Methods of navigating shallow waters

Abstract

This invention provides a shallow-water navigation method that allows the vessel to easily approach the shore. [Solution] A method for navigating a barge 10, which comprises a hull 11 that can float on water and carry cargo, a propulsion device 12 for propelling the hull 11, and a ballast mechanism 13 for adjusting the inclination of the hull 11 with respect to the water surface Sf by changing the position or amount of ballast in the hull 11, into a shallow water area B1 connected to a shore Ld, the method comprising an inclination step S11 and a propulsion step S12. The inclination step S11 raises the shore Ld side of the hull 11 higher than the offshore side, which is the opposite side of the shore Ld, so that the hull 11 is inclined with respect to the water surface Sf. The propulsion step S12 propels the hull 11 toward the shore Ld while the hull 11 is inclined.

Description

Technical Field

[0005]

[0001] The present invention relates to a shallow water navigation method for a ship to navigate in a shallow water area near a quay wall, and particularly to a shallow water navigation method including a process of making a ship enter the shallow water and approach the quay wall.

Background Art

[0002] Generally, when unloading goods loaded on a ship through a shallow water area having insufficient water depth or performing offshore operations in such a shallow water area, a barge ship with a flat bottom capable of transporting heavy goods is widely used. For example, in Patent Document 1, a barge ship type submarine cable laying work ship equipped with facilities for submarine cable laying is moored at a mooring point for the unloading of a cable terminal, and the hull is stabilized by piercing an anchor pad into the seabed ground, and a submarine cable laying method for unloading the cable terminal and laying a submarine cable is disclosed.

Prior Art Documents

Patent Documents

[0006] However, in the barge described in Patent Document 2, the thruster's output is limited because the lower end of the thruster is positioned higher than the bottom of the hull. This presents a problem in that it cannot be applied to large barges or when the weight of the cargo loaded onto the barge is heavy.

[0007] This invention has been made in view of the above problems, and aims to provide a shallow water navigation method that allows a vessel to easily approach the shore, not only for small barges or barges carrying light loads, but also for large barges or barges carrying heavy loads. [Means for solving the problem]

[0008] The invention made to solve the above problems is a shallow water navigation method for a barge, which comprises a hull that floats on water and can carry cargo, a propulsion device for propelling the hull, and a ballast mechanism for adjusting the inclination of the hull with respect to the water surface by changing the position or amount of ballast in the hull, to enter shallow waters connected to the shore. The shallow water navigation method of the present invention includes an inclination step and a propulsion step. The inclination step raises the shore side of the hull higher than the offshore side, which is the opposite side of the shore, so that the hull is inclined with respect to the water surface. The propulsion step propels the hull toward the shore while it is inclined.

[0009] According to the present invention, when the hull is tilted, the draft on the shore side of the hull becomes smaller than that on the offshore side, making it easier for the draft on the shore side of the hull to be shallower than the water depth of the shoal. In this state, as the hull approaches the shore while maintaining its tilted position, it becomes possible to easily bring the hull closer to the shore.

[0010] The shallow water navigation method of the present invention preferably further includes a transfer step of transferring the cargo loaded on the vessel to the shore while the vessel is tilted.

[0011] In the shallow water navigation method of the present invention, the cargo is a cable to be laid on the seabed, and it is preferable that the transfer step further includes a departure step in which one end of the cable is transferred to the shore, and the cable is pulled out and laid on the seabed while the ship is tilted and the ship is moved away from the shore. [Effects of the Invention]

[0012] According to the present invention, as the hull is tilted, the draft on the shore side of the hull becomes smaller than that on the offshore side, making it easier for the draft on the shore side of the hull to be shallower than the water depth of the shoal. Furthermore, since the hull approaches the shore while maintaining its tilted state, the ship can be easily brought closer to the shore. [Brief explanation of the drawing]

[0013] [Figure 1] This shows a barge vessel according to one embodiment of the present invention. [Figure 2] Figure 1 shows a schematic cross-sectional view of a barge's hull as seen from the side. [Figure 3] This diagram shows a schematic cross-section of a barge's hull viewed from above. [Figure 4] This diagram shows a schematic cross-section of a barge's hull viewed from the front. [Figure 5] This shows the hull adjusted to a horizontal position by the ballast system. [Figure 6] This shows the hull adjusted to a tilted state by the ballast system. [Figure 7] This is a flowchart showing a method for navigating shallow waters using a barge according to an embodiment of the present invention. [Figure 8] This diagram shows the inclination step and propulsion step of a barge. [Figure 9] This diagram shows the docking and transfer steps using a barge. [Figure 10] It is a diagram showing the offshore step by the barge ship. [Figure 11] It is a diagram showing a modified example of the propulsion step by the barge ship.

