Vessel

Abstract

To provide a vessel displaying good sailing performance while suppressing air draft.SOLUTION: A sail 10 has an airfoil body 11 freely revolvable around a perpendicular axis X and forming a bilaterally symmetrical streamline in a horizontal section, the aspect ratio consisting of a ratio of length H in a perpendicular direction of the airfoil body 11 to length L in a horizontal direction of the airfoil body 11 is 2.0 or less, and maximum width W of the airfoil body 11 is within a range of 12% to 25% of the horizontal direction length L in a vessel including at least one piece of airfoil sail 10 on an upper deck 3 of a hull 1.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a ship equipped with a wing-shaped sail, and more particularly to a ship that is capable of exhibiting good sailing performance while suppressing air draft. [Background technology]

[0002] Ships such as passenger ships, cargo ships, freight ships, car carriers, and tankers have been proposed that are equipped with a propeller and rudder below the waterline of the hull, and with a wing-shaped sail on a mast on the upper deck (see, for example, Patent Documents 1 and 2). In ships equipped with such sails, when there is wind, the mast can be rotated to give the sail an angle of attack with respect to the relative direction of the wind, thereby generating thrust from the sail.

[0003] However, ships equipped with sails have a large air draft (the distance from the water surface to the highest point), which can cause the sail to interfere with the passage of the bridge. To avoid such interference, for example, the sail must be made foldable, but this has the disadvantage of making the sail structure more complicated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 18594 / 1983 [Patent Document 2] JP 2014-184936 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a watercraft that is capable of suppressing air draft while exhibiting good sailing performance. [Means for solving the problem]

[0006] In order to achieve the above object, the ship of the present invention is a ship equipped with at least one wing-shaped sail on the upper deck of the hull, The sail has a wing body that is freely rotatable around a vertical axis and has a symmetrical streamlined shape in horizontal cross section, an aspect ratio, which is the ratio of the vertical length of the wing body to the horizontal length of the wing body, is 2.0 or less, and the maximum width of the wing body is in the range of 12% to 25% of the horizontal length. Effect of the Invention

[0007] As a result of extensive research into the shape of ship sails, the inventor discovered that a wing-shaped sail having a specific shape can efficiently capture the wind flowing along the upper deck and exhibit good sailing performance, even if it has a small aspect ratio, which led to the invention.

[0008] That is, in the present invention, the airfoil sail has an airfoil body that can rotate freely around a vertical axis and has a symmetrical streamlined shape in horizontal cross section, and the aspect ratio, which is the ratio of the vertical length of the airfoil body to the horizontal length of the airfoil body, is 2.0 or less, and the maximum width of the airfoil body is in the range of 12% to 25% of the horizontal length, so that it can capture the wind flowing along the upper deck during sailing to generate lift and exhibit good sailing performance. In particular, the relative wind on the sea is the combined force of the wind caused by the ship's own sailing and the natural wind, and the relative wind direction changes when the speed of the natural wind changes. Even if the angle of the sail is changed to follow the rapidly changing relative wind direction, the relative wind direction may already have changed by the time the sail angle is changed. In response to this, according to the inventor's findings, by making the wing body thicker by setting the maximum width of the wing body within the range of 12% to 25% of the horizontal length, lift is less likely to change in response to changes in relative wind direction, and lift can be generated stably during sailing even if the aspect ratio of the wing body is small. Moreover, since the aspect ratio of the wing body is 2.0 or less, air drafts can be suppressed. Therefore, there is no need to make the sail folding, and the problem of the sail structure becoming complicated does not arise.

[0009] In the present invention, the blade body preferably has a slit penetrating in the thickness direction at at least one horizontal location. By providing such a slit in the blade body, when the blade body receives wind, the wind escapes from the pressure side to the suction side, preventing stall on the suction side and increasing lift.

[0010] The wing body has a plurality of segments separated by slits, and at least one of the segments is preferably configured to be freely swingable in the horizontal direction relative to the other segments. By configuring at least one segment to be freely swingable in this manner, it is possible to impart an apparent camber to the wing body, thereby increasing lift.

