Method for reducing increased roll resistance of a ship, system for reducing increased roll resistance, and ship

Abstract

To provide a reduction method for increase in rolling resistance, a reduction system for increase in rolling resistance for a vessel, and a vessel capable of improving fuel consumption, etc., of the vessel by rationally reducing increase in rolling resistance.SOLUTION: A method for reducing increase in rolling resistance of a vessel 1 occurring due to rolling of a hull in waves in a navigation method for an automatic navigation vessel reduces increase in rolling resistance in response to characteristic of waves by executing at least one of reduction in rolling attenuation coefficient, reduction in rolling gyration radius, reduction in rolling angle, and increase of draft regarding rolling attenuation coefficient B44, rolling gyration radius kxx, rolling angle, and draft d of the hull dominating increase in rolling resistance RAWRoll.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for reducing an increase in roll resistance of a ship that reduces an increase in roll resistance of the ship caused by the rolling of the hull in waves, a system for reducing an increase in roll resistance of the ship, and a ship. [Background technology]

[0002] It is known that ships experience increased resistance in rough waves, which reduces their speed and increases their fuel consumption. Increased resistance in waves R AW The estimation formula is R AW =R AWM +R AWR and R AWM is the motion component, R AWR is the component of increased resistance due to reflected waves. By using this equation for estimating increased resistance in waves, the increased resistance in head waves and in waves can be estimated with high accuracy, but because the component affected by rolling is not taken into account, the difference from the actual measured value becomes large in oblique waves. Here, Patent Document 1 discloses a roll reduction device that has a roll angle sensor, a gyro, and a control device, and the control device is equipped with a subtractor that determines the deviation from the roll angle to a reference roll angle, a subtractor that determines the deviation from the azimuth angle to a target azimuth angle, and a control calculation unit, and the calculation unit calculates the roll angular velocity deviation determined from the roll angle deviation and the fin operation angle that reduces the azimuth deviation, and outputs the operation angle to the fin stabilizer power unit as a control signal, and at the same time determines the operation rudder angle from the roll angular velocity deviation and the azimuth deviation, and outputs the operation rudder angle to the steering gear as a control signal. Patent Document 2 also discloses a motion suppression device that is fitted to the bow of a ship and is equipped with port and starboard bow wings that protrude respectively to the port and starboard sides of the bow of the ship, and control means that independently control the blade angles of the port and starboard bow wings so as to simultaneously suppress the heave, pitch and roll of the ship and also suppress an increase in resistance in waves. Patent Document 3 also discloses a hull motion monitoring device with a hull motion prediction function that includes a data monitoring device that monitors data on hull motion over a certain period of time from a motion sensor and a heave sensor; a weather and sea state prediction processing device that collects forecast values ​​for weather and sea state for the time period to be predicted; a prediction calculation processing device that analyzes accumulated data on hull motion, calculates a model formula that uniquely determines hull motion, and overlays it with a wave spectrum obtained from the forecast values ​​for weather and sea state for the time period to be predicted to obtain predicted values ​​for the peak values ​​of motion and heave for the time period to be predicted; and an alarm determination device that outputs an alarm if the predicted peak value exceeds an alarm reference value, thereby supporting the landing of helicopters, etc. on board the ship and safe operation. Patent document 4 also discloses a direction control device that controls the direction of a floating body on the water that is swaying due to waves, and that includes a wave analysis unit that calculates the wave characteristics and traveling direction of each wave that makes up the waves, a preferred direction calculation unit that calculates a preferred direction for the floating body on the water that will reduce swaying based on the wave characteristics and traveling direction of each wave, and a turning control unit that points the floating body on the water in the preferred direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-284087 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-193747 [Patent Document 3] Japanese Patent Application Publication No. 11-79076 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-124015 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Documents 1, 2, and 4 attempt to reduce hull resistance in waves, but in doing so they do not take into consideration anything other than suppressing the rolling of the ship, and as they do not rationally reduce the increase in roll resistance, it cannot be said that they sufficiently reduce the increase in roll resistance. Furthermore, the ship motion monitoring device with a ship rolling prediction function of Patent Document 3 does not attempt to reduce the increase in rolling resistance. Therefore, an object of the present invention is to provide a method for reducing an increase in roll resistance of a ship, a system for reducing an increase in roll resistance, and a ship that can rationally reduce the increase in roll resistance and improve the fuel efficiency of the ship, etc. [Means for solving the problem]

[0005] The method for reducing the increase in roll resistance of a ship according to claim 1 is a method for reducing the increase in roll resistance of a ship caused by the roll of the hull in waves, and is based on the roll damping force coefficient of the hull, the roll radius of inertia, the roll angle, and the draft, which govern the increase in roll resistance. In assessing the increase in roll resistance corresponding to wave characteristics based on , roll damping force coefficient number, Rolling inertia half diameter, horizontal sway corner, and draft brain At least Also t Due to changes in Responding to wave characteristics The increase in roll resistance of the ship is evaluated by determining the trend of the increase in roll resistance. It is characterized by reducing the increase in rolling resistance. According to the present invention as set forth in claim 1, the increase in rolling resistance can be rationally reduced to improve the fuel efficiency of the ship.

[0006] The present invention as set forth in claim 2 is characterized in that the increase in rolling resistance is evaluated based on formula (1).

