Marine towing and multi-ship cooperative control method for large-scale culture net cage

Abstract

The present application relates to a kind of large-scale culture net cage sea tow and multi-ship cooperative control method, comprising S1, net cage tow and positioning scheme are made;S2, net cage tow preparation;S3, tow in port;Adopt a three-purpose tug and a harbor tug, three-purpose tug and harbor tug cooperate with each other, tow net cage leaves the wharf, and enters the outport channel;S4, tow outside port;Adopt a three-purpose tug and a harbor tug tow, according to heading and distance, determine the safe speed of navigation and enter safe water area;S5, net cage into court;Cooperative two three-purpose tugs, a harbor tug, a workboat and an engineering ship carry out net cage ship position control and connect four anchor chains prepared in advance, complete large-scale net cage tow and cooperative control installation operation.The present application can safely and effectively carry out sea tow and positioning installation operation for large-scale culture net cage, effectively fill the gap of large-scale culture net cage sea tow and installation positioning technology.

Description

Technical Field

[0001] This invention relates to the field of marine engineering technology, and in particular to a method for the marine towing of large aquaculture cages and the coordinated positioning of multiple vessels. Background Technology

[0002] Marine ranching is a new model of marine economy and a new form of marine industry. In 2023, aquaculture output reached 58.12 million tons, a 4.4% increase compared to 2022, with a net increase of 2.5 million tons. With the continuous transformation of China's aquaculture production towards industrialization and intensification in recent years, deep-sea gravity cages have sprung up in many parts of the country. Cage installation is a key project in the construction of marine ranches, but many technical challenges exist in the process.

[0003] The net cage is a hexagonal column-stabilized frame structure with symmetrical buoys on both sides of the base. After construction at the shipyard, it needs to be transferred to a designated sea area for installation. During construction, the net cage is towed to the aquaculture site. To ensure the structural safety and reliability of the net cage under harsh working conditions, it must be anchored for fixation. However, there are many operational difficulties and safety risks during the towing and positioning of the net cage. Even a slight mistake can cause significant losses. The towing and positioning of net cages at sea is different for marine engineers than for ships or offshore platforms, and the industry lacks mature towing and positioning technologies. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a method for the offshore towing and multi-vehicle coordinated positioning of large aquaculture cages. This method utilizes an engineering vessel, two multi-purpose tugboats, a harbor tugboat, and a workboat to tow and coordinate the positioning of the cages at sea, achieving a safe and effective technical effect for the offshore towing and positioning of large aquaculture cages. This method effectively fills the technical gap in the offshore towing and coordinated multi-vehicle positioning of large aquaculture cages.

[0005] The technical solution adopted in this invention is as follows:

[0006] The present invention proposes a method for marine towing of large aquaculture cages and multi-vehicle coordinated positioning, comprising the following steps:

[0007] S1. Develop a plan for the towing and placement of the net cages;

[0008] S2. Preparation for lifting and towing the cage;

[0009] The net cages need to be prepared in advance with mooring nylon cables, spur cables, and lead cables. The net cages are relatively high, so a three-way tugboat equipped with sufficient special equipment for towing, as well as triangular plates, shackles, and main towing cables required for regular towing, is used.

[0010] According to the construction plan, an engineering vessel and a multi-purpose tugboat II will complete the pre-laying of four anchor chains in the designated sea area so that the cages can be placed and installed as soon as possible after arriving at the designated sea area.

[0011] S3, Inland towing;

[0012] The three-purpose tugboat I and the harbor tugboat are connected to the net cages via towing equipment. The three-purpose tugboat and the harbor tugboat work together to tow the net cages away from the dock and into the outbound channel.

[0013] S4, Outer Harbor Towing;

[0014] The three-purpose tugboat I tows the net cages and assists with the operation of the harbor tugboat attached to the rear of the net cages. During the towing, the buoyancy of the tugboat, towing equipment and net cages is monitored. Based on the course and distance, a safe sailing speed is determined and the vessel enters a safe water area.

[0015] S5, cages arrive at the site;

[0016] Before the net cages were brought into the site, the engineering vessel, with the assistance of the three-purpose tugboat II, completed the anchoring of its six positioning anchors and the pre-laying of the four anchor chains of the net cages. It then waited near the upwind direction of the net cages to be in place to tow the net cages into the site.

