Shallow water navigation

Abstract

To provide a shallow water navigation method capable of easily bringing a ship hull close to the shore. [Solution] A shallow water navigation method for causing a barge 10, which includes a hull 11 that floats on water and can carry cargo, a propulsion device 12 that propels the hull 11, and a ballast mechanism 13 that adjusts the inclination of the hull 11 relative to the water surface Sf by changing the position or amount of ballast on the hull 11, to enter a shallow water area B1 connected to a shore Ld, includes a tilting step S11 and a propulsion step S12. The tilting step S11 causes the shore Ld side of the hull 11 to rise higher than the offshore side, which is the opposite side of the shore Ld, so that the hull 11 is inclined relative to the water surface Sf. The propulsion step S12 propels the hull 11 toward the shore Ld in the inclined state.

Description

[Technical field]

[0001] The present invention relates to a shallow water navigation method for making a ship navigate in shallow water near a quay, and more particularly to a shallow water navigation method including a step of making a ship enter shallow water and approach a quay. [Background technology]

[0002] Generally, barges with flat bottoms capable of transporting heavy loads are widely used when unloading cargo loaded on ships through shallow waters that do not have sufficient water depth, or for carrying out offshore work in such shallow waters. For example, Patent Document 1 discloses a submarine cable-laying method in which a submarine cable-laying work vessel with barge specifications and equipped with facilities for laying a submarine cable is moored at a mooring point for unloading a cable terminal, and anchor spuds are thrust into the seabed to stabilize the vessel, and the cable terminal is unloaded and a submarine cable is laid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 06-056076 [Patent Document 2] Patent No. 4488357 Summary of the Invention [Problem to be solved by the invention]

[0004] In the submarine cable-laying method of Patent Document 1, the seabed is shallow, so it is difficult for the submarine cable-laying work vessel to get close enough to the landing point, and the mooring point ends up being far from the landing point, which is thought to reduce the ease of landing the cable terminal.

[0005] Therefore, the inventor proposes that in the barge of Patent Document 2, the thruster for stabilizing the hull position is attached to a horizontal section that extends horizontally following an inclined section that extends diagonally upward from the bottom of the ship in the ship's width and fore-and-aft directions, so that the lower end of the thruster is positioned higher than the bottom of the ship, thereby making it less likely that the thruster will hit the seabed.

[0006] However, in the barge of Patent Document 2, the lower end of the thruster is positioned higher than the bottom of the ship, which limits the output of the thruster, resulting in the problem that it cannot be applied to large barges or barges carrying heavy loads.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a method of shallow water navigation that can easily move the hull closer to the shore, not only for small barges or barges with light loading weights, but also for large barges or barges carrying heavy cargo. [Means for solving the problem]

[0008] The invention made to solve the above problem is a shallow water navigation method for making a barge enter shallow water leading to a shore, the barge having a hull that floats on water and is capable of carrying cargo, a propulsion device that propels the hull, and a ballast mechanism that adjusts the inclination of the hull relative to the water surface by changing the position or amount of ballast in the hull. The shallow water navigation method of the present invention includes a tilting step and a propulsion step. The tilting step causes the shore side of the hull to rise higher than the offshore side opposite the shore, causing the hull to be inclined relative to the water surface. The propulsion step propels the hull toward the shore in the inclined state. The shallow water navigation method of the present invention further includes a delivery step of delivering the cargo loaded on the hull to the shore while the hull is inclined. In the shallow water navigation method of the present invention, the cargo is a cable to be laid on the seabed, and the delivery step further includes a leaving step of delivering one end of the cable to the shore, and pulling out the cable while moving the hull away from the shore while the hull is inclined, and laying it on the seabed.

