JP7807797B2 - Box-shaped floating structure - Google Patents

Description

The present invention relates to a non-self-propelled box-type floating body.

Non-self-propelled box-shaped floating bodies (barges) have traditionally been used as work vessels on water bodies such as oceans, lakes, and rivers. Various floating bodies equipped with motion reduction means to suppress the floating body's motion caused by waves have also been proposed (see, for example, Patent Document 1).

Conventional non-self-propelled box-type floaters have a working limit wave height of around 0.5 m, and most of them are used in port areas and coastal areas, but they have the problem of being difficult to use in the open ocean, where wave heights exceeding the working limit wave height occur frequently.

Japanese Patent Application Laid-Open No. 2005-029065

In recent years, there has been an increasing demand for work in the open ocean, such as construction work on offshore facilities like offshore wind power generation, and there is a need for box-type floaters that can float stably during work (when stationed on the water surface). At the same time, box-type floaters must be transported to the open ocean, and they must be able to travel smoothly to distant locations in the open ocean.

The objective of this invention is to provide a box-shaped floating body that can float stably while remaining stable on the water surface by suppressing rocking caused by waves, and that can move smoothly on the water surface.

As a result of extensive research into solving the above problems, the inventors discovered that the above problems could be solved by providing a rocking reduction means on the side of the floating body, which comprises an upright rocking suppression plate with an opening at the top and an elevating means for raising and lowering the rocking suppression plate, and thus completed the present invention.

That is, the present invention is as follows.
[1] A non-self-propelled box-shaped floating body comprising a floating body body and a rolling reduction means provided on the side of the floating body body to suppress rolling caused by waves,
The sway reducing means
The apparatus comprises a standing vibration suppression plate having an opening at the top, and a lifting means for lifting and lowering the vibration suppression plate,
A box-shaped floating body characterized in that, when the floating body is stopped on the water surface, the rocking suppression plate remains lowered until the upper opening is located underwater, and, when the floating body is moving on the water surface, the rocking suppression plate remains raised above the bottom of the floating body main body.
[2] The box-shaped floating structure according to [1] above, characterized in that it is provided with a box-shaped rocking suppression plate storage section for storing the rocking suppression plate in the raised state.
[3] The box-shaped floating body described in [2] above, characterized in that the rocking reduction means is composed of a plurality of units connected together, each unit comprising the rocking suppression plate and the box-shaped rocking suppression plate storage section.

[4] The box-shaped floating structure according to any one of [1] to [3] above, characterized in that the lifting means lifts and lowers the rocking suppression plates of each unit independently.
[5] The floating body is approximately rectangular in plan view,
The box-type floating body according to any one of [1] to [4] above, characterized in that the rocking reduction means is provided on both sides of the floating body in the longitudinal direction.
[6] The unit comprises:
The box-shaped rocking suppression plate storage section includes a storage chamber partitioned by a partition wall and an outer wall, and a lift rail extending vertically within the storage chamber,
The box-shaped floating body according to any one of [3] to [5] above, characterized in that the rocking suppression plate comprises a rocking suppression board having a bottom plate of a size corresponding to the storage chamber, and a sliding member attached to the rocking suppression board and extending in the vertical direction and guided by the lift rail.

The box-shaped floating structure of the present invention can float stably while remaining stationary on the water surface, suppressing rocking caused by waves, and can move smoothly when moving across the water surface.

