JP7834802B2 - ship - Google Patents

Description

This invention relates to a vessel equipped with a windbreak, and more particularly to a vessel capable of improving propulsion efficiency while suppressing the height of the windbreak in the vertical direction.

The applicant has already proposed a ship structure equipped with a windbreak (see, for example, Patent Document 1). The ship in Patent Document 1 directs the wind received from the front of the ship upwards and aft, thereby reducing air resistance generated by containers loaded near the bow.

To improve the efficiency of ship transport, the height of containers loaded on the upper deck is sometimes increased. In particular, the height of the containers in the front row, which are directly exposed to the wind, is commonly seven to eight layers high. This means that the front row of containers forms a wall of approximately 20 meters. In this case, increasing the height of the windbreak is considered to reduce the air resistance caused by the containers. However, the higher the windbreak, the greater the air resistance it generates. Furthermore, the wind hitting the windbreak is redirected upwards and separates before reaching the top edge of the windbreak. Increasing the size of the windbreak could potentially reduce the ship's propulsion efficiency. Moreover, increasing the size of the windbreak inevitably leads to increased weight and manufacturing costs.

Japanese Patent Application Publication No. 2015-145214

This invention was made in view of the above-mentioned problems, and its objective is to provide a vessel that can improve propulsion efficiency while suppressing the height of the windshield in the vertical direction.

A vessel for achieving the above objective is a vessel comprising a wall portion erected substantially vertically from the upper end of a bulwark and formed substantially U-shaped in a plan view, and a cover portion erected from the upper end of the wall portion and formed substantially U-shaped in a plan view, with the upper side sloping inward, wherein the cover portion has a first slanted plate erected from the upper end of the wall portion and a second slanted plate erected from the upper end of the first slanted plate, the angle between the second slanted plate and the horizontal plane is set to be smaller than the angle between the first slanted plate and the horizontal plane , the angle between the first slanted plate and the horizontal plane is set to be larger on the rear side of the vessel than on the front side, and the angle between the second slanted plate and the horizontal plane is set to be larger on the rear side of the vessel than on the front side .

According to this invention, the wind that strikes the cover flows along the second swash plate, which has a smaller angle with respect to the horizontal plane. This suppresses air resistance generated in the cover and reduces wind separation and vortex formation. This is advantageous for improving the propulsion efficiency of a vessel while keeping the height of the windshield low.

This is an explanatory diagram showing the general outline of a ship in a side view. This is an explanatory diagram illustrating the ship in Figure 1 from a plan view. This is an explanatory diagram illustrating the A-A section in Figure 2. This is an explanatory diagram illustrating the wall and cover sections from an oblique view. This is an explanatory diagram illustrating a modified example of Figure 1. This is an explanatory diagram illustrating a modified example of Figure 1. Figure 6 is an explanatory diagram illustrating a ship in a plan view. This is an explanatory diagram illustrating the B-B section in Figure 7. Figure 7 is an explanatory diagram illustrating the ship as seen from a frontal view from the bow.

The following description of the vessel is based on the embodiment shown in the figure. In the figure, the ship's width direction is indicated by arrow y, the ship's length direction (perpendicular to the ship's width direction y) is indicated by arrow x, and the vertical direction (perpendicular to both the ship's width direction y and the ship's length direction x) is indicated by arrow z.

As illustrated in Figures 1 and 2, the vessel 1 comprises a wall section 2 and cover sections 3 (3a, 3b) located at the bow. The wall section 2 and cover sections 3 form a windbreak. The vessel 1 is, for example, a container ship. Containers 5 are placed on the upper surface of the upper deck 4 of the vessel 1. In this embodiment, the vessel 1 comprises a forecastle deck 6 formed at the bow and a bulwark 7 formed along the edge of the forecastle deck 6. The bulwark 7 is roughly U-shaped in plan view.

Vessel 1 is not limited to container ships. Vessel 1 can be any vessel with cargo or equipment installed on the upper deck 4 and requiring a windbreak. Vessel 1 may consist of, for example, bulk carriers transporting coal or grain, chip carriers with cargo handling equipment on the upper deck 4, passenger ships and ferries, or tankers transporting liquefied natural gas, etc.

