3.

3 Berth Structures
• Purpose:
– To provide a vertical front where ships can be moored
for load and unloading operation.

• Classification with respect to their arrangement

relative to shoreline:
– Quay or Wharf : parallel to the shoreline
– Pier or jetty : perpendicular or oblique to
shoreline
– Dolphin : isolated on open sea for mooring
ships
• Classification according to structure
Design Loads
Factors affecting the choice of the type
of berth structure
• Soil Conditions
• Water Depth
• Wave Action
• Resistance to Loads
• Materials
• Underwater work
3.3.1 Wharves
• Platforms or landing places are necessary for ships to
come, close enough to the shore, for purposes of
embarkation, disembarkation, etc. at the same time.
• These platform locations should give sufficient depth
of water for the ship to float.
• Such platforms are, called wharves.
• They are built out into or on to the water
• Thus, a wharf affords a working platform alongside the
ship in continuity of the shore.
• A wharf is quay but the term wharf is generally used
for an open structure of piles or posts with bracings,
jutting from the shore towards the sea.
• A wharf may be a sheet pile wall or it may consist of
a piled projection with or without artificial retention
of soil some distance behind or it may be a gravity
wall.
• Wharves may either be parallel to the shore and
abutting against it or they may project into the
water either at right angles or oblique to the shore.
• The former type is adopted at places where depth
of water is sufficient for the ships to berth, say 10 m
to 12 m.
• The latter type is adopted at places where depth of
water near the shore is not enough for the ships to
enter safely.
• The level of wharf should be above the high
water level. But at the same time, it should be
economical to load the vessels when the water
level is low.
• Wharf should act as a unit when there is an
impact from any vessel.
• Hence, it should be properly braced and bolted. It
is desirable to provide rounded corners for
wharves which art likely to be used by large
vessels.
• Such a construction will result in a smooth entry
of vessels into the slips
3.3.2 Quays
• Wharves along and parallel to the’ shore, are
generally called quays and their protection
walls are called quay walls.
• They are built to retain and protect the embankment
or filling:
– Factors affecting the design are as follows
• Character of foundation;
• Pressure due to water that finds its way to the rear of the wall;
• Effect of buoyancy for the portion of the wall submerged;
• Earth pressure at rear;
• Weight of the wall itself;
• live load of vehicles passing on the platform at the rear;
• dead load of the goods stored on the platform;
• force of impact of vessels; etc.
– Quay wails are designed similar to retaining walls;
– But on the water side, they are subject to varying water pressure (owing
to level variations due to tides), and on the land side, earth and
contained water pressures, with proper allowances for surcharge.
Admiral’s Quay, Southampton
 3.3.3 Piers
• The structures which are built perpendicular or oblique to
the shore of a river or sea are known as piers.
• In the sea the piers are constructed where the sea is not
deep and the natural harbour is not convenient for allowing
the ships to berth adjacent to the shore.
• In many cases, the piers are constructed with piles, columns
and braces leaving good space for the ocean current to flow
without causing any obstruction.
• The dimensions of a pier should be worked out very carefully.
• Its length should be sufficient to accommodate the longest
ship likely to take its advantage.
• In other words, it should project beyond the bow or stern of
the ship so as to protect its hull. Its width should be sufficient
to satisfy its utility.
• It can be stated that the pier should be of sufficient width to
allow easy unloading of cargo without any undue delay.
3.3.4 Jetties
• These are the structures in the form of piled
projections and they are built out from the shore to
deep water and they may be constructed either for a
navigable river or in the sea.
• In rivers, the jetties divert the current away from the
river bank and thus, the scouring action is prevented.
• As the current is diverted to deep waters, the
navigation is also controlled.
• In the sea, the jetties are placed where harbour
entrance is affected by littoral drift or the sea is shallow
for a long distance.
• Thus, they extend from the shore to the deep sea to
receive the ships.
• In a limiting sense, a jetty is defined as a narrow
structure projecting from the shore into water with
berths on one or both sides and sometimes at the end
also.
• Jetties are exposed to severe wave action and their
structural design is similar to that of breakwater.
• However, the designed standards may be released to a
certain extent due to the fact that the jetties are
usually built normal to the most dangerous wave front.
• The impact caused by the berthing ships will depend
on the skill of the berthing officer, local condition of
currents, wind, etc.
• The berthing velocity depends upon the condition of
approach, wind, etc. and it decreases with the increase
in the size of the ships.
Foundation of a Jetty
3.3.5 Fenders

• The cushion which is provided on the face of jetty

for ships to come in contact is known as fender.
• Reasons for installation
1. To absorb berthing impact energy
2. To prevent direct contact between vessels and quay
while the vessel is moored
• Principle:
– To absorb the berthing energy and transmit an
acceptable load to the structure
 Different berth structures results in
different fenders.
But Why?
• Reason through example:
– A solid quay will be able to resist a high horizontal
force, whereas
– Open piled structure must have fenders which
absorb energy and reduce the thrust to the
structure
 Types of Fenders
• Numerous type of fenders such as
– Rubber fenders
– Timber grill
– Pneumatic fenders
– Rubbing strips
– Gravity-type fendering system
• The fender system controls the relative
motion between dock and ship caused by
wind and waves.
• Hence, it also prevents the paint of ships
being damaged.
 Classifications of Fenders
• Rubbing Strips
– In its simplest form, the fender system adopted for
small vessels consists of rubbing strips of timber, coir
padding or used rubber tyres
– It is also convenient to use pneumatic inflated tyres,
either by suspending them or installing them at right
angles to jetty face.
– The inflated big-size tyres are useful to transfer cargo
between mother ship and daughter ships.
– The pneumatic rubber fenders are very useful for
transferring cargo from ship to ship of big sizes.
Pneumatic fenders
• Timber grill:
– This system consists merely of vertical and
horizontal timber members fixed to the face piles.
– This is a simple form of fender and to make it
more effective, energy fender piles may be driven
along the jetty face with cushion or spring
inserted between them.
• Gravity-type fendering system:
– As the ships grew in size, this came into force and
in its simplest form, it consists of a weighty fender
which is raised up when there is an impact of the
berthing ship and thus, the initial energy of shock,
is absorbed.
• Rubber tendering:
– Due to the development of rubber technology and
with, further growth in ship size, rubber fendering
is preferred at present.
– The shapes of rubber fenders may be cylindrical,
square, V-shape or cell type.
 Rubber fender
• These can deflect considerably under load and
return to its original shape after unloading.
3.3.6 Dolphins
• Dolphins are individual mooring points to
which vessels may be tied while waiting to
enter a harbour or a dock.
• They are also used as a guide ships entering
narrow harbours.
• Their construction is similar to that of jetties.
Typical Dolphins