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MarineOutfittings Prof.Dr.YousriWelaya
Cargo Handling
Cargo handling is usually divided into four phases:-
Terminal storage Transfer from storage area to apron cargo hook
Hook to hold Stowage of cargo
When ordering a new ship the ship owner normally specifies the
number, safe working load, position and any special features of the
cargo handling derrick to be fitted.
Cargo handling can be divided into the following categories:
1. DERRICK RIG SYSTEMS
Although gradually being ousted by deck cranes, this system has
been the most popular method of handling cargo.
a) Fixed Outreach Systems
The union purchase system is the most common outreach
system.
The system utilizes two derricks and two winches with the
derrick in fixed positions. One derrick is arranged over the
quayside and the other over the hold. By a combination of hoisting
on both winches and hoisting on one winch and
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MarineOutfittings Prof.Dr.YousriWelaya
2. HEAVY LIFTING SYSTEMS
The conventional method of lifting heavy loads is shown in
figure and consists of one or two hoisting winches lifting on a
multi-fall system. In addition, the topping and slewing motions
operate through a multi-part rope system to ensure control of the
load all the time.
The introduction of patented heavy lift systems (and the
introduction of heavy deck cranes) has created a decline in the
heavy lift derrick. A typical patented heavy derrick is shown in
figure below (Stlken Derrick). With this system loads up to 300
tonne can be lifted and it has the unique advantage of being able
to operate in two holds. It is positioned between two outwardly
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MarineOutfittings Prof.Dr.YousriWelaya
Special precautions have to be taken when lifting heavy loads to
ensure adequate stability of the vessel and correct functioning of
equipment as angles of inclination up to 17o could be
encountered.
The yo-yo arrangement
For loads heavier than the safe working load of a single
derrick, two derricks coupled together by a yo-yo arrangement may
be used. The derrick heads must be kept close together during
operation.
3. DECK CRANES
This is the most recent method of handling cargo onboard ships.
They have the following advantages:
Rigging time is negligible, i.e. port time is reduced
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MarineOutfittings Prof.Dr.YousriWelaya
The safe working load can range from 25 to 90 tonne and the jib
radius from 20 to 35 m. For heavy lift cranes these values could
reach 350 tonne and 60 m.
Spotting cargo very accurately Readiness for action They require
only one operator They provide more usable deck space and greater
visibility from the bridge Greater safety is inherent in the crane
over conventional cargo gear The cranes operating gear and controls
can be located within a protecting
enclosure. This protection reduces maintenance and provides
protection for the operator
However, cranes are perhaps less efficient with light loads. For
large beam ships if the cranes are positioned on the ships
centerline, they may require an extremely long jib. Therefore,
fixed cranes, one at each end of the hatch, may be placed at
opposite corners.
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MarineOutfittings Prof.Dr.YousriWelaya
As shown in figure a typical crane consists of a jib which can
be lowered to the horizontal for stowage purposes, and a hoisting
unit which can be on a single fall of rope or multi falls depending
on the lifting capacity. Facility is provided for slewing the crane
through 360o. The main specifications of a deck crane are the
hoisting capacity in tonne, the jib radius in m, and the hoisting
speed in m/min.
Some of the patented deck cranes are shown below. They are all
designed to meet the rules of all classification societies and
regulatory bodies.
MacGregor Compact and Slim Crane
These electro-hydraulic cranes are intended for various duties,
particularly where dimensions must be compact and air-draft is
limited. These cranes can be equipped with the tools needed for
handling various cargoes, such as containers or bulk materials. The
standard range covers lifting capacities from 36 to 45 tonnes.
Outreaches are between 20-34 m.
MacGregor Container and Multipurpose Cargo Crane
These electro-hydraulic cranes are self-contained units with all
machinery enclosed in the crane house. This protects it from the
weather, corrosion and damage. The standard GL range covers lifting
capacities from 25 to 90 tonnes, with outreaches up to 32 m.
Hoisting, luffing and slewing motions are
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MarineOutfittings Prof.Dr.YousriWelaya
independent of each other. This means that at their maximum
capacity GL cranes can operate at full speed using all three
movements at the same time.
MacGregor Heavy Lift and Multipurpose Crane
The standard range covers lifting capacities from 120 to 350
tonnes, with outreaches up to 36 m. Like the previous type,
hoisting, luffing and slewing motions are independent of each
other.
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MarineOutfittings Prof.Dr.YousriWelaya
Liebherr Articulated Deck Crane
This is a double girder container crane especially designed for
use in harbour complexes where high turnover and continuous
operation are required. The control of the turntable ensures the
unchanged position (rotation axis) of the container during loading
and unloading. Driver's cabin is positioned on the underside of the
container rotating arms allowing unrestricted view of the
containers.
Liebherr Heavy Lift Deck Crane
This crane is designed for installation on heavy lift vessels a
well as multi-purpose vessels providing the following
advantages:
Low height allowing for better visibility from the bridge.
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MarineOutfittings Prof.Dr.YousriWelaya
Low weight and centre of gravity leading to improved vessel
stability and moreover increased cargo capacity.
Liebherr Wire-Luffing Cranes
These are designed for bulk and container handling with the
following advantages:
Hydraulic control instead of electronic. Jib brackets are
directly integrated in jib beam for higher rigidity. Wire sheaves
inside beam for better protection.
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MarineOutfittings Prof.Dr.YousriWelaya