[0009] According to the present invention, since the draft of the hull on the shore side is smaller than that on the offshore side due to the inclination of the hull, the draft of the hull on the shore side is likely to be shallower than the water depth of the shallow waters. In this state, the hull approaches the shore while maintaining its inclination, so it is possible to easily move the hull closer to the shore. Furthermore, since the undocking step is performed while the submarine cable is being laid, the hull of the vessel rises by the amount of the lowered submarine cable, further reducing the possibility of the vessel's bottom coming into contact with the seabed when undocking. Effect of the Invention

[0012] According to the present invention, since the draft of the hull on the shore side becomes smaller than that on the offshore side due to the inclination of the hull, the draft of the hull on the shore side tends to become shallower than the water depth of the shallow water. Furthermore, since the hull approaches the shore while maintaining an inclined state, the ship can easily approach the shore. [Brief description of the drawings]

[0013] [Figure 1] 1 illustrates a barge according to one embodiment of the present invention. [Diagram 2] Figure 1 shows a schematic cross-section of the hull of a barge seen from the side. [Diagram 3] FIG. 1 shows a schematic diagram of a cross section of a barge hull seen from above. [Figure 4] The schematic cross-sectional view of the hull of a barge viewed from the front is shown. [Diagram 5] The hull is shown adjusted to a horizontal position by the ballast mechanism. [Figure 6] The hull is shown adjusted to a tilted position by the ballast mechanism. [Figure 7] 1 is a flowchart illustrating a method for shallow water navigation by a barge according to an embodiment of the present invention. [Figure 8] FIG. 13 shows the tilting and propelling steps by a barge. [Figure 9] FIG. 2 is a diagram showing the docking and delivery steps by a barge. [Figure 10] FIG. 1 shows steps for leaving the shore by a barge. [Figure 11] FIG. 13 shows a modified example of a barge propulsion step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiment.

[0015] (Barge) FIG. 1 shows a barge 10 according to one embodiment of the present invention. The barge 10 comprises a hull 11, a power unit 30 (see FIGS. 3 to 5), a propulsion unit 12, and a ballast mechanism 13. The hull 11 navigates a body of water such as the sea, a river, or a lake. Below, a representative example of the barge 10 floating in the sea area Sc will be described. The hull 11 has at least a deck 11A and a ship bottom 11B. In the hull 11 floating in the sea area Sc, the deck 11A is located above the water surface Sf, and the ship bottom 11B is located below the water surface Sf. The power unit 30 includes, for example, an engine or a motor. The power unit 30 is provided in the hull 11.

[0016] The propulsion device 12 propels the hull 11. Typically, the propulsion device 12 is a screw propeller connected to the power unit 30, and can rotate 360 ​​degrees around a vertical axis to generate a propulsive force in any horizontal direction. In this embodiment, the propulsion device 12 is arranged exposed from the hull 11. As an example, the barge 10 is provided with four propulsion devices 12a, 12b, 12c, and 12d, and power units 30a, 30b, 30c, and 30d connected to the propulsion devices 12a, 12b, 12c, and 12d, respectively. The propulsion devices 12a to 12d are provided at the four corners of the hull 11. For example, the propulsion devices 12a, 12c and the propulsion devices 12b, 12d are located on opposite sides of the hull 11, and the propulsion devices 12a, 12b and the propulsion devices 12c, 12d are located on opposite sides of the hull 11. Typically, the rotation plane of each screw propeller of the propulsion devices 12a, 12b, 12c, and 12d is directed in the opposite direction to the propulsion direction of the hull 11. The power unit 30a and the power unit 30c are located between the propulsion device 12a and the propulsion device 12c. The power unit 30b and the power unit 30d are located between the propulsion device 12b and the propulsion device 12d. When each screw propeller rotates with the drive of the power units 30a, 30b, 30c, and 30d, for example, the propulsion devices 12a, 12b, 12c, and 12d propel the hull 11 toward one side D11 of the first direction D1 or the other side D12 of the first direction D1. Typically, the first direction D1 is the longitudinal direction. Hereinafter, one side D11 of the first direction D1 will also be described as "front" or "forward", and the other side D12 of the first direction D1 will also be described as "rear" or "rear". In addition, a direction that intersects with the first direction D1 and runs along the water surface Sf will be referred to as a second direction D2 (FIG. 3), and the second direction D2 will also be described as "side" or "lateral". In the second direction D2, the "right" side toward the one side D11 of the first direction D1 will be referred to as one side D21, and the "left" side toward the one side D11 of the first direction D1 will be referred to as the other side D22. Note that the number of propulsion devices 12 and the number of power devices 30 provided on the barge 10 are not limited to four each. For example, one or more propulsion devices 12 may be further provided between the propulsion device 12a and the propulsion device 12b.