1 is a schematic perspective view of a box-type floating body according to a first embodiment of the present invention, and is an explanatory diagram showing the state of the floating body moored on the water surface. [0023]FIG. 2A and 2B are explanatory diagrams of the box-type floating body shown in FIG. 1, in which FIG. 2A shows a cross-sectional view and FIG. 2B shows a partially enlarged cross-sectional view. 2 is an enlarged plan view of a unit of the rocking reduction means of the box-shaped floating body shown in FIG. 1, showing a state in which the rocking suppression plate is stored in a box-shaped rocking suppression plate storage portion. FIG. FIG. 2 is a perspective view of a rocking suppression plate of the rocking reduction means of the box-shaped floating body shown in FIG. 1 . 2A and 2B are explanatory diagrams of the lifting means of the rocking reduction means of the box-shaped floating body shown in FIG. 1, in which (a) shows the rocking suppression plate in a lowered state, and (b) shows the rocking suppression plate in a raised state. FIG. 2 is a schematic perspective view of the box-type floating body shown in FIG. 1, and is an explanatory diagram showing how it moves on the water surface. 2A and 2B are explanatory diagrams illustrating the behavior of the box-shaped floating body shown in FIG. 1 when it is swaying due to waves, where (a) shows a state where it is not swaying sideways, (b) shows a state where it is swaying sideways in a clockwise direction, and (c) shows a state where it is swaying sideways in a counterclockwise direction. 1A and 1B are explanatory diagrams of a box-shaped ship (box-shaped floating structure) based on an actual vessel, in which (a) is a plan view and (b) is a side view seen from the short side. 5A and 5B are photographs showing the downward movement of the rocking suppression plate of the box-shaped floating body according to Example 1, where (a) is a diagonally downward photograph and (b) is a side photograph. 5A and 5B are photographs showing the state in which the rocking suppression plates of the box-shaped floating body according to Example 1 are stored, where FIG. 5A is a photograph taken obliquely from above, and FIG. 5B is a photograph taken obliquely from behind. 1A and 1B are photographs showing a conventional box-type floating body produced in an example, where (a) is a photograph taken obliquely from above, and (b) is a photograph taken from above. FIG. 1 is an explanatory diagram showing an outline of a swing characteristic test. FIG. 10 is a diagram showing the results of measuring the rolling characteristics of the box-shaped floating body produced in the example in regular waves. FIG. 10 is a diagram showing the results of measuring the rolling characteristics of the box-shaped floating body produced in the example in irregular waves.

The box-type float of the present invention is a non-self-propelled box-type float comprising a float body and a rocking reduction means attached to the side of the float body to reduce rocking caused by waves. The rocking reduction means comprises an upright rocking suppression plate with an opening at the top and an elevating means for raising and lowering the rocking suppression plate. When moored on the water surface, the rocking suppression plate remains lowered until the opening at the top is positioned underwater, and when moving on the water surface, the rocking suppression plate remains elevated above the bottom of the float body. Note that "mooring" in this invention also includes moving at a slow speed of 2 km/h or less.

In this specification, the movement of a box-shaped float around the vertical axis (longitudinal direction) passing through the center of gravity of the box-shaped float is referred to as pitching (swing in the pitch direction), and the movement of a floating structure around the horizontal axis (transverse direction) passing through the center of gravity of the box-shaped float is referred to as lateral rolling (swing in the roll direction) (see Figure 1).

When the box-shaped float of the present invention is moored on the water surface, the rocking suppression plate with an opening at the top remains lowered until the opening is underwater. Therefore, when waves cause the box-shaped float to rock, the fluid below the float body sandwiched between the rocking suppression plates flows out from the upper opening of the rocking suppression plate on the side below the rocking. This outflow generates a damping force in the direction of reducing the rocking, thereby suppressing the rocking of the box-shaped float.
On the other hand, when the box-type floating body of the present invention moves on the water surface (when being pushed or towed), the rocking suppression plate is kept raised above the bottom of the floating body main body, so that the box-type floating body can move smoothly without the rocking suppression plate acting as resistance.

The box-type floating structure of the present invention is a box-shaped structure that floats on water that cannot be navigated by itself, and is typically moved on the water surface by being pushed by a pushboat or towed by a tugboat. It can be used on bodies of water such as the ocean, lakes, and rivers, preferably the ocean. Examples of the ocean include port areas, coastal areas, and the open ocean. The box-type floating structure of the present invention can be used as a work vessel such as a barge or platform used for various marine operations. Specific marine operations include seabed drilling surveys, dredging, mound formation, scouring prevention, reef installation, transport of equipment and repair parts for offshore facilities, maintenance and repair of offshore facilities, and undersea cable laying.

The box-type float of the present invention may be a jack-up type box-type float that is lifted from the water surface during work. Such a jack-up type box-type float does not sway during work, but before jacking up, the box-type float is in a floating state, and the swaying of the box-type float at that time can be suppressed.
The box-type floating body of the present invention is not limited to one manufactured from scratch, but may be one manufactured by attaching a rocking reduction means to an existing floating body body (barge, etc.).

As mentioned above, when the box-type float of the present invention is in operation (moored on the water surface), it includes not only when the box-type float is completely stationary, but also when it is moving at a slow speed of 2 km/h or less. In this case, the moving speed of the box-type float is preferably 1.5 km/h or less. An example of a box-type float that performs such operations is a submarine cable-laying box-type float that is pushed or towed at about 1 km/h while laying submarine cables on the seabed.

