Hull substructure and ship

Abstract

To provide a hull substructure capable of reducing the effects of waves on the ship's hull. [Solution] The hull substructure includes a bow substructure located on the bow side of the hull and a stern substructure located on the stern side of the hull. The bow substructure 10 includes a strut 11 that is vertically suspended downward from the bottom of the hull, and a mountain-shaped plate portion 21 that is connected to the lower end of the strut 11, has a plurality of holes 22, and is provided in a symmetrical shape with respect to the strut 11 as an anti-vertical movement body.

Description

Technical Field

[0001] The present invention relates to a lower hull structure disposed on a hull of a ship and a ship equipped with the same.

Background Art

[0002] Conventionally, in ships navigating the open sea, various lower structures have been proposed to reduce the influence of waves on the hull. For example, in Patent Document 1, a device for preventing pitching of a hull by utilizing the lift acting on a hydrofoil has been proposed. Further, in Patent Document 2, a composite support type ultra-high speed ship is proposed, which includes a lower hull connected to a strut provided to hang down below an upper hull and a hydrofoil attached to a side portion of the lower hull, and which improves the stability of the hull during navigation by utilizing the buoyancy of the lower hull and the lift of the hydrofoil.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the open sea, long-wavelength waves are generated, and ships navigating the open sea repeat hogging (a state where both ends of the hull hang down) in which the center of the hull is lifted to the crest of the wave and sagging (a state where the center of the hull hangs down) in which the bow and stern of the hull are lifted to the crest of the wave depending on the relative position between the wave and the hull. When excessive force is applied to the hull due to hogging or sagging caused by waves, the keel and / or longitudinal bulkhead are affected by metal fatigue and the like.

[0005] In recent years, reduction of the influence of waves on the hull during navigation in the open sea and during docking at ocean facilities has been required, such as work liaison ships to floating offshore structures such as offshore wind power generation facilities.

[0006] The device for preventing pitching described in Patent Document 1 uses a strut lifting drive mechanism to move the hydrofoil up and down underwater when the ship is pitching, but it is insufficient as a countermeasure against rolling.

[0007] Furthermore, in the composite support type ultra-high-speed vessel described in Patent Document 2, since the lower hull has almost the same length as the upper hull, there are concerns about the effects of hogging or sagging on the lower hull that is submerged during ultra-high-speed navigation.

[0008] The problem that this invention aims to solve is to provide a hull substructure capable of reducing the effects of waves on the hull, and a ship equipped therewith. [Means for solving the problem]

[0009] The hull substructure according to the present invention, which was developed to solve the above problems, is a hull substructure disposed in the lower part of a ship's hull, comprising: a strut suspended vertically downward from the bottom of the ship's hull; and a vertical movement prevention body connected to the lower end of the strut and provided in a left-right symmetrical shape with respect to the strut, wherein the strut has a hole formed therein that penetrates in the left-right direction.

[0010] Another aspect of the present invention relates to a hull substructure characterized in that, in the hull substructure, the vertical movement prevention body is provided with a flow straightening member so as to be aligned with the longitudinal direction of the hull.

[0011] Another aspect of the present invention relates to a hull substructure characterized in that, in the hull substructure, the vertical movement prevention body includes a plate-shaped body in which the front portion is angled upward by a predetermined angle.

[0012] Another aspect of the present invention relates to a hull substructure characterized in that the vertical movement prevention body includes a plate body in which a plurality of holes are formed.

[0013] Another aspect of the present invention relates to a hull substructure characterized in that, in the hull substructure, the flow straightening member is a pair of left and right flow straightening plates and / or left and right cover members attached to the left and right edges of the plate, which are provided between the strut and the left and right edges of the plate, extending in the front-rear direction of the plate, with the strut as the center.

[0014] Another aspect of the present invention relates to a hull substructure characterized in that the connection portion between the strut and the vertical movement prevention body is reinforced by a reinforcing member.

[0015] Another aspect of the present invention relates to a hull substructure characterized in that, in the hull substructure, the vertical movement prevention body is composed of a cylindrical body with openings at the front and rear.

[0016] Another aspect of the present invention relates to a hull substructure characterized in that, in the hull substructure, the flow straightening member is a pair of upper and lower flow straightening plates provided in the center of the upper and lower inner wall surfaces of the cylindrical body having a rectangular cross-section, extending in the front-rear direction of the cylindrical body.

[0017] The vessel according to the present invention is characterized in that a plurality of hull substructures are arranged in the lower part of the hull, each comprising a strut that is vertically suspended downward from the bottom of the hull and has a hole formed therein that penetrates in the left-right direction, and an up-and-down movement prevention body connected to the lower end of the strut and provided in a left-right symmetrical shape with respect to the strut, and the bow substructure provided on the bow side of the plurality of hull substructures has a shape in which the front part of the up-and-down movement prevention body is curved upward by a predetermined angle, and the stern substructure provided on the stern side of the hull substructure is provided in the left-right center of the stern side and is arranged in pairs on the left and right sides with a propeller that generates thrust force. [Effects of the Invention]

[0018] The hull substructure according to the present invention includes vertical movement prevention bodies provided symmetrically on both sides with respect to the struts. This reduces the vertical movement of the vessel when the hull substructure is attached, and further reduces the impact on the hull caused by hogging or sagging due to waves. Furthermore, when applied to workboats that dock at facilities such as offshore wind power plants, reducing the vertical movement of the vessel while at anchor allows for smoother movement of people and goods from the vessel to the offshore facilities, which is expected to improve work efficiency. In addition, since the struts have holes that penetrate in the left-right direction, the resistance of the struts to transverse waves is reduced, and the lateral sway of the vessel to which the hull substructure is attached can be reduced.

[0019] Furthermore, according to another embodiment of the present invention, a rectifier member is provided along the longitudinal direction of the hull, thereby rectifying the water flow and reducing the generation of vortices in the vertical direction of the vertical motion prevention body and behind the struts. This further reduces the vertical and lateral motion of the vessel.

[0020] Furthermore, according to another aspect of the hull substructure of the present invention, the plate body of the vertical movement prevention body has a shape in which the front portion is angled upward by a predetermined angle, making it easier to ride waves coming from the front, thereby further reducing the impact on the hull caused by hogging or sagging due to waves.

[0021] Furthermore, according to another aspect of the present invention, since the plate constituting the vertical movement prevention body has multiple holes formed in it, the influence of water flow on the hull can be further reduced by placing the hull underwater.

[0022] According to the lower hull structure according to another aspect of the present invention, since the fairing member is a pair of left and right fairing plates provided in the front-rear direction of the plate body between the strut and the left and right edge portions of the plate body around the strut and / or left and right cover members attached to the left and right edge portions of the plate body, it is possible to rectify the water flow and further reduce the generation of vortices behind the vertical movement prevention body and the strut.

[0023] According to the lower hull structure according to another aspect of the present invention, since the connection portion between the strut and the vertical movement prevention body is reinforced by a reinforcing member, even when receiving a strong impact from waves, it is possible to prevent the vertical movement prevention body from falling off from the lower end of the strut.

[0024] According to the lower hull structure according to another aspect of the present invention, since the vertical movement prevention body is composed of a cylindrical body with openings at the front and rear, as water flows through the cylindrical body, it is possible to further reduce the influence on the hull caused by hogging or sagging generated by waves.

[0025] According to the lower hull structure according to another aspect of the present invention, since the fairing member is a pair of upper and lower fairing plates provided in the front-rear direction of the cylindrical body on the central portions of the upper and lower inner wall surfaces of the cylindrical body with a rectangular cross-section, it is possible to rectify the flow inside the cylindrical body in the front-rear direction and reduce the generation of vortices above and below the vertical movement prevention body and behind the strut. Thereby, it is possible to further reduce the sway of the ship in the vertical and lateral directions.

[0026] According to the ship of the present invention, a plurality of lower hull structures are arranged at the lower part of the hull. Among the plurality of lower hull structures, the bow-side lower structure provided on the bow side has a shape in which the front side portion of the vertical movement prevention body faces upward at a predetermined angle. Among the lower hull structures, the stern-side lower structure provided on the stern side is provided at the left and right center on the stern side and is arranged in pairs on the left and right with a propeller that generates propulsion force interposed therebetween. Therefore, the bow-side lower structure rides on the waves from the front, and the stern-side lower structure can reduce the generation of vortices behind the hull. Thereby, the sway of the ship is reduced.