[0011] The sail preferably has an upper end plate that protrudes in the width direction of the wing body at the top end of the wing body. There is a risk that wind will pass over the top of the wing body, which has a small aspect ratio, and go around from the pressure side to the suction side. However, by installing the upper end plate, such wind can be prevented from going around and lift can be increased.

[0012] It is preferable that the wing body has a flat portion at its front end, which is perpendicular to the centerline of the wing body in the longitudinal direction. This flat portion acts as a wind guide when the wing receives an oblique headwind, and functions as an apparent camber of the wing body, thereby contributing to an increase in lift.

[0013] In the present invention, the shape of the hull should also be optimized to maximize the lift based on the above-mentioned airfoil-shaped sail. That is, in a ship having a bow located at the front of the hull, an upper deck connected to the bow, and a pair of side sections located on both sides of the upper deck and connected to the bow, it is preferable that the bow has a curved surface that forms a first contour line including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull in a vertical cross section of the hull, and forms a second contour line including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull in a horizontal cross section of the hull. By having the above-mentioned curved surface of the bow, the wind received during sailing can be smoothly guided along the hull, and the wind flow can be attached to the upper deck to maximize the lift based on the sail. This allows good sailing performance to be obtained. In addition, by having the above-mentioned curved surface of the bow, separation on the leeward side and the generation of vortices in the wind flow can be reduced, so that wind pressure resistance against an oblique headwind can be effectively reduced. Furthermore, if a bow section is provided with a curved surface including the above-mentioned clothoid curve, the wind speed on the upper deck can be increased. As a result, it is possible to effectively reduce resistance when there is a headwind, and when there is an oblique headwind or crosswind, the wind pressure can be converted to thrust to the maximum extent possible.

[0014] In the present invention, the curved surface of the bow preferably forms a third contour line including a clothoid curve whose radius of curvature increases from the outer side to the inner side in the width direction of the hull in the cross section of the hull. Also, the curved surface of the bow preferably forms a fourth contour line including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull in a cross section parallel to the center line of the hull and inclined to the vertical cross section. This allows the wind received during navigation to be smoothly guided along the hull, and the wind flow to be attached to the upper deck to maximize the lift based on the sails, as well as more effectively reducing wind resistance against diagonal headwinds. Furthermore, when a diagonal headwind or crosswind is received, the wind on the upper deck increases in speed, eliminating stagnation on the leeward side and reducing resistance, and as a result, the wind force can be converted to thrust to the maximum extent.

[0015] It is preferable that the gunwale section connecting the upper deck and each of the sides of the ship has a curved surface that forms a fifth contour line including a clothoid curve in which the radius of curvature increases from the outside to the inside in the width direction of the ship in the cross section of the ship. This allows the wind received during sailing to be smoothly guided along the ship's hull, and the wind flow to be attached to the upper deck to maximize the lift of the sails. In addition, it reduces the separation and generation of vortices on the leeward side of the wind flow, and effectively reduces wind pressure resistance against crosswinds and oblique headwinds. In addition, when a gunwale section having the above-mentioned clothoid curve is provided together with a bow section having a curved surface including the above-mentioned clothoid curve, calculations based on computational fluid dynamics (CFD) show that the wind on the upper deck when an oblique headwind or crosswind is received can be accelerated by about 20% compared to the relative wind speed entering the ship (the combined force of the ship's speed and the natural wind). As a result, when an oblique headwind or crosswind is received, the wind force can be converted to thrust to the maximum extent.

[0016] It is preferable that the upper deck be constructed with a flat surface, which allows the wind received during sailing to be smoothly guided along the hull and the wind flow to be attached to the upper deck to maximize the lift generated by the sails, while also reducing separation and vortex generation on the leeward side of the wind flow, effectively reducing wind resistance to crosswinds and diagonal headwinds.

