What Is Berthing and Unberthing of a Ship?

Berthing and unberthing are the two ends of a ship’s port call. Berthing brings the ship alongside a quay, jetty or pier and makes it fast. Unberthing lets the mooring lines go and takes the ship off the berth.

This guide is written for deck officers, cadets and port staff. It covers the terms, who does what, the step-by-step procedure, the mooring lines and the types of berth.

What Is Berthing of a Ship?

Berthing is the manoeuvre that brings a ship to its allotted berth and secures it until it is all fast. A berth is the place at a quay, wharf, pier or jetty where one ship lies.

A ship can berth port side or starboard side to, or bow or stern on, as in a Mediterranean moor. Ships berth to load or discharge cargo, board passengers, take bunkers and stores, or wait for orders at a lay-by berth. The word also covers an allotted mooring or anchorage position.

Port documents in other languages use their own terms. Spanish uses atraque and desatraque; Indonesian uses sandar and lepas sandar.

What Does Unberthing Mean?

Unberthing is the reverse manoeuvre: the ship lets go its mooring lines and moves off the berth under engines, tugs or both. A ship is unberthed once the last line is clear of the quay.

Unberthing time is the time the last mooring line is let go. The agent and the ship record it in the Statement of Facts, together with arrival, all-fast and cargo times.

Those times matter commercially: they feed laytime, demurrage and berth-hire calculations. Unberthing is not always the same as departure, because some ports record departure when the pilot disembarks or the ship clears the port limits.

Who Is Involved in Berthing and Unberthing?

The master stays responsible for the ship throughout, even with a pilot on board. The pilot advises on local conditions and usually gives helm, engine and tug orders. Tugs, mooring gangs and the terminal do the physical work.

• Master: keeps command. Under the STCW Code (Section A-VIII/2), a pilot’s presence does not relieve the master or watch officer of their safety duties. See the master–pilot relationship.
• Pilot: brings local knowledge of depths, currents and berth layout. The marine pilot and master agree the plan in the master–pilot information exchange before the approach.
• Tugs: push, pull and hold the ship at low speed, when its own rudder has little effect. Port rules often set the number of tugs by ship size and conditions.
• Mooring party on board: officers and ratings at the forward and aft mooring stations handle lines, winches and tug lines, following the agreed mooring plan.
• Linesmen ashore: receive the lines and place the eyes on the quay bollards or hooks.
• Agent, harbour master and terminal: allocate the berth and confirm the time. The ship agent passes berthing orders to the ship and arranges pilots and tugs.

How Is a Ship Berthed, Step by Step?

A ship is berthed in seven stages: preparation, testing, pilot boarding, making tugs fast, the approach, running the mooring lines and making all fast. The pilot and master agree the plan first.

1. Prepare before arrival: the agent confirms the berth, side alongside and time. The ship sends pre-arrival information, including security details under the ISPS Code. The terminal follows the approach on AIS tracking platforms.
2. Test and brief: the crew tests engines, steering and thrusters and prepares the mooring stations. Arrival checklists under the ship’s ISM Code safety management system record these checks.
3. Board the pilot and exchange information: the master gives the manoeuvring data. The pilot gives the berthing plan, tug use and order of lines.
4. Make the tugs fast: tugs connect before the ship enters the basin. A common pattern has the forward tug controlling the bow while the aft tug pushes or holds the stern.
5. Approach the berth: speed comes down in stages, and the ship lands at a small angle to the berth line. Wind, current and tugs then move it sideways onto the fenders.
6. Run the mooring lines: heaving lines carry the mooring lines ashore, and the linesmen place them on bollards in the order the pilot calls.
7. Make all fast: the crew tensions the lines and reports all fast. Tugs are released, the gangway goes down and port formalities begin.

What Decides How the Berth Is Approached?

The approach depends on the environment, the berth and the ship itself. The pilot and master weigh these factors before choosing the side alongside, the tug pattern and the approach line.

• Current and tide: berthing is easier with the ship stemming the current or tide, whichever is stronger, because it acts as a brake.
• Wind: an onshore wind sets the ship onto the berth and helps the landing, but it raises the contact speed. An offshore wind makes holding the ship alongside harder.
• Depth: the ship needs enough under-keel clearance at the berth, allowing for squat on the approach.
• Berth and basin: berth length, distances to ships ahead and astern, and the size of the turning basin.
• Ship handling: the pivot point, propeller transverse thrust, rudder response, astern power and stopping distance. Much of this data appears on the wheelhouse poster.
• Equipment: bow and stern thrusters reduce the number of tugs a port requires.

The berth approach is the last stage of the berth-to-berth passage plan. The pilot’s local plan is added to it when the pilot boards.

How Fast Does a Ship Approach the Berth?

At the moment of contact, a large ship moves sideways at only a few centimetres per second. Fender designers use PIANC berthing-velocity curves, which fall as displacement grows; the table shows the two curves used most often.

Displacement (t)	Difficult berthing, sheltered	Easy berthing, exposed
10,000	0.19 m/s (0.37 kn)	0.29 m/s (0.56 kn)
50,000	0.11 m/s (0.21 kn)	0.16 m/s (0.32 kn)
100,000	0.08 m/s (0.16 kn)	0.13 m/s (0.24 kn)
200,000	—	0.10 m/s (0.18 kn)

Source: PIANC and BS 6349 berthing-velocity curves (Brolsma), as tabulated in a 2026 fender design manual. The values assume tug-assisted berthing; unassisted ships land faster.

Fender design typically assumes a berthing angle between 0° and 20°, with small angles the norm for large ships. A heavy landing at an angle concentrates the ship’s kinetic energy on one fender and can damage both the hull and the berth.

Which Mooring Lines Hold a Ship Alongside?