Brief Description of the Drawings

[0027] [Figure 1] This is a schematic plan view illustrating the arrangement of the hull substructure within the hull according to the first embodiment of the present invention. [Figure 2] This is a schematic side view illustrating the arrangement of the hull substructure within the hull according to the first embodiment of the present invention. [Figure 3] This is a perspective view illustrating the lower structure of the bow. [Figure 4] This is a side view illustrating the lower structure on the bow side of the ship. [Figure 5] This is a plan view illustrating the lower structure of the bow side of the ship. [Figure 6] Figure 5 shows a cross-sectional view along line AA. [Figure 7] Figure 5 shows a cross-sectional view along line BB. [Figure 8] This is a perspective view illustrating the lower structure at the stern of the ship. [Figure 9] This is a side view illustrating the lower structure at the stern of the ship. [Figure 10] This is a plan view illustrating the lower structure at the stern of the ship. [Figure 11] Figure 10 shows a cross-sectional view along the CC line. [Figure 12] Figure 10 is a cross-sectional view along the DD line. [Figure 13] This is a perspective view of a modified example of the lower structure on the bow side of a ship. [Figure 14] This is a bottom view of a modified version of the lower structure on the bow side. [Figure 15] Figure 14 shows a cross-sectional view along the EE line. [Figure 16] Figure 14 shows a cross-sectional view along the FF line. [Figure 17] This is a cross-sectional view of another variation of the bow-side lower structure. [Figure 18] This is a plan view of another modified example of the bow-side lower structure. [Figure 19] Figure 18 is a cross-sectional view along the GG line. [Figure 20]This is a schematic plan view illustrating the arrangement of the hull substructure within the hull according to a second embodiment of the present invention. [Figure 21] This is a schematic side view illustrating the arrangement of the hull substructure within the hull according to a second embodiment of the present invention. [Figure 22] This is a perspective view illustrating the lower structure of the bow. [Figure 23] This is a perspective view illustrating the lower structure of the bow. [Figure 24] This is a side view illustrating the lower structure on the bow side of the ship. [Figure 25] This is a plan view illustrating the lower structure of the bow side of the ship. [Figure 26] Figure 24 is a cross-sectional view along the KK line. [Figure 27] Figure 25 shows a cross-sectional view along the JJ line. [Figure 28] This is a perspective view illustrating the lower structure at the stern of the ship. [Figure 29] This is a side view illustrating the lower structure at the stern of the ship. [Figure 30] This is a plan view illustrating the lower structure at the stern of the ship. [Figure 31] Figure 30 shows a cross-sectional view along the MM line. [Figure 32] This is a perspective view of a modified example of the lower structure on the bow side of a ship. [Figure 33] This is a side view of a modified example of the lower structure on the bow side of the ship. [Figure 34] This is a plan view of a modified example of the lower structure on the bow side of the ship. [Figure 35] This is a front view of a modified example of the lower structure on the bow side. [Figure 36] Figure 33 shows a cross-sectional view along the NN line. [Figure 37] This is a perspective view of a modified example of the stern lower structure. [Figure 38] This is a side view of a modified example of the stern lower structure. [Figure 39] This is a perspective view of another variation of the bow-side lower structure. [Figure 40] This is a side view of another modified example of the bow-side lower structure. [Figure 41] This is a front view of another variation of the bow-side lower structure. [Figure 42] Figure 40 shows a cross-sectional view along the QQ line. [Figure 43] This is a perspective view of another variation of the stern lower structure. [Figure 44] This is a front view of another modified example of the stern lower structure. [Modes for carrying out the invention]

[0028] The present invention reduces the effects of waves on a ship's hull by modifying the ship's understructure. Hereinafter, embodiments of the ship's understructure according to the present invention will be described with reference to the drawings. In each figure, the bow is considered the front, the longitudinal direction of the ship's hull is the X direction, the lateral direction which is the width of the ship's hull is the Y direction, and the vertical direction (up and down direction) which is the height of the ship's hull is the Z direction.

[0029] The following description will use a vessel to which the hull substructure according to the present invention is applied as an example. In the following embodiment, an example of application to a catamaran will be described, but the vessel may also be a monohull, and it is of course applicable to the hulls of catamarans or multihulls, which are also called semi-submersible vessels or side-wall type air cushion vessels.

[0030] [First Embodiment] [Arrangement of the lower structure of a ship's hull] Figure 1 is a schematic plan view illustrating the arrangement of the hull substructure in the hull 100 according to the first embodiment of the present invention, and Figure 2 is a schematic side view thereof. In Figure 1, the hull 100 and the outer shape of the ship are shown by dashed lines.

[0031] A catamaran is a vessel in which two hulls 100, arranged parallel to each other, are joined by a deck 101, and the two hulls 100 have the same structure. The hull 100 has, for example, a roughly V-shape with a ridge extending downward from the bow to the stern in the center of the width direction when viewed from the front. Multiple substructures are arranged below the hull 100.

[0032] In this embodiment, as shown in Figure 1, three hull substructures are provided for a single hull 100. One of the three hull substructures is a bow substructure 10 located on the bow side of the hull 100. The other two hull substructures are a pair of stern substructures 30 located on the stern side. A propeller 102 of the propulsion system is positioned between the pair of stern substructures 30.

[0033] [Hull lower structure] The configuration of the hull substructure according to the first embodiment will now be described. Figures 3 to 7 show the configuration of the bow-side substructure 10. Figure 3 is a perspective view illustrating the bow-side substructure 10 according to the first embodiment, and Figure 4 is a side view thereof. Figure 5 is a plan view illustrating the bow-side substructure 10. Figure 6 is a cross-sectional view along line AA shown in Figure 5, and Figure 7 is a cross-sectional view along line BB shown in Figure 5. Note that in Figure 6, only the cross-section of the member (inclined plate 21b) cut by line AA is shown, and the illustration of other components is omitted.

[0034] The bow-side lower structure 10 includes a strut 11 that extends downward from the bottom of the hull 100, and a V-shaped plate portion 21 provided at the lower end of the strut 11 as an anti-vertical movement body. The anti-vertical movement body is a component that functions to suppress vertical movement of the hull.

[0035] The strut 11 has a roughly elongated elliptical shape in plan view. The upper end of the strut 11 is fixed to the center of the hull 100 in the width direction, such that the major axis of the elongated ellipse is in the longitudinal direction (X direction). In addition, the strut 11 has a roughly trapezoidal shape in side view. That is, in side view, the strut 11 has a shape in which the bow side is lower and the aft side is higher and the aft side is higher.

[0036] As shown in the side view in Figure 4, the height of the strut 11 is set such that the front height H1 is lower than the rear height H2. For example, if the longitudinal length of the strut 11 is 3000 mm and the height H2 of the strut 11 is 300 mm, then height H1 is 30 mm shorter than height H2. The difference between height H1 and height H2 is adjusted to approximately 5-15% of height H2 depending on the longitudinal length of the strut 11. As a result, as shown in Figure 2, when the upper end of the strut 11 is connected to the bottom of the ship, the mountain-shaped plate section 21, which acts as an anti-vertical movement body, is tilted forward and backward as a whole. By allowing the mountain-shaped plate section 21 to ride on waves coming from the front on such an inclined surface, the wave resistance on the hull is reduced, and the vertical movement of the hull is also reduced.

[0037] The strut 11 has multiple (two) holes 12 formed in the front and rear of its central vertical section, with the holes 12 penetrating in the left-right direction. The inner circumferential surface of the rear side of the holes 12 is curved to be convex forward, reducing water resistance during navigation. Furthermore, by forming the holes 12 in the strut 11, water flow from waves coming from the left and right directions relative to the hull 100 passes through the holes 12. This makes it possible to reduce the lateral rolling of the ship when it is at anchor.

[0038] Furthermore, as shown in the cross-section in Figure 7, the strut 11 has a roughly inverted triangular shape, with the connection portion with the mountain-shaped plate portion 21 at the lower end being narrower than the connection portion with the bottom of the hull at the upper end. The vertical length H3 of the strut 11 shown in Figure 7 is approximately 150 mm to 600 mm for a vessel of, for example, a hull length of 30 m.

[0039] As shown in Figure 7, a mountain-shaped plate portion 21 is provided at the lower end of the strut 11, which has a mountain-like shape when viewed in cross-section (section along line BB) at approximately the center in the longitudinal direction in the plan view shown in Figure 5. In plan view, the mountain-shaped plate portion 21 is formed in a roughly arrow-feather shape facing the bow. That is, the mountain-shaped plate portion 21 is formed by connecting one of the long sides of two roughly parallelogram-shaped inclined plates 21a and 21b, whose long sides are in the longitudinal direction. The connection portion of the two inclined plates 21a and 21b is the apex of the mountain shape and has the same length as the longitudinal length of the lower end of the strut 11. Therefore, in the plan view shown in Figure 5, the mountain-shaped plate portion 21 is symmetrical with respect to a straight line L1 that passes through the center of the strut 11 and extends in the longitudinal direction. Also, in the cross-sectional view shown in Figure 7, the mountain-shaped plate portion 21 is symmetrical with respect to a vertical line L2 that passes through the center of the strut 11. In other words, the mountain-shaped plate section 21 is provided in a symmetrical shape with respect to the strut 11. The bow-side lower structure 10 is positioned relative to the hull 100 such that the straight line L1 passing through the center of the strut 11 coincides with the hull centerline CL (see Figure 1).

[0040] Furthermore, in the V-shaped plate section 21, each of the left and right inclined plates 21a and 21b is inclined such that its side end is lower than the side connected to the strut 11. The V-shaped plate section 21 is attached such that it forms a predetermined angle θ1 on the upper surfaces of the inclined plates 21a and 21b with respect to a vertical line L2 (see Figure 7) passing through the center of the strut 11. The predetermined angle θ1 is, for example, 95 to 105 degrees.

[0041] The connection between the V-shaped plate portion 21 and the strut 11 is reinforced by a reinforcing member 25. The reinforcing member 25 has a substantially triangular shape in cross-section and is provided over at least the length in the front-rear direction where the V-shaped plate portion 21 and the strut 11 are in contact. The reinforcing member 25 is reinforced by, for example, wrapping a long steel plate around the lower end of the strut 11 so as to cover the connection between the strut 11 and the V-shaped plate portion 21, and then fixing the long steel plate to both the V-shaped plate portion 21 and the strut 11 by welding.