[0017] It is preferable that the bow has a flat section at its front that is perpendicular to the centerline of the ship. This flat section acts as a wind guide when the ship receives an oblique headwind, and functions as an apparent camber for the wing, thereby contributing to an increase in thrust. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a front perspective view showing a vessel according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a side view of the vessel of FIG. 1. [Diagram 3] 2A and 2B show an example of an airfoil-shaped sail to be mounted on the ship of FIG. 1, where (a) is a front perspective view and (b) is a plan view. [Figure 4] FIG. 2 is a front perspective view showing wind flow relative to the ship of FIG. 1. [Diagram 5] 1A and 1B show a modified airfoil-shaped sail, in which (a) is a front perspective view and (b) is a plan view. [Figure 6] 13A and 13B show another modified example of an airfoil-shaped sail, in which (a) is a front perspective view and (b) is a plan view. [Figure 7] 13A and 13B show yet another modified example of an airfoil-shaped sail, where (a) is a front perspective view and (b) is a plan view. [Figure 8] FIG. 2 is a plan view showing the airfoil sail in a bent state. [Figure 9] FIG. 1 is a plan view showing an airfoil-shaped sail with flats. [Figure 10] FIG. 2 is a perspective view showing contour lines of each part of the ship in FIG. 1. [Figure 11] FIG. 2 is a cross-sectional view showing a first contour line of the bow portion in a vertical cross section of the hull. [Figure 12] FIG. 4 is a cross-sectional view showing a second contour line of the bow portion in a horizontal cross section of the hull. [Figure 13] FIG. 2 is a cross-sectional view showing a third contour line of the bow portion in a cross section of the hull. [Figure 14] FIG. 11 is a cross-sectional view showing a fourth contour line of the bow section in a cross section that is parallel to the centerline of the hull and inclined with respect to a vertical cross section. [Figure 15] A cross-sectional view showing the fifth contour line of the gunwale portion in a cross section of the hull. [Figure 16] FIG. 11 is a front perspective view showing a vessel according to another embodiment of the present invention. [Figure 17] FIG. 11 is a front perspective view showing a vessel according to still another embodiment of the present invention. [Figure 18] FIG. 18 is a side view of the vessel of FIG. 17. [Figure 19] FIG. 18 is a perspective view showing contour lines of each part of the ship in FIG. 17. [Figure 20] 3A and 3B show the thrust generated at the bow, where (a) is a plan view of a bow that does not have a flat portion, and (b) is a plan view of a bow that has a flat portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The configuration of the present invention will be described in detail below with reference to the accompanying drawings. Figures 1 and 2 show a ship according to an embodiment of the present invention, and Figure 3 shows an example of a wing-shaped sail mounted on the ship. Note that the ship shown in Figures 1 and 2 is an example of a car carrier (car carrier), but the present invention is not particularly limited in its application as long as it satisfies certain requirements, and it can also be applied to passenger ships, ferries, etc.

[0020] 1 and 2, the ship of this embodiment is composed of a hull 1 having an overall length in the range of, for example, 40 m to 400 m. The hull 1 has a bow 2 located at the front, an upper deck 3 continuing from the bow 2, and a pair of side sections 4, 4 located on both sides of the upper deck 3 and continuing from the bow 2.

[0021] The hull 1 is provided with multiple decks (not shown) having a hierarchical structure inside, from the bow to the stern, in order to secure and transport automobiles. In addition, an opening for a rampway and its door (not shown) for loading and unloading automobiles are provided at the stern of the hull 1. A chimney 5 and the like are provided on the upper deck 3, but a tower such as a bridge or accommodation space is not provided. In this ship, the bridge (not shown) and accommodation space (not shown) are provided below the upper deck 3, and structures protruding from above the upper deck 3 are eliminated as much as possible. As shown in FIG. 2, a propeller 6 and a rudder 7 are provided at the lower part of the stern side of the hull 1. Here, one shaft and one rudder are provided, but this is not limited to this, and a multi-shaft ship such as two shafts and two rudders may be used.

[0022] In the ship configured as described above, at least one wing-shaped sail 10 is installed on the upper deck 3 of the hull 1. Although four sails 10 are depicted in Figures 1 and 2, it is desirable to install, for example, three or four sails 10 on the upper deck 3.

[0023] As shown in Fig. 3(a) and (b), the wing-shaped sail 10 has a wing body 11 that can rotate around a vertical axis X and has a symmetrical streamlined shape in a horizontal cross section. The sail 10 including the wing body 11 is a rigid body made of metal materials such as steel, stainless steel, and aluminum alloy, or fiber-reinforced composite materials such as carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic. The aspect ratio (H / L), which is the ratio of the vertical length H of the wing body 11 to the horizontal length L of the wing body 11, is set to 2.0 or less, and more preferably, is set to 0.5 or more and 1.0 or less. The height H of the wing body 11 is not particularly limited, but is set in the range of 5 m to 20 m, for example. The maximum width W of the wing body 11 is set in the range of 12% to 25% of the horizontal length L.