[Floating body]
The float body of the present invention is a main part constituting the box-type float and is a box-shaped structure. The shape of the float body is not particularly limited as long as it is a box-shaped shape that can float on the water surface, and examples include a substantially square or rectangular shape in plan view. Note that the bottom of either side of the float body where the rocking reduction means is not provided may be cut up.

The size of the floating body, which is roughly rectangular in plan view, is not particularly limited, but examples include a longitudinal length of 50 to 100 m and a transverse length of 15 to 30 m. Furthermore, for example, a crane, living quarters, work machinery, etc. are mounted on the top surface of the floating body.

[Sway reduction means]
The rocking reduction means is a means for suppressing rocking caused by waves, provided on the side of the floating body, and comprises an upright rocking suppression plate with an opening at the top, and a lifting means for raising and lowering the rocking suppression plate. When the box-shaped float is moored on the water surface, the rocking suppression plate remains lowered until the opening at the top is located underwater, and when the box-shaped float moves on the water surface (when being pushed or towed), the rocking suppression plate remains raised above the bottom of the floating body.

The rocking reduction means are typically provided on opposing sides of the float body. Furthermore, if the float body is generally rectangular in plan view, it is preferable that they be provided on the longitudinal sides. In other words, it is preferable that the box-shaped float of the present invention has a float body that is generally rectangular in plan view, and that the rocking reduction means be provided on both longitudinal sides of the float body. This makes it possible to reduce and suppress rolling caused by waves, which is larger than pitching. Note that the rocking reduction means may also be provided on all sides of the float body.

(Swing suppression plate)
The rocking suppression plate is an upright plate-like member with an opening at the top. When the rocking suppression plate is lowered until the upper opening is underwater, it can suppress rocking, allowing the floating structure to float stably. Specifically, when the box-shaped floating structure is lowered until the upper opening is underwater, if the box-shaped floating structure rolls clockwise with its short side facing forward, water remaining below the floating body sandwiched between the rocking suppression plates flows out forcefully from the opening of the rocking suppression plate on the side below the rocking, providing a damping force for the rolling and suppressing the rolling (see FIG. 7( b)). Similarly, when the box-shaped floating structure rolls counterclockwise with its short side facing forward, water remaining below the floating body sandwiched between the rocking suppression plates flows out forcefully from the opening of the rocking suppression plate on the side below the rocking, providing a damping force for the rolling and suppressing the rolling (see FIG. 7( c)).

The rocking suppression plate can be set appropriately to match the size of the floating body, and its width and height are preferably formed to lengths close to the width and height of the side of the floating body to be installed. For example, a width (long side) of 10 to 200 m and a height (short side) of 1 to 20 m are preferred, a width (long side) of 20 to 150 m and a height (short side) of 2 to 15 m are more preferred, and a width (long side) of 30 to 100 m and a height (short side) of 3 to 10 m are even more preferred. The rocking suppression plate may be a divided body composed of multiple plate-shaped members.

The openings are preferably located in the upper one-third of the entire sway suppression plate, more preferably in the upper one-quarter, and even more preferably in the upper one-fifth. The shape of the openings is not particularly limited, and examples include circular, elliptical, and polygonal shapes. The openings are preferably located continuously or intermittently across the width of the sway suppression plate. The height of the openings (vertical length) can be set appropriately depending on the size of the float, etc., but is preferably 0.01 to 0.8 m, more preferably 0.03 to 0.6 m, and even more preferably 0.05 to 0.4 m.

(Lifting means)
The lifting means is a means for raising and lowering the rocking suppression plate. This allows the rocking suppression plate to be lowered until its upper opening is underwater, and also allows it to be raised above the bottom of the floating body. The driving method of the lifting means is not particularly limited, and examples include methods using a winch, hydraulic cylinder, pneumatic cylinder, electric motor, gearbox, etc.

(Box-shaped vibration suppression plate storage section)
The rocking reduction means may be provided in an exposed state on the side of the floating body, but is preferably provided in a surrounded and covered state on the side of the floating body. That is, the box-type float of the present invention is preferably provided with a box-shaped rocking suppression plate storage section that stores the rocking suppression plate in a raised state. This makes it possible to protect the rocking reduction means when docking at a quay or land, or when being pushed or towed by another ship.
The box-shaped anti-sway plate storage section is arranged so that its lower end does not protrude from the underside of the floating body, thereby reducing resistance during movement and enabling smooth movement.