[0042] Multiple holes 22 are provided in the mountain-shaped plate section 21. The holes 22 are formed at predetermined intervals in the front-rear and left-right directions, except for predetermined areas on the front and rear ends of the left and right inclined plates 21a and 21b. The predetermined areas are regions that extend approximately 10% to 20% of the length from the front and rear ends of the left and right inclined plates 21a and 21b in the front-rear direction. The multiple holes 22 are formed with the same diameter (approximately 30 mm to 100 mm). The multiple holes 22 are formed such that the total area of ​​the holes is 30% to 50% of the surface area of ​​the respective inclined plates 21a and 21b. As shown in Figure 5, for example, 15 holes 22 are formed in the front-rear direction and 3 rows in the left-right direction. The diameter and number of holes 22 can be changed as appropriate.

[0043] In the front-end regions of the left and right inclined plates 21a and 21b where no holes are formed, the tips are curved upward at a predetermined angle θ2, as shown in the cross-section in Figure 6. The predetermined angle θ2 here is between 5 and 40 degrees. On the other hand, the rear end of the mountain-shaped plate portion 21 is a region where no holes 22 are formed. The regions on the rear ends of the left and right inclined plates 21a and 21b where no holes 22 are formed may be sloped more gently in a cross-sectional view, with the front higher and the rear lower, than the regions further forward where holes 22 are formed. By curving the front ends of the left and right inclined plates 21a and 21b upward, it is possible to prevent the bow from being suddenly lifted from a hogging state caused by waves, and to reduce the effects of waves on the hull, such as metal fatigue. Furthermore, since a certain area on the rear end side of the mountain-shaped plate portion 21 is a flat surface without holes, when the ship sails forward, the mountain-shaped plate portion 21, acting as an anti-vertical movement body, rides the waves, and the relative flow of water from the front flows over the plate surface of the mountain-shaped plate portion 21 and towards the rear. As a result, the vertical movement of the ship is further suppressed, and the effects of waves on the ship, such as metal fatigue, can be further reduced.

[0044] In the mountain-shaped plate section 21 of the bow-side lower structure 10, a cover section 23 is provided on the outer edge. The cover section 23 is a member that reinforces each inclined plate 21a, 21b by being attached to the outer edge of the mountain-shaped plate section 21. In order to reduce water resistance, the cover section 23 is formed from a round bar or tubular member with a roughly circular cross-section, and its front and rear ends are hemispherical curved surfaces. The cover section 23 also has a similar function to the flow straightening plate 24, which will be described later, in blocking the flow of water in the left-right direction according to the inclination of the plate surfaces of the left and right inclined plates 21a, 21b. The distance W1 (see Figure 7) between the two ends of the mountain-shaped plate section 21 to which the cover section 23 is attached is approximately 300 mm to 600 mm.

[0045] A rectifier plate 24 is provided on the mountain-shaped plate section 21. The rectifier plate 24 is provided in the front-to-back direction at a position close to the center in the width direction of each of the left and right inclined plates 21a and 21b (approximately midway between the straight line L1 and the outer ends in the left-right direction). The rectifier plate 24 is composed of an upper protruding plate 24a and a lower protruding plate 24b, which are provided in pairs, protruding above and below the inclined plates 21a and 21b. The upper protruding plate 24a on the upper surface side of the inclined plates 21a and 21b and the lower protruding plate 24b on the side of the inclined plates 21a and 21b are provided so that their height direction is parallel to the vertical line L2 and their plate thickness direction is in the left-right direction (Y direction). The length of the upper protruding plate 24a and the lower protruding plate 24b protruding from the plate surface of the inclined plates 21a and 21b is approximately 30 mm to 50 mm. In this embodiment, the rectifier plate 24 is positioned to avoid multiple holes 22, but it may also be provided with some of the holes 22 closed. Furthermore, since the bow-side lower structure 10 is positioned relative to the hull 100 such that the straight line L1 passing through the center of the strut 11 coincides with the hull centerline CL (see Figure 1), the rectifier plate 24, which extends in the longitudinal direction parallel to the straight line L1 in a plan view, will be aligned with the longitudinal direction of the hull 100.

[0046] Such a flow straightening plate 24 straightens the water flow generated above and below the mountain-shaped plate section 21 by blocking a portion of the water flow from the strut 11 toward the outer edges of the inclined plates 21a and 21b along the inclination of the inclined plates 21a and 21b. Furthermore, the cover section 23 provided on the outer edge of the mountain-shaped plate section 21 also has a similar function to the flow straightening plate 24, as it has portions that protrude above and below the plate surfaces of the inclined plates 21a and 21b. In other words, the water flow between the flow straightening plate 24 and the strut 11, and between the flow straightening plate 24 and the cover section 23, is straightened on the upper and lower surfaces of the inclined plates 21a and 21b, and the generation of vortices is suppressed. As a result, the vertical movement of the bow-side lower structure 10 is suppressed, and the vertical rolling of the ship can be reduced.

[0047] Next, the stern-side lower structure 30 will be described with reference to Figures 8 to 12. Figure 8 is a perspective view illustrating the stern-side lower structure 30 according to this embodiment, and Figure 9 is a side view thereof. Figure 10 is a plan view illustrating the stern-side lower structure 30. Figure 11 is a cross-sectional view along line CC shown in Figure 10, and Figure 12 is a cross-sectional view along line DD shown in Figure 10. Note that in Figure 12, only the cross-section of the member (horizontal plate portion 41) cut by line CC is shown, and the illustration of other components is omitted.

[0048] The stern lower structures 30 are provided in pairs on the left and right sides at the rear of the hull 100 (see Figure 1). The propellers 102 of the propulsion system are positioned between the left and right stern lower structures 30.

[0049] The stern lower structure 30 has a rectangular shape in plan view, with the longer side being in the front-to-rear direction. The stern lower structure 30 consists of a strut 31 that is suspended downward from the bottom of the hull 100 and a horizontal plate portion 41 that serves as an anti-vertical movement body provided at the lower end of the strut 31.

[0050] In a side view, the strut 31 has the same shape as the strut 11 of the bow-side lower structure 10 (see Figures 2 and 9). The side view shape of the strut 31 may be approximately trapezoidal or approximately rectangular. The strut 31 has multiple (2) holes 32 that penetrate in the left-right direction, similar to the strut 11. The number of holes 32 may be one. In other words, the number and shape of the holes 32 can be changed according to the length of the strut 31 in the longitudinal direction.

[0051] As shown in the side view in Figure 9, the height of the strut 31 is set such that the front height H4 is lower than the rear height H5. For example, if the longitudinal length of the strut 31 is 3000 mm and the height H5 of the strut 31 is 300 mm, then height H4 is 10 mm shorter than height H5. As a result, as shown in Figure 2, when the upper end of the strut 31 is connected to the bottom of the hull 100, the horizontal plate section 41, which acts as an anti-vertical movement body, is tilted forward and backward as a whole. The difference between the heights H4 and H5 of the strut 31 is set to about one-third of the difference between the heights H1 and H2 of the strut 11 in the bow-side lower structure 10. In other words, since wave resistance is less at the stern than at the bow, the inclination angle of the horizontal plate section 41 in a side view when the stern-side lower structure 30 is attached to the bottom of the hull 100 is made gentler than the inclination angle of the mountain-shaped plate section 21 of the bow-side lower structure 10.

[0052] The strut 31 has a roughly spindle shape in the cross-sectional view shown in Figure 12, and is thinner in the left-right direction than the strut 11 on the bow side. In other words, the contact area between the bottom of the hull and the strut 31 is reduced, so as shown in Figure 12, not only the connection between the lower end of the strut 31 and the horizontal plate portion 41, but also the connection between the upper end of the strut 31 and the bottom of the hull 100 is reinforced by the reinforcing member 35. The vertical length H6 of the strut 31 is approximately 150 mm to 250 mm for a ship of the 30 m class in terms of hull length. The shape of the strut 31 in the longitudinal section (section along line BB in Figure 5) may be roughly rectangular, or it may be roughly triangular, similar to the strut 11 of the bow side lower structure 10.

[0053] A horizontal plate portion 41 is fixed to the lower end of the strut 31, extending in the longitudinal direction along its width. The connection between the lower end of the strut 31 and the horizontal plate portion 41 is reinforced by a reinforcing member 35. The reinforcing member 35 is configured similarly to the reinforcing member 25 that reinforces the connection between the strut 11 and the V-shaped plate portion 21 in the bow-side lower structure 10.

[0054] The horizontal plate section 41 has a roughly rectangular shape in plan view. The longer side of the roughly rectangular horizontal plate section 41 has the same length as the length of the strut 31 in the longitudinal direction. Also, the width of the horizontal plate section 41 is shorter than the V-shaped plate section 21 on the bow side. In the plan view shown in Figure 10, the horizontal plate section 41 is provided in a shape that is symmetrical with respect to a straight line L3 that extends in the longitudinal direction through the center of the strut, and in the cross-sectional view shown in Figure 12, it is symmetrical with respect to a vertical line L4 that passes through the center of the strut 31. In other words, the horizontal plate section 41 is provided in a shape that is symmetrical with respect to the strut 31.