A ship alongside is held by headlines, breast lines, springs and stern lines at each end. Breast lines hold it against the berth, while springs, headlines and stern lines stop it surging fore and aft.

Line	Where it runs	What it does
Headlines	From the bow, leading forward of the ship	Hold the bow in and stop the ship moving aft
Forward breast lines	From the bow, roughly at right angles to the berth	Hold the bow against the berth
Forward springs	From the forward part of the ship, leading aft	Stop the ship moving ahead
After springs	From the after part of the ship, leading forward	Stop the ship moving astern
After breast lines	From the stern, roughly at right angles to the berth	Hold the stern against the berth
Stern lines	From the stern, leading aft of the ship	Hold the stern in and stop the ship moving ahead

On board, the lines run from mooring winches through fairleads to the shore bollards. The number of lines in each group depends on the ship’s size, the berth and the expected weather.

Since 1 January 2024, amended SOLAS Regulation II-1/3-8 requires all ships to inspect and maintain mooring equipment and lines under MSC.1/Circ.1620. New ships of 3,000 GT and above must have mooring arrangements designed to MSC.1/Circ.1619.

A parting line can snap back with lethal force. Gard and the UK Code of Safe Working Practices treat the whole mooring deck as a danger area, rather than relying on painted snap-back zones.

How Is a Ship Unberthed?

To unberth, the ship tests its engines, boards the pilot, makes tugs fast, singles up and lets go in the agreed order. It then moves off under tugs, engines or a spring.

1. Prepare for sea: the crew completes the departure checklist, tests engines, steering and thrusters, and secures cargo gear and hatches.
2. Board the pilot and make tugs fast: the master and pilot agree the departure plan, including which end leaves the berth first.
3. Single up: the crew reduces the lines to the minimum, typically one headline and spring forward and one stern line and spring aft.
4. Let go: lines are let go in the order the pilot calls and recovered quickly so they cannot foul the propeller.
5. Move off the berth: tugs pull the ship off, or the ship springs off. It holds a forward spring and goes slow ahead with the rudder toward the berth, so the stern swings clear before going astern.
6. Clear the berth: the last line let go is logged as the unberthing time. Tugs are released and the ship proceeds to the pilot station.

What Are the Types of Berths?

Berths are classified by how they are built, the cargo they handle and how they connect to the shore. Most ports combine several types, sited in the most sheltered part of the harbour or in the lee of breakwaters.

Berths by Construction

Solid berths are quay walls with a continuous vertical face, built as gravity walls or sheet-pile walls with filled ground behind. They suit heavy cargo-handling equipment and storage on the quay.

Open berths are decks carried on piles, set out from the natural shoreline so water flows underneath. Their deck load capacity is a design limit, which affects heavy-lift and container stack weights.

Berths by Cargo

• Container berths: long straight quays with ship-to-shore gantry cranes and a container yard behind. They grow longer as container ships grow larger.
• Dry bulk berths: served by grabs, ship loaders and conveyor belts, with stockpiles or silos near the berth.
• Liquid bulk berths: tanker and gas berths with pipelines and loading arms, usually sited away from other traffic for safety.
• General cargo and multipurpose berths: handle break-bulk, project cargo and containers with ship or shore cranes and stevedores.
• Ro-ro and passenger berths: have ramps or linkspans for vehicles and terminals for passengers.
• Lay-by berths: used for waiting, repairs or layup, with no cargo work.

Berths by Shore Connection

Marginal quays run along the shoreline. Finger piers project from the shore like fingers, giving more berth length per metre of waterfront; ferries, small craft and smaller passenger ships use them.

Offshore berths stand away from the shore, mainly for oil and gas cargoes, for safety and deeper water. The ship lies against breasting dolphins fitted with fenders and moors to mooring dolphins with bollards or quick-release hooks.

In port charges, the use of a berth is billed as berth dues or wharfage. These are among the main items in port costs, dues and fees.

Where Is the Berthing Area on a Ship?

A ship’s berthing areas are its mooring stations: the forecastle at the bow and the poop deck or aft mooring deck. They carry the winches, windlass, bitts, fairleads and chocks used to handle lines and tug lines.

These decks get anti-slip coatings and clear walkways because crews work there with lines under load. On board, “berth” can also mean a sleeping bunk, so “crew berthing” refers to accommodation, not mooring.

What Berthing Aids Help Large Ships?

Berthing aid systems use lasers or sonar on the berth to measure the ship’s speed and distance on the final approach. Quay displays show these values, with alarms when speed is too high.

Speed over the ground is the most valuable reading for very large ships. Their kinetic energy at contact must stay below what the fenders and berth can absorb. That speed is hard to judge by eye.

Hull markings support the same job: tug-push marks and no-tug zones on the ship hull markings show where tugs may push without damaging the hull.

What Is the Difference Between Berthing, Mooring and Docking?

Berthing is bringing a ship to its allotted place at a quay or jetty. Mooring is securing it to any fixed point, and docking loosely means coming alongside or entering a dry dock.

Term	Meaning	Example
Berthing	Bringing a ship to its allotted berth and making it fast	A container ship berths at a terminal
Mooring	Securing a ship with lines, chains or anchors to a fixed point	Mooring to buoys, dolphins or a Mediterranean moor
Docking	Coming alongside a dock; also entering a dry dock for repairs	“Dock” is the whole facility; the berth is one ship’s place in it
Unberthing	Letting go and leaving the berth	Last line let go at 06:40

A dock is like a car park, and a berth is one marked space within it. In US usage, “dock” often means the berth itself, so check how the port uses the word.

Related Topics

• How tugboats can pull so much weight
• Maritime Transportation Security Act (US ports)
• What does a longshoreman do

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