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[0007] The present invention as set forth in claim 3 is characterized in that the increase in roll resistance is reduced in response to wave characteristics by changing at least one of the roll radius of inertia and the transverse metacentric height, which are related to the ship's roll natural period, and thereby changing the roll natural period. According to the present invention as set forth in claim 3, the roll natural period of the hull can be appropriately changed to effectively reduce the increase in roll resistance in a rational manner.

[0008] The present invention as set forth in claim 4 is characterized in that the roll natural period is evaluated based on equation (2).

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[0009] The present invention as set forth in claim 5 changes the weight distribution in the lateral direction of the hull to adjust the dimensionless rolling radius of inertia k xx By changing the value, the increase in rolling resistance is reduced. According to the present invention as set forth in claim 5, the dimensionless roll radius of inertia can be appropriately changed by changing the weight distribution in the lateral direction, thereby changing the roll natural period and effectively reducing the increase in roll resistance.

[0010] The present invention as set forth in claim 6 is characterized in that the increase in roll resistance is reduced by changing the weight distribution in the vertical direction of the hull to change the transverse metacentric height GM. According to the present invention as set forth in claim 6, the lateral metacentric height can be appropriately changed by changing the weight distribution in the vertical direction, thereby changing the roll natural period and effectively reducing the increase in roll resistance.

[0011] The present invention as set forth in claim 7 is to change at least one of the draft d and trim of the hull to adjust the dimensionless rolling radius of inertia k xxAlternatively, the increase in rolling resistance is reduced by changing the lateral metacentric height GM. According to the present invention as set forth in claim 7, the roll natural period can be changed by appropriately changing the dimensionless roll radius of inertia or the transverse metacentric height by changing the draft or trim of the hull, thereby effectively reducing the increase in roll resistance.

[0012] The present invention as set forth in claim 8 changes the shape of the hull to adjust the roll angle amplitude φ a This reduces the increase in rolling resistance. According to the present invention as set forth in claim 8, the shape of the hull can be changed to suppress rolling, thereby effectively reducing the increase in rolling resistance.

[0013] The present invention as set forth in claim 9 provides a method for increasing or decreasing the ship speed to adjust the roll damping force coefficient. B 44 of By changing the angle, the increase in rolling resistance is reduced. According to the present invention as set forth in claim 9, the roll damping force coefficient related to the roll angular velocity is changed to suppress roll. do, The increase in rolling resistance can be effectively reduced.

[0014] The present invention as set forth in claim 10 is characterized in that the roll natural period T φ By changing the value, the increase in rolling resistance is reduced. According to the invention as defined in claim 10 By changing the roll natural period related to the roll angular velocity, the increase in roll resistance can be effectively reduced.

[0015] Claim 11 The present invention is characterized in that the hull is equipped with a wind-powered propulsion device, and the wind-powered propulsion device is controlled to change the constant inclination of the hull caused by the wind, thereby changing the roll natural period, thereby reducing the increase in roll resistance. Claim 11 According to the present invention described above, the roll natural period can be changed by changing the constant inclination of the hull caused by the wind, thereby effectively reducing the increase in roll resistance.

[0016] Claim 12The invention described is characterized in that the wind propulsion device is a sail or a Flettner rotor, and control is performed by changing the angle of the sail or the rotation speed of the Flettner rotor. Claim 12 According to the present invention described above, the sail or Flettner rotor can be controlled to appropriately suppress roll and change the roll natural period, thereby effectively reducing the increase in roll resistance.

[0017] Claim 13 The present invention is characterized by the provision of a movable center keel at the bottom of the hull, which can be moved in and out to change the natural rolling period, thereby reducing the increase in rolling resistance. Claim 13 According to the present invention described above, the roll natural period can be appropriately changed by extending or retracting the center keel, thereby effectively reducing the increase in roll resistance.

[0018] Claim 14 The present invention described is characterized by providing a rudder or a controllable pitch propeller on the hull, controlling the rudder or the controllable pitch propeller, and changing the timing of encountering waves related to the wave characteristics, thereby reducing the increase in roll resistance. Claim 14 According to the present invention described above, the increase in rolling resistance can be effectively reduced by controlling the rudder or the controllable pitch propeller to change the timing of encounter with waves.

[0019] Claim 15 The present invention described is characterized by the fact that the ship is provided with propellers on the left and right sides of the hull, and the increase in roll resistance is reduced by controlling the rotation speed of the left and right propellers and changing the timing of encounter with waves related to the wave characteristics. Claim 15 According to the present invention described above, by controlling the rotation speed of the left and right propellers, the timing of encounter with waves can be changed, thereby effectively reducing the increase in roll resistance.

[0020] Claim 16The present invention described is characterized in that it acquires wave characteristics to determine a wave spectrum, determines the tendency for increased roll resistance from the relationship between the wavelength of the waves and the inter-perpendicular length, which are related to the wave characteristics, and the roll natural period, and reduces the increase in roll resistance by changing at least one of the angle of encounter with the waves and the ship's speed so that the peak of the wave spectrum and the peak of increased roll resistance do not overlap. Claim 16 According to the present invention described above, by changing the angle of encounter with waves and the ship's speed, the peak of the increase in roll resistance can be shifted from the peak of the wave spectrum, thereby effectively reducing the increase in roll resistance.