[0024] In the ship constructed as described above, the wing-shaped sail 10 has a wing body 11 that can rotate freely around the vertical axis X and has a symmetrical streamlined shape in horizontal cross section. The wing body 11 has a thickened structure with a maximum width W in the range of 12% to 25% of the horizontal length L, so that even if the wind direction changes during sailing and the attack angle on the sail 10 changes, the sail can generate a stable lift and exhibit good sailing performance. Moreover, since the aspect ratio of the wing body 11 is 2.0 or less, air draft can be suppressed. Therefore, the sail 10 does not need to be a folding type, and the structure of the sail 10 can be avoided from becoming complicated. Here, if the maximum width W of the wing body 11 is out of the above range, the generation of lift becomes insufficient. Also, if the aspect ratio of the wing body 11 is more than 2.0, it becomes difficult to suppress the air draft.

[0025] In the above-mentioned ship, as shown in Fig. 5(a), (b), Fig. 6(a), (b) or Fig. 7(a), (b), the blade body 11 may have a slit 12 penetrating the blade body 11 in the thickness direction at least at one position in the horizontal direction, and may have a plurality of divided pieces 13 divided by these slits 12. By providing such a slit 12 in the blade body 11, when the blade body 11 receives wind, the wind escapes from the pressure side to the suction side, so that the stall on the suction side can be prevented and the lift can be increased. When providing the slit 12, in a plan view of the blade body 11, the center line of the slit 12 may be a straight line extending in the width direction of the blade body 11 or a circular arc that is convex toward the front of the blade body 11. In the case of a circular arc, the radius of curvature of the circular arc may be set to B / 2 or more with respect to the width B of the blade body 11 at the position of the center line of the slit 12. The slit 12 having such a shape allows the wind to escape from the pressure side to the suction side when the blade body 11 receives wind.

[0026] As shown in Figures 7(a) and (b), it is preferable that the sail 10 has an upper end plate 14 that protrudes in the width direction of the wing body 11 at the upper end of the wing body 11. Since the aspect ratio of the wing body 11 is small, there is a risk that wind will pass above the wing body 11 and go around from the pressure side to the suction side. However, by providing the upper end plate 14 at the upper end of the wing body 11, it is possible to suppress such wind going around and increase lift.

[0027] As described above, when the wing body 11 has a plurality of segments 13 separated by slits 12, it is preferable that at least one of these segments 13 is configured to be freely swingable in the horizontal direction relative to the other segments 13. For example, in FIG. 8, when the wing body 11 has a plurality of segments 13a, 13b, and 13c separated by slits 12, the segments 13a and 13c on both sides are configured to be freely swingable in the horizontal direction relative to the segment 13b located in the center. By configuring at least one segment 13 to be freely swingable in this manner, it is possible to impart an apparent camber to the wing body 11, thereby increasing the lift. For example, the front camber angle α and the rear camber angle β can each be set within a range of, for example, ±10°. In FIG. 8, the swing axes of the segments 13a and 13c coincide with the vertical axis X, which is the rotation axis of the wing body 11, but they do not necessarily have to coincide.

[0028] The wing body 11 has a forward contour Cf that is symmetrical and streamlined in cross section (the planar shapes in Figs. 5(b), 6(b), and 7(b) correspond to the cross-sectional shapes). This allows the wind received at the leading edge of the wing body 11 to be smoothly guided along the wing body 11, increasing lift.

[0029] In particular, it is preferable that the wing body 11 has a flat section 15 at its forefront, which is a plane perpendicular to the centerline of the wing body 11 in the longitudinal direction, as shown in Fig. 9. This flat section 15 acts as a wind guide when an oblique headwind strikes, and functions as an apparent camber for the wing body 11, thereby contributing to an increase in lift. It is preferable that the width Wf of the flat section 15 be 1 / 3 or less of the maximum width W of the wing body 11.