[0017] The ballast mechanism 13 adjusts the draft ds, which indicates the distance from the water surface Sf to the ship bottom 11B of the hull 11 floating in the sea area Sc, and the inclination of the hull 11 relative to the water surface Sf. The configuration and principle of the ballast mechanism 13 will be described later with reference to Figures 2 to 6.

[0018] In this embodiment, a submarine cable 101 to be laid on the seabed is loaded on the hull 11 of the barge 10. The submarine cable 101 is an example of cargo. For example, the barge 10 is used to transport the loaded submarine cable 101 while laying it on the seabed.

[0019] Specifically, the barge 10 further includes a cable-laying mechanism 20. The cable-laying mechanism 20 is provided on the deck 11A. The cable-laying mechanism 20 includes a tower 21, a cable guide 22, and a chute 23.

[0020] Typically, a cable coil 101C, which is a submarine cable 101 formed into a coil shape, is installed on the deck 11A. A tower 21 is provided above the cable coil 101C. Meanwhile, a chute 23 is provided at the end of the deck 11A on the other side D12 in the first direction D1. A cable guide 22 is provided between the tower 21 and the chute 23, which pulls out the submarine cable 101 from the cable coil 101C and transports it to the chute 23. Specifically, the submarine cable 101 pulled out from the cable coil 101C is placed in the cable guide 22 via above the tower 21. The submarine cable 101 transported by the cable guide 22 is paid out from the chute 23 to the seabed.

[0021] (Ballast mechanism) FIG. 2 shows a schematic cross-sectional view of the hull 11 of the barge 10 as viewed from the side. FIG. 3 shows a schematic cross-sectional view of the hull 11 of the barge 10 as viewed from above. FIG. 4 shows a schematic cross-sectional view of the hull 11 of the barge 10 as viewed from the front, passing through the propulsion device 12a, the power unit 30a, the power unit 30c, and the propulsion device 12c. As shown in FIGS. 2 to 4, the propulsion device 12a and the propulsion device 12b are provided at the end of the hull 11 on one side D21 in the second direction D2. The propulsion device 12c and the propulsion device 12d are provided at the end of the hull 11 on the other side D22 in the second direction D2. The power unit 30a is located closer to the propulsion device 12a than the power unit 30c. In addition, a plurality of ballast tanks 130 are provided as the ballast mechanism 13 in the hull 11. The multiple ballast tanks 130 are arranged side by side along the first direction D1 and the second direction D2, respectively. Each of the multiple ballast tanks 130 has at least a bottom and a sidewall extending from the bottom, and stores seawater or the like in a storage space formed by the bottom and the sidewall.

[0022] As an example, five ballast tanks 130 are arranged side by side along the first direction D1, and three ballast tanks 130 are arranged side by side along the second direction D2. In Figs. 2 and 3, the multiple ballast tanks 130 are arranged adjacent to each other, but strictly speaking, the multiple ballast tanks 130 are provided avoiding a predetermined space arranged in the hull 11, such as a space for the power unit 30. In Figs. 2 and 3, the ballast tanks 130 are depicted as rectangular (rectangular parallelepiped), but the shape of the ballast tanks 130 is not particularly limited. For example, the ballast tanks 130 may be cylindrical or spherical.