[0021] Claim 17 The present invention is characterized by obtaining the wave characteristics of the ship's route, planning steering and main engine rotation speed to change at least one of the encounter angle with the waves and the ship's speed in order to reduce the increase in roll resistance in the route, and formulating an optimal voyage plan. Claim 17 According to the present invention described above, fuel consumption and the like can be reduced by operating the ship by changing the steering and the main engine speed based on the formulated optimal navigation plan.

[0022] Claim 18 The system for reducing the increase in roll resistance of a ship corresponding to the description is characterized by being equipped with an optimal navigation plan formulation means for formulating an optimal navigation plan in a method for reducing the increase in roll resistance of a ship, or an optimal navigation plan execution means for executing the formulated optimal navigation plan. Claim 18 According to the present invention described above, the increase in roll resistance over the entire ship's route can be effectively reduced by automatically or semi-automatically formulating an optimal navigation plan using an optimal navigation plan formulation means and automatically or semi-automatically executing the optimal navigation plan using an optimal navigation plan execution means.

[0023] Claim 19 A vessel according to the invention is characterized in that it is equipped with a system for reducing increased roll resistance of the vessel. Claim 19 According to the present invention described above, by executing an optimal voyage plan, it is possible to effectively reduce the increase in rolling resistance and improve the fuel efficiency of the ship.

[0024] Claim 20 A ship corresponding to the description is characterized in that it is operated based on a method for reducing the increase in roll resistance of a ship. Claim 20 According to the present invention described above, the increase in rolling resistance can be rationally reduced to improve the fuel efficiency of the ship, thereby enabling it to be operated with good energy efficiency. [Effects of the Invention]

[0025] According to the method for reducing an increase in roll resistance of a ship of the present invention, it is possible to rationally reduce the increase in roll resistance and improve the fuel efficiency, etc. of the ship.

[0026] Furthermore, when the increase in roll resistance is evaluated based on formula (1), the increase in roll resistance can be evaluated with high accuracy, and the increase in roll resistance can be reduced more appropriately and rationally.

[0027] Furthermore, when the increase in roll resistance is reduced in response to wave characteristics by changing at least one of the roll radius of inertia and the lateral metacentric height, which are related to the hull's natural roll period, and changing the hull's natural roll period, the increase in roll resistance can be reduced rationally and effectively by appropriately changing the hull's natural roll period.

[0028] Furthermore, when the natural roll period is evaluated based on equation (2), the natural roll period can be evaluated with high accuracy, and the increase in roll resistance can be reduced more appropriately and rationally.

[0029] In addition, the weight distribution in the lateral direction of the hull is changed to change the dimensionless rolling radius of inertia k xx When the increase in roll resistance is reduced by changing the weight distribution in the lateral direction, the dimensionless roll radius of inertia can be appropriately changed to change the roll natural period, thereby effectively reducing the increase in roll resistance.

[0030] In addition, when the increase in roll resistance is reduced by changing the vertical weight distribution of the hull and changing the transverse metacentric height GM, the change in the vertical weight distribution can appropriately change the transverse metacentric height to change the roll natural period, thereby effectively reducing the increase in roll resistance.

[0031] In addition, by changing at least one of the hull draft d and trim, the dimensionless rolling radius of inertia k xx Alternatively, when the increase in roll resistance is reduced by changing the transverse metacentric height GM, the hull draft or trim can be changed to appropriately change the dimensionless roll radius of inertia or the transverse metacentric height, thereby changing the roll natural period and effectively reducing the increase in roll resistance.

[0032] In addition, the roll angle amplitude φ a When the increase in roll resistance is to be reduced by reducing the hull shape, the roll can be suppressed and the increase in roll resistance can be effectively reduced.

[0033] In addition, the roll damping coefficient B 44 Or rolling natural period T φ When the increase in roll resistance is to be reduced by changing the roll damping force coefficient related to the roll angular velocity, the roll can be suppressed by changing the roll natural period, and the increase in roll resistance can be effectively reduced.

[0034] In addition, if the hull is equipped with a wind-powered propulsion device and the increase in roll resistance is reduced by controlling the wind-powered propulsion device to change the constant inclination of the hull caused by the wind and thereby change the natural roll period, the increase in roll resistance can be effectively reduced by changing the constant inclination of the hull caused by the wind and changing the natural roll period.

[0035] Furthermore, when the wind propulsion device is a sail or a Flettner rotor and control is performed by changing the angle of the sail or the rotation speed of the Flettner rotor, the sail or the Flettner rotor can be controlled to appropriately suppress roll and change the roll natural period, thereby effectively reducing the increase in roll resistance.

[0036] Furthermore, if the ship is provided with a movable center keel at the bottom of the hull and the increase in roll resistance is reduced by extending or retracting the center keel to change the natural roll period, the natural roll period can be appropriately changed by extending or retracting the center keel, thereby effectively reducing the increase in roll resistance.

[0037] In addition, when the hull is equipped with a rudder or a controllable pitch propeller, and the increase in roll resistance is reduced by controlling the rudder or controllable pitch propeller and changing the timing of encounter with waves related to the wave characteristics, the increase in roll resistance can be effectively reduced by controlling the rudder or controllable pitch propeller and changing the timing of encounter with waves.

