Tank supporting structure for hull and liquefied gas carrier

Abstract

The present invention provides a tank supporting structure for a hull which allows a hull having a hull outer plate and a hull inner plate disposed above the hull outer plate to support a liquefied gas tank disposed in a hold surrounded by the hull inner plate, said tank supporting structure comprising: at least one protruding deck which extends substantially horizontally from the hull inner plate toward the inside of the hold; a plurality of tank skirts which support the liquefied gas tank by being joined to the protruding deck or the hull inner plate and which include a first skirt joined to an upper surface of the protruding deck; and a plurality of skirt back reinforcing materials which reinforce joined parts of the plurality of tank skirts by being joined to the protruding deck or the hull inner plate and which include a first skirt back reinforcing material joined to a lower surface of the protruding deck.

Description

Tank support structure of ship hull and liquefied gas carrier

[0001] The present disclosure relates to a liquefied gas carrier that transports liquefied gas and a tank support structure of the hull of the carrier.

[0002] BACKGROUND ART Liquefied gas carriers equipped with liquefied gas tanks for storing liquefied gas in their hulls have been known. Patent Document 1 discloses such a liquefied gas carrier.

[0003] The conventional liquefied gas carrier disclosed in Patent Document 1 comprises a hull, spherical cargo tanks, and tank skirts that support the cargo tanks on the hull. The hull has a double bottom composed of a bottom outer plate and a bottom inner plate. Bilge hoppers extending in the ship's longitudinal direction are arranged on both the left and right sides of the double bottom. The top of the bilge hopper is covered by a bilge hopper upper plate, and the sides of the bilge hopper are covered by a bilge hopper sloping plate. The bilge hopper sloping plate connects the bilge hopper upper plate to the bottom inner plate. A recess that receives the lower part of the cargo tank is formed between the port-side bilge hopper upper plate and the starboard-side bilge hopper upper plate in the ship's width direction, and the tank skirts are erected on the bilge hopper upper plate.

[0004] International Publication No. WO 2005 / 073069 (see Figures 3 and 4)

[0005] The tank skirt is generally cylindrical and extends in the vertical direction, and the skirt-back reinforcement is a ring-shaped member with the same diameter as the tank skirt. The tank skirt and the skirt-back reinforcement are arranged so that they overlap in the vertical direction in a plan view.

[0006] Double-hull tanks, which include an inner hull that contains liquefied gas and an outer hull that surrounds the inner hull, are known as liquefied gas tanks. Ships equipped with double-hull tanks are provided with two tank skirts: an inner skirt that supports the inner hull on the hull, and an outer skirt that supports the outer hull on the hull. A bilge hopper sloping plate extending in the longitudinal direction of the ship intersects with the two skirt-back reinforcement strips at four or more locations. The working space for joining the skirt-back reinforcement strips to the bilge hopper sloping plate at the intersections between the bilge hopper sloping plate and the skirt-back reinforcement strips is surrounded by the bilge hopper upper plate and sloping plate, and the longitudinal beams that reinforce the bilge hopper upper plate and sloping plate and the two skirt-back reinforcement strips are concentrated in a narrow space, making it difficult for workers to access.

[0007] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide a tank support structure for supporting a liquefied gas tank on a ship hull, which is equipped with two or more tank skirts that support the liquefied gas tank and a skirt back reinforcement material that reinforces the joined portion of the tank skirt, and which can improve the workability of joining the skirt back reinforcement material.

[0008] In order to solve the above problems, a tank support structure for a hull according to one embodiment of the present disclosure is a tank support structure for a hull that supports a liquefied gas tank arranged in a hold surrounded by the inner hull plate on a hull having a hull outer plate and an inner hull plate arranged above the hull outer plate, and comprises: one or more overhanging decks extending approximately horizontally from the inner hull plate toward the inside of the hold; a plurality of tank skirts, including a first skirt joined to the upper surface of the overhanging deck, that are joined to the overhanging deck or the inner hull plate and support the liquefied gas tank; and a plurality of skirt back reinforcements, including a first skirt back reinforcement joined to the underside of the overhanging deck, that are joined to the overhanging deck or the inner hull plate and reinforce the joined portions of the plurality of tank skirts.

[0009] A liquefied gas carrier according to one aspect of the present disclosure comprises a hull having a hull outer plating and an inner hull plating arranged above the hull outer plating, a liquefied gas tank arranged in a hold surrounded by the inner hull plating, and the tank support structure.