[0017] After the net cages enter the site, they gradually approach the engineering vessel. When the three-purpose tugboat I tows the net cages and approaches the engineering vessel on the transverse side, the harbor tugboat tows the net cages close to the stern of the engineering vessel to prepare for the installation of the mooring line. At this time, the net cages are towed to a different location. The three-purpose tugboat II and a workboat stand by near the net cages, ready to assist and respond to emergencies.

[0018] After the net cages are towed, they are pulled back by the harbor tugboat until they are within the range of the stern of the engineering vessel where mooring lines can be attached. At this point, the workboat transports the net cage mooring lines to the engineering vessel. The engineering vessel, in conjunction with the harbor tugboat and the three-way tugboat I, gradually tightens the four mooring lines to a suitable distance. After the net cages are moored to the engineering vessel, the three-way tugboat II retrieves the four pre-laid anchor chains and, in conjunction with the engineering vessel, connects the net cage mooring lines to the pre-laid anchor chains and buoys. During this process, the three-way tugboat I maintains a certain tension to tighten the net cages and, in conjunction with the engineering vessel's mooring lines, controls the position of the net cages to prevent displacement. The engineering vessel, with the assistance of the three-way tugboat I, adjusts the length of the six anchor cables and the positioning anchor to move the engineering vessel and net cages to the vicinity of the pre-laid anchor chain ends. With the assistance of the three-way tugboat II, the connection of the mooring chains and the pre-laid anchor chains is performed, and tension testing is conducted. Once the connection of the four pre-laid anchor chains and the net cage mooring lines is completed and a tensile test is performed, the installation operation is finished.

[0019] Furthermore, in step S1, the scheme includes accurately obtaining various parameters of the cage and determining the type and number of vessels for the towing and positioning stages.

[0020] Furthermore, in step S2, the special equipment for casting the line includes a casting line rope and a casting line gun.

[0021] Furthermore, in step S3, the three-purpose tugboat I tows the net cage through the connection of the mooring nylon cable, the spur cable, the short cable, the triangular plate, the short cable and the main towing cable, and the harbor tugboat hooks the stern of the net cage with the nylon cable to control the navigation and floating state of the net cage.

[0022] Furthermore, in step S4, a steel cable is connected to the temporary anchor chain fixing point of the cage, and the other end is fixed to the root of the eye plate by a steel wire to control the movement of the anchor chain. The remaining part of the anchor chain is laid on the three-way tugboat I and the spare anchor, short cable, buoy and nylon cable are connected.

[0023] Furthermore, in step S4, after entering safe waters, the tow cable length is adjusted in real time according to weather and sea conditions, hydrology, traffic density in the navigation area, water depth and draft, and the magnitude of the towing force used.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. This invention includes key technical points for towing in harbors, outside harbors, and in safe waters, as well as methods for emergency anchoring of net cages, which greatly improves the safety of towing large aquaculture net cages and provides effective protection for the marine towing operation of large aquaculture net cages.

[0026] 2. Before the net cage leaves port and goes to sea, the four anchor chains of the net cage have been pre-laid, and the engineering vessel has prepared to moor the net cage on the upstream side of the two anchor chains. This has bought time to reduce the incomplete controllability of the net cage at sea and avoids missing the best time for the net cage to enter the site and be connected.

[0027] 3. After the cages arrived near the sea placement site, the coordinated operation of an engineering vessel, two multi-purpose tugboats, one harbor tugboat, and one workboat greatly improved the efficiency of cage placement and installation, demonstrating that the placement and construction scheme for this large aquaculture cage has technical characteristics such as clear division of labor and coordinated cooperation. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the pre-laying effect of the anchor chain for the gabion in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the cage towing in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of temporary anchorage of the cage in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the cage entering the site in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the cage turning 90° in an embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of the anchor chain (C11 end) connection in an embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of the cable connection between the net cage and the engineering vessel in an embodiment of the present invention. Detailed Implementation

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] See appendix Figure 1 The specific implementation process of the large-scale aquaculture cage marine towing and multi-vehicle coordinated positioning method proposed in this invention is as follows:

[0037] S1. Develop a plan for the towing and placement of the net cages;

[0038] The voyage mission must be clearly defined, including the start and end points of the towing mission, the shape of the net cage, and any special requirements from the owner. Then, based on its characteristics and the requirements of the towing and positioning tasks, it must be broken down into several stages. For each stage, engineering vessels, tugboats, resources, and towing technical solutions must be rationally configured. The solutions must be optimized in conjunction with local meteorological and hydrological characteristics to ensure optimal safety, economy, and seaworthiness. Accurate understanding of the net cage's parameters—draft, center of gravity height, longitudinal and transverse trim—is crucial to ensure that variable loads meet the towing requirements. The types and quantities of tugboats and engineering vessels, as well as towing equipment, must be determined.

[0039] S2. Preparation for lifting and towing the cage;

[0040] Based on the structural characteristics of the fish cage, a suitable towing connection method is selected. From the fish cage to the three-purpose tugboat I2, the sequence is: mooring nylon cable, keel cable, 5m short cable, triangular plate, and main towing cable. Select appropriate towing points: Two 25m mooring nylon cables are led out from the towing eyeplate at positions C5 and C9 on the three-purpose tugboat I2. The nylon cables are connected to the keel cable. The φ70mm×70m keel cable is connected to the main towing cable using a 125t shackle through a triangular plate (for ease of connection, a short φ70mm×5m steel cable is added between the keel cable and the triangular plate). Simultaneously, harbor tugboat 4 is arranged as an escort vessel.

[0041] The towing connection method of the pontoon cable using a shore crane at the dock involves connecting the anchor chains of two pontoon posts to the trapezoidal opening behind the eye plate, using shackles to connect them to the nylon cable, and then connecting them to the pontoon cable with a 125t shackle. The two pontoon cables are then towed by connecting the triangular plate and the main towing cable. Figure 1 As shown.

[0042] The net cages need to be equipped with mooring nylon cables, spur cables, and lead cables (for return). The net cages are relatively high overall. The three-way tugboat I2 should be equipped with sufficient special equipment for towing, such as towing ropes, towing guns, etc., as well as triangular plates, shackles, main towing cables, etc. required for regular towing.

[0043] According to the construction plan, an engineering vessel 1 and a three-purpose tugboat II3 will complete the pre-laying of four anchor chains in the designated sea area so that the cages can be placed and installed as soon as possible after arriving at the designated sea area.

[0044] S3, Inland towing;

[0045] A three-purpose tugboat I2 and a harbor tugboat 4 were used. The three-purpose tugboat I2 was located directly in front of the net cage, and the harbor tugboat 4 was located on the starboard side behind the net cage. The three-purpose tugboat I2 towed the net cage through the connection of mooring nylon cable, spur cable, short cable, triangular plate, short cable and main tow cable. The harbor tugboat 4 hooked the stern of the net cage with nylon cable to help control the navigation and floating state of the net cage. According to the wind, current and sea conditions at the time, under the command of the pilot, the main tugboat and the harbor tugboat cooperated to leave the dock and enter the outbound channel.

[0046] S4, Outer Harbor Towing;

[0047] 1) The three-purpose tugboat I2 is used as the main tug, and the harbor tugboat 4 is attached to the rear of the net cage as an auxiliary tug to assist in the towing. During the towing, the three-purpose tugboat I2, the harbor tugboat 4, the towing equipment, and the towed net cage are monitored. Based on the course and distance, a safe speed is determined and the vessel enters a safe water area. After entering the safe water area, the towing cable length is adjusted according to the weather, sea conditions, hydrology, traffic density in the navigation area, water depth and draft, and the amount of towing force used. Since the towing of net cages is different from that of engineering vessels or offshore platforms, which can be temporarily anchored by themselves or by stakes to avoid wind, net cages do not have anchoring equipment or stake-insertion equipment. Therefore, temporary anchoring measures need to be formulated according to the characteristics of the net cages.