Embodiment for Carrying out the Invention

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

[0015] (Barge ship) FIG. 1 shows a barge ship 10 according to an embodiment of the present invention. The barge ship 10 includes a hull 11, a power plant 30 (see FIGS. 3 to 5), a propulsion device 12, and a ballast mechanism 13. The hull 11 sails in waters such as the sea, river or lake. Hereinafter, the barge ship 10 floating in the sea area Sc will be described as a representative example. The hull 11 has at least a deck 11A and a bottom 11B. In the hull 11 floating in the sea area Sc, the deck 11A is located above the water surface Sf, and the bottom 11B is located below the water surface Sf. The power plant 30 includes, for example, an engine or a motor. The power plant 30 is provided on 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 device 30 and can rotate 360 degrees around the vertical axis to generate a propulsion force in any horizontal direction. In the present embodiment, the propulsion device 12 is disposed so as to be exposed from the hull 11. As an example, the barge 10 is provided with four propulsion devices 12a, 12b, 12c, 12d and power devices 30a, 30b, 30c, 30d respectively connected to the propulsion devices 12a, 12b, 12c, 12d. 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, 12d is directed in the direction opposite to the propulsion direction of the hull 11. The power device 30a and the power device 30c are located between the propulsion device 12a and the propulsion device 12c. The power devices 30b and 30d are located between the propulsion device 12b and the propulsion device 12d. When each screw propeller rotates with the driving of the power devices 30a, 30b, 30c, 30d, for example, the propulsion devices 12a, 12b, 12c, 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 front-rear 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 "backward". Also, the direction that intersects the first direction D1 and is along the water surface Sf is defined as the second direction D2 (FIG. 3), and the second direction D2 will also be described as "sideways" or "lateral". Among the second direction D2, the "right" side toward one side D11 of the first direction D1 is defined as one side D21, and the "left" side toward one side D11 of the first direction D1 is defined as the other side D22. Note that the number of the propulsion devices 12 provided on the barge 10 and the number of the power devices 30 are not limited to four respectively. 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 is the distance from the water surface Sf to the bottom 11B of the hull 11 floating in the sea area Sco, and the inclination of the hull 11 with respect to the water surface Sf. The configuration and principle of the ballast mechanism 13 will be explained later with reference to Figures 2 to 6.

[0018] In this embodiment, the hull 11 of the barge 10 is loaded with a submarine cable 101 for laying on the seabed. 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 is further equipped with a cable laying mechanism 20. The cable laying mechanism 20 is located 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, in which a submarine cable 101 is formed into a coil, is installed on deck 11A. A tower 21 is provided above the cable coil 101C. Meanwhile, a chute 23 is provided at the other end D12 of the first direction D1 on deck 11A. Between the tower 21 and the chute 23, a cable guide 22 is provided to pull the submarine cable 101 from the cable coil 101C and transport it to the chute 23. Specifically, the submarine cable 101 pulled from the cable coil 101C is placed in the cable guide 22 via the tower 21. The submarine cable 101 transported by the cable guide 22 is then paid out from the chute 23 to the seabed.

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

[0022] As an example, five ballast tanks 130 are arranged in a row along a first direction D1, and three ballast tanks 130 are arranged in a row along a second direction D2. In Figures 2 and 3, the multiple ballast tanks 130 are arranged adjacent to each other, but strictly speaking, the multiple ballast tanks 130 are provided while avoiding predetermined spaces located in the hull 11, such as the space for the power unit 30. Also, in Figures 2 and 3, the ballast tanks 130 are depicted as rectangles (cuboids), 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 arranged 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. Similarly, the ballast tanks 130 arranged 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 either takes in seawater from outside the hull 11 to increase the amount of seawater stored in its containment space, or releases seawater stored in its containment space to the outside of the hull 11 to decrease the amount of seawater stored in its containment space. Alternatively, the ballast tank 130 transfers seawater stored in its containment space to the containment space of another ballast tank 130. Hereinafter, the seawater stored in the ballast tank 130 will also be referred to as "ballast water W (Figures 5 and 6)".