[0030] In the ship configured as described above, the shape of the hull 1 is also optimized to maximize the lift force based on the airfoil sail 10. That is, as shown in FIG. 10, the bow 2 has a curved surface. In a vertical cross section P1 of the hull 1, the curved surface of the bow 2 forms a first contour line C1 (see FIG. 11) including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1, and in a horizontal cross section P2 of the hull 1, the curved surface of the bow 2 forms a second contour line C2 (see FIG. 12) including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1. Furthermore, in a transverse cross section P3 of the hull 1, the curved surface of the bow 2 forms a third contour line C3 (see FIG. 13) including a clothoid curve whose radius of curvature increases from the outer side to the inner side in the width direction of the hull 1. Furthermore, the curved surface of the bow 2 forms a fourth contour line C4 (see FIG. 14) that includes a clothoid curve whose radius of curvature increases from the front to the rear of the hull 1, on a cross section P4 that is parallel to the center line CL of the hull 1 and inclined relative to the vertical cross section P1. The center line CL of the hull 1 is an imaginary line that extends along the longitudinal direction (horizontal direction) of the hull 1 at the center position in the width direction of the hull 1.

[0031] A clothoid curve is a trajectory that is traced when the curvature is changed at a constant rate. The first contour line C1 of the bow section 2 in the vertical cross section P1 of the hull 1 includes a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1 continuously or intermittently, and preferably includes the clothoid curve continuously. Therefore, the radii of curvature R11 to R13 of the first contour line C1 gradually increase toward the rear side of the hull 1, and the first contour line C1 is smoothly connected to the upper deck 3. Similarly, the second contour line C2 of the bow section 2 in the horizontal cross section P2 of the hull 1 includes a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1 continuously or intermittently, and preferably includes the clothoid curve continuously. Therefore, the radii of curvature R21 to R23 of the second contour line C2 gradually increase toward the rear side of the hull 1, and the second contour line C2 is smoothly connected to the side section 4. The third contour line C3 of the bow 2 in the cross section P3 of the hull 1 includes a clothoid curve whose radius of curvature increases from the outside to the inside in the width direction of the hull 1 continuously or intermittently, and preferably includes the clothoid curve continuously. Therefore, the radii of curvature R31 to R33 of the third contour line C3 are gradually increased toward the inside in the width direction of the hull 1. The fourth contour line C4 of the bow 2 in the cross section P4, which is parallel to the center line CL of the hull 1 and inclined with respect to the vertical cross section P1, includes a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1 continuously or intermittently, and preferably includes the clothoid curve continuously. Therefore, the radii of curvature R41 to R43 of the fourth contour line C4 are gradually increased toward the rear side of the hull 1, and the fourth contour line C4 is smoothly connected to the upper deck 3 or the side section 4.

[0032] In addition, in the ship configured as described above, the gunwale section 8 connecting the upper deck 3 and each of the ship's side sections 4 has a curved surface. The curved surface of the gunwale section 8 forms a fourth contour line C5 (see FIG. 15) including a clothoid curve whose radius of curvature increases from the outside to the inside in the width direction of the hull 1 in the cross section P5 of the hull 1. In other words, the fifth contour line C5 of the gunwale section 8 in the cross section P5 of the hull 1 includes a clothoid curve whose radius of curvature increases from the outside to the inside in the width direction of the hull 1 continuously or intermittently, and preferably includes the clothoid curve continuously. Therefore, the radii of curvature R51 to R53 of the fifth contour line C5 gradually increase toward the inside in the width direction of the hull 1, and the fifth contour line C5 is smoothly connected to the upper deck 3.

[0033] According to the above-mentioned ship, the bow section 2 has a curved surface that forms a first contour line C1 including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1 in the vertical cross section P1 of the hull 1, and a second contour line C2 including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1 in the horizontal cross section P2 of the hull 1. As a result, as shown in FIG. 4, the wind received during sailing can be smoothly guided along the hull 1, and the wind flow can be attached to the upper deck 3 to maximize the lift force based on the sail 10. This allows for good sailing performance. In addition, since the bow section 2 has the above-mentioned curved surface, it is possible to reduce separation and vortex generation on the leeward side in the wind flow, so that the wind resistance against an oblique headwind can be effectively reduced, and further, when an oblique headwind is received, the wind pressure can be converted to thrust to the maximum extent. As a result, fuel efficiency can be improved and energy can be saved in the operation of the ship.

