Views: 0 Author: Site Editor Publish Time: 2026-09-15 Origin: Site
Watching a large ship approach a berth can make the final few meters look almost impossible.
A vessel weighing tens or even hundreds of thousands of tonnes is moving toward a concrete or steel structure. Even at very low speed, it carries considerable kinetic energy.
So what happens when the ship reaches the dock?
In a normal controlled berthing operation, the ship should not simply “hit” the quay.
Instead, a marine fender system compresses between the ship and berth, absorbs part of the vessel's kinetic energy, controls the reaction force, and protects both structures from direct impact.
Understanding this process explains why ports use large rubber fenders, steel panels, plastic face pads, and mooring bollards along their berths.
Table of Contents
During normal berthing, the objective is controlled contact.
Pilots, tugboats, thrusters, engines, and mooring teams work together to reduce vessel speed before contact.
The final transverse velocity is usually very low compared with normal sailing speed.
But low speed does not mean zero energy.
The vessel still needs to transition from moving toward the berth to being stationary alongside it.
The fender system helps manage that transition.
Kinetic energy depends on both mass and velocity.
A large commercial ship can have enormous mass.
So even when moving sideways very slowly, it can still carry enough energy to damage:
concrete quay walls
piles
dolphins
hull plating
berth equipment
The goal is therefore not simply to stop the ship as quickly as possible.
Stopping it too abruptly would create a very large reaction force.
Instead, the fender needs to deform in a controlled way.
Think of the difference between:
stopping on a hard wall
and
stopping against a large engineered spring
A marine rubber fender performs a similar cushioning function, although real fender behavior is more complex.
A fender system primarily needs to balance two requirements:
The fender must have enough energy capacity for the design berthing event.
It must not transfer excessive force into:
vessel
panel
anchor system
berth structure
This balance is why fenders are rated using both:
energy absorption
and
reaction force
Choosing only the fender with the highest energy rating can be misleading if its reaction exceeds structural or hull limits.
Different rubber fenders deform in different ways.
These are buckling-type fenders.
As the vessel pushes against the panel, the rubber unit compresses and changes shape.
The geometry is designed to achieve a useful relationship between:
deflection
energy absorption
reaction force
CMR's Cone Fender and Cell Fender systems are typical heavy-duty examples for commercial terminals.
These simpler profiles are often used where load requirements and installation geometry are different.
They can suit:
smaller berths
workboats
quay edges
general protection
These use compressed air rather than rubber buckling as the primary energy-absorbing medium.
CMR's Pneumatic Fender range is commonly associated with floating applications and ship-to-ship operations.
When the fender compresses, it pushes back.
This is the reaction force.
That force passes through the fender into both:
the ship
the marine structure
If reaction force is too high, potential problems include:
excessive hull pressure
anchor overload
panel damage
quay structural stress
The ideal fender therefore does not simply “feel soft.”
It provides enough controlled resistance to absorb the required energy without creating unacceptable loads.
On heavy-duty fender systems, the vessel does not usually press directly against a small rubber surface.
Instead, the rubber unit supports a large steel frontal panel.
CMR's Frontal Panel is designed to distribute the reaction force from the fender unit over a larger area of the ship's hull.
The front of that steel panel can be covered with UHMW-PE pads.
These pads serve another purpose:
reduce friction.
When the ship moves slightly along the berth, a low-friction facing allows sliding without transferring excessive shear into the rubber fender.
So a complete system may look like:
ship hull → UHMW-PE pad → steel panel → rubber fender → anchors → quay
Every part matters.
Once transverse movement has been controlled, the job shifts from berthing to mooring.
Fenders are not meant to hold a ship permanently in position by themselves.
Mooring lines connect the vessel to bollards on the berth.
CMR's Bollard range includes hardware used to secure vessels after berthing.
The mooring system limits longitudinal and transverse movement caused by:
wind
current
passing vessels
tide
The fenders remain between ship and berth to protect against continued contact.
So the two systems have different jobs:
Fenders: manage contact and protect structures
Mooring: control vessel position
An undersized fender can reach its maximum useful compression before the vessel's energy has been safely absorbed.
Potential consequences include:
fender over-compression
high reaction load
anchor damage
frontal-panel damage
direct structural contact
vessel hull damage
This is why fender sizing should be based on design conditions rather than copying what was installed at another port.
Two vessels of similar length can produce different berthing requirements because of differences in:
displacement
velocity
hull shape
tug assistance
Direct contact between a ship and rigid quay can be severe.
Possible damage includes:
dented hull plating
damaged coatings
cracked concrete
damaged steel structure
equipment damage
Even if one low-speed contact does not produce catastrophic failure, repeated direct contact can create long-term wear.
Ports therefore use fenders to create a replaceable energy-absorbing interface between two very expensive structures.
The fender is designed to take wear and deformation so the ship and berth do not have to.
There is no universal port fender.
Different terminals use different systems.
Application | Common Fender Options |
|---|---|
Container terminal | Cone, Cell |
Bulk terminal | Cone, Cell |
Tanker berth | Cone, Cell, Pneumatic |
Tug/workboat berth | D, Cylindrical, Arch |
Ferry/RoRo | Cone, Cell, specialized systems |
Ship-to-ship | Pneumatic, Foam |
For a broader overview, CMR's marine fender selection guide explains how operating conditions influence fender choice.
In a controlled berthing operation, ships approach at very low speed. However, their large mass means even low-speed contact can involve substantial energy.
They help absorb berthing energy and reduce impact loads. Vessel speed is primarily controlled before contact by navigation, propulsion, thrusters, and tugs.
Rubber can deform repeatedly and absorb energy while returning toward its original shape.
The panel distributes reaction force over a larger hull area.
They are commonly UHMW-PE face pads, used to reduce friction between ship and fender panel.
Mooring lines attached to bollards control the ship's position after it is alongside.
When a ship reaches a dock under normal operating conditions, the process should be controlled rather than violent.
The vessel's remaining berthing energy is managed through a carefully designed chain:
ship → fender panel → rubber fender → berth structure
Then the mooring system takes over to keep the vessel in position.
That is why marine fender engineering is not simply about placing “big rubber blocks” along a quay.
The system needs to balance:
energy absorption
reaction force
hull pressure
friction
supporting structure
vessel geometry
Explore CMR's complete marine rubber fender range, including cone, cell, pneumatic, cylindrical, and profile fenders for different port and vessel applications.
