Container Ship Cargo Stowage and Planning Procedures
The aim of ship's officers and crew members on board should be to prevent
damage or deterioration while the cargo is under their care and to deliver it, as
far as possible, in as good condition and order as it was when received aboard. If
unacquainted with a certain type of cargo should ascertain as to its nature and
any necessary precautions. Therefore, the Master and officers of all vessels
require a good working knowledge of the various kinds of cargo they are likely to
carry their peculiar characteristics, liability to damage, decay, or deterioration,
their measurement, and the usual methods of packing, loading and discharging,
stowage, dunnage, etc., as the Master is responsible for the safe loading of his
vessel and the proper storage of the cargo.
The actual handling of the cargo in loading and discharging is done by
stevedores, who are experienced men appointed for this purpose when a vessel
arrives at a port. It does not release the Master from the responsibility for the
safety of the ship and cargo, and he must supervise the work of the stevedores for
general safety.
Therefore, during stowage, the first consideration must be given to safety. The cargo must be stowed so that the ship will be stable and seaworthy, and it must be secured in such a manner that it cannot shift if the vessel encounters terrible weather.
The type of vessel, the cubic capacity of her compartments destined for the cargo and the appliances on board or ashore for loading or discharging, as well as the nature of the cargo, influences how to stow the cargo in the best possible manner. The ship must be made neither stiff nor too tender. The next consideration is for the safety of the cargo itself: it must not be damaged by shifting; certain commodities become easily tainted by others; rainwater might penetrate. By appropriate ventilation, condensation or sweating must be prevented. Valuable
cargo may be stolen or broached.
Finally, the Chief Officer must bear in mind the various destinations of the goods
the ship carries, and arrange things, as far as he can, to see that the cargo for a
specific place can be lifted without disturbing the other cargo. The Chief
Officer must watch closely the ship's stability (i.e., what the ship's trim is or how
she is sitting).
Since a ship is supported by fluid pressure, she will incline in any direction
according to the position of the weights placed on her.
The trim, therefore, is the angle that a ship is making, fore and aft, with the water.
The levels are read by numbers painted on the ship's stem and stem. These are
called draught marks. Another word is a heel. It means a list or inclination from
one side to another, caused by loading. The Chief Officer must watch the load
lines. They are welded or punched on and then painted.
Working stowage plans are drawn up to assist in planning. Master plans definitively document the positioning of containers on board.
Fore and aft stowage
Load stowed along the length of the container or the ship. Contrast athwartships stowage. In the context of load securing, it is of utmost importance whether a container is stowed fore and aft or athwartships on a ship. In the case of athwartships stowage, the greatest acceleration forces act on the actual container longitudinally rather than transversely.
Load securing measures must then be taken with this in mind.
Container Stowage (DOORS AFT)
Containers are whenever possible to bestowed with the doors facing aft. However, reefer containers can be stowed doors facing forward as per plug socket arrangements on a case by case basis.
Container Stowage (OPEN TOPS)
Whenever possible, open-top containers on deck are to be stowed in such a position; a standard container can be stowed on top of them. If this is not possible, due to overweights, or any other peculiarities, consideration is given to stowing them with the maximum shelter and all tarpaulin lashings checked and tightened by the stevedores.
Bay-tier-row system
A numbering system for the arrangement of containers on a vessel allows the bay is specified first, then the tier (vertical layer), and finally, the container row, which runs the length of the ship.
According to this principle, bays are the container blocks in the transverse direction; rows are the lengthwise rows and tiers are the vertical layers.
Cargo information
Goods can be rendered fit for container transport by taking into account individual transport information relating to loss prevention. Fitness for container transport may depend on the season or the route the cargo will take over land or sea. It must be adapted to the conditions of the transport route.
The cargo information may also be helpful when considering how best to utilize a standard container or the possible use of other container types.
Fig: Lashing bridge at containership
Transport requirement
Individual packages are known as general cargo, which may be divided, depending on atmosphere requirements (natural, partially air-conditioned or temperature-controlled atmosphere), into general cargo, general cargo requiring ventilation and refrigerated cargo, which place corresponding requirements on containers (general-purpose container, ventilated container, refrigerated container), or indeed into further sub-categories .
Compatibility characteristics
If goods are to be stowed together when packing a container, the interrelationships between the transport properties of products must be taken into account, since disregarding them may result in quality degradation and damage. Goods may react with one another and possibly with their environment.
principles of stowage
When stowing and securing containers, the following points should be borne in mind:
a deck stack of containers is only as strong as the weakest component in that stack.
