Bulk carriers

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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 or a combination carrier
• (International Convention for the Safety of Life
  at Sea, 1999).

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• dry cargo
• ore
• ore/crude oil
• OBO

• 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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• all kinds of dry cargo in bulk,
• large cargo hold volume,
• hatchways as large as possible, to accelerate the
  discharge of cargo,
• all holds should be self-trimming to facilitate
  loading,
• the number of holds such as to permit the loading
  of various types of e.g. grain and also to ensure
  full holds,
• the ballast capacity should be such as to ensure
  immersion of the propeller and reasonable trim.

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• Bulk carriers of all types have certain features
  in common
• Single cargo deck, without tween decks.
• Machinery aft of cargo spaces so shaft tunnel
  does not interfere with discharging gear.
• Large ballast capacity.
• Double bottoms under bulk cargo holds.
• To facilitate rapid cargo discharge minimise
  cleaning requirements, holds are
• designed with a minimum of internal
  obstructions that might catch and hold cargo.
• Hold cross section, is arranged so that cargo is
  self-trimming and self-loading
• 1. Cargo will flow outwards from the point of
  discharge of bucket grabs or gravity chutes
• to fill the entire cargo space with a minimum of
  hand trimming.2. The narrowing width at the top
  of the hold limits transverse cargo shifts when
  the hold is not completely filled.3. During
  discharge, remaining cargo will flow to a fairly
  small area where it can be picked
• up by the discharging equipment.

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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 a bulk carrier, shaped
  positioned to create a hopper form to the cargo
  hold).

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.
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• Structural configuration

• Single deck ship with a double bottom 1
• Hopper tanks (donji bocni tank) 2
• Single skin transverse framed side shell
  (jednostruka poprecna oplata boka)3
• Topside tanks 4
• Deck hatchways 5
• End brackets (završne konzole) 6
• Corrugated transverse bulkheads (naborane
  poprecne pregrade)7

5.
4.
7.
6.
3.
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
2.
1.
Typical structural arrangement of a bulk carrier
cargo hold space
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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 bocni tank), 4. saddle tank -
serves to shape the upper region of the cargo
hold and trim the cargo, 5. double bottom
ballast tank, 6. Cofferdam (koferdam,
meduprostor, pregrada), 7. wing ballast tank
(bocni 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.
• transverse bulkheads, 5. inner bottom,
• 6. topside and hopper tank sloping
• plating provides boundaries of the
• structure 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 or longitudinal.

3.
6.
1.
5.
6.
2.
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Specific safety concerns related to this type of
ship

• 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 the
  appropriate 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 importance that bulk
  cargoes be properly distributed throughout the
  ship so that the structure is not overstressed
  and the ship has an adequate standard of
  stability. Code of Practice for the safe loading
  and unloading of bulk carriers (resolution
  A.862(20).

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Overloading the cargo in insufficient
draftresults in an excessive vertical load on
the double bottom which may distort the overall
structural configuration
Sheer stress in transverse corrugated bulkhead
Cargo weight
Cargo weight
Buoyancy force
Buoyancy force
Buoyancy force
Sheering of the transverse corrugated bulkhead
the comprehension of the deck
Excessive deformation of the double bottom
structure
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 for
loading/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 operational limits.

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• A cargo loading/unloading plan should demonstrate
  an
• Indication of
• The quantity of cargo the corresponding hold
  number to be laded/unladed.
• The amount of water ballast the corresponding
  tank / hold number to be discharged / loaded.
• The ships draft trim.
• Estimated time for completion of each step.

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Ballast free design allows water to flow into
trunks and to pass out