[0023] Hereinafter, the ballast tanks 130 lined up along the first direction D1 will be referred to as ballast tanks 130A to 130E in order from one side D11 to the other side D12. Also, the ballast tanks 130 lined up along the second direction D2 will be referred to as ballast tanks 130a to 130c in order from one side D21 to the other side D22.

[0024] The ballast tank 130 takes in seawater from outside the hull 11 to increase the amount of seawater contained in the accommodation space, or releases seawater contained in the accommodation space to the outside of the hull 11 to decrease the amount of seawater contained in the accommodation space. Alternatively, the ballast tank 130 transfers the seawater contained in the accommodation space to the accommodation space of another ballast tank 130. Hereinafter, the seawater contained in the ballast tank 130 is also referred to as "ballast water W (FIGS. 5 and 6)".

[0025] In this way, as the position or amount of ballast water W in each of the multiple ballast tanks 130 changes, the weight balance of the hull 11 changes, causing at least one of the draft ds of the hull 11 and the inclination of the hull 11 relative to the water surface Sf to change.

[0026] Figures 5 and 6 are diagrams showing adjustment of the inclination of the hull 11 along the first direction D1 by the ballast mechanism 13. Figure 5 shows the hull 11 whose inclination along the first direction D1 has been adjusted by the ballast mechanism 13 to be approximately parallel (horizontal) to the water surface Sf. Figure 6 shows the hull 11 whose inclination along the first direction D1 has been adjusted by the ballast mechanism 13 to be inclined relative to the water surface Sf. In Figures 5 and 6, it is assumed that the hull 11 floating in the sea area Sc with no cargo loaded and all ballast tanks 130 empty is horizontal.

[0027] As shown in Fig. 5, when the ballast water W contained in each of the ballast tanks 130A-130E is all adjusted to approximately the same amount, the weight of the hull 11 is balanced between one side D11 and the other side D12 in the first direction D1. Therefore, the inclination of the hull 11 along the first direction D1 becomes horizontal. Hereinafter, the barge 10 in which the inclination of the hull 11 along the first direction D1 has been adjusted to be horizontal will also be referred to as being in a horizontal state.

[0028] On the other hand, as shown in FIG. 6, if the amount of ballast water W stored in the ballast tanks 130A-130E on one side D11 in the first direction D1 is adjusted to be larger, the weight balance of the hull 11 in the first direction D1 becomes heavier on the one side D11 than on the other side D12. Therefore, the one side D11 of the hull 11 sinks deeper than the other side D12 of the hull 11. In other words, the other side D12 of the hull 11 rises higher than the one side D11 of the hull 11. As a result, the inclination of the hull 11 along the first direction D1 is inclined with respect to the water surface Sf. Hereinafter, the barge 10 in a state in which the hull 11 is inclined with respect to the water surface Sf along the first direction D1 will also be referred to as an inclined state.

[0029] Next, the navigation of the barge 10 will be described with reference to Fig. 1. As shown in Fig. 1, the sea area Sc in which the barge 10 navigates includes a shallow water area B1 connected to the shore Ld and an offshore area B2 that is further away from the shore Ld than the shallow water area B1. The water depth d2 from the water surface Sf to the bottom of the offshore area B2 is deeper than the draft ds. On the other hand, the water depth d1 from the water surface Sf to the bottom of the shallow water area B1 becomes shallower toward the shore Ld, and there is an area where the water depth is shallower than the draft ds. For example, the barge 10 navigates with its front facing the shore Ld and its rear facing offshore to approach the shore Ld.

[0030] When the barge 10 is in a horizontal position, the draft ds is constant along the first direction D1, so the barge 10 in a horizontal position cannot navigate through areas of the shallow water area B1 that are shallower than the draft ds, and cannot approach the shore Ld.

[0031] In contrast, the shallow water navigation method of the barge 10 according to this embodiment makes it possible for the barge 10 to easily approach the shore Ld.