[0010] According to the present disclosure, in a tank support structure that supports a liquefied gas tank on a ship hull, which is equipped with two or more tank skirts that support the liquefied gas tank and a skirt back reinforcement material that reinforces the joined portion of the tank skirt, the workability of joining the skirt back reinforcement material can be improved.

[0011] Fig. 1 is a side view showing a liquefied gas carrier equipped with a tank support structure according to an embodiment of the present disclosure. Fig. 2 is a cross-sectional view passing through the center of a liquefied gas tank of the liquefied gas carrier in the longitudinal direction of the ship. Fig. 3 is an enlarged cross-sectional view of the tank support structure shown in Fig. 2. Fig. 4 is a partial perspective view of a hull including an overhanging deck. Fig. 5 is a partial cross-sectional view of a tank support structure according to a first modified embodiment. Fig. 6 is a partial cross-sectional view of a tank support structure according to a second modified embodiment. Fig. 7 is a partial cross-sectional view of a tank support structure according to a third modified embodiment.

[0012] Next, an embodiment of the present disclosure will be described with reference to the drawings. A side view showing a liquefied gas carrier 1 equipped with a tank support structure 100 according to one aspect of the present disclosure. The liquefied gas carrier 1 shown in Fig. 1 includes a hull 10 and a plurality of liquefied gas tanks 30 mounted on the hull 10 and aligned in the longitudinal direction of the hull 10. The hull 10 has a plurality of holds 41 separated by bulkheads 42. Each hold 41 is provided with a tank support structure 100 that supports a liquefied gas tank 30.

[0013] FIG. 2 is a cross-sectional view of a liquefied gas tank 30 of a liquefied gas carrier 1, taken along the longitudinal centerline of the ship. As shown in FIG. 2, the liquefied gas tank 30 is a spherical tank independent of the hull 10. However, the shape of the liquefied gas tank 30 is not limited to a spherical shape. The liquefied gas tank 30 is a double-shell tank having a first shell 31 and a second shell 32 surrounding the first shell 31. However, the liquefied gas tank 30 may be a multi-shell tank having three or more shells with one or more intermediate shells between the first shell 31 and the second shell 32. The liquefied gas cargo is stored in the first shell 31. The liquefied gas is, for example, a low-temperature liquid such as LNG or liquefied hydrogen. The first shell 31 and the second shell 32 are radially separated, and a thermal insulating layer is formed between the first shell 31 and the second shell 32. A heat insulating material may be filled between the first shell 31 and the second shell 32, or a vacuum heat insulating layer may be formed between the first shell 31 and the second shell 32.

[0014] The hull shell plating 24 that forms the outer shape of the hull 10 includes a pair of side shell platings 12 spaced apart in the ship's width direction, and a bottom shell plating 14 that is disposed between the pair of side shell platings 12 in the ship's width direction. The hull 10 has a double bottom composed of the bottom shell plating 14 and a bottom inner plate 15 that is disposed above the bottom shell plating 14.

[0015] Bilge hoppers 16 extending in the longitudinal direction of the ship are provided at the lower port and starboard sides of the hull 10. The bilge hoppers 16 are used as ballast tanks for storing ballast water, but may also be used for purposes other than storing ballast water. The bilge hoppers 16 are surrounded by a bilge hopper upper plate 11, side outer plates 12, a bilge hopper sloping plate 17, and a longitudinal bulkhead 18. A bottom inner plate 15 is disposed between the left and right bilge hopper sloping plates 17 in the ship's width direction. The left and right bilge hopper upper plates 11, the left and right bilge hopper sloping plates 17, the bottom inner plate 15, and the bulkheads 42 constitute an inner ship plate 25 that forms a hold 41.

[0016] The lower part of the liquefied gas tank 30 is housed in the hold 41 , and the part of the liquefied gas tank 30 that protrudes upward from the hold 41 is covered with a tank cover 43 .

[0017] Figure 3 is an enlarged cross-sectional view of the tank support structure 100 shown in Figure 2. As shown in Figures 2 and 3, the tank support structure 100 provided in the hold 41 is composed of at least one projecting deck 5, a plurality of tank skirts 2 including a tank skirt 2 supported by the projecting deck 5, and a plurality of skirt back reinforcements 6 including a skirt back reinforcement 6 that reinforces the jointed portion of the tank skirt 2 on the projecting deck 5.