Premature failure of a component can cause loss of an entire stack. During loading,
containers should be inspected for damage and, if damaged, they should be rejected
twist locks limit vertical and transverse movement. Diagonally crossed lashing rods, placed
at the ends of a container, can withstand large tensile loads
outside lashings are sometimes used. These are lashings that lead away from a
container. However, although this arrangement provides a more rigid stow than a
combination of crossed lashings and twist locks, it is less common
containers exposed to wind loading need additional or stronger lashings. When carried in
block stowage, it is the outer stacks that are exposed to wind loading. However, when
carried on a partially loaded deck, isolated stacks and inboard containers can also be
exposed to wind, in which case, additional lashings need to be applied
if containers of non-standard length, that is, 45, 48 or 53 feet are carried, the ship
arrangement will need to be specially adapted
45-foot containers fitted with additional corner posts at 40-foot spacing can be stowed
on top of 40-foot containers. Lashings can be applied in the normal way. It should
be noted, however, that the new corner posts may not be suitable for carrying
the required loads, either from the container or from those stowed above.
Lashings should not be applied to the overhang. The container specification and the
Cargo Securing Manual should be consulted
40-foot containers may be stowed on top of 45-foot containers. However, this
arrangement of stowage will present difficulties in fastening/unfastening twist locks, and it
will not be possible to apply lashings to the 40-foot containers
when carrying over-width containers, for example 45-foot or 53-foot containers with
width 8' -6", adaptor platforms may be used. These must be certified by a class society or
an appropriate recognized body. The arrangement must be defined and approved in the
ship's Cargo Securing Manual
twist locks should always be locked, even when the ship is at anchor, except during
container loading and unloading. Lashing rods should be kept taut and, where possible,
have even tension. Lashing rods should never be loose, nor should they be overtightened.
Turnbuckle locking nuts should be fully tightened
as a ship rolls, pitches and heaves in a seaway, tension, compression and racking forces
are transmitted through the container frames, lashings and twist locks to the ship's
structure. However, clearances between securing components and the elasticity of the
container frame and lashing equipment produce a securing system that forms a flexible
structure. Thus, a deck stow of containers will move
containers can be held by only twist locks when two or three tiers are carried on deck,
depending upon container weights
arrangements with automatic and semi-automatic twist locks are used to reduce time
spent securing the stow and to eliminate the need for lashers to climb the stacks
Checks and tests during discharge and loading
regularly examine lashing components that look for wear and tear, as well as damage or distortion.
Check that left-hand and right-hand locking twist locks are not being mixed in the same
storage bin. Remove from the ship any lashing component found to be worn, damaged
or distorted
make arrangements for some damaged or distorted lashing components to be sent for
non-destructive testing. It will determine their strength and help to establish
replacement criteria
carefully check twist locks that stevedores return to the ship as the locks might not
originate from own ship, that is, their strength and locking direction could differ
discourage stevedores from treating lashing equipment roughly as this can induce
weakness
examine dovetail foundations, D rings and pad-eyes for damage. Repair if the damage is
found
observe the loading of containers to determine if stowage is in accordance with the
stowage plan and that best practice is always followed
observe the application of lashings to make sure that they are correctly applied in
accordance with the requirements set out in the Cargo Securing Manual
Checks and tests at sea
24 hours after sailing, examine, check and tighten turnbuckles. Check that lashings are
applied in accordance with the Cargo Securing Manual and that twistlocks have been
locked
examine lashings daily. Check that they have not become loose and tighten turnbuckles
as necessary
before the onset of bad weather, examine lashings thoroughly and tighten turnbuckles,
being careful to keep an equal tension in individual lashing rods. If necessary, apply
additional lashing rods to the outboard stacks and to stacks with 20-foot containers in
40-foot bays
re-check lashings after passing through bad weather
make sure that lashing equipment that is not in use is correctly stored in baskets or racks
make an inventory of lashing equipment and order spares before they are needed
check that refrigerated boxes remain connected to the ship’s power supply
Additional guideline while planning a container cargo stowage plan:
Containership operation : Cargo Securing There are six degrees of motion at sea that a ship may have to encounter in a voyage. However, pitching, heaving, and rolling are three major forces that impact most on a containership's lashing arrangement. Lateral rolling motion factors the greatest challenge for piles of containers. If containers are to be carried safely on the deck of a container vessel, they must be tightly connected to the ship. It is done with the aid of devices known as twist locks.