The wall section 2 is erected approximately vertically from the upper end of the bulwark 7 and is formed in a roughly U-shape in plan view. The wall section 2 may be formed to incline outward from the bulwark 7, or to incline inward. However, it is desirable that it be formed to be perpendicular to the bulwark 7. As illustrated in Figure 1, the wall section 2 is formed such that the rear side (stern side) is longer in the vertical direction z than the front side (bow side). The configuration is not limited to this; the wall section 2 may be formed so that the front and rear sides are the same length. The wall section 2 is made of, for example, steel plate.

As illustrated in Figure 2, the cover portion 3 is erected from the upper end of the wall portion 2 and formed in a roughly U-shape. The cover portion 3 is inclined upwards toward the inside of the roughly U-shape. The inside of the roughly U-shape refers to the direction away from the bulwark 7 toward the centerline S of the vessel 1 in Figure 2. The centerline S is a hypothetical line that passes through the center of the vessel 1 in the width direction y and extends along the length direction x. In Figure 2, a portion of the centerline S is shown as a dashed line for illustrative purposes. For example, the front end of the cover portion 3 is inclined toward the rear. The vicinity of the rear end of the cover portion 3 is inclined toward the centerline S. The cover portion 3 is made of, for example, steel plate.

The cover section 3 has a first slanted plate 3a erected from the upper end of the wall section 2, and a second slanted plate 3b erected from the upper end of the first slanted plate 3a. As illustrated in Figure 1, the first slanted plate 3a is fixed to the wall section 2 at an angle θ1 with respect to the horizontal plane. The horizontal plane is a plane parallel to the ship's length direction x and ship's width direction y. The angle θ1 related to the first slanted plate 3a is, for example, 60°.

As illustrated in Figure 1, the second swash plate 3b is fixed to the first swash plate 3a at an angle θ2 with respect to the horizontal plane. The angle θ2 for the second swash plate 3b is, for example, 45°. As illustrated in Figure 1, the first swash plate 3a and the second swash plate 3b are formed such that the rear side is longer than the front side in the vertical direction z. This configuration is not limited to this; the first swash plate 3a and the second swash plate 3b may be formed so that the front and rear sides are of equal length, or so that the rear side is shorter than the front side. The wall section 2, the first swash plate 3a, and the second swash plate 3b are fixed to each other, for example, by welding. Furthermore, the rear end faces of the wall section 2 and the cover section 3 coincide in the ship's length direction x and are formed perpendicular to the horizontal plane. The rear end faces of the wall section 2 and the cover section 3 are not limited to the above. It is desirable to form them in a structure that is as perpendicular to the horizontal plane as possible, in accordance with the hull structure and fittings.

The magnitudes of the angle θ1 related to the first swash plate 3a and the angle θ2 related to the second swash plate 3b are not limited to those stated above. The angle θ2 between the second swash plate 3b and the horizontal plane only needs to be set smaller than the angle θ1 between the first swash plate 3a and the horizontal plane. In other words, the two angles only need to be set within the range that satisfies the equation θ2 < θ1. Furthermore, the two angles θ1 and θ2 are set within the range greater than 0° and less than 90°.

As illustrated in Figure 3, the first swash plate 3a has an angle of θ1' with respect to the horizontal plane at the aft (stern) end. Similarly, the second swash plate 3b has an angle of θ2' with respect to the horizontal plane at the aft end. In this embodiment, angle θ1' is set to be greater than angle θ1. In other words, the angle θ1 of the first swash plate 3a gradually increases from the front to the rear.

Similarly, angle θ2' is set to be greater than angle θ2. In other words, the second slanted plate 3b is in a state where angle θ2 gradually increases from the front to the rear.

The angle θ1' of the first swash plate 3a may be set to be equal to the angle θ1. In this case, the angle θ1 of the first swash plate 3a with the horizontal plane remains constant not only on the front side but throughout the entire roughly U-shaped structure. Alternatively, the angle θ1' may be smaller than the angle θ1. In this case, the angle θ1 of the first swash plate 3a gradually decreases from the front to the rear.

Similarly, the angle θ2' may be set to be equal to the angle θ2 related to the second swash plate 3b. Alternatively, the angle θ2 may be configured to gradually decrease from the front to the rear. Even when angles θ1 and θ2 change from the front to the rear, θ2 < θ1 is maintained at their respective positions. In other words, at any cross-section of the cover portion 3, the angle in that cross-section is θ2 < θ1.

