6. Introduction to Cargo Handling and Stowage 

General cargo 

General cargo is a term which covers a great variety of goods. Those goods may be in bags,  cases, crates, drums or barrels, or they may be kept together in bales. They could be individual parcels, castings or machinery parts, earthenware or confectionary. They all come under the collective term of ‘general cargo’. In order to carry goods safely, the vessel must be seaworthy and the cargo spaces must be in such a condition as not to damage cargo parcels by ships sweat, taint or cause any other harmful factor. 

Bulk cargo 

The demand for raw materials continues to sustain a major sector of the shipping industry. Bulk products are shipped all over the world from their point of origin to that position of demand. The ‘bulkers’ transport everything from grain and coal to chemicals and iron ore. The bulk trades involve vast tonnage movement of any one commodity and such movement can present its own hazards and problems associated with the cargo.

Bulk cargo examples are;  Ore, Concentrates, Nitrates, Phosphates, Sulphur, Nuts, Copra, Salt, Sugar, Steel and Iron products, Scrap metal, Cement and Coal, etc. 

Grain cargo examples are;  Wheat, Maize (Corn), Oats, Rye, Barley, Rice, Pulses, Seeds and Soya bean, etc.

Refrigerated cargo 

Refrigerated cargoes mainly fall into the category of foodstuffs by way of meat, dairy products, fruit and vegetables, poultry, etc. and typically used to transport perishable cargo. 

The increase in container and Ro-Ro trades has, to some extent, brought about the demise of the conventional ‘reefer’ ship (one that was dedicated to carry refrigerated and chilled cargoes in its main cargo-carrying compartments), the compartments being constructed with insulation to act as very large giant refrigerators. 

Refrigerated cargoes, other than those specifically carried in container or Ro-Ro units, will be carried under the operation of the ship’s own refrigeration plant. 

In the commercial fishing world, transshipment is the transfer of catch from one vessel to another. During a transshipment, a fishing vessel meets up with a large refrigerated cargo-type ship, known as a “reefer” which to transports the fresh fishes as refrigerated cargo.

Tanker cargo 

At the present time modern civilization is largely dependent on oil and its by-products. Vast quantities of liquid products are transported by tankers throughout the world. 

It should be realized from the outset that not all tankers are in the oil trade. Many transport  wine or liquid chemicals, or liquid natural gas (LNG), but generally the tanker vessel is synonymous with the carriage of bulk oil or oil-based products. 

Examples of tanker cargoes are;  Bitumen, Chemicals (various), Creosote, Crude oil, Diesel oil, Fuel oil, Gas oil, Gasoline (petrol), Kerosene (paraffin), Latex, Liquefied gases, Lubricating oils, Molasses, Propane, Vegetable oils, Whale oil, Wine, Palm oil and edible oil, etc.

Containerization has revolutionized world trade and commerce as the benefits of containerization over general cargo ships. The cargo in the container can be transported from door to door and this has reduced ware housing costs and increased security in transit. Time in port is minimized and port labour costs are also reduced due to the lower numbers of people required for loading and unloading a cellular container ship. 

Container sizes have been standardized as follows; 

• 20 ft x 8ft x 8.5ft (General) 

• 40 ft x 8ft x 8.5ft (General) 

• 20 ft x 8ft x 9.5ft (High Cube) 

• 40 ft x 8ft x 9.5ft (High Cube) 

• 45 ft/ 48 ft/ 53 ft x 8ft x 9.5ft (Special Long)

Types of containers as follows; 

• General purpose container [ 8ft x (8.5ft, 9.5 ft) x (20ft, 40ft, 45ft, 48ft)] 

• Open Top container 

• Open Sided container 

• Reefer container 

• Tank container 

• Bulk container 

• Ventilated container 

• Insulated container (or) CONAIR 

• Half height container 

• Flat rack container 

• Bolster (or) Platform 

• Specialized container

Hazardous goods covered by the International Maritime Dangerous Goods (IMDG) Code are deeply entrenched under this particular umbrella of special cargoes. 

There are comprehensive and specific requirements for the transport of dangerous goods by sea. The purpose of these requirements is to effectively protect the lives of seafarers, the safety of vessels and the maritime environment. 