[0055] The horizontal plate section 41 is provided with multiple holes 42. The holes 42 are formed at predetermined intervals in the front-rear and left-right directions, except for predetermined areas on the front and rear ends of the plate surface of the horizontal plate section 41. The predetermined areas are regions of approximately 10% to 20% of the length from the front and rear ends of the horizontal plate section 41 in the front-rear direction. The multiple holes 42 are formed with the same diameter (approximately 30 mm to 100 mm) and are provided at predetermined intervals in the front, rear, left, and right directions. The area of ​​the holes 42 is formed to be 30% to 50% of the surface area of ​​the plate surface of the horizontal plate section 41. As shown in Figure 10, there are 15 holes 42 in the front-rear direction and 2 rows in the left-right direction. The diameter and number of holes 42 can be changed as appropriate. Since a pair of stern-side lower structures 30 are provided on the left and right sides of the stern, the diameter and number of holes 42 should be adjusted so that the ratio of the area of ​​the holes 42 to the area of ​​the horizontal plate section 41 is approximately the same as the ratio of the area of ​​the holes 22 to the area of ​​the mountain-shaped plate section 21 of the bow-side lower structure 10, when considering both stern-side lower structures 30 together.

[0056] Furthermore, as shown in Figure 12, the horizontal plate section 41 is attached to the lower end of the strut 31 with its plate surface horizontal in a cross-sectional view (DD line section) at approximately the center in the longitudinal direction shown in Figure 10. That is, the horizontal plate section 41 is attached such that its plate surface is approximately perpendicular to the vertical line L4 passing through the center of the strut 31. In the forward region where the holes 42 are not formed, the front end of the horizontal plate section 41 is curved upward at a predetermined angle θ3, similar to the bow-side mountain-shaped plate section 21 (see Figure 11). The angle θ3 at the front end of the horizontal plate section 41 may be the same as, or even smaller than, the angle θ2 at the tip of the bow-side lower structure 10. In addition, the rear end region of the horizontal plate section 41 where the holes are not formed is gently sloped from front to rear. The inclination angle θ4 at the rear end of the horizontal plate section 41 is set to 5 to 40 degrees, similar to the angle θ2 at the tip of the bow-side lower structure 10.

[0057] In the horizontal plate section 41 of the stern-side substructure 30, cover sections 43 are provided on the left and right outer edges, similar to the mountain-shaped plate section 21 of the bow-side substructure 10. The cover sections 43 are equivalent to the cover sections 23 of the bow-side substructure 10. The cover sections 43 reinforce the left and right outer edges of the horizontal plate section 41. The distance W2 (see Figure 12) between the two ends of the horizontal plate section 41 with the cover sections 43 attached is approximately 200 mm to 300 mm for a vessel of the 30 m class in terms of hull length.

[0058] In a vessel equipped with the bow-side lower structure 10 and stern-side lower structure 30 according to the above-described embodiment, the vessel's navigation is not hindered by the bow-side lower structure 10 and stern-side lower structure 30. This reduces fatigue to the hull 100 due to impacts from waves, etc., and also reduces the pitch and roll of the vessel when navigating in rough seas and when docking with offshore facilities such as offshore wind power plants.

[0059] [Modified version of the first embodiment] Next, a modified example of the bow-side lower structure according to the first embodiment will be described. Figure 13 is a perspective view illustrating the bow-side lower structure 50 according to the first modified example of the first embodiment, and Figure 14 is a bottom view thereof. Figure 15 is a cross-sectional view along the EE line in Figure 4, and Figure 16 is a cross-sectional view along the FF line in Figure 14. In Figure 15, only the cross-section of the member cut by the EE line (inclined plate 21b and lower plate portion 51) is shown, and the illustration of other components is omitted. Components similar to those of the bow-side lower structure 10 described earlier with reference to Figures 3 to 7 are denoted by the same reference numerals, and detailed explanations are omitted.

[0060] The bow-side lower structure 50 is similar to the bow-side lower structure 10 described above in that it comprises struts 11, a mountain-shaped plate portion 21 with multiple holes 22 formed therein, and a cover portion 23, and the connection portion between the struts 11 and the mountain-shaped plate portion 21 is reinforced by a reinforcing member 25. On the other hand, the bow-side lower structure 50 differs from the bow-side lower structure 10 described above in that a lower plate portion 51 is provided so as to span between the left and right edges of the mountain-shaped plate portion 21.

[0061] Furthermore, in the aforementioned bow-side lower structure 10, the mountain-shaped plate portion 21 functions as a vertical movement prevention body, whereas in the bow-side lower structure 50 according to this modified example, the mountain-shaped plate portion 21 mainly functions as a support portion that supports the lower plate portion 51, and the lower plate portion 51 functions as a vertical movement prevention body.

[0062] The lower plate portion 51 has a rectangular shape in which one of the shorter sides is rounded in a roughly semi-circular shape when viewed from below. The front end of the lower plate portion 51 is curved upward at a predetermined angle θ5 when viewed from the side (see Figure 15). The predetermined angle θ5 here is between 5 and 40 degrees. The front edge of the lower plate portion 51 is fixed to the front edges of the inclined plates 21a and 21b of the mountain-shaped plate portion 21 by welding or the like. That is, the front side of the mountain-shaped plate portion 21 is closed by the front end of the lower plate portion 51. The front ends of the inclined plates 21a and 21b of the mountain-shaped plate portion 21 are curved upward at a predetermined angle θ2. Therefore, the predetermined angle θ5 at the front end of the lower plate portion 51 is appropriately changed to correspond to the predetermined angle θ2. Furthermore, if a lower plate portion 51 with an upwardly curved front end is provided as in this modified example, the upward curvature of the front end of the inclined plates 21a and 21b of the mountain-shaped plate portion 21 may be omitted.

[0063] Multiple holes 52 are formed in the lower plate portion 51. When viewed from the bottom, the multiple holes 52 are formed at positions corresponding to the positions of multiple holes 22 formed in the inclined plates 21a and 21b of the mountain-shaped plate portion 21, which are located above the lower plate portion 51. In this modified example, the multiple holes 52 are provided in the same number and with the same diameter as the multiple holes 22, but this is not limited to this. The diameter and / or number of holes formed in the lower plate portion 51 and the inclined plates 21a and 21b of the mountain-shaped plate portion 21 may be different.

[0064] The area at the rear end of the lower plate portion 51 where the holes 52 are not formed is a horizontal, flat surface that is on the same plane as the area where the holes 52 are formed, but it may also be inclined downward, similar to the rear end of the mountain-shaped plate portion 21.

[0065] The lower plate portion 51 is provided with a lower protruding plate 54b that protrudes downward and extends in the front-rear direction, forming a rectifier plate 54. The lower protruding plate 54b on the lower surface of the lower plate portion 51 is positioned in a vertically corresponding position to the upper protruding plate 24a that protrudes from the upper surface of the inclined plates 21a, 21b. The lower protruding plate 54b, which is vertically installed on the lower surface of the lower plate portion 51 with the left-right direction as the plate thickness direction, forms a pair with the upper protruding plate 24a of the inclined plates 21a, 21b to form a rectifier plate 54. In this modified example, the lower protruding plate 54b is positioned to avoid multiple holes 52, but it may also be installed with some of the holes 52 closed.

[0066] The left and right edges of the lower plate portion 51 are fixed to the left and right edges of the mountain-shaped plate portion 21 by welding or the like, and the connection between the two is covered by the cover portion 23. This protects the left and right edges of both the lower plate portion 51 and the mountain-shaped plate portion 21 from impacts and the like.

[0067] Next, a second modified example of the first embodiment, the bow-side substructure 60, will be described. Figure 17 is a cross-sectional view illustrating the bow-side substructure 60. Figure 17 shows a cross-section at the same position as the FF line in Figure 14. The same components as those in the bow-side substructure 10 and bow-side substructure 50 described above are denoted by the same reference numerals, and detailed descriptions are omitted.

[0068] The bow-side lower structure 60 is similar to the bow-side lower structure 10 and bow-side lower structure 50 described above in that it includes struts 11 and mountain-shaped plate sections 21 with multiple holes 22, and the connection between the struts 11 and the mountain-shaped plate sections 21 is reinforced by reinforcing members 25. The bow-side lower structure 60 is also similar to the bow-side lower structure 50 described above in that a lower plate section 51 is provided to span between the left and right edges of the mountain-shaped plate sections 21. On the other hand, the bow-side lower structure 60 differs from the bow-side lower structure 50 described above in that instead of providing a flow straightening plate on the plate surface of the mountain-shaped plate sections 21 and the lower plate section 51, it provides a flow straightening plate 64 on the left and right end edges of the lower plate section 51 and the mountain-shaped plate sections 21 instead of a cover section 23.

[0069] The rectifier plate 64 is a long plate body that is rectangular in cross-section and elongated in the front-to-back direction. The plate thickness direction is the left-to-right direction, and the plate height direction is parallel to the vertical line L2. The rectifier plate 64 is fixed by welding or the like to the connection portion of the left and right end edges of the lower plate portion 51 and the mountain-shaped plate portion 21, with the approximate center of the height direction of one of the long plate bodies of the rectifier plate 64 at the height direction. The length of the rectifier plate 64 that protrudes above the plate surface of the mountain-shaped plate portion 21 is approximately 30 mm to 50 mm, and the length that protrudes below the lower surface of the lower plate portion 51 is approximately 30 mm to 100 mm. By providing such a rectifier plate 64, it is possible to obtain a rectifying effect while reinforcing the outer edges of the lower plate portion 51 and the mountain-shaped plate portion 21, similar to the cover portion 23.