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Containership operation : Common reasons for stowfall
Container stows often fail due to container stacks being too heavy and too high overall, exposing the lower containers to excessive transverse racking and compressive forces due to the tipping effect. Such an anomaly may occur if the ship is unable to calculate the forces acting on stow with precision. The Cargo/Container Securing Manual is limited in this respect as the examples of container weight distributions shown may not cover all permutations and eventualities. Software programs have the advantage of taking into account all known variables........
Containership operation: Cargo hold ventilation
Cargo holds ventilation onboard a containership is very important as it minimizes the risk of harm or damage to cargo. A proper ventilation system assures the quality of the transported goods by preventing the formation of condensation in cargo spaces, reducing the harmful heating of the shipment, and removing potential hazardous gases from cargo spaces........
Containership operation: Safety of personnel
In port stevedores board the vessel for lashing, unlashing and cargo operations and their safety whilst on board is the vessels responsibility. It is important to understand that any injury caused to stevedores or shore personnel due to a condition on board being unsafe, can result in very large claims to the vessel.
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Containership operation: wet damage in cargo hold When water entered into a ship's cargo, hold it may cause wet damage to the cargo inside containers especially to those stowed on the bottom stack, unless the bilge water is drained in a proper and swift manner. The regular sounding of bilge well or monitoring bilge alarm must be one of the very important or rather essential routine jobs on board. However, this job requires special attention on board. All bilge alarm need to be tested regularly......
Reefer cargo care at sea Unlike permanent cold stores or refrigerated ships, where robust equipment is under constant care by qualified personnel, the ISO refrigerated container may travel by several different modes and be in the care of many and varied people. Before being despatched to load refrigerated cargo (usually at shippers' premises), the container and its machinery should be subjected to a rigorous examination.......
Containership cargo stowage and planning Master and officers of all vessels require a good working knowledge of the various kinds of cargo they are likely to carry their peculiar characteristics, liability to damage, decay, or deterioration, their measurement, and the usual methods of packing, loading and discharging, stowage, dunnage, etc., as the Master is responsible for the safe loading of his vessel and the proper storage of the cargo......
Stacking Weights Restrictions
rior loading cargo, stacking weights of containers must be checked against the allowable stack weights on board the vessel both on deck and under deck. Neglecting above may cause serious damage to ships structure, hull and eventually overall stabilty of ship may get affected. Maximum allowable stack weights of Tank tops, Hatch covers and Decks shall not be exceeded at any time......
Lashing strength calculation Lashing strength of deck cargo shall be ascertained by using the appropriate lashing strength calculation software where provided. All resulting values for lashing strength must be within the tolerance limits prescribed by the vessels classification society......
Dangerous goods stowage and segregation Clear guidelines apply to the stowage and segregation of Dangerous Goods and in some cases may require particular commodities to be carried in completely separate holds. The interaction of two cargoes will not occur if the packaging of that cargo remains intact. However, the Master must always consider the possible effect should the cargo escape for any reason and should not restrict his consideration to those cargoes which are listed in the IMDG Code......
Reefer Container Stowage
Reefer containers proposed for stowage must be accompanied by a reefer manifest. This reefer manifest should contain Container No., Stow position, Commodity, Temperature, and Ventilation status......
Out of Gauge Container Stowage
It is essential that, during out of gauge cargo operations, a careful watch is kept for any damage caused to the vessel, her equipment, or to containers. Notice of any damage must be immediately brought to the attention of the Stevedore's representative, the Port Captain/Supercargo and Charterers Agent. Damage reports must be completed in all cases giving the full and comprehensive details of damage caused......
Special Container Stowage After receiving stowage plan ships, Chief Officer must ensure that all Deck Officers are aware of any specialized containers due to be worked, such as reefers, vents, over-heights, over-widths, flat racks, etc. and their unique requirements.....
20 or 40 or 45 feet Compulsory Stowage Locations
Most cargo securing manual provide a guideline for different container types. These stow positions of 20 feet,40 feet, or 45 feet are also incorporated in a ship-specific stowage planning software and highlight errors if any violations occur......