[0034] In the above-mentioned ship, the curved surface of the bow section 2 desirably forms a third contour line C3 including a clothoid curve whose radius of curvature increases from the outer side to the inner side in the width direction of the hull 1 in the cross section P3 of the hull 1. In this case, the wind received during navigation can be smoothly guided along the hull 1, and the wind flow can be attached to the upper deck 3 to maximize the lift based on the sail 10, and the wind pressure resistance against the diagonal headwind can be more effectively reduced. In addition, the curved surface of the bow section 2 desirably forms a fourth contour line C4 including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1 in a cross section P4 that is parallel to the center line CL of the hull 1 and inclined with respect to the vertical cross section P1. In this case, the wind received during navigation can be smoothly guided along the hull 1, and the wind flow can be attached to the upper deck 3 to maximize the lift based on the sail 10, and the wind pressure resistance against the diagonal headwind can be more effectively reduced.

[0035] Furthermore, in the above-mentioned ship, it is desirable that the gunwale sections 8 connecting the upper deck 3 and each of the ship's side sections 4 have a curved surface that forms a fifth contour line C5 including a clothoid curve whose radius of curvature increases from the outer side to the inner side in the width direction of the hull 1 in the cross section P5 of the hull 1. In this case, the wind received during navigation can be smoothly guided along the hull 1, and the wind flow can be attached to the upper deck 3 to maximize the lift force based on the sail 10. In addition, separation and vortex generation on the leeward side of the wind flow can be reduced, and wind pressure resistance against crosswinds and oblique headwinds can be effectively reduced.

[0036] In addition, in the above-mentioned ship, it is preferable that the upper deck 3 is configured as a flat surface extending in the horizontal direction. In this case, the wind received during sailing is smoothly guided along the hull 1, and the wind flow is made to stick to the upper deck 3, maximizing the lift force based on the sails 10. In addition, separation and generation of vortexes on the leeward side of the wind flow are reduced, and wind pressure resistance against crosswinds and diagonal headwinds can be effectively reduced. It is preferable that the upper deck 3 is configured as flat as possible, but the provision of a minimum number of protrusions such as a chimney 5 is permitted. For example, it is sufficient that the ratio of the area of ​​the flat parts to the total area of ​​the upper deck 3 (excluding the curved parts and corner cut parts of the bow section 2 and the gunwale section 8) is 90% or more.

[0037] FIG. 16 shows a ship according to another embodiment of the present invention. In FIG. 16, the same parts as those in FIG. 1 and FIG. 2 are given the same reference numerals, and detailed description of those parts is omitted. In the ship of this embodiment, the gunwale section 8 connecting the upper deck 3 and each of the ship's side sections 4 has a recessed section 16 at a position corresponding to the sail 10. The position corresponding to the sail 10 is a position overlapping with the sail 10 in the fore-aft direction of the hull 1. In FIG. 16, a plurality of recessed sections 16 are arranged at positions corresponding to a plurality of sails 10. When such recessed sections 16 are provided, high-speed wind flows into the position of the sail 10 when an oblique headwind is received during sailing, so that the lift force based on the sail 10 can be maximized.

[0038] 17 to 19 show a ship according to still another embodiment of the present invention. In Figs. 17 to 19, the same parts as those in Figs. 1 and 2 are denoted by the same reference numerals, and detailed description of those parts is omitted. In the ship of this embodiment, the bow section 2 satisfies the condition that the bow section 2 has a curved surface that forms a first contour line C1 including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1 in a vertical cross section P1 of the hull 1, a second contour line C2 including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1 in a horizontal cross section P2 of the hull 1, a third contour line C3 including a clothoid curve whose radius of curvature increases from the outside to the inside in the width direction of the hull 1 in a transverse cross section P3 of the hull 1, and a fourth contour line C4 including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull 1 in a cross section P4 that is parallel to the center line CL of the hull 1 and inclined with respect to the vertical cross section P1. However, the shape of the bow section 2 is slightly different from that of the above-mentioned embodiment.