Dangerous Goods are divided into 9 classes based on their associated risks when transported by land, sea or air. 

Dangerous goods classes are as follows; 

Class 1: Explosives 

Class 2: Gases 

Class 3: Flammable Liquids 

Class 4: Flammable Solids 

Class 5: Oxidizing Substances and Organic Peroxides 

Class 6: Toxic and Infectious Substances 

Class 7: Radioactive Material 

Class 8: Corrosive Substances 

Class 9: Miscellaneous Dangerous Substances and Articles and Marine Pollutants (MP) 

In the event of any dangerous goods or harmful substances being carried aboard the vessel, ‘The IMDG Code should be consulted. Additionally, the Chemical Data Sheets contained in the Tanker Safety Guide (Gas and Chemical) issued by the International Chamber of Shipping may be appropriate.

In the event that a cargo parcel/unit is found to be ‘leaking’ or have exposed hazards, the nature of the cargo should be ascertained and personnel kept clear of the immediate area until the degree of hazard is confirmed. In any event the unit should not be accepted for shipment and rejected until satisfactorily contained. Where a hazardous substance is discovered at sea also to be a threat to pollution and impact to marine environments.

Deck cargoes are carried on the weather-deck and/or hatch-covers of a ship which are exposed to the elements and are often the first to suffer from any misadventure which may be fall the ship’s voyage. Deck cargoes, by their very nature, may fall into the class of hazardous goods or they may, like timber deck cargoes, have their own inherent dangers, which may threaten the well-being of both ship and cargo. Whatever goods are shipped, it is essential that correct stowage and securing procedures are taken from the onset. 

Cargoes and commodities are handled a wide variety of lifting gear for loading and unloading of cargo operation. 

Cargo handling gears fitted on ship depend on the types of vessels are; 

• Derrick 

• Deck crane 

• Ramp/Bow door, stern door and other riggings

Derrick 

The most widely used derricks in the marine industry are of a welded structure, consisting of 

• either three or five welded sections of tubular steel 

• wires, blocks and shackles should be used for cargo handling and lifting operations. 

Velle Derrick 

This is a single swinging derrick, the distinguishing feature of which is provides stability when discharging or loading containers or heavy lifts. 

Hallen Derrick 

The Hallen is another patented design in common use and an arrangement similar to that employed by the Velle derrick can be used. 

Stulken Heavy Lift Derrick 

Of particular note in the very heavy lift range is the patent Stulken heavy lift derrick. 

Jumbo Heavy Lift Derrick 

This type of derrick is also intended for lifting a wide range of heavy lifts.

Deck Cranes 

Most shipboard cranes can be fitted to swing through 360°, but for the purpose of safe handling, limit switches often act as cut-outs to stop the jib of the crane fouling obstructions. 

Pedestal Cranes 

Shipboard pedestal cranes rotate on a pedestal and are permanently mounted. The main housing normally consists of the operator's cabin, winches and the jib, which projects from the pedestal. 

The crane is either electrically or hydraulically operated and the housing rotates on the pedestal. There are usually two winches inside the housing, one for the topping of the jib and the other for the hoist. Both are controlled from inside the cabin, using a joystick. To handling the bulk cargo and container cargoes, the grabs, container spreaders, etc. can be fitted to the cargo hook.

Twin operation of deck cranes 

Some deck cranes are designed on the basis of the technology of hydraulic single deck cranes and electric double deck cranes; all operations of these cranes, including the synchronous control system between both single cranes, are conducted by means of a hydraulic system. 

These can be combined operating as the fully hydraulic double deck crane (2x15 tons=30 tone type) and some type cranes with hoisting capacity ranging from 20 to 60 tons. 

Shipboard Gantry Cranes 

Gantry cranes have steel girders across the beam of a vessel, supported by legs and travelling on rails mounted on the ship's decks. The gantry houses the operator's cabin as well as the lifting mechanism, and it can travel athwartships on the bridge girders. The whole gantry can travel fore and aft on wheels mounted at the base.

Hose Handling Crane/Davit 

Hose handling crane is for lifting and transiting the hose on board the tanker vessel. 

Provision crane and Bunker Davit 

Provision cranes are fitted for handling the provisions and stores to lift up onboard. Bunker Davits are also designed for handling the bunker hoses during replenishment of fuel onboard. 

