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Risk of Heavy cargoes loaded in Bulk carriers & deviation from the loading limitations


In most cases in which bulk carriers have been lost, heavy cargoes such as iron and other dense ores are a common factor. Ships are also vulnerable when carrying certain break-bulk cargoes such as steel products. This could include other ship types.



The small volume taken up by the cargo in the ships' holds results in a large unoccupied space. This provides potential in a flooding scenario for large volumes of water to rapidly destroy the ship's residual buoyancy and, in the case of smaller vessels, its stability. Larger vessels are also highly susceptible to structural failure due to increases of weights caused by the influx of water.

Heavy cargoes place high loads on the structure, and structural failure is therefore more probable when subjected to the additional forces associated with flooding.


Monitoring the Ship's Loading limits

Exceeding the permissible limits specified in the ship's approved loading manual will lead to over-stressing of the ship's structure and may result in catastrophic failure of the hull structure. When deviating from the cargo load conditions contained in the ship's approved loading manual, it is necessary to ensure that both the global and local structural limits are not exceeded.

It is important to be aware that over-stressing of local structural members can occur even when the hull girder still water shear forces (SWSF) and bending moments (SWBM) are within their permissible limits. Exceeding the maximum permissible cargo load in any hold will lead to over-stressing of local structure. Over-stressing of the local structure will occur when:-

1) The weight of cargo loaded into a hold exceeds the maximum permissible value specified at full draught.

2) The weight of cargo loaded into adjacent holds exceeds the maximum combined value at full or reduced draught.

Over-stressing of the local structure may also occur when the weight of cargo loaded into an individual hold has insufficient support of upward buoyancy force; this circumstance can occur when cargo is transported by the ship in a shallow draught condition (for example, partial load condition with some holds full and remaining holds empty).


Bulk carrier Grand Glory preparing for loading


Proper Monitoring and how to load cargo in a shallow draught condition


Loading cargo in a shallow draught condition can impose high stresses in the double bottom, cross deck and transverse bulkhead structures if the cargo in the hold is not adequately supported by the buoyancy upthrust. If applicable, the cargo weight limits for each cargo hold, and two adjacent cargo holds, as a function of draught, (the local loading criteria) are not to be exceeded.

To minimise the risks of over-stressing the local structure, the largest possible number of non-successive pours should be used for each cargo hold.

Special care needs to be taken with heavy cargoes such as iron ore, scrap iron, lead and other concentrates. On general bulk carriers with uniform hold lengths alternate hold loading or block hold loading may be utilized to stow high density cargoes.


INTERCARGO Issues Nickel ore guidance

The International Association of Dry Cargo Shipowners, INTERCARGO has issued a formal guidance document, which aims to guide and inform Shipowners, Masters and other industry stakeholders regarding the particular risks associated with carrying Nickel Ore.

The guide gives practical advice to shippers, shipowners and charterers. The guide also points to other areas of assistance including from a vessel's P&I Club. The Club would like to remind Members of its own extensive information regarding the carriage of Group A cargoes and especially those regarding Nickel Ore in particular. (Source: UK |P&I |CLUB)

In response to the loss of many Bulk carrying vessels and life of seafarers in little under 12 months INTERCARGO has sought to highlight the potential dangers of carrying Nickel Ore cargoes. There were problem reported relating to loading of nickel ore in Indonesian ports and elsewhrere in particular the failure of certain parties to adhere to the IMSBC code , and an apparent refusal to allow access for third party surveying of cargoes.

Intercargo has been lobbying the IMO to change the existing IMSBC code. One problem INTERCARGO stated , was lack of a specific section in the code relating to the loading of nickel ore. The cargo is prone to liquefy when its moisture content is too high. Cargo surveyors and ship masters often face too much pressure to accept cargoes.The cargo needs to have a well- defined moisture content, a legal requirement with SOLAS.




Related Information

  1. Hazards of handling bulk sulphur

  2. Loading, carrying and discharging of bulk coal


  3. Special precaution & IMSBC code guideline for handling bulk coal


  4. Special arrangements for carrying grain cargo


  5. Grain handling precautions - various limitations


  6. Safety precautions for loading and carriage of iron ores


  7. Risk of carrying high density iron ores in bulk


  8. Salt loading guideline - Precautions & hold preparation


  9. Pig iron preparations for bulk loading


  10. Risk of iron ore liquefaction during sea passage & countermeasures


  11. Preparations, loading, carrying & discharging bulk cement


  12. Petcoke loading in bulk & associated problems for bulk carriers


  13. Handling of bauxite - The environmental impact of Jamaica bauxite mining


  14. Carrying gypsum -Toxins, physical reactions & environmental degradation


  15. Cargo liquefaction & potential problem for transporting bulk cargo


Our detail pages illustrated many safety aspects of Bulk carrier

Home page |||Bulk carrier types ||| Handling of bulk coal |||Cargo planning ||| Carriage of grain |||Risk of iron ores |||Self unloading bulk carriers |||Care of cargo & vessel |||Cargoes that may liquefy |||Suitability of ships |||Terminal guideline |||Hold cleaning |||Cargo cranes |||Ballast handling procedure |||Bulk carrier safety |||Fire fighting systems |||Bulk carrier General arrangement






Related Information

  1. Additional cargo documents required for bulk cargo loading


  2. Suitability of Shore Terminals for handling bulk cargo


  3. Bulk carrier acceptability of loading regulation


  4. Preparation for ships carrying bulk cargo & standard loading condition


  5. Information to ship from terminal prior loading bulk cargo


  6. Local loading criteria defining maximum allowable cargo weight in each cargo hold


  7. High loading rates by shore terminal and potential problems for bulk carriers


  8. Risk of partially filled ballast tanks


  9. Shearing forces & bending moments limitations in bulk carriers


  10. Deterioration of ships hull and consequences of hull damage /forward flooding


  11. Bulk carrier hull damage - causes and preventive measures


  12. Risk of exceeding loading limits provided in the loading manual


  13. Local loading criteria defining maximum allowable cargo weight in each cargo hold


  14. Bulk carrier water ingress problem




Operation of sea going bulk carriers involved numerous hazards . Careful planning and exercising due caution for all critical shipboard matters are important . This site is a quick reference to international shipping community with guidance and information on the loading and discharging of modern bulk carriers so as to remain within the limitations as specified by the classification society.
It is vital to reduce the likelihood of over-stressing the ship's structure and also complying with all essential safety measures for a safe passage at sea. Our detail pages contain various bulk carrier related topics that might be useful for people working on board and those who working ashore in the terminal. For any remarks please Contact us

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