[0025] Thus, 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, which in turn changes at least one of the draft ds of the hull 11 and the inclination of the hull 11 with respect to the water surface Sf.

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

[0027] As shown in Figure 5, when the ballast water W contained in ballast tanks 130A to 130E is adjusted to approximately the same amount, the weight balance of the hull 11 in the first direction D1 is balanced between one side D11 and the other side D12. Therefore, the inclination of the hull 11 along the first direction D1 becomes horizontal. Hereafter, the barge 10 with the inclination of the hull 11 along the first direction D1 adjusted to be horizontal will also be referred to as the horizontal state.

[0028] On the other hand, as shown in Figure 6, if the amount of ballast water W contained in the ballast tanks 130A to 130E is increased on one side D11 in the first direction D1, the weight balance of the hull 11 in the first direction D1 will be such that one side D11 is heavier than the other side D12. Therefore, 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 floats higher than the one side D11 of the hull 11. As a result, the inclination of the hull 11 along the first direction D1 becomes tilted with respect to the water surface Sf. Hereafter, the barge 10 in a state where the hull 11 is tilted with respect to the water surface Sf along the first direction D1 will also be referred to as the tilted state.

[0029] Next, the navigation of the barge 10 will be described with reference to Figure 1. As shown in Figure 1, the sea area Sc in which the barge 10 navigates includes a shallow area B1 connected to the shore Ld and an offshore area B2 further from the shore Ld than the shallow area B1. The water depth d2 from the water surface Sf to the seabed 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 seabed of the shallow area B1 becomes shallower towards the shore Ld, and there are areas where it is shallower than the draft ds. For example, the barge 10 navigates with its front facing the shore Ld and its rear facing the open sea, in order to approach the shore Ld.

[0030] In a horizontal barge 10, since the draft ds is constant along the first direction D1, the horizontal barge 10 cannot navigate the shallow area B1 where the draft is shallower than ds, and therefore cannot approach the shore Ld.

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

[0032] (Methods for navigating shallow waters) Figure 7 is a flowchart showing a shallow water navigation method using a barge 10 according to an embodiment of the present invention. The shallow water navigation method of the present invention comprises an inclination step S11, a propulsion step S12, a docking step S13, a transfer step S14, and a departure step S15.

[0033] (Inclined step S11) In the method of navigating shallow waters using a barge 10, the barge 10 performs an inclination step S11 in which the shore side of the hull 11 is raised higher than the offshore side which is the opposite side of the shore side, so that the hull 11 is inclined with respect to the water surface Sf.

[0034] Figure 8 shows the inclination step S11 and propulsion step S12 (Figure 7) performed by the barge 10. In the offshore area B2, the barge 10 adjusts the ballast water W in the ballast tank 130, causing the other side D12 of the first direction D1, which is the shore side Ld of the hull 11, to float higher than the one side D11 of the first direction D1, which is the offshore side of the hull 11, thereby tilting the inclination of the hull 11 along the first direction D1 with respect to the water surface Sf. In other words, the draft ds on the other side D12 of the hull 11 in the first direction D1 becomes smaller than the draft ds on the one side D11 of the hull 11 in the first direction D1.

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

[0036] (Promotion step S12) As shown in Figure 8, the barge 10 maintains its inclination state and drives at least one of the propulsion devices 12a to 12d to propel its hull 11 toward the shore Ld. In this way, the inclination step S11 and the propulsion step S12 are performed using the shallow water navigation method, making it easier for the barge 10's hull 11 to enter the shallow water area B1 and approach the shore Ld.

[0037] Next, as shown in Figure 7, the barge 10 performs a docking step S13, bringing its hull 11 closer to the shore Ld.

[0038] (Docking step S13) Figure 9 shows the docking step S13 and transfer step S14 (Figure 7) by the barge 10. As shown in Figure 9, the barge 10, with its hull 11 propelled toward the shore Ld, docks the other side D12 of the hull 11 in the first direction D1 toward the shore Ld. Here, docking means that the barge 10 approaches the shore Ld to a distance where the cargo loaded on the barge 10 can be transferred between the barge 10 and the shore Ld.