(unit)
The sway reduction means is preferably configured by a series of multiple units each equipped with a sway suppression plate and a box-shaped sway suppression plate storage section. In this configuration, the lifting means may lift and lower the sway suppression plates of each unit simultaneously, or may lift and lower the sway suppression plates of each unit independently. This allows even a small lifting means to reliably lift and lower the plates. Furthermore, even if a malfunction occurs, repairing only some of the units is sufficient, preventing the entire sway reduction means from becoming inoperable. Furthermore, when the sway suppression plates of each unit are lifted and lowered independently, adjustments can be made, such as lowering the sway suppression plates at positions corresponding to the direction of incoming waves, allowing the boat to stay more stably on the water surface.

Specific preferred embodiments of the box-shaped sway suppression plate storage section and sway suppression plate in the above-mentioned unit include, for example, a box-shaped sway suppression plate storage section comprising a storage chamber separated by a partition wall and an outer wall, and a lift rail extending vertically within the storage chamber, and a sway suppression plate comprising a sway suppression board with a bottom plate sized to fit the storage chamber, and a sliding member attached to the sway suppression board and extending vertically and guided by the lift rail. Multiple lift rails may be provided. The lift rails and sliding members may comprise rolling members such as rollers. Having a bottom plate sized to fit the storage chamber prevents seawater and foreign matter from entering the storage chamber. It is also preferable that the sway suppression board of the sway suppression plate comprises a ceiling plate sized to fit the storage chamber. This prevents water from flowing into the box-shaped sway suppression plate storage compartment when the sway suppression plate is lowered, and allows more water to be guided toward the opening in the sway suppression plate (sway suppression board), resulting in greater damping force against sway.

Below, one embodiment of the box-type floating body of the present invention will be specifically described using drawings, but the present invention is not limited to this embodiment.

Here, Figure 1 is a schematic oblique view of a box-type float according to a first embodiment of the present invention, and is an explanatory diagram showing the state when it is moored on the water surface. Figure 2 is an explanatory diagram of the box-type float shown in Figure 1, where (a) is a cross-sectional view and (b) is a partially enlarged cross-sectional view. Figure 3 is an enlarged plan view of a unit of the rocking reduction means of the box-type float shown in Figure 1, showing the state in which the rocking suppression plate is stored in the box-shaped rocking suppression plate storage section. Figure 4 is a perspective view of the rocking suppression plate of the rocking reduction means of the box-type float shown in Figure 1. Figure 5 is an explanatory diagram of the lifting means of the rocking reduction means of the box-type float shown in Figure 1, where (a) shows the state in which the rocking suppression plate is lowered and (b) shows the state in which the rocking suppression plate is raised. Figure 6 is a schematic oblique view of the box-type float shown in Figure 1, and is an explanatory diagram showing the state in which it is moving on the water surface. Figure 7 is an explanatory diagram of the behavior of the box-shaped floating structure shown in Figure 1 when it is swaying due to waves, where (a) shows a state where it is not swaying, (b) shows a state where it is swaying clockwise, and (c) shows a state where it is swaying counterclockwise.

As shown in Figure 1, a box-type floating body 10 according to a first embodiment of the present invention comprises a floating body main body 12 and a rocking reduction means 14 provided on the longitudinal side of the floating body main body 12. The rocking reduction means 14 comprises a rocking suppression plate 16 provided in an upright position on the side of the floating body main body 12, and a hydraulic cylinder 18 as a lifting means for raising and lowering the rocking suppression plate 16.

As shown in Figure 2, the box-shaped float 10 is equipped with a box-shaped rocking suppression plate storage section 20 that stores the rocking suppression plates 16a, 16b in a raised state. In Figure 2, the rocking suppression plate 16a on one side (the right side) of the float body 12 is shown lowered until its upper opening 22 is located underwater, and the rocking suppression plate 16b on the other side (the left side) is shown raised above the bottom of the float body 12 and stored in the box-shaped rocking suppression plate storage section 20; however, normally both are in the same raised or lowered state.