[0018] The tank skirt 2 supports the liquefied gas tank 30 on the hull 10. The multiple tank skirts 2 include two tank skirts 2, an inner skirt 21 that supports the first shell 31 and an outer skirt 22 that supports the second shell 32. The multiple tank skirts 2 have different diameters and are arranged concentrically. The first skirt 21 and the second skirt 22 are both tubular and extend in the vertical direction. The diameter of the first skirt 21 is smaller than the diameter of the second skirt 22. The first skirt 21 and the second skirt 22 are arranged concentrically, and the second skirt 22 surrounds the outer periphery of the first skirt 21. The tank skirt 2 according to this embodiment has a wall that is continuous in the circumferential direction, but the wall of the tank skirt 2 may be composed of multiple walls arranged in the circumferential direction.

[0019] At least one projecting deck 5 is provided in the hold 41. FIG. 4 is a partial perspective view of the hull 10 including the projecting deck 5, showing one projecting deck 5 (a second deck 52 described later). As shown in FIGS. 3 and 4 , the projecting deck 5 is a deck that projects from the inner hull plating 25 toward the inside of the hold 41. The base end of the projecting deck 5 is supported by the inner hull plating 25, and the tip of the projecting deck 5 is located near the outer wall of the liquefied gas tank 30. The projecting deck 5 is composed of multiple deck plates 55 with approximately horizontal surfaces. The projecting deck 5 is supported from below by multiple support plates 56. The support plates 56 in this embodiment are braced between the inner hull plating 25 and the deck plates 55 in the vertical direction.

[0020] The upper surface of the overhang deck 5 serves as a platform for supporting the tank skirt 2. The lower end of the tank skirt 2 is joined to the upper surface of the overhang deck 5. In this embodiment, the overhang deck 5 and the tank skirt 2 are joined by welding, but the method for joining the overhang deck 5 and the tank skirt 2 is not limited to welding. In addition, a skirt back reinforcement 6 is fixed to the underside of the overhang deck 5. In this embodiment, the overhang deck 5 and the skirt back reinforcement 6 are joined by welding, but the method for joining the overhang deck 5 and the skirt back reinforcement 6 is not limited to welding.

[0021] The skirt back reinforcement 6 is provided on the underside of the overhang deck 5 along the joint line between the tank skirt 2 and the overhang deck 5. As in this embodiment, the cylindrical tank skirt 2 is combined with a ring-shaped skirt back reinforcement 6 having substantially the same diameter as the tank skirt 2. The ring-shaped skirt back reinforcement 6 may be made up of a single continuous member, or may be made up of a plurality of members combined to form a ring shape.

[0022] The joining work between the overhanging deck 5 and the skirt underside reinforcement 6 is carried out in the space directly below the overhanging deck 5. The upper surface of the skirt underside reinforcement 6 is joined to the overhanging deck 5. The space directly below the overhanging deck 5 is open toward the inside of the hold 41. The overhanging deck 5 does not have side walls that would hinder the joining work of the skirt underside reinforcement 6. Therefore, there are no narrow areas in the work space for joining the overhanging deck 5 and the skirt underside reinforcement 6, improving access to the joint between the overhanging deck 5 and the skirt underside reinforcement 6 and the ease of joining. The improved accessibility and ease of joining work simplify the joining work, contributing to reduced construction costs and improved machining accuracy.

[0023] As shown in Figure 3, the liquefied gas carrier 1 has two tank skirts 2, a first skirt 21 and a second skirt 22, and therefore has two skirt back reinforcements 6, a first skirt back reinforcement 61 and a second skirt back reinforcement 62. The jointed portion of the first skirt 21 of the extending deck 5 is reinforced by the first skirt back reinforcement 61. The jointed portion of the second skirt 22 of the extending deck 5 is reinforced by the second skirt back reinforcement 62.

[0024] The liquefied gas carrier 1 shown in FIGS. 2 and 3 is provided with two upper and lower overhanging decks 5, a first deck 51 and a second deck 52, which are at different heights.

[0025] The first deck 51 is disposed below the bilge hopper upper plate 11. Both side portions of the first deck 51 in the ship's width direction overhang from the bilge hopper sloping plate 17 of the inner hull 25 toward the inside of the hold 41. The first deck 51 supports a first skirt 21 joined to the first shell 31. The first skirt 21 is joined to the upper surface of the first deck 51, and a first skirt back reinforcement 61 is joined to the lower surface of the first deck 51.