[0039] Next, as shown in Figure 7, the barge 10 performs a transfer step S14 in which it hands over the submarine cable 101 loaded on the hull 11 to the shore Ld.

[0040] (Delivery step S14) As shown in Figure 9, the barge 10, with its hull 11 tilted, transfers one end 101L of the submarine cable 101 loaded on the hull 11 to the shore Ld via a chute 23 (Figure 1) mounted on the hull 11. Specifically, a float (buoy) is attached to the submarine cable 101 as it is unfurled 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 then unloaded at the shore Ld. The end 101L of the submarine cable 101 that has been transferred to the shore Ld is then connected to a predetermined piece of equipment at the shore Ld. In this embodiment, since the transfer step S14 is performed after docking by the propulsion step S12, the hull 11 rises higher than when the barge 10 entered the shallow water area B1, thus further suppressing contact between the bottom 11B and the seabed.

[0041] Next, as shown in Figure 7, the barge 10 performs a docking step S15 in which the hull 11 moves away from the shore Ld while the hull 11 is tilted.

[0042] (Departure Step S15) Figure 10 shows the departure step S15 by the barge 10. As shown in Figure 10, the barge 10 maintains its inclination and drives at least one of the propulsion devices 12a to 12d to propel the hull 11 out to sea. At this time, the cable laying mechanism 20 continues to pay out the submarine cable 101. As a result, the submarine cable 101 is laid on the seabed of area Sc as the barge 10 is propelled out to sea. In this embodiment, since the departure step S15 is performed while laying the submarine cable 101, the hull 11 floats up by the amount of the lowered submarine cable 101, further reducing the possibility of the bottom 11B contacting the seabed when leaving the shore.

[0043] Furthermore, the barge 10 approaches a shore different from shore Ld while continuing to lay the submarine cable 101, and hands over the end of the submarine cable 101 opposite to the end 101L to the shore. At this time, the barge 10 may perform shallow water navigation as it did when approaching shore Ld.

[0044] (modified version) Figure 11 shows 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 in this embodiment, except that the hull 11 is propelled by propulsion device 12e instead of propulsion devices 12a and 12b.

[0045] Specifically, the barge 10 is further equipped with a propulsion device 12e as part of the propulsion system 12. The propulsion device 12c is, for example, a winch capable of winding the wire 12f onto a reel. The propulsion device 12e is positioned, for example, on the deck 11A. When the barge 10 is in a tilting state, it extends the wire 12f to the shore Ld and connects one end of the wire 12f to a structure Lda located 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 is propelled toward the shore Ld. The structure Lda may be an artificial structure such as a bollard (mooring post) installed on the shore Ld, or it may be a natural tree or rock.

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

[0047] Furthermore, although an example was described in which the other side D12 (stern) of the first direction D1 of the hull 11 is the shore Ld side, the orientation of the hull 11 and the shore Ld side are unrelated. Specifically, either the forward or lateral side of the hull 11 may be the shore Ld side, or the hull 11 may be positioned diagonally to the shore Ld to avoid the current, etc. In this case, at the inclined step S11, the barge 10 raises the side of the hull 11 that is on the shore Ld side higher than the side facing the open sea.

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

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

Claims

1. A method for navigating a barge, which comprises a hull capable of floating on water and carrying cargo, a propulsion device for moving the hull, and a ballast mechanism for adjusting the inclination of the hull with respect to the water surface by changing the position or amount of ballast in the hull, into shallow waters connected to the shore, An inclined step that causes the shore side of the hull to be raised higher than the offshore side, which is the opposite side of the hull, so that the hull is inclined relative to the water surface, A propulsion step of moving the ship towards the shore while the ship is tilted. A method of navigating shallow waters using a barge, including this.

2. A transfer step in which the cargo loaded on the vessel is handed over to the shore while the vessel is tilted. The shallow water navigation method according to claim 1, further comprising:

3. The aforementioned cargo consists of cables to be laid on the seabed. In the handover step, one end of the cable is handed over to the shore. The shallow water navigation method according to claim 2, further comprising a step of pulling out the cable and laying it on the seabed while the hull is tilted and the hull is moved away from the shore.

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