Irregular Stowage of Containers
The Terminal Planner shall present the pre-loading plan to the Chief Officer to obtain his approval/comments. The Chief Officer, in turn, enters the cargo data in the loading computer and must ensure that the required criteria, concerning stack weights, trim/stability/stresses/ visibility limitations, DG cargo segregation, and specialized container requirements, are met. He should allow the bunker/freshwater consumption during the voyage and all possibilities of ballasting / deballasting. The completed loading plan must be presented to the ship's Master for approval.....
Over-stow of Containers With a closed roof, the hardtop the container offers the same reliable protection as provided by a standard box. Hardtop containers have more lashing points than other container types. This guaran- tees reliable and convenient securing of cargo.
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Other matters regarding cargo stowage as necessary Bulk products carried in a closed container might include malt, grain, seed, polythene granules, chemically inert powders, brake fluid, detergent, fruit juice, wine, non-hazardous oils, sodium silicate, fatty acids and maple syrup amongst many others......
Our additional pages contain somewhat larger lists of resources where you can find useful informations
Container handling more info pages:
Definition of various containers in containership The exterior dimensions of all containers conforming to ISO standards are 20 feet long x 8 feet wide x 8 feet 6 inches high or 9 feet 6 inches high for high cube containers.
Some of the most commonly used types are:Read more......
Containers are standardized cargo units. They are manufactured in a large variety of sizes and types, each designed to meet specific cargo and transportation requirements. Their length is usually 20 or 40 feet, although longer containers are used, principally in the US trade; these containers are 45, 48 and 53 feet long.
Read more......
Containership advantages : In principle they are boxes or containers within a box. These boxes or containers have dimensions of 2.60 x 2.45 m with lengths of 6.10, 9.15 and 12.20 m. Containers are made in steel, aluminium or GRP. They are also of refrigerated design, thus advantageous for long voyages between Australia or New Zealand and the UK. Read more......
Containership cargo stowage and planning : When considering acceptability of a container cargo stowage plan, the following procedures / guidelines concerning cargo stowage shall be taken into account:
Stacking Weights Restrictions,
Lashing strength calculation,
Dangerous goods stowage and segregation,
Reefer Container Stowage ,
Out of Gauge Container Stowage , ....Read more......
DG cargo handling - IMDG code guideline :The general provisions for segregation between the various classes of dangerous goods are shown in "Segregation table" (IMDG Code Chapter 7.2.1.16). In addition to the general provisions, there may be a need to segregate a particular substance, material or article from other goods which could contribute to its hazard. Read more......
How to avoid irregular stowage of containers ? Stowage plan must be checked for any irregular stowage like those mentioned here :
Stacking Weights,
Lashing Strength,
Special Container Stowage,
Over-stow of Containers,
Dangerous Cargo Stowage & Segregation,
20 or 40 or 45 feet Compulsory Stowage Locations,
Hatch Cover Clearance (High cube containers Under Deck ),
Out of Gauge Container Stowage etc.Read more......
Measures against lashing failure : Lashing strength of deck cargo shall be ascertained by using the appropriate lashing strength calculation software where provided.
All resulting values for lashing strength must be within the tolerance limits prescribed by vessels classification society.Read more......
Reefer container stowage guideline : Reefer containers proposed for stowage must be accompanied by a reefer manifest. This reefer manifest should contain information regarding Container No., Stow position, Commodity, Temperature and Ventilation status. Read more......
Care of Reefer container during sea passage :Reefer containers require special care after they are loaded on board ship. These containers need to be supplied with power, monitored closely for proper function and repaired as required in case of malfunction. Read more......
Container ships procedures for securing for sea :All movable items on deck, inside accommodation and in E/R spaces, including under-deck passages and steering flat are firmly secured. Any unsecured items, in heavy weather, risk not only being damaged themselves, but could also pose a danger to vessel safety by violent contact with sensitive equipment or fittings.Read more......
Cargo securing procedure for container ship :Securing equipment will vary depending on the type of ship but is likely to include;
Twistlocks Lashing bars Turnbuckles Extension hooks Stacking cones (single and double) Twist Stackers Lashing D rings Shoes/Sockets for base twistlocks ...Read more......
Containership operation -Check items upon completion of repair works
: As the nature of container ship operation, it’s tread to be lack of stability, due to Top Heavy Load, the Master shall always take special attention for her stability. Also the Master should remind factors to cause reducing stability more such as Alternating course with Big angle of Rudder, Towing by tugs at the scene of Berthing / Un-berthing, etc. Read more......
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