[0038] In addition, when the ship is equipped with propellers on the left and right sides of the hull and the rotation speed of the left and right propellers is controlled to change the timing of encounter with waves related to the wave characteristics, the rotation speed control of the left and right propellers can change the timing of encounter with waves, thereby effectively reducing the increase in roll resistance.

[0039] In addition, by acquiring wave characteristics and determining a wave spectrum, and determining the tendency for increased roll resistance from the relationship between the wavelength of the waves and the inter-perpendicular length, which are related to the wave characteristics, and the roll natural period, and changing at least one of the angle of encounter with the waves and the ship's speed so that the peak of the wave spectrum and the peak of increased roll resistance do not overlap, the increase in roll resistance can be reduced by changing the angle of encounter with the waves or the ship's speed, thereby shifting the peak of increased roll resistance from the peak of the wave spectrum and effectively reducing the increase in roll resistance.

[0040] In addition, when the wave characteristics of the ship's route are obtained, and steering and main engine speed are planned to change at least one of the encounter angle with the waves and the ship's speed to reduce the increase in roll resistance in the route, and an optimal navigation plan is formulated, fuel consumption, etc. can be reduced by operating the ship by changing steering and main engine speed based on the formulated optimal navigation plan.

[0041] Furthermore, according to the system for reducing the increase in roll resistance of a ship of the present invention, the increase in roll resistance over the entire ship's route can be effectively reduced by automatically or semi-automatically formulating an optimal navigation plan using an optimal navigation plan formulation means and automatically or semi-automatically executing the optimal navigation plan using an optimal navigation plan execution means.

[0042] Furthermore, according to the ship of the present invention, the increase in rolling resistance can be effectively reduced by executing an optimal voyage plan, thereby improving the fuel efficiency of the ship.

[0043] Furthermore, according to the ship of the present invention, the increase in rolling resistance can be rationally reduced, improving the fuel efficiency of the ship and enabling it to be operated with good energy efficiency. [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 1 is a diagram showing an evaluation of fuel efficiency by performing an actual operation simulation in the case where the increase in roll resistance is taken into account and in the case where the increase in roll resistance is not taken into account, in relation to the method for reducing the increase in roll resistance of a ship according to an embodiment of the present invention. [Figure 2] Figure showing the wave resistance increase coefficient or roll resistance increase coefficient of the container ship [Figure 3] FIG. 10 shows an example of how to increase or decrease the roll radius of inertia. [Figure 4] A diagram showing an example of how to increase or decrease the horizontal metacentric height [Figure 5] FIG. 10 shows an example of how to increase or decrease the lateral metacentric height and the lateral radius of inertia. [Figure 6] FIG. 10 is a cross-sectional view of the hull of a ship equipped with the movable protrusion. [Figure 7] FIG. 10 is a cross-sectional view of the hull of a ship equipped with the movable buoyant body. [Figure 8] Figure showing the change in the natural rolling period for the same ship speed [Figure 9] FIG. 1 is a cross-sectional view of a hull of a ship equipped with the wind-powered propulsion device. [Figure 10] A diagram showing a vessel equipped with propellers on both sides of the hull [Figure 11] An example of the same frequency spectrum [Figure 12] Figure showing an example of the optimal navigation plan [Figure 13] FIG. 1 is a diagram showing a ship equipped with a system for reducing increased roll resistance of a ship according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0045] A method for reducing an increase in roll resistance of a ship, a system for reducing an increase in roll resistance, and a ship according to an embodiment of the present invention will be described. In the present invention, the increase in resistance in waves is estimated taking into account the increase in roll resistance (roll influence component). AW Roll Then, the equation for estimating the increase in resistance in waves is R AW =R AWM +R AWR +R AW Roll It is expressed as: The increase in roll resistance is governed by and influenced by the hull's roll damping coefficient, roll radius of inertia, roll angle, and draft. Therefore, the increase in roll resistance can be reduced by implementing at least one of the following measures in response to the wave characteristics: reducing the roll damping coefficient, reducing the roll radius of inertia, reducing the roll angle, and increasing the draft. Here, the roll angle is the roll angle in regular waves φ=Re[φ a *Exp(i*ω e *t+i*ε)]. Re is the real part, φ a is the roll angle amplitude, i is the imaginary unit, ε is the phase difference, and t is time. The roll angle includes irregular waves (spectrum) and is composed of amplitude, phase difference, and wave spectrum.

[0046] Increased roll resistance R AW Roll is evaluated based on the following formula (1): This allows the increase in roll resistance to be evaluated with high accuracy, and the increase in roll resistance can be reduced more precisely and rationally.

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[0047] Figure 1 shows an evaluation of fuel efficiency through an actual operation simulation with and without taking into account increased roll resistance, with the vertical axis representing daily fuel consumption FPD [tons / day] and the horizontal axis representing significant wave height Hw [m]. "w / oRoll" in Figure 1 indicates data estimated without taking into account increased roll resistance, "withRoll" indicates values ​​calculated using equation (1), i.e., data estimated with increased roll resistance taken into account, and "deg." indicates the angle of encounter with head waves taken as 0 degrees. From Figure 1, for example, the significant wave height H w When the wind speed is 3 m (Beaufort wind scale: BF6) and the encounter angle α is 90 to 135 degrees, fuel consumption increases by approximately 1 to 2%. When the increase in roll resistance is taken into account, fuel consumption increases compared to when the increase in roll resistance is not taken into account. This shows that fuel consumption can be estimated with high accuracy by taking the increase in roll resistance into account.

