The invention and development of bulk carrier is an interesting thing to know and discover. In the late of 19th century, most of the trading logistic and shipping services used simple, not-so-specialized transportations for carrying products around the world, which means that all kinds of commodity were packed in the same place, normally on deck or under basement. Then came the invention of bulk carriers, which were firstly developed in the 1850s. This specialized merchant ship was designed for carrying enormous quantities of non-packed commodities, and helped advancing the shipping services to world commodities’ transportaion. In the following decades, bulk carriers have been under several constructional developments to ensure that all kinds of cargo are carried in good condition, and the specialized cargo is in the significant types of bulker. So, what exactly these bulk carriers can do in order to contribute to the world’s trading logistic?
Bulk carriers are massive vessels with great operating capacity for worldwide shipping industry. They can carry dry cargo in bulk such as coal, iron ore, grain, sulfur, scrap without packaging; which are directly contained in the vessel’s waterproof cargo compartments.
Bulk carriers are also defined as ships that constructed with a single deck, solid structure with hulls and hangers located on either side of the cargo hold to reduce cargo spaces and to increase the ability to adjust the center of gravity when necessary. The vessels have wide hatchways which make it easier for the bulk carrier’s crew to load and upload of cargo. The cargo holds are reinfored to be able to resistant impact of goods and equipments caused by shifting cargo.
Bulk carrier general arrangement
There are two types of basic bulk carrier:
• Bulkers with cranes: the cranes are used for loading and uploading cargo at some ports that are lack of shifting facilities on the left side of the vessel.
The capacity of bulk carriers comes in variety of size. The most common size is about 24000 ~ 35000DWT (Handysize, Handymax). The average size is about 75000DWT (Panamax – limited by the Panama canal’s lock chambers). Some bulkers can be very large, their size can reach to 200000DWT and even more.
For the “Capesize”, bulkers are classified by regional trade, such as Kamsarmax (capacity of 75000DWT, suitable for berthing at the Port of Kamsar - Equatorial Guinea), Newastlemax (capacity of 185000DWT, the largest vessel able to enter the port of Newcastle – Australia) and Setouchmax (capacity of 203000DWT , being the largest vessels able to navigate the Setouch Sea – Japan). With the continuous increasing of shipping needs, the VLCC (Very Large Crude Carrier – vessel for carrying dry cargo in bulk) are being transformed into VLOC (Very Large Ore Carrier – vessel for carrying ore) with the capacity beyond 200000DWT. Due to the heavy cargo shipping with enormous loads, the actual bulk carrier’ lifetime are usually shorter than the original design’s.
• Gearless Bulkers: these are bulkers without cranes or conveyors. Therefore, the process of loading and uploading cargo of these vessels depends on the shore-based equipment at the destined ports.
Bulk carrier with cranes arriving at a port
Here are some of the general types of bulk carrier:
• Handysize: 20000DWT- 40000DWT;
• Handymax: 40000DWT- 50000DWT;
• Supramax: 50000DWT- 60000DWT;
• Panamax: 60000DWT- 80000DWT;
• Post-Panamax: (“ Baby capers”) < 125000DWT;
• Capesize: 125000- 200000DWT.
The International Maritime Solid Bulk Cargoes Code (IMSBC Code) has divided bulk cargoes into 3 general categories:
• Group A: cargoes that may be liquefied during transportation;
• Group B: cargoes that may self-ignite, cause explosion, corrosive, noxious gases, or produce carbon dioxide and burn oxygen,…
• Group C: other cargoes that do not belong to group A and B.
Bulk carriers safety:
Bulk cargoes can usually cause dust and dirt during loading and uploading process. And the dust and dirt can go in cabin crew, engine rooms, cockpit, cargo holds and engine on deck. This problem can do harm to the crew’s health, cause corrosive damages to vessel’s engine, vessel’s structure and other equipments on deck.
The loading cargo process consumes a lot of time and can be extremely dangerous (thousands of tons/hour). Therefore, the impact of the cargoes on the hull structures is so strong that it can damage the equipment or deform the vessel’s hull unless there are precautions. When the loading speed is high, the cargoes are usually packed in one place. This can cause partial stresses and deform the vessel’s hull structure easily.