[0032] (Shallow Water Navigation) 7 is a flowchart showing a shallow water navigation method by the barge 10 according to the embodiment of the present invention. The shallow water navigation method of the present invention includes a tilting step S11, a propulsion step S12, a docking step S13, a delivery step S14, and an undocking step S15.

[0033] (Tilt step S11) In the shallow water navigation method by the barge 10, the barge 10 performs a tilting step S11 in which the bank Ld side of the hull 11 is raised above the offshore side opposite the bank Ld, so that the hull 11 is tilted relative to the water surface Sf.

[0034] Fig. 8 is a diagram showing the tilting step S11 and the propulsion step S12 (Fig. 7) performed by the barge 10. In the offshore area B2, the barge 10 adjusts the ballast water W in the ballast tank 130, and raises the other side D12 of the hull 11 in the first direction D1, which is the bank Ld side, above the one side D11 of the hull 11 in the first direction D1, which is the offshore side, to tilt the hull 11 along the first direction D1 with respect to the water surface Sf. In other words, the draft ds of the hull 11 on the other side D12 in the first direction D1 becomes smaller than the draft ds of the hull 11 on the one side D11 in the first direction D1.

[0035] Next, as shown in FIG. 7, the barge 10 performs a propulsion step S12 in which the hull 11 is propelled toward the shore Ld in a state in which the hull 11 is inclined with respect to the water surface Sf.

[0036] (Propulsion step S12) As shown in Fig. 8, the barge 10 drives at least one of the propulsion devices 12a to 12d while maintaining the tilted state, and propels the hull 11 toward the shore Ld. In this way, by using the tilting step S11 and the propulsion step S12 as a shallow water navigation method, the hull 11 of the barge 10 can easily enter the shallow water area B1 and approach the shore Ld.

[0037] Next, as shown in FIG. 7, the barge 10 performs a docking step S13 in which the hull 11 approaches the shore Ld.

[0038] (Borne-docking step S13) Fig. 9 is a diagram showing the docking step S13 and the delivery step S14 (Fig. 7) by the barge 10. As shown in Fig. 9, the barge 10 propels the hull 11 toward the shore Ld and docks the other side D12 of the hull 11 in the first direction D1 at the shore Ld. Here, docking means that the barge 10 approaches close enough to allow delivery of the cargo loaded on the barge 10 between the barge 10 and the shore Ld.

[0039] Next, as shown in FIG. 7, the barge 10 performs a delivery step S14 in which the submarine cable 101 loaded on the hull 11 is delivered to the shore Ld.

[0040] (Delivery step S14) As shown in FIG. 9, the barge 10 delivers one end 101L of the submarine cable 101 loaded on the hull 11 to the shore Ld via the chute 23 (FIG. 1) mounted on the hull 11 while the hull 11 is inclined. Specifically, a float (buoy) is attached along the submarine cable 101 to the submarine cable 101 that is let out from the chute 23. As a result, the float (buoy) attached to the submarine cable 101 floats on the water surface Sf, and the submarine cable 101 is suspended from the float (buoy). The submarine cable 101 floating on the water surface Sf together with the float (buoy) is landed on the shore Ld. In this way, the end 101L of the submarine cable 101 delivered to the shore Ld is connected to predetermined equipment and the like on the shore Ld. In this embodiment, after docking by the propulsion step S12, the handover step S14 is performed, so that the hull 11 floats higher than when the barge 10 enters the shallow water area B1, thereby further preventing the bottom 11B from contacting the seabed.

[0041] Next, as shown in FIG. 7, the barge 10 performs an unberthing step S15 in which the hull 11 is moved away from the shore Ld while the hull 11 is in an inclined state.