As illustrated in Figure 4, when wind from the front left (diagonally forward) of vessel 1 collides with the bow of vessel 1, the wind flows towards the rear, changing direction along the wall section 2 and cover section 3. Figure 4 only shows the windbreak consisting of the wall section 2 and cover section 3 for illustrative purposes. The direction of wind flow is indicated by arrows for illustrative purposes. In the area indicated by the dashed line in Figure 4, the wind flow velocity increases, creating negative pressure and generating a force in the direction indicated by the white arrow. This force includes a component in the direction of propulsion for vessel 1.

For example, some of the wind that strikes wall 2 changes direction in the ship's width direction y and flows along wall 2 toward the rear (stern side). Also, some of the wind that strikes wall 2 changes direction upward and flows toward the rear along the first swash plate 3a to the second swash plate 3b. Wind that strikes the first swash plate 3a flows toward the rear along the first swash plate 3a, or flows toward the rear via the first swash plate 3a to the second swash plate 3b.

The angle θ2 between the second swash plate 3b and the horizontal plane is smaller than the angle θ1 between the first swash plate 3a and the horizontal plane. Therefore, the wind impacting the first swash plate 3a is redirected and flows along the second swash plate 3b towards the rear. The wind impacting the second swash plate 3b continues to flow along it towards the rear. By diverting the wind to the rear via the second swash plate 3b, the air resistance generated at the cover section 3 can be reduced. The windbreak installed on the ship 1 can improve its air resistance reduction effect through design improvements. This is advantageous for improving the propulsion efficiency of the ship 1 while suppressing the height of the windbreak in the vertical direction z. Furthermore, since the windbreak installed on the ship 1 can reduce air resistance without increasing its size, it can suppress the increase in weight and manufacturing costs associated with the windbreak.

The wind flowing along the cover section 3 moves from the first swash plate 3a to the second swash plate 3b. Since the angle θ2 related to the second swash plate 3b is smaller than the angle θ1 related to the first swash plate 3a, wind separation is suppressed at the second swash plate 3b. Because the wind is smoothly guided along the cover section 3 and flows as if adhering to it, separation and vortex generation can be reduced on the leeward (rear) side. This is advantageous for improving the propulsion efficiency of the vessel 1 while suppressing the height of the windbreak in the vertical direction z.

As illustrated in Figure 5, the cover portion 3 may have a third inclined plate 3c erected from the upper end of the second inclined plate 3b. The angle θ3 between the third inclined plate 3c and the horizontal plane is set to be smaller than the angle θ2 between the second inclined plate 3b and the horizontal plane. For example, the angle θ3 related to the third inclined plate 3c is 30°. The angles in the cover portion 3 satisfy the condition θ3 < θ2 < θ1.

The more stages (number of swash plates) there are in the cover section 3, the closer the surface of the cover section 3 can be to a clothoid curve. By making the surface of the cover section 3 closer to a clothoid curve, the wind received by the ship 1 during navigation can be smoothly guided along the cover section 3, causing the wind flow to adhere to the cover section 3. This suppresses wind separation and vortex generation on the leeward side in the direction of wind flow. This is advantageous for improving the propulsion efficiency of the ship 1.

In this embodiment, the cover section 3 is composed of three sections. The cover section 3 may have four or more sections. Increasing the number of sections allows for a shape closer to a clothoid curve, which is advantageous for improving the propulsion efficiency of the vessel 1. Reducing the number of sections in the cover section 3 simplifies its shape, thus reducing manufacturing costs.

As illustrated in Figure 5, it is desirable that the length L1 of the cover portion 3 be greater than the length L0 of the wall portion 2 in the vertical direction z on the forward side (bow side).

Compared to the wall section 2, which is erected almost vertically, the cover section 3 is formed to be larger in the vertical direction z. For example, even when wind blows from diagonally in front of the ship 1, this wind can be more easily directed downwind along the cover section 3 in the direction of wind flow. As illustrated in Figure 4, the accelerated wind flow generates negative pressure, which consequently becomes leading-edge thrust, reducing the resistance of the ship 1. This is advantageous for improving the propulsion efficiency of the ship 1.

Lengths L0 and L1 are such that L0 < L1 even at the rear ends of the wall portion 2 and the cover portion 3. In the embodiment illustrated in Figure 5, the length L11 of the first swash plate 3a, the length L12 of the second swash plate 3b, and the length L13 of the third swash plate 3c may be the same in the vertical direction z. The length of the cover portion 3 in the vertical direction z may be L13 < L12 < L11.