As the bulk cargoes are movable, the bulk carriers can be tilted during loading and uploading process or while traveling if the crew does not place the cargoes evenly or lack of trimming on time. Also, this problem can deform the vessel by sheering force or bending moment.
Cargoes listed in group A must meet the requirement of TML – Transportation Moisture Limit, or else the bulk carriers could be overturned while traveling.
Cargoes listed in group B are very dense, corrosive and flammable. If they are not packed in well-ventilated isolation area, they can threaten cabin crew’s life and cause explosion.
Some important notices for bulk carriers stowage planning:
Normally, the crew only open one hatchway at a time when loading the bulk cargoes so the loading schedule must be compiled and calculated for each loading down the holds. Also, the lower corners of the hold are used as ballast tanks for controlling the vessel’s trim. The loading schedule should follow these steps:
1. Cargoes should be loading in the correct order with calculated weight;
2. Make sure that bulk carrier’s height remains the same after each loading (GoM);
3. Check partial stresses on the hold’ s bottom area and total cargoes’ weight after each loading;
4. Check if the ballast tanks need to be adjusted (in/out);
5. Check the bulk carrier’s waterline after each loading;
6. Check sheering force and bending moment after each loading (if required);
7. Classify all types of bulk cargo and put them in different cargo holds (if required);
8. Flammable bulk cargoes must be kept away from heat sources and close to well-ventilated area;
9. Check the amount of loaded cargo in each cargo hold;
Partial stresses, sheering force, bending moment, GoM and waterline must be calculated and always stay in control during the whole loading and shipping cargo process.
Supervising the loading and uploading bulk cargoes process:
Before loading, the bulk carrier and the port must agree on the loading schedule. If the bulk cargo is in group A, please ensure the moisture of the cargo does not exceed allowable level (TML%). If the bulk cargo is in group B or marked as dangerous cargo, please strictly follow the IMDG Code/IMSBC Code.
Deck officers must clearly understand the line layout and closely supervise the process of handling bulk cargo in accordance with the approved plan.
Deck officers must check the waterline regularly after each loading and report the amount of loaded cargo in every hold.
If any error occurs during loading process and affects the bulk carrier’s safety, solutions must be taken to prevent any harm or the process must be ended immediately. Cabin crew and onshore’s officer must discuss together to find out the best solution to overcome the error before continuing the process.
Deck officers must strictly follow the order of loading cargo plan as well as the calculated duration and amount of each load, highest allowable waterline after each load. Also, deck officers should understand the physical and chemical characteristic of every bulk cargo in order to prevent any error and take the necessary precautions.
Bulk cargo loading process
Supervising the bulk cargoes while traveling
The deck officers must closely supervise every cargo hold during shipping process. They must check the waterline, moisture and the heat in the cargo holds. After each check, they must report the bulk carrier’s safety status in the bulk cargo diary and deck diary. Do not fuel the engine in the double bottom area next to the flammable bulk cargo holds. For noxious gas and explosive gas bulk cargoes, deck officers need to place them in well-ventilated area and have detailed check schedule. For moisture-avoid bulk cargo, cargo holds moisture must be checked frequently for well-ventialted concern.
In case of any emergency that requires cabin crew to work in deep cargo holds, oxygen concentration must be checked before any actions taken.
Uploading bulk cargoes
The safe uploading process is the process that follows the exact opposite steps of loading. The shifting must be done skillfully in the approved order by chief officer. Loads of cargo in all holds and ballast tanks must be calculated carefully and be added if necessary.
Precautions of fire and explosion must be taken carefully during uploading process. Do not directly touch the bulk cargoes if they are dangerous.
Keep all cargo holds well-ventilated beforing entering.
Avoid pollutant while sweeping and cleaning the cargo holds after uploading.
Some questions that should be asked before shipping by bulk carriers:
1. What type of product/bulk cargo is it?
2. What are their physical and chemical characteristics?
3. Is there any specific shipping regulation for them?
4. May they threaten cabin crew’s life or do any harm to the environment?
5. Is there any precaution or solution in case of emergency?