[0070] Furthermore, the distance W3 between the two ends of the lower plate section 51, which serves as an anti-vertical movement body to which the rectifier plate 64 is attached, is approximately 200 mm to 300 mm for vessels of the 30 m class in length.

[0071] Next, a third modified example of the first embodiment of the bow-side lower structure 70 will be described. Figure 18 is a plan view of the bow-side lower structure 70. Figure 19 is a cross-sectional view taken along the GG line in Figure 18. The same components as those in the bow-side lower structure 10 described above are denoted by the same reference numerals, and detailed explanations are omitted.

[0072] The bow-side lower structure 70 differs from the bow-side lower structure 10 described above in that it is provided with a flat plate section 71 as an anti-vertical movement body instead of the mountain-shaped plate section 21.

[0073] In a plan view, the flat plate portion 71 has a shape in which one of the shorter sides of a rectangle is rounded in a roughly semi-circular shape. The length of the flat plate portion 71 in the front-rear direction is the same as the length of the lower end of the strut 11 in the front-rear direction.

[0074] The flat plate portion 71 is provided with a plurality of holes 72. Similar to the holes 22 formed in the mountain-shaped plate portion 21 of the bow-side lower structure 10 described earlier, the holes 72 are formed at predetermined intervals in the longitudinal and lateral directions, except for predetermined areas on the front and rear ends of the plate surface of the flat plate portion 71. The flat plate portion 71 is curved upward at a predetermined angle at the front end, similar to the mountain-shaped plate portion 21 described with reference to Figure 6.

[0075] Furthermore, as shown in Figure 19, the flat plate portion 71 is attached to the strut 11 such that, in a cross-sectional view of the central part of the flat plate portion 71 in the front-rear direction in Figure 18 (cross-section along the GG line), the plate surface is parallel to the lower end of the strut 11. In other words, the flat plate portion 71 is attached such that its plate surface is approximately perpendicular to the vertical line L2 passing through the center of the strut 11. In the plan view shown in Figure 18, the flat plate portion 71 is provided in a shape that is symmetrical with respect to the line L1 extending in the front-rear direction through the center of the strut 11, and in the cross-sectional view shown in Figure 19, it is symmetrical with respect to the vertical line L2 passing through the center of the strut 11. In other words, the flat plate portion 71 is provided in a shape that is symmetrical with respect to the strut 11.

[0076] In the flat plate section 71 of the bow-side lower structure 70 according to this modified example, similar to the mountain-shaped plate section 21 of the bow-side lower structure 10, cover sections 23 are provided on the left and right edges to reinforce the outer edge of the flat plate section 71. The distance W4 (see Figure 19) between the two ends of the flat plate section 71 to which the cover sections 23 are attached is approximately 300 mm to 400 mm for a vessel of the 30 m class in terms of hull length.

[0077] A rectifier plate 74 is provided on the flat plate section 71. The rectifier plate 74 is provided on the flat plate section 71, extending in the front-to-back direction, approximately midway between the straight line L1 and the outer ends in the left-right direction. The rectifier plate 74 is composed of an upper protruding plate 74a and a lower protruding plate 74b, which are provided as a pair, protruding from the upper and lower surfaces of the flat plate section 71. The upper protruding plate 74a on the upper side of the flat plate section 71 and the lower protruding plate 74b on the lower side are provided so that their height direction is parallel to the vertical line L2 and their plate thickness direction is in the left-right direction (Y direction). The length of the upper protruding plate 74a and the lower protruding plate 74b protruding from the plate surface of the horizontal plate section 71 is approximately 30 mm to 50 mm.

[0078] In this modified example, the bow-side lower structure 70 is equipped with a flow straightening plate 74, but the flow straightening plate 74 may be omitted. Also, the strut 11 may be replaced with the strut 31 of the stern-side lower structure 30, which has different thickness and height in the lateral direction. Of course, if the thickness of the strut 11 in the lateral direction is changed, the connection between the lower end of the strut 11 and the flat plate portion 71, as well as the connection between the bottom of the hull 100 and the upper end of the strut 11, should be reinforced with the reinforcing member 25.

[0079] As seen in the first to third modifications of the first embodiment described above, the bow-side lower structures 50, 60, and 70, the cross-sectional shape of the vertical motion prevention body at the center in the longitudinal direction (X direction), the arrangement of the rectifier plate on the vertical motion prevention body, and the shape of the strut can be modified in various ways.

[0080] [Second Embodiment] [Arrangement of the lower structure of a ship's hull] A hull substructure according to the second embodiment will be described. The arrangement of the hull substructure according to the second embodiment in a ship will be described with reference to Figures 20 and 21. Figure 20 is a schematic plan view illustrating the arrangement of the hull substructure according to the second embodiment of the present invention in the hull 100, and Figure 21 is a schematic side view thereof. In Figure 20, the hull 100 and the outer shape of the ship are shown by dashed lines.

[0081] Figure 20 shows a catamaran identical to the vessel shown in Figure 1. Multiple (three) hull substructures according to the second embodiment are arranged on a single hull 100. One of the three hull substructures shown in Figure 20 is a bow substructure 210 located on the bow side of the hull 100. The other two hull substructures are a pair of stern substructures 230 located on the stern side. A propeller 102 of the propulsion system is arranged between the pair of stern substructures 30.

[0082] [Hull lower structure] Figures 22 to 27 show the configuration of the bow-side substructure 210. Figures 22 and 23 are perspective views illustrating the bow-side substructure 210 according to the second embodiment. Figure 24 is a side view illustrating the bow-side substructure 210, and Figure 25 is a plan view thereof. Figure 26 is a cross-sectional view along the KK line shown in Figure 25, and Figure 27 is a cross-sectional view along the JJ line shown in Figure 24.

[0083] The bow-side lower structure 210 comprises a strut 211 and a cylindrical structure 220 that acts as an anti-vertical movement body. The bow-side lower structure 210 is positioned relative to the hull 100 such that its longitudinal centerline coincides with the hull centerline CL (see Figure 20). The bow-side lower structure 210 is positioned relative to the hull 100 such that the opening of the cylindrical structure 220 faces the longitudinal direction of the hull 100.

[0084] The strut 211 has a roughly elongated ellipse shape in a plan view, tapering towards the rear more than towards the front, and a roughly rectangular shape in a side view, with the longer side running in the longitudinal direction. The upper end of the strut 211 is fixed to the center of the hull 100 in the width direction, such that the axis of the long axis of the elongated ellipse shape runs in the longitudinal direction (X direction).

[0085] Similar to the bow-side lower structure 10 of the first embodiment, the strut 211 has multiple (two) holes 212 formed in the front and rear directions, with the left-right direction being the penetrating direction. The holes 212 have an elliptical shape with the front-rear direction as the major axis in a side view. In addition, as shown by the dashed line in Figure 25, the holes 212 are provided with a mortar-shaped inclination that narrows inward from the elliptical openings on the left and right sides of the strut 211, so that the inner circumferential surface of the holes 212 forms a triangular convex shape inward. The ellipse traced by the tip of the triangular convex shape on the inner wall of the holes 212 is concentric with the ellipse traced by the opening ends on the left and right sides of the strut 211 in a side view. This shape of the inner circumferential surface of the holes 212 reduces water resistance during navigation. Since the water flow from waves coming from the left and right directions relative to the hull 100 passes through the holes 212 of the strut 211, it is possible to reduce the lateral rolling of the ship when it is anchored.

[0086] The lower end of the strut 211 is formed with an upward inclination at the front portion, corresponding to the shape of the cylindrical structure 220 described later in a side view. The cylindrical structure 220 is connected to the lower end of the strut 211. In addition, a projection 225 is formed at the lower end of the strut 211, penetrating the upper surface of the cylindrical structure 220 and projecting toward the inner wall. The projection 225 has a roughly inverted triangular shape in a cross-sectional view (JJ line cross-section) (see Figure 27). The projection 225 is provided on the inner wall side of the cylindrical structure 220 over its length in the front-rear direction.

[0087] As shown in Figure 27, the cylindrical structure 220 has a cylindrical shape, with a roughly square shape in the JJ line cross-section of the side view shown in Figure 24. The cylindrical structure 220 is composed of an upper plate portion 222, a lower plate portion 223, and left and right side plate portions 224, all of which have the same length as the front-rear length of the lower end of the strut 211. In addition, multiple rectifier plates 226 are arranged on the inner wall surface of the cylindrical structure 220 as rectifier members.

[0088] The upper plate portion 222 of the cylindrical structure 220 is composed of a right upper plate 222a and a left upper plate 222b, which are formed symmetrically. The cylindrical structure 220 is attached to the lower end of the strut 211 by welding or other means to the right upper plate 222a and the left upper plate 222b. In other words, the cylindrical structure 220 is provided in a symmetrical shape with respect to the strut 211 (see Figures 25 and 27). The lower end of the strut 211 is located between the right upper plate 222a and the left upper plate 222b, so as to penetrate the center of the upper plate portion 222 of the cylindrical structure 220 in the front-rear direction. As a result, the protruding portion 225 of the lower end of the strut 211 is provided on the inner wall side of the cylindrical structure 220. The protruding portion 225 functions as a flow straightening member by protruding on the inner wall side of the cylindrical structure 220.