[0048] Figure 2 shows the wave resistance increase coefficient or roll resistance increase coefficient for a container ship (fully loaded) when the encounter angle α between the ship and the waves is 90 degrees. The vertical axis shows the wave resistance increase coefficient K AW or roll resistance increase coefficient K AW Roll , the horizontal axis is the wavelength-to-ship length ratio λ / L pp The encounter angle α is 0 degrees when the waves are head-on. Figure 2(a) shows the rolling natural period T φis equivalent to the actual ship and is 16.2 [s]. Figure 2(b) shows the data for the rolling natural period T φ is the data for 19.6 [s] equivalent to a full-scale ship, "◇" (exp.) indicates the resistance increase coefficient in waves obtained from experiments using a model ship, the dashed line (without roll component) indicates the resistance increase coefficient in waves estimated without considering the increase in roll resistance, the solid line (with roll component) indicates the resistance increase coefficient in waves calculated using equation (1), and the dotted line (roll component) indicates the calculated roll resistance increase coefficient. Table 1 below shows the conditions for the experiment using the model ship. [Table 1]

[0049] Figure 2 shows that the calculated value using equation (1), which reflects the increase in roll resistance, differs little from the experimental value, and captures the tendency of changes in the roll resistance increase coefficient better than when estimating without taking the increase in roll resistance into account. Furthermore, Figure 2 shows that the roll resistance augmentation coefficient changes when the roll natural period is 16.2 s and when it is 19.6 s. Therefore, by changing (increasing or decreasing) the roll natural period, the roll resistance increase can be reduced and the ship's fuel efficiency can be improved. It can also reduce motion, reduce ship speed loss in rough waves, and improve maneuverability.

[0050] The natural roll period is related to the roll radius of inertia and the transverse metacentric height. Therefore, by appropriately changing the natural roll period of the hull by changing at least one of the roll radius of inertia and the transverse metacentric height, it is possible to effectively reduce the increase in roll resistance in a rational manner in response to the wave characteristics. Rolling natural period T φ is preferably evaluated based on the following formula (2): This allows the roll natural period to be evaluated with high accuracy, and the increase in roll resistance to be reduced more precisely and rationally.

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[0051] Figure 3 shows an example of how to increase or decrease the roll radius of inertia. Figure 3(a) shows a state in which a heavy object is located near the center of the ship's width, and Figure 3(b) shows a state in which a heavy object is located near the port end and near the starboard end. In ship 1, the dimensionless roll radius of inertia can be increased or decreased by changing the weight distribution in the lateral direction by moving heavy objects 10, such as ballast, from the position shown in Figure 3(a) to the position shown in Figure 3(b). Therefore, by changing the weight distribution in the lateral direction of the hull and appropriately changing the dimensionless roll radius of inertia, the roll natural period can be changed, and the increase in roll resistance can be effectively reduced.

[0052] Figure 4 shows an example of how to increase or decrease the horizontal metacentric height, where Figure 4(a) shows a state in which the heavy object is at a relatively low position, and Figure 4(b) shows a state in which the heavy object is at a relatively high position. In the ship 1, the transverse metacentric height can be increased or decreased by changing the weight distribution in the vertical direction by moving the heavy load 10, such as ballast, from the position shown in Figure 4(a) to the position shown in Figure 4(b). Therefore, by changing the weight distribution in the vertical direction of the hull and appropriately changing the transverse metacentric height, the roll natural period can be changed and the increase in roll resistance can be effectively reduced.

[0053] FIG. 5 shows an example of how to increase or decrease the transverse metacentric height and the roll radius of inertia, where FIG. 5(a) shows a state where the draft is relatively small, and FIG. 5(b) shows a state where the draft is relatively large. In the ship 1, the roll radius of inertia and the transverse metacentric height can be increased or decreased by changing the draft or trim through ballast adjustment. Therefore, by changing at least one of the hull draft and trim to appropriately change the dimensionless roll radius of inertia or the transverse metacentric height, the roll natural period can be changed, and the increase in roll resistance can be effectively reduced.

[0054] In addition, changes to the weight distribution or changes to the draft and trim to increase or decrease the roll radius of inertia and transverse metacentric height are generally carried out before the voyage, but even during the voyage, by knowing in advance the weight distribution that reduces roll and increased roll resistance, it is possible to move heavy objects 10 and adjust ballast water accordingly, and increase or decrease the roll radius of inertia and transverse metacentric height.

