Views: 3992 Author: CTASF Publish Time: 2020-08-03 Origin: China Ship Inspection
About the general principles of mooring rope management:
1. Principles of Rope Management
◉ The goal of good rope management is to ensure that all ropes are as balanced as possible, and to limit the movement of the ship in the berth (leave or move back and forth along the berth).
◉ When using ropes with different lengths and stiffnesses, adjust the rope tension in advance (for example, use a winch to adjust the rope load before the external force is applied), which can reduce the movement of the ship and improve the distribution of the rope load.
◉ The management of the bow and stern cables may cause a series of problems. They should be managed in an operation similar to the inverted or cross cables. The key depends on the longitudinal or lateral restraint of the ship. For example, if the bow encounters a strong longitudinal force. Flow, then the first cable should be pre-twisted, and the stub cable is tightened to offset the slack of the stub cable.
◉ In order to prevent the ship from moving excessively along the berth surface, it is important to distinguish between the inverted line and the horizontal line.
The following general rules apply to rope management:
◉The slack rope should be tightened first. When the environment changes suddenly, the loose rope may cause excessive movement of the ship.
◉ Only one cable can be tightened at a time. When a rope is tightened, it may temporarily change or may increase the load on other ropes. Tightening two ropes at the same time may cause accidental movement of the ship in the berth, causing excessive stress on other ropes and possible loss of mooring ropes.
◉ The inverted cables should be adjusted together, but not at the same time. Care should be taken not to make the ship move excessively along the berth surface to maintain the position of the ship and the oil transfer arm or hose.
2. Use the rope to adjust the operation of the ship when berthing
During mooring operations, it is not recommended to use ropes to adjust the ship's position. Instead, tugboats, main engines or side thrusters should be used to adjust the position of the ship, and the cables should be forced to maintain the position.
If it is unavoidable to use ropes to adjust the ship's position after the ship has been moored, the risk assessment to verify the safest operation method should include the following factors:
◉ Whether the current environmental conditions (weather, tide and tide) are sufficient to ensure that the movement of the ship is always under control.
◉ Is there enough crew to ensure supervision and control of operations?
◉ Whether the operation of twisting the rope to adjust the ship's position is supervised by a senior crew member from a position that can control the overall situation, for example, the bridge.
◉ Whether the risk assessment fully considers the potential needs of using the ship's main engine or thruster, or requiring port tugboats to assist and/or control operations.
◉ In the process of ship displacement, whether the cargo operation has been stopped and/or the oil transfer arm/cargo hose has been disconnected.
◉ Before carrying out the operation of ship displacement, whether the requirements of the terminal or port authority are clear.
Recommendations for ship management:
◉ Vessels should make a reasonable cable plan according to the arrangement of the pier bollards, and ensure that the horizontal cable and the reverse cable have the appropriate cable length and angle. The vertical angle of the horizontal cable and the inverted cable relative to the horizontal has a significant impact on the horizontal, longitudinal and lateral forces shared by the cable. Generally, the horizontal force in these two directions of the ship is mainly borne by the horizontal cable and the inverted cable. However, if the cable length is relatively short and the vertical angle is relatively large, as in the usual way of hanging, the ability to resolve the horizontal force is only It is very limited. At this time, the horizontal components of the two directions are mainly broken down by the first cable and the stern cable. The tightness of the first cable and the stern cable at this time is crucial to whether the ship can effectively close to the dock.
◉ During berthing, generally when the tide height changes greatly, or the ship's draft changes greatly due to loading and unloading, the vertical angle of the mooring rope to the horizontal direction of the wharf is large, and special attention should be paid to checking and adjusting the force of the rope. But when the rope is adjusted, especially when the rope is to be loosened, it should be particularly cautious and judged. Use the cable car to make fine adjustments one by one. It is forbidden to use the brake to slide the rope. At the same time, personnel should be arranged to observe the ship's close to the dock.
◉ When there is a certain angle between the design of the berth and the direction of the rising and falling tides, which causes the current to push away the ship to a certain extent, adjust the horizontal cable and the fore stern cable that bear the lateral force, and the slack cable should be tightened first , Try to balance the force as much as possible, and then appropriately adjust the cables that are too stressed due to changes in tides and draughts according to the situation.