[0089] The front portions of the upper plate portion 222 and the lower plate portion 223 are inclined upward at a predetermined angle θ6, as shown in Figure 26. The predetermined angle θ6 is between 5 and 40 degrees. This forward-upward inclination is formed from the front end of the upper plate portion 222 and the lower plate portion 223 to a point approximately 1 / 4 to 1 / 3 of the length in the front-to-back direction.

[0090] The surface of the upper plate portion 222 is horizontal from the rear end to approximately 2 / 3 to 3 / 4 of the way from the rear end in the front-to-back direction. The front portion of the surface of the upper plate portion 222 is inclined upward at the tip such that, in a side view, the lower surface of the upper plate portion 222 forms an angle θ6 with a straight line L7 parallel to the upper end of the strut 211.

[0091] Furthermore, the plate surface of the lower plate portion 223, from the front portion which is inclined at a predetermined angle θ6, downwards toward the rear end at a predetermined angle θ7. The angle θ7 is between 2 and 10 degrees. In other words, the plate surface of the lower plate portion 223 is gently inclined upwards at a predetermined angle θ7 with respect to a straight line L5 that extends horizontally from the rear end forward through the rear end of the cylindrical structure portion 220, up to position P1, which is approximately 2 / 3 to 3 / 4 of the length in the longitudinal direction from the rear end. Then, the plate surface of the lower plate portion 223, in the longitudinal direction, forward of position P1, is inclined upwards at an angle θ6 greater than the predetermined angle θ7 with respect to a straight line L6 that is parallel to the straight line L5 passing through position P1 and above the straight line L5. Therefore, the lower plate portion 223 of the cylindrical structure portion 220, as a whole, is inclined with respect to the baseline BL of the hull 100, with the front higher and the rear lower (see Figure 21). The inclined surface on the front of the lower plate section 223 rides the waves coming from the front, reducing the wave resistance of the cylindrical structure section 220 and also reducing the vertical movement of the hull 100. The length of the lower plate section 223 in the longitudinal direction is formed so that its front end is shorter by a length d1 than that of the upper plate section 222 (see Figure 26).

[0092] The upper and lower ends of the left and right side plate sections 224 are shaped to match the side profile of the front portion of the upper plate section 222 and the lower plate section 223. In other words, the lower ends of the left and right side plate sections 224 are positioned so that the front end is higher than the rear end by a length of H7 + H8, and the upper ends of the left and right side plate sections 224 are positioned so that the front end is higher than the rear end by a length of H8. Therefore, the cylindrical structure section 220 has its front opening slightly higher than the rear opening. This shape of the cylindrical structure section 220 prevents the bow from being suddenly lifted when the ship is hogging due to waves, and reduces the effects of waves on the hull, such as metal fatigue. Furthermore, when the ship is sailing forward, the lower plate section 223 of the bow-side lower structure 210, which acts as an anti-vertical movement body, rides the waves, and the water flow from the front flows through the inside of the cylindrical bow-side lower structure 210 towards the rear. Therefore, the vertical movement of the hull can be further suppressed, and the effects of waves on the hull 100, such as metal fatigue, can be further reduced.

[0093] The rectifier plate 226 is a long plate of a predetermined width and is provided in the center of the lower plate portion 223 in the left-right direction and in the center of the left and right side plate portions 224 in the up-down direction, extending in the front-rear direction. The rectifier plate 226 of the lower plate portion 223 is provided on the upper surface of the lower plate portion 223 such that the plate thickness direction is in the left-right direction (Y direction) (see Figures 24 and 27). The front portion of the rectifier plate 226 of the lower plate portion 223 is angled upwards at the tip, following the slope of the plate surface of the lower plate portion 223. The rectifier plate 226 of the side plate portion 224 is provided such that the plate thickness direction is in the up-down direction. In a side view, the rectifier plate 226 of the side plate portion 224 has approximately the same shape as the upper plate portion 222 in a cross-sectional view (KK line cross-section), as shown in Figure 26. The rectifier plate 226 rectifies the flow of water within the cylindrical structure portion 220 and suppresses the generation of vortices.

[0094] The lower bow structure 210 is capable of reducing the vertical motion of the ship through the action of the protruding portion 225 and the rectifying plate 226, which act as flow straightening members.

[0095] Next, the stern lower structure 230 will be described with reference to Figures 28 to 31. Figure 28 is a perspective view illustrating the stern lower structure 230 according to this embodiment, and Figure 29 is a side view thereof. Figure 30 is a plan view illustrating the stern lower structure 230. Figure 31 is a cross-sectional view taken along the MM line shown in Figure 30.

[0096] The stern lower structure 230 consists of a strut 231 that is vertically mounted downward from the bottom of the hull 100, and a cylindrical structure 240 that serves as an anti-vertical movement body, provided at the lower end of the strut 231. Similar to the stern lower structure 30 according to the first embodiment, it is provided in pairs on the left and right sides of the rear of the hull 100 (see Figure 20). That is, the stern lower structure 230 is positioned on either side of the propeller 102 of the propulsion system, with the openings of the cylindrical structure 240 facing in the front-rear direction. Furthermore, the stern lower structure 230 is positioned on the bottom of the hull 100 such that the baseline of the cylindrical structure 240 is substantially parallel to the baseline BL of the hull 100 (see Figure 21).

[0097] The stern substructure 230 has a rectangular shape with the longer side running in the longitudinal direction when viewed from above. The longitudinal length of the stern substructure 230 is approximately two-thirds the longitudinal length of the bow substructure 210.

[0098] Strut 231, like strut 211, has a roughly elongated elliptical shape in plan view, tapering towards the rear more than the front, and a roughly rectangular shape in side view, with the longer side running in the front-rear direction. In side view, a hole 232 is formed in the center of strut 231, with the left-right direction running through it. The hole 232 has the same shape as the hole 212 of strut 211 of the bow-side lower structure 210. The height of strut 231 is the same as that of strut 211 of the bow-side lower structure 210.

[0099] A cylindrical structure 240 is fixed to the lower end of the strut 231 in the longitudinal direction. A projection 245 is also formed at the lower end of the strut 231, penetrating the upper surface of the cylindrical structure 240 and projecting toward the inner wall. The projection 245 is configured similarly to the projection 225 of the strut 211 of the bow-side lower structure 210, and has a roughly triangular shape in cross-section. The projection 245 is provided on the lower side of the upper plate portion 242 of the cylindrical structure 240, which will be described later, and extends over the longitudinal length.

[0100] As shown in Figure 30, the cylindrical structure 240 has a rectangular shape, which is approximately rectangular in plan view. The cylindrical structure 240 is composed of an upper plate portion 242, a lower plate portion 243, and left and right side plate portions 244, all of which have the same length as the strut 231 in the longitudinal direction. Furthermore, the width (left-right direction) and vertical length of the cylindrical structure 240 are shorter than the cylindrical structure 220 of the bow-side lower structure 210.

[0101] The upper plate portion 242 of the cylindrical structure 240 is composed of a right upper plate 242a and a left upper plate 242b, which are formed symmetrically. The cylindrical structure 220 is attached to the lower end of the strut 231 by welding or other means to the right upper plate 242a and the left upper plate 242b. The lower end of the strut 231 is located between the right upper plate 242a and the left upper plate 242b, so as to pass through the center of the upper plate portion 242 of the cylindrical structure 240. Therefore, the cylindrical structure 240 is provided in a symmetrical shape with respect to the strut 231. The protruding portion 245 that protrudes inward from the cylindrical structure 240 so as to pass through the center of the upper plate portion 242 functions as a flow straightening member.

[0102] The lower plate portion 243 and the left and right side plate portions 244 of the cylindrical structure portion 240 each have the same rectangular shape. A flow straightening plate 246 is provided on the upper surface of the lower plate portion 243, which forms the inner wall surface of the cylindrical structure portion 240, as a flow straightening member. The flow straightening plate 246 is made of the same material as the flow straightening plate 226 provided on the cylindrical structure portion 220 of the bow-side lower structure 210. The flow straightening plate 226 is provided in the center of the lower plate portion 243 of the cylindrical structure portion 240 in the left-right direction, extending in the front-rear direction with the plate thickness direction in the left-right direction (Y direction).

[0103] In the cylindrical structure 240, the protruding portion 245 and the rectifying plate 246, which act as flow straightening members, straighten the water flow within the cylindrical structure 240 and suppress the generation of vortices. Therefore, the vertical motion of the ship can be reduced.

[0104] [Modified version of the second embodiment] Next, a first modified example of the hull substructure according to the second embodiment will be described with reference to Figures 32 to 38. Figure 32 is a perspective view illustrating the bow substructure 250 according to this modified example. Figure 33 is a side view of the bow substructure 250. Figure 34 is a plan view of the bow substructure 250. Figure 35 is a front view of the bow substructure 250. Figure 36 is a cross-sectional view taken along the line NN in Figure 34. Figure 37 is a perspective view illustrating the stern substructure 280 according to this modified example, and Figure 38 is a side view thereof. Note that components similar to those described earlier with reference to Figures 22 to 27 for the bow substructure 210 and Figures 28 to 31 for the stern substructure 230 are denoted by the same reference numerals, and detailed explanations are omitted.

