there are two lifting positions of the crane, one at the tail of the stern ramp S1 and the other at the bow of the stern ramp S2. Figure 6 ;

[0092] The ship is moored close to the pier, the center of the stern ramp is 14.2 meters away from the ship's side, and the distance from the center of the crane is: 14.2+11.5+0.8=26.5 meters (assuming that the crane is in parallel with the stern ramp). At this time, the lifting distance is less than the minimum lifting radius of the crane, so the crane cannot be in parallel with the stern ramp. In order to ensure the maximum lifting capacity of the crane, the distance between the center of the crane and the center of the stern ramp lifting lug 2 should be within the range of 42 meters to 50 meters. Considering that the crane driver should have a good field of vision during operation, the crane should be in the rear position of the stern ramp. The crane position is set at the stern of the stern ramp. See the position diagram. Figure 1 .

[0093] (4) The stern ramp is lifted by a crane and tested; the stern ramp is opened to a horizontal position, the crane is connected to the ramp by means of wire ropes and shackles, the ramp is set to floating mode, and the crane is used to lift and lower the ramp at a preset speed;

[0094] (5) Test conclusion and inspection: The crane is tested at a preset lifting speed and the flow meter reading on the hydraulic pipeline is observed. If the flow meter reading on the hydraulic pipeline is greater than or equal to the theoretical value, the stern ramp meets the requirements. If the flow meter reading on the hydraulic pipeline is less than the theoretical value, it is necessary to determine whether the solenoid valve is blocked or damaged, whether the hydraulic pipeline is blocked, or whether there are too many bends in the hydraulic pipeline, and correct them one by one until the flow meter reading on the hydraulic pipeline is greater than or equal to the theoretical value.

[0095] (6) End of floating test: When the stern ramp is in horizontal position, adjust the stern ramp mode to control mode, remove the crane, remove the wire rope and shackle, disconnect the crane from the stern ramp, operate the stern ramp normally to open and close the door three times, and check whether there is any abnormality. If there is no abnormality, the floating mode test is ended.

Claims

1. A floating test method for testing the performance of a ship's stern ramp, characterized in that The performance test floating test method steps are as follows: (1) Determine the lifting capacity of the crane based on the load lifted by the stern ramp; (2) Select a crane; (3) Determine the location of the crane and install and move the crane to the dock location; (4) The stern ramp is hoisted by crane and tested; (5) Test conclusion and inspection: The crane is tested at a preset lifting speed and the flow meter reading on the hydraulic pipeline is observed. If the flow meter reading on the hydraulic pipeline is greater than or equal to the theoretical value, the stern ramp meets the requirements. If the flow meter reading on the hydraulic pipeline is less than the theoretical value, it is necessary to determine whether the solenoid valve is blocked or damaged, whether the hydraulic pipeline is blocked, or whether there are too many bends in the hydraulic pipeline, and correct them one by one until the flow meter reading on the hydraulic pipeline is greater than or equal to the theoretical value. (6) End of floating test: remove the crane, operate the stern ramp normally to open and close the door three times, and check whether there is any abnormality. If there is no abnormality, the floating mode test is ended.

2. A floating test method for testing the performance of a ship stern ramp according to claim 1, characterized in that The step (1) of determining the lifting capacity of the crane according to the load of the stern ramp is specifically as follows: calculating the lifting force F2 for lifting the stern ramp, that is, the lifting force of the crane, the hinge support force of the hinge support point of the stern ramp of the ship to be tested is F1, the center of gravity of the ramp weight is G, the distance between the center of gravity of the ramp and the hinge support is L1, and the distance between the crane lifting point and the hinge support is L2. According to the formula F2=G*L1 / L2, the lifting force for lifting the stern ramp is obtained, that is, the lifting force F2 of the lifting capacity that the crane needs to meet, and this force is the minimum lifting force of the crane.

3. A floating test method for testing the performance of a ship stern ramp according to claim 1, characterized in that The step (2) of selecting an appropriate crane specifically comprises: selecting a crane according to the lifting force of the crane obtained in step (1); and after the crane is selected, obtaining a corresponding lifting capacity curve of the crane according to the crane.

4. A floating test method for testing the performance of a ship stern ramp according to claim 1, characterized in that The step (3) of determining the position of the crane and installing and moving the crane to the dock position is specifically as follows: according to the crane lifting capacity curve obtained in step (2), determine the boom span that meets the lifting capacity, when the minimum lifting radius R1 and the maximum lifting radius R2, the crane lifting capacity is greater than the lifting force F2, and then according to the position of the ship docked at the dock, measure the center distance L4 of the stern ramp lifting point, measure the fender distance L5 between the dock edge and the ship side, and measure the distance L6 between the center position of the crane and the dock side. According to the minimum lifting radius R1, the maximum lifting radius R2 and the distance L6 between the center position of the crane and the dock side, determine the position range of the crane lifting.

5. A floating test method for testing the performance of a ship stern ramp according to claim 1, characterized in that The step (4) of lifting and testing the stern ramp by a crane specifically comprises: opening the stern ramp to a horizontal position, connecting the crane to the ramp via a wire rope and a shackle, adjusting the ramp to a floating mode, and lifting and lowering the ramp by the crane at a preset speed.

6. A floating test method for testing the performance of a ship stern ramp according to claim 1, characterized in that The floating test of step (6) is terminated as follows: when the stern ramp is in a horizontal position, the stern ramp mode is adjusted to a control mode, the crane is removed, the wire rope and the shackle are removed, the crane is disconnected from the stern ramp, and the stern ramp is opened and closed three times in a normal manner to check whether there is any abnormality. If there is no abnormality, the floating mode test is terminated.

7. A floating test method for testing the performance of a ship stern ramp according to claim 3, characterized in that In the step (2), the maximum lifting capacity of the minimum distance between the crane and the center of the stern ramp is greater than the force on the lifting point of the lifting force F2, and the lifting and lowering speed of the crane is greater than or equal to the speed required when the ship's stern ramp is in floating mode.

8. A floating test method for testing the performance of a ship stern ramp according to claim 4, characterized in that In the step (3), there are two lifting positions of the crane, one at the tail of the stern ramp and the other at the bow of the stern ramp.

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