Similarly, in the embodiment illustrated in Figure 1, the length L11 of the first swash plate 3a and the length L12 of the second swash plate 3b may be the same in the vertical direction z. The length of the cover portion 3 in the vertical direction z may be L12 < L11. The inclination of the cover portion 3 with respect to the horizontal plane decreases as the swash plates positioned higher up become higher. Therefore, by reducing the height of the upper swash plates, the amount of material constituting the cover portion 3 can be reduced. This is advantageous for reducing the weight of the cover portion 3.

As illustrated in Figures 6 and 7, the ship 1 may be provided with a pair of end members 8 positioned at both ends of the cover portion 3, which is formed in a substantially U-shape in plan view, and erected from the upper end of the wall portion 2. The end members 8 are, for example, made of flat steel plates. The end members 8 are not limited to flat plates; they may also be made of steel plates with curved shapes.

As illustrated in Figure 6, the end member 8 is set to a length of 30% of the total length of the windshield in the ship's longitudinal direction x. The total length of the windshield refers to the length from the foremost position of the cover portion 3 to the rearmost position of the end member 8 in the ship's longitudinal direction x. The length of the end member 8 is not limited to this; it can be set to, for example, 10% to 50% of the total length of the windshield. The end member 8 has a configuration in which the upper side slopes inward toward the inside of the roughly U-shaped cover portion 3.

As illustrated in Figure 8, it is desirable that the angle θ4 between the end member 8 and the horizontal plane be set to be greater than the angle θ1 between the first slanted plate 3a and the horizontal plane. For example, the angle θ4 related to the end member 8 is set to 75°. The angle θ4 is set within the range greater than 0° and less than 90°. The forward end (bow side) of the end member 8 is connected to the rear end (stern side) of the cover portion 3. In this embodiment, the end member 8 and the cover portion 3 are connected without gaps at the connecting portion 8a. The end member 8 and the cover portion 3 are connected, for example, by welding. By smoothly deforming the cover portion 3 toward the rear to match the position of the forward end of the end member 8, the connecting portion 8a is connected without gaps. With this configuration, the rear side of the cover portion 3 rises to match the end member 8. That is, the angles θ1' and θ2' of the cover portion 3 with respect to the horizontal plane increase toward the rear, and at the connecting portion 8a, θ1' = θ2' = θ4.

As illustrated in Figure 9, the end member 8 expands the area covering the containers 5 loaded on the ship 1. Even when the number of loaded containers 5 is increased in the ship's width direction (y) or vertical direction (z), the end member 8 can still cover them. In Figure 9, for illustrative purposes, the edge of the cover portion 3 in the embodiment illustrated in Figure 1 is shown with a dashed line. Furthermore, the area expanded by the end member 8 compared to the embodiment illustrated in Figure 1 is indicated with a diagonal line. Wind impacting the cover portion 3 flows from the cover portion 3 along the end member 8 towards the rear.

When viewing vessel 1 from bow to stern, the area covered by the windbreak is increased, thus reducing air resistance caused by the containers 5 positioned behind the windbreak. Even on vessel 1 where the containers 5 are loaded relatively high, air resistance can be reduced.

Because the angle θ4 of the end member 8 with respect to the horizontal plane is larger than the angle θ1 or angle θ2 of the cover portion 3 with respect to the horizontal plane, it becomes easier to cover the front of the containers 5 stacked at both ends in the ship's width direction y. Without the end member 8, the cover portion 3 is inclined towards the center of the ship's width direction y (see dashed line in Figure 9), so the corners of the containers 5 may protrude from the cover portion 3. In other words, the cover portion 3 and end member 8 illustrated in Figure 8 are more effective at covering the front of the containers 5 over a wider area than the cover portion 3 illustrated in Figure 3. By suppressing the air resistance of the containers 5, the propulsion efficiency of the ship 1 can be easily improved.