[0105] The bow-side lower structure 250 is similar to the bow-side lower structure 210 described above in that it is provided with a cylindrical structure 220 having a roughly square cross-sectional shape as an anti-vertical movement body. On the other hand, the bow-side lower structure 250 is equipped with a strut 251 in which a hole 252 has a different shape from the hole 212 of the strut 211 of the bow-side lower structure 210 described above.

[0106] The position and number of holes 252 in the strut 251 of this modified example are the same as the holes 212 formed in the strut 211 of the bow-side lower structure 210 described above. In addition, the holes 252 have an elliptical shape with the longitudinal direction as the major axis when viewed from the side. On the other hand, the shape of the holes 252 of the strut 251 differs from the holes 212 formed in the strut 211 of the bow-side lower structure 210 described above in that the reduced ellipse drawn by the triangular cross-sectional convexity on the inside of the holes 252 is not a concentric ellipse in the direction of the major axis of the ellipse, but an ellipse shifted forward. Furthermore, the tip of the triangular-shaped protrusion on the inner wall of the hole 252 has a rounded shape.

[0107] The stern lower structure 260 is similar to the aforementioned stern lower structure 230 in that it is provided with a cylindrical structure 240 with a roughly square cross-sectional shape as an anti-vertical movement body. On the other hand, the stern lower structure 260 is equipped with a strut 261 in which a single hole 262 has the same shape as the hole 252 of the strut 251 of the bow lower structure 250 is formed.

[0108] In a vessel equipped with a bow-side substructure 250 and a stern-side substructure 260, holes 252 that penetrate in the lateral direction are formed in the struts 251 of the bow-side substructure 250, and holes 262 that penetrate in the lateral direction are also formed in the struts 261 of the stern-side substructure 260, thereby reducing water resistance to the hull substructure and reducing lateral rolling.

[0109] Next, a second modified example of the hull substructure according to the second embodiment will be described with reference to Figures 39 to 44. Figure 39 is a perspective view illustrating the bow-side substructure 270 according to this modified example. Figure 40 is a side view of the bow-side substructure 270. Figure 41 is a front view of the bow-side substructure 270. Figure 42 is a cross-sectional view taken along the QQ line in Figure 40. Figure 43 is a perspective view of the stern-side substructure 280 according to this modified example. Figure 44 is a front view of the stern-side substructure 280. Note that components similar to those described earlier with reference to Figures 32 to 36 for the bow-side substructure 250 and Figures 37 and 38 for the stern-side substructure 260 are denoted by the same reference numerals, and detailed explanations are omitted.

[0110] The bow-side lower structure 270 is similar to the bow-side lower structure 250 described earlier in that it has a strut 251 with a hole 252 formed in it. On the other hand, the bow-side lower structure 270 differs from the bow-side lower structure 250 described above in that a cylindrical structure 271, which has a different shape from the cylindrical structure 220, is provided at the lower end of the strut 251 as an anti-vertical movement body.

[0111] The cylindrical structure 271 is formed by an upper plate portion 272, a lower plate portion 273, and left and right side plate portions 274, all having the same length as the strut 251 in the front-rear direction. The cylindrical structure 271 is provided in a symmetrical shape with respect to the strut 251, with the opening of the cylinder in the front-rear direction (see Figure 41). In addition, multiple rectifier plates 276 are arranged on the inner wall surface of the cylindrical structure 271 as rectifier members.

[0112] The cylindrical structure 271, like the bow-side lower structure 250 described earlier, has a roughly rectangular shape in plan view, and as shown in Figure 42, the cylindrical cross-sectional shape is roughly square. However, since the upper plate portion 272 and the lower plate portion 273 are slightly inclined with respect to the horizontal line L8, it can also be said that the cylindrical cross-section is configured in a roughly arrowhead shape.

[0113] The upper plate portion 272 of the cylindrical structure portion 271 is composed of a right upper plate 272a and a left upper plate 272b, which are formed symmetrically. The cylindrical structure portion 271 is attached to the lower end of the strut 251 by welding or other means to the right upper plate 272a and the left upper plate 272b. At this time, the right upper plate 272a is inclined at an angle θ10 with respect to the horizontal line L8 in the left-right direction such that the side connected to the right side plate portion 274 is higher than the side connected to the strut 251, and the left upper plate 272b is inclined at an angle θ10 with respect to the horizontal line L8 in the left-right direction such that the side connected to the left side plate portion 274 is higher than the side connected to the strut 251. Therefore, the upper plate portion 272 forms an obtuse V-shape as shown in Figures 41 and 42. The angle θ10 can be, for example, approximately 3 to 20 degrees.

[0114] The lower plate portion 273 of the cylindrical structure 271 has a shape that is bent in a roughly V-shape from front to back in the center in the left-right direction, so as to form an inclination similar to that of the upper plate portion 272 and the upper right plate 272a and upper left plate 272b. Therefore, the cross-section shown in Figure 42 has a roughly V-shape with an obtuse angle.

[0115] The lower end of the strut 261 is positioned between the upper right plate 272a and the upper left plate 272b, so as to penetrate the center of the upper plate portion 272 of the cylindrical structure portion 271 in the front-to-back direction. As a result, the protruding portion 275 at the lower end of the strut 261 is provided on the inner wall side of the cylindrical structure portion 271. The protruding portion 275 functions as a flow straightening member by protruding on the inner wall side of the cylindrical structure portion 271.

[0116] The front portions of the upper plate portion 272 and the lower plate portion 273 are inclined upward, as shown in Figure 40, similar to the cylindrical structure portion 220 of the bow-side lower structure 210, which was described earlier with reference to Figures 24 and 26.

[0117] The upper and lower ends of the left and right side plate sections 274 are shaped to match the side shapes of the front portions of the upper plate section 272 and lower plate section 273. Therefore, the cylindrical structure section 271 has its front opening slightly higher than its rear opening. This shape of the cylindrical structure section 271 prevents the bow from being suddenly lifted when hogging due to waves, and reduces the effects of waves on the hull, such as metal fatigue. Furthermore, when the hull is sailing forward, the lower plate section 273 of the bow-side lower structure 270, which acts as an anti-vertical movement body, rides the waves, and the water flow from the front flows through the inside of the cylindrical bow-side lower structure 270 towards the rear. This further suppresses the vertical movement of the hull and reduces the effects of waves on the hull 100, such as metal fatigue.

[0118] The rectifier plate 276 is a long plate of a predetermined width and is provided in the center of the lower plate portion 273 in the left-right direction and in the center of the left and right side plate portions 274 in the up-down direction, extending in the front-rear direction. The rectifier plate 276 of the lower plate portion 273 is provided on the upper surface of the lower plate portion 273 such that the plate thickness direction is in the left-right direction (Y direction) (see Figures 24 and 27). The front portion of the rectifier plate 276 of the lower plate portion 273 is angled upward along the slope of the plate surface of the lower plate portion 273. The rectifier plate 276 of the side plate portions 224 is provided such that the plate thickness direction is in the up-down direction. The rectifier plate 276 rectifies the flow of water within the cylindrical structure portion 271 and suppresses the generation of vortices.

[0119] The stern lower structure 280 is similar to the stern lower structure 260 described earlier in that it has a strut 261 with a hole 262 formed in it. On the other hand, the stern lower structure 280 differs from the aforementioned stern lower structure 260 in that a cylindrical structure 281, which has a different shape from the cylindrical structure 240, is provided at the lower end of the strut 261 as an anti-vertical movement body.

[0120] The cylindrical structure 281 is composed of an upper plate portion 282, a lower plate portion 283, and left and right side plate portions 284, all having the same length as the strut 261 in the front-rear direction. The cylindrical structure 281 is provided in a symmetrical shape with respect to the strut 261, with the opening of the cylindrical body in the front-rear direction (see Figure 44). In addition, a rectifier plate 286 is provided on the inner wall surface of the cylindrical structure 281 as a flow rectifier.

[0121] The cylindrical structure 281 has a rectangular shape in plan view, with the longer side being in the front-to-back direction, similar to the stern-side lower structure 260 described earlier. Furthermore, in the front view shown in Figure 44, the cylindrical structure 281 has a roughly square-like arrow-shaped cross-section, similar to the cylindrical structure 271 of the bow-side lower structure 270 described earlier. In other words, the cylindrical structure 281 has an upper plate portion 282 and a lower plate portion 283 that form an obtuse V-shape in front view, and the upper ends of the left and right side plate portions 284 are connected to the upper plate portion 282, and the lower ends to the lower plate portion 283, thereby forming a cylindrical body with an arrow-shaped cross-section.

[0122] The lower end of the strut 261 is positioned between the upper right plate 282a and the upper left plate 282b, so as to penetrate the center of the upper plate portion 282 of the cylindrical structure portion 281 in the front-to-back direction. As a result, the protruding portion 285 at the lower end of the strut 261 is provided on the inner wall side of the cylindrical structure portion 281. The protruding portion 285 functions as a flow straightening member by protruding on the inner wall side of the cylindrical structure portion 281.