[0055] FIG. 6 is a diagram showing a cross section of a hull of a ship equipped with a movable protrusion, and FIG. 7 is a diagram showing a cross section of a hull of a ship equipped with a movable buoyant body. The ship 1 in Figure 6 has retractable / deployable protrusions 20 installed on both the port and starboard sides above the static water level rise position W as structures for changing the shape of the hull. The protrusions 20 are configured to be rotatable relative to the hull around their lower ends as axes, and are positioned in a retracted position when rotated toward the hull (Figure 6(a)), and in a deployed position when rotated away from the hull (Figure 6(b)). In the retracted position, the protrusions 20 do not protrude to the side of the hull, and in the deployed position, the upper surface protrudes to the side of the hull approximately perpendicular to the side of the hull. Furthermore, the ship 1 in Figure 7 is provided with retractable / deployable buoyant bodies 30 installed on both the port and starboard sides above the static water level raised position W as structures for changing the shape of the hull. The buoyant bodies 30 are configured to be slidable in the left-right direction relative to the hull, and are positioned in the retracted position by sliding them in the direction of being stored in the hull (Figure 7(a)), and in the deployed position by sliding them out of the hull (Figure 7(b)). In the retracted position, the buoyant bodies 30 do not protrude to the side of the hull, and in the deployed position, they protrude to the side of the hull. The static water level rise position W is the position of the rise in the water surface that occurs at the bow of the ship 1 when the ship is traveling in calm water, i.e., without waves, at a navigation speed that is set at the time of design as a typical speed for each ship. When the transverse waves become larger than a predetermined size, the protrusions 20 or buoyancy bodies 30 are deployed to change the shape of the hull, suppressing the rolling and reducing the roll angle amplitude, thereby effectively reducing the increase in roll resistance.

[0056] Figure 8 shows the change in the natural roll period with respect to ship speed obtained through tests using a medium-sized model ship with a length of approximately 4.5 m. The vertical axis shows the natural roll period T φ [s], the horizontal axis is the Froude number (a dimensionless number of velocity) F r The test was conducted with different initial inclinations, and in Figure 8, "Right" indicates an initial inclination on the starboard side, "Left" indicates an initial inclination on the port side, and "Average" indicates no initial inclination. The roll damping force coefficient varies with ship speed, and the natural roll period also varies with ship speed, as shown in Figure 8. Therefore, by increasing or decreasing ship speed to change the roll damping force coefficient or the natural roll period, the roll damping force coefficient related to the roll angular velocity can be changed to suppress roll, and the natural roll period can be changed to effectively reduce the increase in roll resistance.

[0057] FIG. 9 is a cross-sectional view of a hull of a ship equipped with a wind-powered propulsion device. The vessel 1 in this embodiment is equipped with a sail 40 as a wind-powered propulsion device. The angle of the sail 40 is controlled to control the wind-powered propulsion device. Changing the angle of the sail 40 to alter the hull's heel changes the underwater shape of the hull, so by appropriately adjusting the angle of the sail 40, roll can be suppressed. The natural roll period can also be changed. Therefore, by appropriately changing the angle of the sail 40 to suppress roll and change the natural roll period, an increase in roll resistance can be effectively reduced. The wind-powered propulsion device can also be a Flettner rotor that utilizes the Magnus effect. In this case, the rotation speed of the Flettner rotor is controlled to control the wind-powered propulsion device. Changing the rotation speed of the Flettner rotor to change the hull's heel changes the underwater shape of the hull, so roll can be suppressed by appropriately adjusting the rotation speed of the Flettner rotor. The natural roll period can also be changed. Therefore, by appropriately changing the rotation speed of the Flettner rotor to suppress roll and change the natural roll period, an increase in roll resistance can be effectively reduced. In this way, by equipping the hull with a wind-powered propulsion device and controlling the wind-powered propulsion device to change the constant tilt of the hull caused by the wind and thereby changing the natural roll period, the natural roll period can be changed, thereby effectively reducing the increase in roll resistance.

[0058] The vessel 1 also has a movable center keel 50 at the bottom of the hull, and the center keel 50 is configured to be able to move in and out of the water from the bottom of the hull. The natural roll period changes when the center keel 50 is extended or retracted, and therefore, by appropriately changing the natural roll period by extending or retracting the center keel 50, the increase in roll resistance can be effectively reduced.

[0059] FIG. 10 shows a ship equipped with propellers on both sides of the hull. The ship 1 in Figure 10 is a twin-screw ship, equipped with propellers 3 on both sides of the hull. In this case, controlling the rotation speed of the left and right propellers 3 changes the timing of encounter with waves, which is related to the wave characteristics, and can effectively reduce the increase in roll resistance. FIG. 10(a) shows a state in which the rotation speed of the propeller 3 is controlled to change the orientation of the hull so that the crest X of the beam wave reaches the bow side before the stern side, and FIG. 10(b) shows a state in which the rotation speed of the propeller 3 is controlled to change the orientation of the hull so that the crest X of the beam wave reaches the stern side before the bow side.

[0060] The timing of encounter with waves can also be changed by using a rudder equipped on the hull. In this case, the rudder angle can be controlled by steering to change the timing of encounter with waves related to the wave characteristics, thereby effectively reducing the increase in roll resistance. Furthermore, if the hull is equipped with a controllable pitch propeller (CPP), it is possible to change the timing of encounter with waves by using the controllable pitch propeller. In this case, by controlling the angle of the blades of the controllable pitch propeller and changing the timing of encounter with waves related to the wave characteristics, it is possible to effectively reduce the increase in roll resistance.