[0026] The second deck 52 is disposed at substantially the same height as the bilge hopper upper plate 11. Both side portions of the first deck 51 in the ship's width direction overhang from the bilge hopper upper plate 11 of the inner hull plating 25 toward the inside of the hold 41. The second deck 52 supports the second skirt 22 joined to the second hull 32. The second skirt 22 is joined to the upper surface of the second deck 52, and a second skirt back reinforcement 62 is joined to the lower surface of the second deck 52.

[0027] Because the first deck 51 is located lower than the second deck 52, the first skirt 21 supported on the first deck 51 has a larger vertical dimension than the second skirt 22 supported on the second deck 52. This larger vertical dimension of the first skirt 21 is preferable from the standpoint of reducing the impact of cold on the second shell 32 and the hull 10 when the temperature of the liquefied gas stored in the first shell 31 is low.

[0028] In the liquefied gas carrier 1 configured as described above, both of the two tank skirts 2 supporting the liquefied gas tanks 30 are supported by the overhanging deck 5, and there are no intersections between the inner hull plate 25 and the skirt lining reinforcement 6. This makes it possible to design the support structures for the inner hull plate 25 and the tank skirt 2 independently, increasing the degree of freedom in the design of both the inner hull plate 25 and the tank skirt 2. Furthermore, because there are no intersections between the inner hull plate 25 and the skirt lining reinforcement 6, the structure of the skirt lining reinforcement 6 can be simplified, and the number of components can be reduced. This simplification of the structure makes it possible to reduce the number of stress concentration points, which is expected to be effective in preventing problems such as cracking after the vessel is put into service.

[0029] [Modifications] In the tank support structure 100 for the liquefied gas carrier 1 according to the above embodiment, the first skirt 21 and the second skirt 22 are supported by the overhanging decks 5 at different heights. However, if at least one of the multiple tank skirts 2 including the first skirt 21 and the second skirt 22 is supported by the overhanging deck 5, it is expected that the workability of joining the skirt back reinforcement member 6 will be improved. Below, modifications of the tank support structure 100 for the hull 10 of the liquefied gas carrier 1 according to the above embodiment will be described.

[0030] 5 is a partial cross-sectional view of a tank support structure 100 according to Modification 1 of the embodiment. In the description of this modification, the same or similar members as those in the above-described embodiment are denoted by the same reference numerals in the drawings, and the description thereof will be omitted.

[0031] As shown in Fig. 5 , the tank support structure 100 according to the first modification has a single-stage extending deck 5. The height of the extending deck 5 is substantially the same as that of the bilge hopper upper plate 11. A first skirt 21 is supported on the extending deck 5, and a second skirt 22 is supported on the bilge hopper upper plate 11. A second skirt back reinforcement 62 that reinforces the joined portion of the second skirt 22 of the bilge hopper upper plate 11 intersects with the bilge hopper swash plate 17, which is a component of the inner hull plate 25. Although a narrow working space is required for joining the second skirt back reinforcement 62 at the point where the second skirt back reinforcement 62 intersects with the bilge hopper swash plate 17, this narrowness can be reduced compared to when both the first skirt back reinforcement 61 and the second skirt back reinforcement 62 are supported on the bilge hopper upper plate 11.

[0032] 6 is a partial cross-sectional view of a tank support structure 100 according to Modification 2 of the embodiment. In the description of this modification, the same or similar members as those in the above-described embodiment are denoted by the same reference numerals in the drawings, and the description thereof will be omitted.

[0033] As shown in Fig. 6 , the tank support structure 100 according to the first modification has a single-stage overhanging deck 5 located above the bilge hopper upper plate 11. A first skirt 21 is supported on the bilge hopper upper plate 11, and a second skirt 22 is supported on the overhanging deck 5. A first skirt back reinforcement 61 that reinforces the joined portion of the first skirt 21 of the bilge hopper upper plate 11 intersects with the bilge hopper swash plate 17 of the inner hull plate 25. Although a narrow working space is required for joining the first skirt back reinforcement 61 at the point where the first skirt back reinforcement 61 intersects with the bilge hopper swash plate 17, this narrowness can be reduced compared to when both the first skirt back reinforcement 61 and the second skirt back reinforcement 62 are supported on the bilge hopper upper plate 11.

[0034] 7 is a partial cross-sectional view of a tank support structure 100 according to Modification 3 of the embodiment. In the description of this modification, the same or similar members as those in the above-described embodiment are denoted by the same reference numerals in the drawings, and the description thereof will be omitted.