[0123] A rectifier plate 286 is provided in the center of the lower plate portion 283 of the cylindrical structure portion 281 in the left-right direction, extending in the front-rear direction so as to face the protruding portion 285.

[0124] In the stern-side lower structure 280, the water flow is straightened by the protrusions 285 and the flow straightening plates 286, thereby reducing the generation of vortices.

[0125] As described above, in the hull substructure according to the second embodiment, the shape and number of holes formed in the strut with the penetration direction being the left-right direction, and the cylindrical cross-sectional shape of the cylindrical structure connected to the lower end of the strut can be modified in various ways.

[0126] The hull substructures (bow substructures 10, 50, 60, 70, 210, 250, 270, stern substructures 30, 230, 260, 280) according to the first embodiment and its modified form, and the second embodiment and its modified form, having the above configuration, can be said to have the following configuration. In other words, the hull substructure, which is disposed at the bottom of the hull 100, comprises struts (11, 31, 211, 231, 251, 261) that are suspended vertically downward from the bottom of the hull (100), and vertical movement prevention bodies (mountain-shaped plate portion 21, horizontal plate portion 41, lower plate portion 51, flat plate portion 71, cylindrical structural portion 220, 240, 271, 281) that are connected to the lower ends of the struts (11, 31, 211, 231, 251, 261) and provided in a left-right symmetrical shape with respect to the struts (11, 31, 211, 231, 251, 261), and the struts (11, 31, 211, 231, 251, 261) have holes (12, 32, 212, 232, 252, 262) that penetrate in the left-right direction.

[0127] Furthermore, the lower structure (bow-side lower structure 10, 50, 60, 70, 210, 250, 270, stern-side lower structure 30, 230, 260, 280) is provided with flow straightening members (flow straightening plates 24, 54, 64, 74, 226, 246, 256, 266, 276, 286, protrusions 225, 245, 275, 285, cover portion 23) that are arranged along the longitudinal direction of the hull 100.

[0128] Furthermore, in the hull substructure (bow substructure 10, 50, 60, 70, 210), the vertical movement prevention body includes a plate shape in which the front portion is angled upward by a predetermined angle (mountain-shaped plate portion 21, lower plate portion 51, upper plate portion 222 and lower plate portion 223 of the cylindrical structure portion 220, upper plate portion 272 and lower plate portion 273 of the cylindrical structure portion 271).

[0129] Furthermore, in the hull substructure (bow substructures 10, 50, 60, 70, stern substructure 30), the vertical movement prevention body includes a plate body (mountain-shaped plate portion 21, lower plate portion 51) with multiple holes (22, 42) formed therein.

[0130] Furthermore, in the hull substructure (bow substructure 10, 50, 60, 70, stern substructure 30), the flow straightening members are a pair of left and right flow straightening plates (24, 54, 64, 74) that are provided between the struts (11, 31) and the left and right end edges of the plate body (mountain-shaped plate section 21, lower plate section 51) and / or left and right cover members (cover section 23) attached to the left and right end edges of the plate body (mountain-shaped plate section 21, lower plate section 51).

[0131] Furthermore, in the hull substructure (bow substructure 10, 50, 60, 70, stern substructure 30), the connection between the struts (11, 31) and the vertical movement prevention plate is reinforced by reinforcing members (25, 35).

[0132] Furthermore, in the lower hull structure (bow-side lower structure 10, 50, 60, 70), cover portions (cover portion 23, flow straightening plate 64) are provided at the left and right edges of the plate portions (mountain-shaped plate portion 21, lower plate portion 51) of the vertical movement prevention body.

[0133] Furthermore, in the hull substructure (bow substructure 210, 250, 270, stern substructure 230, 260, 280), the vertical movement prevention body is composed of a cylindrical body (cylindrical structure 220, 240, 271, 281) with openings at the front and rear.

[0134] Furthermore, in the hull substructure, the flow straightening members are flow straightening plates (226, 246, 276, 286) provided on the inner wall surface of a cylindrical body with a rectangular cross-section, extending in the longitudinal direction of the cylindrical body (bow substructure 210, 250, 270, stern substructure 230, 280).

[0135] Furthermore, a vessel equipped with the hull substructure according to the first and second embodiments having the above configuration can be said to have the following configuration: The vessel has struts (11, 31, 211, 231, 251, 261) that are vertically suspended downward from the bottom of the hull 100 and have holes formed therein that penetrate in the left-right direction, and vertical movement prevention bodies (mountain-shaped plate portion 21, horizontal plate portion 41, lower plate portion 51, flat plate portion 71, cylindrical structure portion 220, 240, 271, 281) that are connected to the lower ends of the struts (11, 31, 211, 231, 251, 261) and provided in a left-right symmetrical shape relative to the struts (11, 31, 211, 231, 251, 261). Multiple hull substructures are provided below the hull 100, and among the multiple hull substructures, the bow substructures (10, 50, 60, 70, 210, 250, 270) provided on the bow side have a shape in which the front part of the vertical movement prevention body faces upward by a predetermined angle, and the stern substructures (30, 230, 260, 280) provided on the stern side are arranged in pairs on the left and right sides of the propeller 102, which is provided in the left and right center of the stern side and generates thrust.

[0136] The above-described embodiments and modifications are examples of the present invention, and the present invention is not limited to the embodiments described above. Therefore, it goes without saying that various modifications are possible depending on the design, etc., even in embodiments other than those described above, as long as they do not depart from the technical spirit of the present invention. Furthermore, the configurations of the above-described embodiments and modifications can be combined as appropriate. [Explanation of Symbols]

[0137] 10. Bow-side lower structure (hull lower structure) 11 strut 12 Hole 21 Chevron-shaped plate part (vertical movement prevention body) 21a Inclined plate 21b Inclined plate 22 Hole 23 Cover section 24 Rectifier plate 24a Upper protruding plate 24b Lower protruding plate 30. Stern lower structure (hull lower structure) 31 Strut 32 Hole 41 Flat plate part (vertical movement prevention body) 42 Hole 43 Cover section 50. Bow-side lower structure (hull lower structure) 51 Lower plate part (vertical movement prevention body) 52 Hole 54 Rectifier plate 54b Lower protruding plate 60. Bow-side lower structure (hull lower structure) 64 Rectifier plate 70. Bow-side lower structure (hull lower structure) 71 Horizontal plate part (vertical movement prevention body) 74 Rectifier plate 74a Upper protruding plate 74b Lower protruding plate 100 hulls 210 Bow-side lower structure (hull lower structure) 211 Strut 212 Hole 220 Cylindrical structure (up / down movement prevention body) 222 Upper plate section 223 Lower plate part 224 Side plate part 225 Protrusion 226 Rectifier plate 230 Stern lower structure (hull lower structure) 231 Strut 232 Hole 240 Cylindrical structure (up / down movement prevention body) 245 Protrusion 246 Rectifier plate 250 Bow-side lower structure 251 Strut 252 Hole 260 Stern lower structure 261 Strut 262 Hole 270 Lower structure on the bow side 271 Cylindrical structure (up / down movement prevention body) 280 Stern lower structure 281 Cylindrical structure (up / down movement prevention body)

Claims

1. A hull substructure located at the bottom of the ship's hull, A strut is suspended vertically downward from the bottom of the hull, A vertical movement prevention body is connected to the lower end of the strut and is provided in a symmetrical shape with respect to the strut, Equipped with, The lower hull structure is characterized in that the strut has a hole formed therein that penetrates in the left-right direction.

2. The lower hull structure according to claim 1, characterized in that the vertical movement prevention body is provided with a flow straightening member so as to be aligned with the longitudinal direction of the hull.

3. The ship's lower structure according to claim 2, characterized in that the vertical movement prevention body includes a plate-shaped body whose front portion is angled upward by a predetermined angle.

4. The ship's lower structure according to claim 2, characterized in that the vertical movement prevention body includes a plate body in which a plurality of holes are formed.

5. The rectifying member is a pair of left and right rectifying plates and / or left and right cover members attached to the left and right edges of the plate, which are provided between the strut and the left and right edges of the plate, extending in the front-rear direction of the plate, and / or the left and right edges of the plate, as described in claim 3 or 4.

6. The ship's lower structure according to claim 1, characterized in that the connection portion between the strut and the vertical movement prevention body is reinforced by a reinforcing member.

7. The hull lower structure according to any one of claims 1 to 3, characterized in that the vertical movement prevention body is composed of a cylindrical body with openings at the front and rear.

8. The hull substructure according to claim 7, characterized in that the flow straightening member is a flow straightening plate provided on the inner wall surface of the cylindrical body having a rectangular cross-section, extending in the front-rear direction of the cylindrical body.

9. Multiple hull substructures are arranged in the lower part of the hull, each comprising a strut that is vertically suspended downward from the bottom of the hull and has a hole formed therein that penetrates in the left-right direction, and a vertical movement prevention body connected to the lower end of the strut and provided in a left-right symmetrical shape with respect to the strut. Of the aforementioned plurality of hull substructures, the bow-side substructure provided on the bow side has a shape such that the front portion of the vertical movement prevention body faces upward by a predetermined angle. The aft-side substructure of the aforementioned hull substructure is located at the stern, and is arranged in pairs on either side of a propeller that generates thrust, which is located in the center of the stern. A vessel characterized by the following features.

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