As shown in Figure 1, the rocking reduction means 14 is composed of five units 24 connected together, each equipped with a rocking suppression plate 16 and a box-shaped rocking suppression plate storage section 20. As shown in Figure 3, the box-shaped rocking suppression plate storage section 20 is equipped with a storage chamber 30 separated by a bulkhead 26 and an outer wall 28 for each unit 24, and a lifting rail 32 provided in the storage chamber 30, and the raised rocking suppression plate 16 is stored in an enclosed state in the storage chamber 30. This allows the rocking reduction means 14 to be protected when docking at a quay or land, or when being pushed or towed by another ship.

As shown in Figure 4, the sway suppression plate 16 includes a sway suppression board 34 that is 9 m wide (length in the left-right direction) and 5 m high (length in the up-down direction), and a sliding member 36 that extends in the up-down direction and is attached to the sway suppression board 34. The sway suppression board 34 is configured in a box shape, surrounded by two side plates 38, a bottom plate 40, and a ceiling plate 42. The box-shaped sway suppression plate storage section 20 and the sway suppression plate 16 of one unit 24 are connected such that the sliding member 36 of the sway suppression plate 16 can slide on an elevation rail 32 provided in the storage chamber 30 of the box-shaped sway suppression plate storage section 20.
In addition, three openings 22, each 1.5 m wide (length in the left-right direction) and 0.3 m high (length in the up-down direction), are provided intermittently at a predetermined interval across the width of the sway suppression plate 16 at its upper part.

As shown in Figure 5, a hydraulic cylinder 18 is fixed to the sway suppression board 34 of the sway suppression plate 16 of each unit 24, and the extension and contraction of this hydraulic cylinder 18 raises and lowers the sway suppression plate 16. The hydraulic cylinder 18 can raise and lower the sway suppression plate 16 of each unit 24 independently.

As shown in Figure 6, when the box-shaped float 10 moves on the water surface (when being pushed or towed), the rocking suppression plates 16a, 16b rise above the bottom of the float body 12 and are stored in the box-shaped rocking suppression plate storage section 20. The box-shaped rocking suppression plate storage section 20 is positioned so that its lower end does not protrude from the underside of the float body 12. This reduces resistance caused by protrusions and gaps during movement, allowing for smooth movement on the water surface.

Next, the operation of the box-type floating body 10 according to the first embodiment of the present invention will be described with reference to Fig. 7. Fig. 7 shows the box-type floating body 10 in a state where the rocking suppression plates 16a, 16b provided on both sides of the floating body main body 12 have been lowered until the upper opening 22 is positioned underwater.
First, as shown in Figure 7(a), when the box-shaped floating body 10 is not swaying sideways, the sway reduction means 14 keeps the sway suppression plates 16a, 16b in a lowered position until the upper opening 22 is positioned underwater, and the floating body remains stationary on the water surface.
As shown in Figure 7(b), when the box-type floating body 10 rolls clockwise, the fluid below the floating body main body 12 sandwiched between the rolling suppression plates 16a and 16b flows out from the upper opening 22 of the rolling suppression plate 16a on the lower side of the rolling. This outflow generates a damping force in the direction to reduce the rolling, and the rolling of the box-type floating body 10 is suppressed.
As shown in Figure 7(c), when the box-type floating body 10 rolls counterclockwise, the fluid below the floating body main body 12 sandwiched between the rolling suppression plates 16a and 16b flows out from the upper opening 22 of the rolling suppression plate 16b on the lower side of the rolling. This outflow generates a damping force in the direction to reduce the rolling, and the rolling of the box-type floating body 10 is suppressed.

[Oscillation characteristic test]
Example 1
A rolling characteristic test was carried out using the box-type floating structure according to Example 1 of the present invention.
Fig. 8 is an explanatory diagram of a box-shaped ship (box-shaped floating body) simulating an actual vessel, where (a) is a plan view and (b) is a side view seen from the shorter side. Fig. 9 is a photograph showing the rolling suppression plate of the box-shaped floating body according to Example 1 when it is lowered, where (a) is a diagonally downward photograph and (b) is a side photograph. Fig. 10 is a photograph showing the rolling suppression plate of the box-shaped floating body according to Example 1 when it is stored, where (a) is a diagonally upward photograph and (b) is a diagonally rearward photograph. Fig. 11 is a photograph showing a conventional box-shaped floating body produced in the example, where (a) is a diagonally upward photograph and (b) is a plan photograph.
The box-type floating bodies used in this test (Example 1, Comparative Example 1) were assumed to be 1/50 scale models of the actual vessel.