The rear end of the end member 8 is preferably positioned close to the front end of the container 5 located behind it in the ship's longitudinal direction x. In the case of a ship 1 without an end member 8, it is preferable that the cover portion 3 and the container 5 are close to each other in the ship's longitudinal direction x. The closer the windbreak and the container 5 are in the ship's longitudinal direction x, the less wind resistance impacting the container 5 can be reduced. Due to the structure of the ship 1, it may not be possible to position the container 5 close to the rear end of the end member 8 in the ship's longitudinal direction x. In this case, the wind resistance impacting the container 5 can be reduced by adjusting the angles θ1, θ1' related to the first swash plate 3a, the angles θ2, θ2' related to the second swash plate 3b, and the angle θ4 related to the end member 8, in accordance with the airflow impacting the cover portion 3.

The angle θ4 related to the end member 8 is not limited to a configuration where it is greater than the angle θ1 related to the first slanted plate 3a. The angle θ4 may be set to be equal to the angle θ1, or it may be set to be smaller. The angle θ4 only needs to be set to be greater than the angle related to the uppermost slanted plate of the cover portion 3. If the cover portion 3 has two stages, the angle θ4 should be greater than the angle θ2 related to the second slanted plate 3b, and if the cover portion 3 has three stages, it should be greater than the angle θ3 related to the third slanted plate 3c. This configuration allows the area that the end member 8 can cover the container 5 to be expanded.

The front end of the end member 8 may be partially connected to the cover portion 3. Alternatively, the end member 8 and the cover portion 3 may not be connected. In this case, at least partially, air can pass through the connecting portion 8a. A seamless connection between the end member 8 and the cover portion 3 at the connecting portion 8a allows air to flow more smoothly along the cover portion 3 and the end member 8, thus reducing air resistance.

If wind passes through the connecting section 8a, the air resistance of the vessel 1 may increase depending on the conditions. On the other hand, since there is no need to process the rear side of the cover section 3 to match the end member 8, the manufacturing of the cover section 3 becomes easier. This is advantageous in suppressing the manufacturing cost of the cover section 3.

1. Ship 2. Wall section 3. Cover section 3a. First slanted plate 3b. Second slanted plate 3c. Third slanted plate 4. Upper deck 5. Container 6. Forecastle deck 7. Bulwark 8. End member 8a. Connecting section x. Length direction y. Width direction z. Vertical direction θ1. Angle θ2 (related to the first slanted plate). Angle θ3 (related to the second slanted plate). Angle θ4 (related to the third slanted plate). Angle (related to the end member).

Claims (6)

In a vessel comprising a wall portion erected almost vertically from the upper end of a bulwark and forming a roughly U-shape in plan view, and a cover portion erected from the upper end of this wall portion and forming a roughly U-shape in plan view, with the upper side sloping inward,
The cover portion comprises a first inclined plate erected from the upper end of the wall portion and a second inclined plate erected from the upper end of the first inclined plate.
The angle between the second swash plate and the horizontal plane is set to be smaller than the angle between the first swash plate and the horizontal plane .
A vessel characterized in that the angle between the first swash plate and the horizontal plane is set to be larger on the aft side of the vessel than on the forward side, and the angle between the second swash plate and the horizontal plane is set to be larger on the aft side of the vessel than on the forward side . The cover portion has a third inclined plate erected from the upper end of the second inclined plate,
The vessel according to claim 1, wherein the angle between the third swash plate and the horizontal plane is set to be smaller than the angle between the second swash plate and the horizontal plane. The vessel according to claim 1 or 2, wherein the length of the cover portion is set to be greater than the length of the wall portion in the vertical direction. In a vessel comprising a wall portion erected almost vertically from the upper end of a bulwark and forming a roughly U-shape in plan view, and a cover portion erected from the upper end of this wall portion and forming a roughly U-shape in plan view, with the upper side sloping inward,
The cover portion comprises a first inclined plate erected from the upper end of the wall portion and a second inclined plate erected from the upper end of the first inclined plate.
The angle between the second swash plate and the horizontal plane is set to be smaller than the angle between the first swash plate and the horizontal plane.
The cover portion, which is formed in a substantially U-shape in plan view, is provided with a pair of end members that are positioned at both ends of the cover portion and are erected from the upper end of the wall portion.
The end member is characterized in that its upward side is inclined toward the inside of the substantially U-shaped cover portion. The ship according to claim 4, wherein the angle between the end member and the horizontal plane is set to be greater than the angle between the first slanted plate and the horizontal plane. The vessel according to claim 4, wherein the bow-side end of the end member is connected to the stern-side end of the cover portion.