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Bulk carriers
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BULK CARRIERS“a ship constructed with a single
deck, top side tanks and hopper
side tanks in cargo spaces and
intended to primarily carry dry
cargo in bulk; an ore carrier; ora combination carrier ”
(International Convention for
the Safety of Life at Sea, 1999).
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dry bulk carrier is used to distinguish bulk carriers from bulk liquid
carriers such as:
• oil,
• chemical, or
• liquefied petroleum gas carriers.
OBO - a bulk carrier which carries a combination of ore, bulk , and oil .
"O/O" is used for combination oil and ore carriers.
VLOC, ULOC, VLBC and ULBC - very large and ultra large ore and bulk
carriers.
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Bulk carriers of all types have certain features in common:
1. Single cargo deck, without ’tween decks.
2. Machinery aft of cargo spaces so shaft tunnel does not interfere with
discharging gear.3. Large ballast capacity.
4. Double bottoms under bulk cargo holds.
To facilitate rapid cargo discharge & minimise cleaning requirements,
holds are designed with a minimum of internal obstructions that mightcatch and hold cargo.
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all kinds of dry cargo in bulk,
large cargo hold volume,
hatchways as large as possible,to accelerate the discharge ofcargo,
all holds should be self-trimming to facilitate loading,
the number of holds such as topermit the loading of varioustypes of e.g. grain and also to
ensure full holds,
the ballast capacity should besuch as to ensure immersion ofthe propeller and reasonabletrim.
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Cross section of a typical bulker
1. Cargo hold
2. Hatch cover
3. Upper hopper tank for water
ballast or oil (uzvojni tank)
4. Double bottom
5. Lower hopper tank, for water
ballast (lower side ballast tank in abulk carrier, shaped & positioned to
create a hopper form to the cargo hold ).
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Hopper hold – found in bulk carriers; they
have the cut-away corners found in some
hoppers behind which are hoppered tanks
used for ballast or for stability when carrying
certain cargo.
http://en.wikipedia.org/wiki/File:Bulk_carrier_midship_section-i18.svg
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Structural configurationSingle deck ship with a double
bottom 1
Hopper tanks (donji bočni tank) 2
Single skin transverse framed sideshell (jednostruka poprečna oplata boka)3
Topside tanks 4
Deck hatchways 5
End brackets (završne konzole) 6
Corrugated transverse bulkheads(naborane poprečne pregrade)7
Typical structural arrangement of a bulk carrier cargo hold space
Corrugated (especially of sheets of iron or
cardboard) having parallel rows of folds which
look like a series of waves when seen from the edge
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1.
2.
3.
4.
5.
6.
7.
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1. side-rolling hatch covers - reduce cargo-handling time during loading and unloading,
2. self-trimming cargo holds,
3. Hoppers (donji bočni tank),
4. saddle tank - serves to shape the upper region ofthe cargo hold and trim the cargo,
5. double bottom ballast tank,
6. Cofferdam (koferdam, međuprostor, pregrada),
7. wing ballast tank (bočni balastni tank).
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A typical transverse section of a
cargo hold
In general
• the plating (oplata): 1. side shell,
2. bottom shell, 3. strength deck, 4. inner
bottom, 5. topside and hopper tank sloping
plating provides boundaries of thestructure & carries static & dynamic
pressure loads exerted by e.g. the cargo,
ballast and the sea.
The plating is supported by secondary
stiffening members such as frames orlongitudinal.
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1.
2.
3.
4.
6.
5.
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Specific safety concerns related to this type ofship Loading of cargo must be done carefully,
ensure cargo cannot shift during a voyage leading to stability problems,
large hatch covers must be watertight and secure.
The International Maritime Solid Bulk Cargoes Code (IMSBC Code), & amendments to
SOLAS chapter VI to make the Code mandatory, were adopted by the Maritime Safety Committee
(MSC), 85th session, in 2008.
The amendments expected to enter into force on 1 January 2011.
The IMSBC Code replaces the Code of Safe Practice for Solid Bulk Cargoes (BC Code), which
was first adopted as a recommendatory code in 1965 and has been updated at regular
intervals since then.
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The aim of the mandatory IMSBC Code is: to facilitate the safe stowage and shipment of solid bulk cargoes by providing information on
the dangers associated with the shipment of certain types of cargo and instructions on theappropriate procedures to be adopted.
The Code
highlights the dangers associated with the shipment of certain types of bulk cargoes, gives guidance on various procedures which should be adopted; lists typical products which are shipped in bulk, gives advice on their properties & how they should be handled, and describes various test procedures which should be employed to determine the characteristic
cargo properties.
The Code contains a number of general precautions & says it is of fundamental importancethat bulk cargoes be properly distributed throughout the ship so that the structure is notoverstressed and the ship has an adequate standard of stability. Code of Practice for the safeloading and unloading of bulk carriers (resolution A.862(20).
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Overloading the cargo in insufficient draft
results in an excessive vertical load on the double bottom which maydistort the overall structural configuration:
Sheer stress
in transverse
corrugated
bulkhead
Cargoweight
Buoyancy force
Buoyancy force
Cargo weight
Excessive deformation of
the double bottom
structure
Sheering of the transverse
corrugated bulkhead &
the comprehension of the
deck
Buoyancy force
Corrugated (especially of sheets of iron or cardboard) having
parallel rows of folds which look like a series of waves when seen from the edge
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Cargo distributions along the ships length – direct
influence on the bending & shearing of the hull girder
& on the stress in the hull
Homogenous hold loading conditions
(fully loaded)
Block hold loading conditions
Alternate hold loading conditions
(fully loaded)
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Stages in the development of a plan forloading/unloading
• 1. given the intended voyage the amount of cargo and/or
water ballast to be carried & imposed operational limits ,create a departure condition: develop a stowage plan.
• 2. given the arrival condition & having the stowage plan,
plan loading/unloading according to imposed operationallimits.
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A cargo loading/unloading plan should demonstrate an
Indication of:
The quantity of cargo & the corresponding hold number to beladed/unladed.
The amount of water ballast & the corresponding tank / hold
number to be discharged / loaded.
The ship’s draft & trim.
Estimated time for completion of each step.
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