[0061] Figure 11 shows an example of a frequency spectrum, where the vertical axis is the frequency spectrum (wave spectrum) S(ω) and the horizontal axis is the wavelength-to-ship length ratio λ / L. pp where ω is the angular frequency of the incident wave (wavelength / ship length ratio λ / L pp (parameters that have a one-to-one relationship with The wave characteristics are acquired to determine the wave spectrum, and the tendency for increased roll resistance is determined from the relationship between the wave wavelength and inter-perpendicular length related to the wave characteristics and the roll natural period, and the increase in roll resistance can be reduced by changing at least one of the angle of encounter with the waves and the speed of ship 1 so that the peak of the wave spectrum and the peak of increased roll resistance do not overlap. In this way, by determining in advance the frequency that gives the peak of the increase in roll resistance, and changing the angle of encounter with the waves or the speed of ship 1 so that the peak of the measured or predicted wave spectrum does not coincide with the peak of the increase in roll resistance, the peak of the increase in roll resistance can be shifted from the peak of the wave spectrum, thereby effectively reducing the increase in roll resistance.

[0062] Figure 12 shows an example of an optimal navigation plan. In Figure 12, the dotted line Y indicates the conventional route selected without taking into account the increased roll resistance, and the solid line Z indicates the route based on the optimal navigation plan that takes into account the increased roll resistance. The optimal navigation plan is formulated by obtaining the wave characteristics of the ship's 1 route and planning steering and main engine rotation speed to change at least one of the encounter angle with the waves and the ship's speed in order to reduce the increase in roll resistance along the route. By changing the steering and main engine speed based on the optimal navigation plan, it is possible to reduce the increase in roll resistance, thereby reducing fuel consumption, etc., even if the navigation distance is longer than the previously selected route.

[0063] In this way, according to the method for reducing an increase in roll resistance of a ship of the present invention, it is possible to rationally reduce the increase in roll resistance and improve fuel efficiency, etc. Therefore, by operating the ship 1 based on the method for reducing an increase in roll resistance of a ship, it is possible to rationally reduce the increase in roll resistance and improve the fuel efficiency, etc. of the ship 1, thereby enabling energy-efficient operation.

[0064] FIG. 13 is a diagram showing a ship equipped with a system for reducing increased roll resistance of a ship according to an embodiment of the present invention. The ship 1 includes a main engine 2, a propeller 3, a rudder 4, and a roll resistance increase reduction system 60. The roll resistance increase reduction system 60 includes an optimal voyage plan formulation means 61 that formulates an optimal voyage plan in a method for reducing the roll resistance increase of a ship, an optimal voyage plan execution means 62 that executes the formulated optimal voyage plan, and a wave characteristics acquisition means 63. The wave characteristics acquisition means 63 acquires wave characteristics based on actual wave information encountered by the navigating ship 1. The actual wave information is collected by visual observation by crew members or by measuring equipment such as wave radar. A management department 70 on land that manages the operation of the ship 1 etc. formulates an optimal navigation plan for a method of reducing the increase in roll resistance of the ship, and transmits the optimal navigation plan to the ship 1 via communication means. The wave characteristics of the ship 1's route can be statistically predicted values, or can be acquired by the wave characteristics acquisition means 63 of the ship 1. If the management department 70 develops the optimal navigation plan, the optimal navigation plan development means 61 of the ship 1 can be omitted. An optimal navigation plan can also be formulated on board the ship using the optimal navigation plan formulation means 61. The optimal navigation plan formulation means 61 performs wave estimation (numerical prediction) based on wave information acquired by the wave characteristics acquisition means 63, and formulates an optimal navigation plan. The formulated optimal navigation plan is transmitted to the optimal navigation plan execution means 62 and the management department 70 via communication means. The optimal navigation plan formulated by the management department 70 based on statistically predicted values ​​of wave characteristics can also be modified and used based on the wave information acquired by the wave characteristics acquisition means 63. The optimal sailing plan execution means 62 receives the optimal sailing plan sent from the management department 70 or the optimal sailing plan formulation means 61, and executes ship maneuvering based on the optimal sailing plan. In this way, according to the system for reducing the increase in roll resistance of a ship, the increase in roll resistance over the entire route of the ship 1 can be effectively reduced by automatically or semi-automatically formulating an optimal navigation plan using the optimal navigation plan formulation means 61 and automatically or semi-automatically executing the optimal navigation plan using the optimal navigation plan execution means 62. Furthermore, by providing the ship 1 with the roll resistance increase reduction system 60, the roll resistance increase can be effectively reduced by executing an optimal navigation plan, thereby improving fuel efficiency and the like. [Industrial Applicability]

[0065] The present invention can be applied to various types of ships, including container ships and chemical tankers, and further to ships of various sizes, from large ships to small ships. [Explanation of symbols]

[0066] 1 ship 2 Main engine 3 propellers 4 Rudder 40 Sails (wind propulsion device) 50 Center Keel 60 Roll Resistance Increase Reduction System 61 Optimal Voyage Planning Method 62 Optimal Voyage Planning Implementation Method

Claims

1. A method for reducing an increase in roll resistance of a ship caused by rolling of the hull in waves, comprising: A method for reducing an increase in roll resistance of a ship, characterized in that when evaluating the increase in roll resistance corresponding to wave characteristics based on the roll damping force coefficient, roll radius of inertia, roll angle, and draft of the hull which govern the increase in roll resistance, the method determines the trend of the increase in roll resistance corresponding to the wave characteristics due to changes in at least one of the roll damping force coefficient, roll radius of inertia, roll angle, and draft, evaluates the increase in roll resistance of the ship, and reduces the increase in roll resistance.