[0048] 2) Temporary anchorage setup: Connect a φ70mm×35m steel cable to a temporary anchorage point near point C5 of the gabion cage. The other end is secured to the root of the eyelet plate at point C3 with a φ20mm steel wire to control the movement of the anchor chain. Figure 3As shown, a 200m anchor chain is laid on the three-purpose tugboat I2, and a spare anchor is connected. A φ38mm×60m short cable is connected to the crown of the spare anchor. A buoy with a buoyancy of 2t is equipped, with a φ38mm×60m short cable connected to the bottom and a 10m nylon cable connected to the top.

[0049] 3) Deployment and Retrieval of Temporary Anchorage: When the net cage arrives at the temporary anchorage point, the multi-purpose tugboat I2 approaches the net cage and sends personnel onto the pontoon. The control anchor chain cable is released and connected to the winch cable of the multi-purpose tugboat I2. After personnel withdraw, the winch is used to retrieve the anchor chain to the stern deck of the multi-purpose tugboat I2 and secured with shark clamps. The deck anchor chain and spare anchor are connected, and the pontoon is connected to the spare anchor crown. In case of emergency release, the anchor can be pulled directly into the water. When anchoring is required, the harbor tugboat 4 coordinates to control the net cage, and the multi-purpose tugboat 2 first salvages the pontoon. After the pontoon is on the deck, it is released. The working towline is connected to the anchor head short cable to raise the anchor. The anchor is pulled onto the deck, and the shark clamps are used to lock the anchor chain and release the emergency anchor. The vessel uses chain locks to tighten the anchor chain, and then connects the anchor-raising working cable to tighten the anchor chain. After approaching the net cage, personnel board the pontoon to release the anchor chain, completing the retrieval of the spare anchor.

[0050] S5, cages arrive at the site;

[0051] Before the net cages were brought into the site, the engineering vessel 1, with the assistance of the three-purpose tugboat II3, completed the anchoring of its six positioning anchors and the pre-laying of the four anchor chains of the net cages. It then waited near the upwind direction of the net cages to be in place to tow the net cages into the site.

[0052] like Figure 4 and Figure 5 As shown, after the net cage enters the site, it gradually approaches the engineering vessel 1. When the three-purpose tugboat I2 tows the net cage and approaches the engineering vessel 1 on the transverse side, the harbor tugboat 4 tows the net cage close to the stern of the engineering vessel 1 to prepare for the cable-laying. At this time, the net cage is towed back. The three-purpose tugboat II3 and a workboat 5 stand by near the net cage, ready to assist and respond to emergencies.

[0053] After the net cage is towed, it is towed back by the harbor tugboat 4 until it is within the range of the stern of the engineering vessel 1 where the mooring line can be attached. At this time, the workboat 5 transports the net cage mooring line to the engineering vessel 1. The engineering vessel 1, together with the harbor tugboat 4 and the three-purpose tugboat I2, gradually tightens the four mooring lines to a suitable distance. After the net cage is moored to the engineering vessel 1, the three-purpose tugboat II3 retrieves the four pre-laid anchor chains and, together with the engineering vessel 1, connects the net cage mooring line with the pre-laid anchor chain and buoy. During this process, the three-purpose tugboat I2 maintains a certain tension to tighten the net cage and, together with the mooring line of the engineering vessel 1, controls the position of the net cage to prevent displacement of the net cage, which would pose a danger to the three-purpose tugboat II3 in connecting the net cage mooring chain and the pre-laid anchor chain. With the assistance of the three-purpose tugboat I2, the engineering vessel 1 and the net cage were moved to the vicinity of the pre-laid anchor chain end by adjusting the length of the six anchor cables and positioning anchors. With the assistance of the three-purpose tugboat II3, the mooring chain and the pre-laid anchor chain were connected and tension tests were performed. The connection of the four pre-laid anchor chains and the net cage mooring cables was completed and the tensile test was performed. Once the requirements were met, the installation work was completed.

[0054] The cage undergoes a submersion test. After the test, the cage floats to the surface, where acceptance personnel inspect the connection and installation of the cage. Once the inspection is passed, the entire operation is completed.

[0055] The method of this invention solves the problem of towing and controlling the positioning of large aquaculture cages by decomposing the towing and positioning stages and using multiple vessels to coordinate and control the cages for towing and positioning operations. It is suitable for towing and multi-vessel coordinated positioning applications for large aquaculture cages.

