3.4 Manoeuvring Merchant Vessels - Berthing and Unberthing
The safe and efficient manoeuvring of merchant vessels is a critical aspect of maritime commerce. This chapter looks at ship handling, with a particular focus on the delicate operations of berthing and unberthing.
Ship Control Systems
Modern merchant vessels rely on a sophisticated suite of systems to facilitate manoeuvring. The primary tools include:
Rudder: This hinged plate at the stern directs the flow of water, influencing the vessel's turning direction.
Propeller: The rotating blades propel the ship forward or backward, providing thrust for movement and control.
Bow and Stern Thrusters: These are transverse propellers positioned at the bow and stern, enabling lateral movement for precise positioning.
Anchors: Large flukes deployed from the seabed to hold the vessel stationary.
The Bridge: Orchestrating Manoeuvres
The bridge serves as the nerve center for all ship operations, including manoeuvring. Key personnel for berthing and unberthing include:
Captain: Holds ultimate responsibility for the vessel's safety and oversees the entire operation.
Chief Officer: Assists the captain and coordinates communication between the bridge and deck crew.
Pilot: A port authority expert with in-depth knowledge of local conditions, often called upon to advise during berthing and unberthing in complex ports.
Deck Crew: Responsible for executing commands from the bridge, operating lines, fenders, and mooring equipment.
Berthing refers to the process of securely mooring a vessel alongside a designated berth at a port facility. Here's a breakdown of a typical berthing operation:
Approach: The vessel approaches the berth at a slow, steady speed, maintaining a safe distance.
Positioning: Using a combination of rudders, propellers, and thrusters, the crew carefully positions the vessel parallel to the berth.
Line Handling: Deck crew secures mooring lines to bollards (heavy posts) on the quayside, ensuring the vessel remains alongside the berth.
Fenders: Inflatable or foam fenders are deployed between the vessel and the berth to prevent damage during contact.
Anchors: Depending on weather conditions and berth configuration, one or both anchors may be deployed for added stability.
Securing: Once lines and fenders are secured, the vessel is considered properly berthed, ready for cargo operations.
Unberthing: Setting Sail
Unberthing is the process of safely departing the berth to resume the voyage. The sequence typically involves:
Line Unmooring: Deck crew carefully unfastens the mooring lines from the bollards in a coordinated manner.
Winch Operation: Winches on board are used to take tension on the lines, slowly pulling the vessel away from the berth.
Engine and Thrusters: Main engines are engaged, and thrusters are utilized to maneuver the vessel away from the berth and into the open water.
Anchor Retrieval: Anchors are raised as the vessel clears the berth area.
Clearance: Once clear of the berth and surrounding obstacles, the vessel increases speed and assumes its designated course.
Challenges and Considerations
Both berthing and unberthing operations present unique challenges:
Environmental Conditions: Wind, current, and water depth can significantly impact manoeuvrability.
Vessel Size and Configuration: Larger vessels and those with limited maneuverability require extra caution and planning.
Berth Configuration: The layout of the berth, including depth alongside and available mooring points, influences the approach and securing procedures.
Communication and Teamwork: Clear communication and coordinated actions between bridge crew and deck crew are paramount for safe and efficient operations.
Advanced Manoeuvring Techniques
In complex situations, advanced techniques may be employed to facilitate berthing and unberthing:
Tugboat Assistance: Tugboats, powerful harbor vessels, can be used to provide additional pushing or pulling force, particularly for large ships or in challenging weather conditions.
Spud Anchors: These temporary anchors are deployed from the vessel's bottom to hold position momentarily during manoeuvring.
Bow Thruster Assisted Turns: By strategically using the bow thruster, the vessel can be "turned on its own axis" within the confines of the berth.