[0039] In particular, the bow 2 is provided with a flat portion 9 at its front end, which is a plane perpendicular to the center line CL of the ship 1. When such a flat portion 9 is provided, the flat portion 9 acts as a wind guide and functions as an apparent camber of the wing when the ship 1 receives an oblique headwind, so that the thrust can be increased. That is, when the bow 2 has a flat portion 9 as shown in FIG. 20(b), the flat portion 9 functions as an apparent camber of the wing when guiding the wind downwind, so that a larger thrust F can be obtained, compared to when the bow 2 does not have a flat portion 9 as shown in FIG. 20(a). This effect is produced for winds flowing in from both the left and right sides. The width of the flat portion 9 is preferably 1 / 3 or less of the overall width of the hull 1.

[0040] The area of ​​the flat section 9 can be adjusted according to the normal operating speed of the ship. For example, in the case of a ship traveling at a high speed and thus experiencing less frequent crosswinds, the flat section 9 is made smaller or a structure without a flat section 9 (see FIG. 1) is used. On the other hand, in the case of a ship traveling at a low speed and thus experiencing more frequent crosswinds, a structure with a larger flat section 9 (see FIG. 17) is used. [Explanation of symbols]

[0041] 1. Hull 2 Fore part 3 Upper Deck 4 Ship side 5. Chimney 6 Propellers 7. Rudder 8 Gunwale 9 Flat section 10 sails 11 Wing body 12 Slit 13 Split pieces 14 Upper end plate 15 Flat section C1 First contour line C2 Second contour line C3 Third contour line C4 Fourth contour line C5 Fifth contour line Cf Front contour

Claims

1. In a vessel equipped with at least one wing-shaped sail on the upper deck of the hull, The sail has a wing body that is freely rotatable around a vertical axis and has a symmetrical streamlined shape in horizontal cross section, an aspect ratio, which is the ratio of the vertical length of the wing body to the horizontal length of the wing body, is 2.0 or less, and the maximum width of the wing body is in the range of 12% to 25% of the horizontal length.

2. 2. The ship according to claim 1, wherein the wing body has a slit penetrating in a thickness direction at least at one position in a horizontal direction.

3. 3. The ship according to claim 2, wherein the wing body has a plurality of segments separated by the slits, and at least one of the segments is configured to be freely swingable in the horizontal direction relative to the other segments.

4. 4. The ship according to claim 1, wherein the sail has an upper end plate at an upper end of the wing body that protrudes in the width direction of the wing body.

5. 4. The ship according to claim 1, wherein the wing body has, at its forefront, a flat portion formed of a plane perpendicular to a center line in the fore-aft direction of the wing body.

6. A ship having a bow located at the front of the hull, an upper deck connected to the bow, and a pair of side sections located on both sides of the upper deck and connected to the bow, 2. The ship according to claim 1, wherein the bow has a curved surface that, in a vertical cross section of the hull, forms a first contour line including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull, and that, in a horizontal cross section of the hull, forms a second contour line including a clothoid curve whose radius of curvature increases from the front side to the rear side of the hull.

7. 7. The ship according to claim 6, wherein the curved surface of the bow defines a third contour line in a cross section of the hull, the third contour line including a clothoid curve whose radius of curvature increases from the outer side to the inner side in the width direction of the hull.

8. 7. The ship according to claim 6, wherein the curved surface of the bow defines a fourth contour line including a clothoid curve having a radius of curvature increasing from the front side to the rear side of the hull in a cross section that is parallel to the center line of the hull and inclined to the central vertical cross section.

9. The ship described in claim 6, characterized in that the gunwale portions connecting the upper deck and each of the side portions have a curved surface that forms a fifth contour line in a cross section of the hull, the fifth contour line including a clothoid curve whose radius of curvature increases from the outer side to the inner side in the width direction of the hull.

10. The ship according to any one of claims 6 to 9, characterized in that the upper deck is constructed of a flat surface.

11. 10. The ship according to claim 6, wherein the bow has at its foremost part a flat portion consisting of a plane perpendicular to the center line of the ship.

Images