[0042] (Departure step S15) Fig. 10 is a diagram showing the undocking step S15 by the barge 10. As shown in Fig. 10, while maintaining the inclined state, the barge 10 drives at least one of the propulsion devices 12a to 12d to propel the hull 11 toward the sea. At this time, the cable-laying mechanism 20 continues to pay out the submarine cable 101. As a result, as the barge 10 propels toward the sea, the submarine cable 101 is laid on the water bottom of the sea area Sc. In this embodiment, the undocking step S15 is performed while laying the submarine cable 101 in this way, and the hull 11 floats up by the amount of the lowered submarine cable 101, further reducing the possibility that the ship bottom 11B will come into contact with the sea bottom when undocking.

[0043] Furthermore, the barge 10 approaches a shore different from the shore Ld while continuing laying the submarine cable 101, and delivers the end of the submarine cable 101 opposite to the end 101L to the shore. At this time, the barge 10 may execute the shallow water navigation method in the same manner as when approaching the shore Ld.

[0044] (Modification) 11 is a diagram showing a modified example of the propulsion step S12 by the barge 10. The modified example of the propulsion step S12 is the same as the propulsion step S12 of this embodiment, except that the hull 11 is propelled by the propulsion device 12e instead of the propulsion device 12a and the propulsion device 12b.

[0045] Specifically, the barge 10 further includes a propulsion device 12e as the propulsion device 12. The propulsion device 12c is, for example, a winch that can wind the wire 12f onto a reel. The propulsion device 12e is disposed, for example, on the deck 11A. The barge 10 in an inclined state extends the wire 12f to the shore Ld and connects one end of the wire 12f to a structure Lda present on the shore Ld. The propulsion device 12e winds up the other end of the wire 12f on the barge 10 side. As the wire 12f is wound up, the hull 11 propels toward the shore Ld. The structure Lda may be an artificial object such as a bitt (mooring post) installed on the shore Ld, or a natural tree or rock.

[0046] In this embodiment, the ballast tank 130 and the ballast water W have been described as an example of the ballast mechanism 13, but the ballast mechanism 13 may be solid ballast. In this case, by changing the position of the solid ballast in the hull 11, the weight balance of the hull 11 changes, and at least one of the draft ds of the hull 11 and the inclination of the hull 11 relative to the water surface Sf changes.

[0047] Also, although an example has been described in which the other side D12 (rear) of the hull 11 in the first direction D1 is on the shore Ld side, the orientation of the hull 11 is unrelated to the shore Ld side. Specifically, either the front or side of the hull 11 may be on the shore Ld side, or the hull 11 may be positioned at an angle to the shore Ld to avoid tidal currents, etc. In this case, in the tilting step S11, the barge 10 raises the side of the hull 11 that is on the shore Ld side above the offshore side.

[0048] Furthermore, although the chute 23 of the cable-laying mechanism 20 is described as being provided at the rear of the hull 11, the chute 23 may be provided at either the front or side of the hull 11. [Explanation of symbols]

[0049] 10: Barge 11: Hull 12: Propulsion device 13: Ballast mechanism 101: Submarine cables B1: Shallow water area Ld :shore S11: Inclined step S12: Promotion step S14: Delivery step S15: Offshore step SF: water surface

Claims

[Claim 1] A shallow water navigation method for causing a barge, which includes a hull that floats on water and can carry cargo, a propulsion device that propels the hull, and a ballast mechanism that adjusts the inclination of the hull relative to the water surface by changing a position or amount of ballast in the hull, to enter shallow water leading to a shore, the method comprising: a tilting step for raising the shore side of the hull above the offshore side, which is the opposite side of the shore side, so that the hull is tilted relative to the water surface; a propulsion step of propelling the hull toward the shore in a tilted state; a delivery step of delivering the cargo loaded on the hull to the shore while the hull is inclined; Including, the cargo is a cable for laying on the ocean floor; In the delivery step, one end of the cable is delivered to the shore; The method for shallow water navigation by a barge further includes a step of undocking, pulling out the cable and laying it on the seabed while moving the hull away from the shore in a tilted state.

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