[0056] All matters not covered in this invention are common knowledge.

[0057] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for offshore towing of large aquaculture cages and coordinated positioning by multiple vessels, characterized in that, The method includes the following steps: S1. Develop a plan for the towing and placement of the net cages; S2. Preparation for lifting and towing the cage; The net cages need to be prepared in advance with mooring nylon cables, spur cables, and lead cables. The net cages are relatively high overall, so a three-way tugboat equipped with sufficient special equipment for towing, as well as triangular plates, shackles, and main towing cables required for regular towing, is used. According to the construction plan, an engineering vessel and a multi-purpose tugboat II will complete the pre-laying of four anchor chains in the designated sea area so that the cages can be placed and installed as soon as possible after arriving at the designated sea area. S3, Inland towing; The three-purpose tugboat I and the harbor tugboat are connected to the net cages via towing equipment. The three-purpose tugboat and the harbor tugboat work together to tow the net cages away from the dock and into the outbound channel. S4, Outer Harbor Towing; The three-purpose tugboat I tows the net cages and assists with the operation of the harbor tugboat attached to the rear of the net cages. During the towing, the buoyancy of the tugboat, towing equipment and net cages is monitored. Based on the course and distance, a safe sailing speed is determined and the vessel enters a safe water area. S5, cages arrive at the site; Before the net cages were brought into the site, the engineering vessel, with the assistance of the three-purpose tugboat II, completed the anchoring of its six positioning anchors and the pre-laying of the four anchor chains of the net cages. It then waited near the upwind direction of the net cages to be in place to tow the net cages into the site. After the net cages enter the site, they gradually approach the engineering vessel. When the three-purpose tugboat I tows the net cages and approaches the engineering vessel on the transverse side, the harbor tugboat tows the net cages close to the stern of the engineering vessel to prepare for cable-laying. At this time, the net cages are towed to a different location. The three-purpose tugboat II and a workboat stand by near the net cages, ready to assist and respond to emergencies. After the net cages are towed, they are pulled back by the harbor tugboat until they are within a safe distance from the stern of the engineering vessel. At this point, the workboat transports the net cage mooring cables to the engineering vessel. The engineering vessel, in conjunction with the harbor tugboat and tugboat I, gradually tightens the four mooring cables to a suitable distance. After the net cages are moored to the engineering vessel, tugboat II retrieves the four pre-laid anchor chains and, in conjunction with the engineering vessel, connects the net cage mooring cables to the pre-laid anchor chains and buoys. During this process, tugboat I maintains a certain tension to tighten the net cages and, in conjunction with the engineering vessel's mooring cables, controls the position of the net cages to prevent displacement. The engineering vessel, with the assistance of tugboat I, adjusts the length of the six anchor cables and the positioning anchor to move the engineering vessel and net cages to the vicinity of the pre-laid anchor chain ends. With the assistance of tugboat II, the four pre-laid anchor chains and net cage mooring cables are connected and a tensile test is conducted. Once the requirements are met, the installation is complete. In step S3, the three-purpose tugboat I tows the net cage through the connection of the mooring nylon cable, the spur cable, the short cable, the triangular plate, the short cable and the main towing cable. The harbor tugboat hooks the stern of the net cage with the nylon cable to control the navigation and floating state of the net cage. In step S4, a steel cable is connected to the temporary anchor chain fixing point of the cage, and the other end is fixed to the root of the eye plate by a steel wire to control the movement of the anchor chain. The rest of the anchor chain is laid on the three-way tugboat I and the spare anchor, short cable, float and nylon cable are connected. In step S4, after entering safe waters, the tow cable length is adjusted in real time according to weather and sea conditions, hydrology, traffic density in the navigation area, water depth and draft, and the magnitude of the towing force used.

2. The method for large-scale aquaculture cage towing at sea and multi-vehicle coordinated positioning according to claim 1, characterized in that: In step S1, the scheme includes accurately obtaining various parameters of the net cage and determining the type and number of vessels for towing and positioning.

3. The method for large-scale aquaculture cage towing at sea and multi-vehicle coordinated positioning according to claim 1, characterized in that: In step S2, the special equipment for casting the line includes a casting line rope and a casting line gun.

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