[0035] As shown in FIG. 7 , the tank support structure 100 according to Modification 3 has a single-stage projecting deck 5. The height of the projecting deck 5 is the same as that of the bilge hopper upper plate 11, but is preferably substantially the same height as the neutral axis of the hull 10. The first skirt 21 is supported by the projecting deck 5, and the second skirt 22 is also supported by the projecting deck 5. Because both the first and second skirt back reinforcements 61 and 62 are joined to the projecting deck 5, no intersections are formed between the first and second skirt back reinforcements 61 and 62 and the inner hull plate 25. This allows the support structure for the liquefied gas tank 30 and the inner hull plate 25 to be designed independently. Furthermore, no narrow areas are formed at the joints between the first and second skirt back reinforcements 61 and 62 and the projecting deck 5, improving the workability of joining the first and second skirt back reinforcements 61 and 62 to the projecting deck 5.

[0036] [Summary] The tank support structure 100 for a hull 10 according to the first item of the present disclosure is a tank support structure 100 for a hull 10 that causes a hull 10 having a hull outer plating 24 and an inner hull plating 25 arranged above the hull outer plating 24 to support a liquefied gas tank 30 arranged in a hold 41 surrounded by the inner hull plating 25, and is equipped with one or more overhanging decks 5 extending approximately horizontally from the inner hull plating 25 toward the inside of the hold 41, a plurality of tank skirts 2 that are joined to the overhanging deck 5 or the inner hull plating 25 and support the liquefied gas tanks 30, including a first skirt 21 joined to the upper surface of the overhanging deck 5, and a plurality of skirt back reinforcements 6 that are joined to the overhanging deck 5 or the inner hull plating 25 and reinforce the joined portions of the plurality of tank skirts 2, including a first skirt back reinforcement 61 joined to the underside of the overhanging deck 5.

[0037] In the tank support structure 100 for the hull 10 configured as described above, the first skirt back reinforcement 61 that reinforces the joint portion of the first skirt 21 of the extending deck 5 does not intersect with the inner hull plate 25. Therefore, no narrow areas are created in the working space for joining the first skirt back reinforcement 61 to the extending deck 5, ensuring access to the joint portion and ease of joining work. In addition, because the inner hull plate 25 and the first skirt back reinforcement 61 do not intersect, the structure of the first skirt back reinforcement 61 can be simplified.

[0038] The tank support structure 100 for a hull 10 relating to the second item of the present disclosure is the tank support structure 100 for a hull 10 relating to the first item, wherein the one or more stages of overhanging decks 5 include a first deck 51 and a second deck 52 of different heights, the plurality of tank skirts 2 include a first skirt 21 joined to the upper surface of the first deck 51 and a second skirt 22 joined to the upper surface of the second deck 52, and the plurality of skirt back reinforcements 6 include a first skirt back reinforcement 61 joined to the lower surface of the first deck 51 and a second skirt back reinforcement 62 joined to the lower surface of the second deck 52.

[0039] In the tank support structure 100 configured as described above, the first skirt 21 and the second skirt 22 are each supported by an independent overhang deck 5, making it easy to install the first skirt back reinforcement 61 and the second skirt back reinforcement 62.

[0040] The tank support structure 100 for the hull 10 relating to the third item of the present disclosure is the tank support structure 100 for the hull 10 relating to the second item, wherein the liquefied gas tank 30 has a first shell 31 that contains liquefied gas and a second shell 32 that surrounds the first shell 31, the first shell 31 is supported on the first deck 51 by a first skirt 21, and the second shell 32 is supported on the second deck 52 by a second skirt 22, and the height of the first deck 51 is lower than the height of the second deck 52.

[0041] According to the tank support structure 100 configured as described above, the vertical dimension of the first skirt 21 that supports the first shell 31 that contains low-temperature liquefied gas can be made larger than that of the second skirt 22. This reduces the impact of the cold heat of the liquefied gas contained in the first shell 31 on the second shell 32 and the hull 10.

[0042] The tank support structure 100 for the hull 10 relating to the fourth item of the present disclosure is the tank support structure 100 for the hull 10 relating to the first item, wherein the multiple tank skirts 2 include a first skirt 21 and a second skirt 22 joined to the upper surface of the overhang deck 5, and the multiple skirt back reinforcements 6 include a first skirt back reinforcement 61 and a second skirt back reinforcement 62 joined to the lower surface of the overhang deck 5.

[0043] In the tank support structure 100 configured as described above, the first skirt 21 and the second skirt 22 are supported by a single overhang deck 5, so the number of overhang decks 5 can be reduced.