As shown in Figure 8, the box-shaped ship modeled after the actual ship has a length (L) of 65.0 m, a width (B) of 25.0 m, a depth (D) of 5.0 m, a draft of 3.0 m, and a displacement of 4,997 tons. The box-shaped anti-rolling plate storage section is composed of eight units connected together on each side of the longitudinal direction of the box-shaped ship, with each unit having a length (l) of 6.3 m and a width (w) of 1.5 m, a length (d) from the bottom of the box-shaped anti-rolling plate storage section (floating body main body) when the anti-rolling plates are lowered of 2.5 m, a width (b) of the bottom plate of the anti-rolling plate of 1.0 m, and a height (g) of the opening of 0.25 m.
Table 1 shows the box-shaped ship that was assumed to be the actual ship and the scale of the model used.

The oscillation characteristic test was carried out under the following conditions.
As shown in Figure 12, in a marine test tank with a length of 60 m, a width of 4 m, and a depth of 2.3 m, a motion sensor was attached to the top of the box-type float according to this embodiment, and the float was moored so as not to affect its motion. Waves were generated by a wave-making device, and the pitch amplitude/wave amplitude (deg/m) of the floating structure in a wave period (sec) was measured. Measurements were made in two patterns: regular waves and irregular waves.

The results are shown in Figures 13 and 14.
As shown in Figures 13 and 14, it was confirmed that the box-type floating body of Example 1 can reduce rolling caused by regular waves and irregular waves by approximately 40 to 60% in the mean period of around 5 to 7 seconds, where waves frequently occur, compared to the box-type floating body of Comparative Example 1, which is not equipped with a rolling reduction means.
Therefore, it was confirmed that the box-type floating body according to Example 1 of the present invention can suppress rocking caused by waves and float stably.

[Towing test]
A towing test was carried out using the box-type floating body according to Example 1 of the present invention.
It was confirmed that the box-shaped floating body of Example 1 (Figure 10) with the rocking suppression plate stored can be towed as smoothly as the box-shaped floating body of Comparative Example 1 (Figure 11) which is not equipped with a rocking reduction means.

The floating structure of the present invention is industrially useful because it can be used for non-self-propelled work vessels at sea, etc.

10 Box-shaped floating body 12 Floating body main body 14 Sway reducing means 16 Sway suppressing plate 18 Hydraulic cylinder (lifting means)
20 Box-shaped rocking suppression plate storage section 22 Opening 24 Unit 26 Partition wall 28 Outer wall 30 Storage room 32 Lifting rail 34 Rocking suppression board 36 Sliding member 38 Side plate 40 Bottom plate 42 Ceiling plate

Claims (6)

A non-self-propelled box-type floating body comprising a floating body main body and a rolling reduction means provided on a side of the floating body main body for suppressing rolling caused by waves,
The sway reducing means
The apparatus comprises an upright vibration suppression plate and a lifting means for lifting and lowering the vibration suppression plate,
A box- shaped floating body characterized in that an opening is provided at the top of the rocking suppression plate, penetrating the rocking suppression plate in the plate thickness direction, and when the floating body is stopped on the water surface, the upright rocking suppression plate remains lowered until the opening is positioned underwater, and when the floating body is moving on the water surface, the upright rocking suppression plate remains raised above the bottom of the floating body main body. A box-shaped floating structure as described in claim 1, characterized in that it is provided with a box-shaped rocking suppression plate storage section that stores the rocking suppression plate in the raised state. A box-shaped floating structure as described in claim 2, characterized in that the rocking reduction means is composed of a series of multiple units each equipped with the rocking suppression plate and the box-shaped rocking suppression plate storage section. 4. The box-type floating structure according to claim 3 , wherein the lifting means lifts and lowers the rocking suppression plates of the plurality of units independently. The floating body is generally rectangular in plan view,
5. The box-shaped floating body according to claim 1, wherein the rocking reduction means is provided on both sides of the floating body in the longitudinal direction. The unit comprises:
The box-shaped sway suppression plate storage section includes a storage chamber partitioned by a partition wall and an outer wall, and an elevation rail extending vertically within the storage chamber,
5. The box-shaped floating body according to claim 3 or 4, characterized in that the rocking suppression plate comprises a rocking suppression board having a bottom plate of a size corresponding to the storage chamber, and a sliding member attached to the rocking suppression board and extending in the vertical direction and guided by the lifting rail.