◉ Attention should be paid to the interaction between the bow cable, the stern cable, and the bow and stern cable and the cross cable. When adjusting the cable, it should be considered comprehensively. For example, if the stern cable is twisted too tightly and the force is too large, it will increase the tendency of the ship's bow to drift to the outer gear of the wharf. Similarly, if the bow cable is too loose, or the angle of the bow cable approaching the cross cable cannot share the longitudinal force of the ship, Or the stern cable is too tight, which will increase the load of the stern cable.
◉ Some wharves are equipped with mooring rope load monitoring systems, and ships should reasonably analyze the rope load data provided by the wharf according to the site conditions. The increase in the load of individual ropes may be caused by the lack of balanced force on the ropes in the same direction, or the failure of other ropes that bear the force in the same direction. Tightening these ropes with a smaller load can also make the rope with a larger load. Reduce the load.
Berth mooring management:
◉ For ships mooring at berths, the optimal mooring rope length should be between 35 meters and 50 meters, and the length of the rope with the same function should be equal to ensure the even distribution of the rope force.
◉ In order to maximize the carrying capacity of the mooring rope and minimize the rope adjustments required to adapt to changes in tide and draught, the following points should be considered:
• The vertical angle of the mooring rope should be kept below 25 degrees from the horizontal as much as possible.
• The mooring structure of the horizontal cable and the inverted cable should be kept at a sufficient distance from the direction of the fender to limit the vertical angle of the mooring cable under all tidal and ship draught conditions.
◉ Berth designers should consider the range of ship sizes and types that the berth can accept. Even on ships of the same size, their physical parameters, fairlead positions and mooring equipment will be different.
Monitoring requirements for mooring ropes at berths:
◉ After the ship is secured at the berth, the berth operator should confirm that the arrangement of the rope meets or exceeds the requirements of the dock mooring plan. Not only should the number, strength and direction of the rope be considered, but also the fixing of the rope on the winch drum, the setting of the brake and the state of the winch motor clutch.
◉ Berth operators should also regularly inspect the mooring ropes through visual inspection to monitor the rope management of the ship, especially during cargo operations and when weather conditions change.
◉ In addition to visual inspection, berth operators should consider installing equipment to monitor the load of mooring lines. If the rope load becomes higher or the rope is loose, the berth operator can notify the ship. In some berths, rope load information is transmitted to the ship’s display, which can be read directly by the crew, which helps to ensure that the rope is better managed.
◉ If it is observed that people on board are not doing well in rope management, berth operators may have to take measures, such as stopping cargo operations until the problem is resolved.
◉ No matter where the mooring rope load measuring equipment is installed, the terminal should have operation and maintenance procedures for use, including:
• Alarm settings for high/low tension values.
• What to do in case of an alarm.
• Verification of load accuracy.
Recommendations for the management of the terminal:
◉ Before the ship berths, the dock should review the size of the ship and the arrangement of the mooring equipment. From the length of the parallel body of the ship, the position of the oil pipeline, the position of the fairlead, the length of the cable, the vertical angle of the cable, etc., confirm whether it meets the design of the terminal Claim. At the same time, the berth layout plan is provided to the ship, so that the ship can formulate a preliminary mooring plan according to the position of the dock bollards and the oil delivery arm, evaluate the safety of the mooring, and review the implementation of the plan when berthing.
◉ Wharf duty personnel shall inspect and supervise the mooring rope conditions of ships according to the content of the ship-shore safety checklist. If there is a rope load monitoring system, relevant data and changes shall be provided to the ship in time to help the ship better manage the system. Mooring rope.
◉ Wharf staff must correctly understand the load monitoring data of mooring ropes, know that the load of a certain rope increases, which may be caused by the unbalanced force of other ropes in the same direction, and can promptly remind the ship to check, but should not blindly request the ship Loosen the cables with heavy loads.
◉ The wharf shall prepare emergency plans for the mooring ropes of ships due to severe weather and sea conditions, such as rope breaks, rope slips, etc., which cannot be effectively moored, formulate emergency measures such as emergency pump stop, dismantle oil delivery arms, and arrange tugboat assistance. Control possible pollution risks.
◉ According to MEG4’s 10.3.3 mooring limit principle, terminal operators should formulate corresponding limits for ships mooring at the pier based on quantitative analysis. When the ship reaches or approaches the “sway, pitch, heave” limit At the time of value, take off-berth measures.
◉ For piers equipped with quick-release hooks as shown in the figure below, it should be noted that only one rope can be attached to each hook to ensure the normal function of the quick-release hooks.