2. 2. A method for reducing an increase in roll resistance of a ship according to claim 1, wherein the increase in roll resistance is evaluated based on equation (1). [Equation 1] R ＡＷ Ｒｏｌｌ : Increased rolling resistance k: Angular wave number (wave characteristics) ω ｅ : Encounter wave angular frequency (wave characteristics) B ４４ : Roll damping force coefficient k ｘｘ : Non-dimensional roll inertia radius (roll inertia radius) φ ａ : Roll angle amplitude d: Draft L ｐｐ : Length between perpendiculars

3. 3. A method for reducing the increase in roll resistance of a ship as described in claim 1 or claim 2, characterized in that the increase in roll resistance is reduced in response to the wave characteristics by changing at least one of the roll radius of inertia and the lateral metacentric height, which are related to the roll natural period of the hull, and changing the roll natural period.

4. 4. The method for reducing an increase in roll resistance according to claim 3, wherein the roll natural period is estimated based on equation (2). [Equation 2] T φ : Roll natural period k ｘｘ : Non-dimensional roll inertia radius (roll inertia radius) B: Maximum ship width g: gravitational acceleration GM: Lateral metacentric height

5. The weight distribution in the left-right direction of the hull is changed to change the dimensionless roll radius of inertia k ｘｘ 5. The method for reducing an increase in roll resistance of a ship according to claim 4, wherein the increase in roll resistance is reduced by changing the value of the roll resistance.

6. 6. A method for reducing the increase in roll resistance of a ship as described in claim 4 or claim 5, characterized in that the increase in roll resistance is reduced by changing the vertical weight distribution of the hull to change the transverse metacentric height GM.

7. At least one of the draft d and trim of the hull is changed to adjust the dimensionless roll radius of inertia k ｘｘ Alternatively, the method for reducing the increase in roll resistance of a ship according to claim 4 which depends on claim 2, characterized in that the increase in roll resistance is reduced by changing the transverse metacentric height GM.

8. The shape of the hull is changed to adjust the roll angle amplitude φ ａ 5. The method for reducing an increase in roll resistance of a ship according to claim 4, which is derived from claim 2, wherein the increase in roll resistance is reduced by reducing the

9. 3. The method for reducing an increase in roll resistance of a ship according to claim 2, wherein the increase in roll resistance is reduced by increasing or decreasing the ship speed to change the roll damping force coefficient B 44 .

10. A method for reducing the increase in roll resistance of a ship as described in claim 4, characterized in that the increase in roll resistance is reduced by increasing or decreasing the ship's speed to change the roll natural period T φ.

11. 5. A method for reducing an increase in roll resistance of a ship according to claim 3 or claim 4, characterized in that the hull is provided with a wind-powered propulsion device, and the wind-powered propulsion device is controlled to change the constant inclination of the hull caused by the wind and change the roll natural period, thereby reducing the increase in roll resistance.

12. 12. The method for reducing an increase in roll resistance of a ship according to claim 11, wherein the wind-powered propulsion device is a sail or a Flettner rotor, and control is performed by changing the angle of the sail or the rotation speed of the Flettner rotor.

13. 13. A method for reducing an increase in roll resistance of a ship as described in claim 11 or claim 12, characterized in that a movable center keel is provided on the bottom of the hull, and the increase in roll resistance is reduced by moving the center keel in and out to change the roll natural period.

14. 14. A method for reducing an increase in roll resistance of a ship as described in any one of claims 1 to 13, characterized in that the hull is equipped with a rudder or a controllable pitch propeller, and the increase in roll resistance is reduced by controlling the rudder or the controllable pitch propeller to change the timing of encounter with waves related to the wave characteristics.

15. 14. A method for reducing an increase in roll resistance of a ship as described in any one of claims 1 to 13, characterized in that the ship is provided with propellers on the left and right sides of the hull, the rotation speeds of the left and right propellers are controlled, and the timing of encounter with waves related to the wave characteristics is changed to reduce the increase in roll resistance.

16. 5. A method for reducing an increase in roll resistance of a ship as described in claim 3 or claim 4, characterized in that the wave characteristics are acquired to determine a wave spectrum, the tendency for the increase in roll resistance is determined from the relationship between the wavelength of the waves and the inter-perpendicular length related to the wave characteristics and the roll natural period, and the increase in roll resistance is reduced by changing at least one of the angle of encounter with the waves and the ship speed so that the peak of the wave spectrum and the peak of the increase in roll resistance do not overlap.

17. A method for reducing an increase in roll resistance of a ship as described in claim 16, characterized in that the wave characteristics of the ship's route are obtained, steering and main engine rotation speed are planned to change at least one of the encounter angle with the waves and the ship speed in order to reduce the increase in roll resistance on the route, and an optimal voyage plan is formulated.

18. A system for reducing the increase in roll resistance of a ship, characterized in that it is equipped with an optimal navigation plan formulation means for formulating an optimal navigation plan in the method for reducing the increase in roll resistance of a ship described in claim 17, or an optimal navigation plan execution means for executing the formulated optimal navigation plan.

19. A ship characterized by being equipped with a system for reducing increased roll resistance of a ship as described in claim 18.

20. A ship operated in accordance with the method for reducing an increase in roll resistance of a ship according to any one of claims 1 to 16.

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