[0044] The tank support structure 100 for the hull 10 according to the fifth item of the present disclosure is the tank support structure 100 for the hull 10 according to the first item, wherein the plurality of tank skirts 2 include a second skirt 22 joined to the inner hull plate 25, and the plurality of skirt lining reinforcements 6 include a second skirt lining reinforcement 62 joined to the inner hull plate 25.

[0045] In the tank support structure 100 configured as described above, the second skirt 22 is joined to the inner hull plate 25 , so that the installation locations of multiple tank skirts 2 can be distributed across the overhang deck 5 and the inner hull plate 25 .

[0046] The liquefied gas carrier 1 according to the sixth item of the present disclosure comprises a hull 10 having a hull outer plating 24 and an inner hull plating 25 arranged above the hull outer plating 24, a liquefied gas tank 30 arranged in a hold 41 surrounded by the inner hull plating 25, and a tank support structure 100 according to any one of claims 1 to 5.

[0047] In the liquefied gas carrier 1 configured as described above, one or more of the skirt back reinforcements 6 that reinforce the joints of the tank skirt 2 of the overhanging deck 5 do not intersect with the inner hull plate 25. This reduces the number of locations where the working space for joining the skirt back reinforcement 6 to the overhanging deck 5 becomes narrow, improving access to the joints and workability of the joining. Furthermore, because one or more of the skirt back reinforcements 6 do not intersect with the inner hull plate 25, the structure of the skirt back reinforcement 6 can be simplified.

[0048] The foregoing discussion of the present disclosure has been presented for purposes of illustration and description and is not intended to limit the present disclosure to the form disclosed herein. For example, in the foregoing detailed description, various features of the present disclosure are grouped together in a single embodiment for the purpose of streamlining the disclosure, but some of the features may also be combined. Furthermore, the features included in the present disclosure may be combined into alternative embodiments, configurations, or aspects other than those discussed above.

[0049] 1: Liquefied gas carrier 2: Tank skirt 21: First skirt 22: Second skirt 5: Overhanging deck 51: First deck 52: Second deck 6: Skirt lining reinforcement 61: First skirt lining reinforcement 62: Second skirt lining reinforcement 10: Hull 24: Hull outer plating 25: Inner plating 30: Liquefied gas tank 31: First hull 32: Second hull 41: Hold 100: Tank support structure

Claims

1. A tank support structure for a hull that supports a liquefied gas tank arranged in a hold surrounded by the inner hull plate on a hull having a hull outer plate and an inner hull plate arranged above the hull outer plate, the tank support structure comprising: one or more overhanging decks extending approximately horizontally from the inner hull plate toward the inside of the hold; a plurality of tank skirts, including a first skirt joined to the upper surface of the overhanging deck, that are joined to the overhanging deck or the inner hull plate and support the liquefied gas tank; and a plurality of skirt back reinforcements, including a first skirt back reinforcement joined to the underside of the overhanging deck, that are joined to the overhanging deck or the inner hull plate and reinforce the joined portions of the plurality of tank skirts.

2. A tank support structure for a hull as set forth in claim 1, wherein the one or more stages of the overhanging deck include a first deck and a second deck of different heights, the plurality of tank skirts include the first skirt joined to the upper surface of the first deck and a second skirt joined to the upper surface of the second deck, and the plurality of skirt back reinforcements include the first skirt back reinforcement joined to the lower surface of the first deck and a second skirt back reinforcement joined to the lower surface of the second deck.

3. A tank support structure for a ship hull as set forth in claim 2, wherein the liquefied gas tank has a first shell that stores liquefied gas and a second shell that surrounds the first shell, the first shell is supported on the first deck by the first skirt, and the second shell is supported on the second deck by the second skirt, and the height of the first deck is lower than the height of the second deck.

4. A tank support structure for a ship hull as described in claim 1, wherein the plurality of tank skirts include the first skirt and second skirt joined to the upper surface of the overhang deck, and the plurality of skirt back reinforcements include the first skirt back reinforcement and second skirt back reinforcement joined to the lower surface of the overhang deck.

5. A tank support structure for a hull as set forth in claim 1, wherein the plurality of tank skirts includes a second skirt joined to the inner hull plating, and the plurality of skirt back reinforcements includes a second skirt back reinforcement joined to the inner hull plating.

6. A liquefied gas carrier comprising: a hull having a hull shell plating and an inner hull plating arranged above the hull shell plating; a liquefied gas tank arranged in a hold surrounded by the inner hull plating; and a tank support structure according to any one of claims 1 to 5.

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