Dunnage 

This is material used when stowing cargo to protect it from contact with steelwork, other cargoes, or any possibly damaging influences. 

Dunnage means any material, permanent or temporary, that is used to ensure good stowage, and protect cargo during carriage.  Dunnage can be wood, plastic, tarpaulin or a range of other materials. 

There are two basic types of dunnage, Permanent dunnage and Temporary dunnage. 

The permanent dunnage of the ship’s side is known as Spar Ceiling or Cargo Batten. It consists of timber of about 150mm X 50mm fitted over the side frames. It is usually fitted horizontally into cleats on the frames. There is a vertical distance of not more  than 230mm between battens. 

Dunnage is used

• to protect goods and their packaging from moisture, contamination or mechanical damage. 

• to protect cargo from water damage caused by contact with water from bilges, other cargo or double bottom tanks. 

• to protect moisture-sensitive cargoes, such as bagged cargo (e.g. coffee, cocoa) or bales cargo (e.g. tobacco, tea) from sweat, which forms a ship’s sides, frames, bulkheads, etc. and run off over the deck. 

• to prevent damage to goods through contact with either the ship’s structure or with other cargo. 

• to provide air channels between stows to aid ventilation. 

• to aid in the effective distribution of weight on tank tops or hatch covers. 

• to aid in filling broken stowage, especially unevenly shaped cargoes.

Based on the different kinds of cargoes and various types of merchant vessels, there has to be performed the cargo care onboard upon certain types of vessels and their carrying cargoes. 

Hold preparation 

Before cargo can be loaded onboard, the cargo holds/tanks/compartments have to be prepared properly. 

There are different procedures of hold preparation base on their types of cargoes and vessels, such as; for general cargo, breakbulk cargo, solid bulk cargo, grain, liquids and chemical in bulk and refrigerated cargo, etc. 

“Make the holds, refrigerating and cooling chambers and all other parts of the ships where goods are carried, fit and safe for their reception, carriage and preservation.”

Before loading, the cargo space should be inspected and prepared for the particular material that they are intended to load. Preparation should also include inspection of ancillary equipment such as bilges, sounding pipes and other service lines within the cargo space. 

The preparation of holds for the next cargo depends on 

• About of last cargo carried 

• Requirement of the next cargo 

• Available time 

• Available equipment and manpower 

If the next cargo is compatible with the last cargo, good sweep down and removal of left-over cargo. 

If the next cargo is incompatible with the last cargo or if the loading of sensitive cargoes like foodstuffs, more thorough cleaning may be required. 

In general, there are essentially five grades of hold cleanliness:

• Load on top 

• Shovel clean 

• Normal clean 

• Grain clean, or high cleanliness 

• hospital clean or stringent cleanliness

Hold preparation for bulk cargoes 

Bulk cargoes are generally loaded in designated ‘bulk carrier’ vessels, but they can be equally transported in general cargo ships alongside other commodities. However, in such circumstances, specific stowage criteria and hold preparation would probably be a requirement. 

In virtually every case, except where perhaps the same commodity from the previous voyage is being carried, the cargo holds would need to be thoroughly cleaned and made ready to receive the next cargo. 

(1) The holds would be swept down and cleared of any residuals from the previous cargo. 

(2) All rubbish and waste matter must be removed from the cargo space, before loading of the next cargo can commence. 

(3) The hold bilge system would need to be inspected and checked to ensure that: 

• the bilge suctions are operational; 

• the bilge bays are clean and smelling sweet (not liable to cause cargo taint). 

(4) All hold lighting arrangements, together with relevant fittings, would be inspected and seen to be in good order.

(5) The space, depending on the nature of the previous cargo and the nature of the next  cargo to be carried, would probably require to be washed down with a salt water wash. If necessary, washed down of followed by Fresh water wash.

(6) Clean bilge well covers properly secured for grain tide.

General principles of securing cargoes

All cargoes should be stowed and secured in such a way that the ship and persons on board are not put at risk. The safe stowage and securing of cargoes depend on proper planning, execution and supervision. Personnel commissioned to tasks of cargo stowage and securing should be properly qualified and experienced. Personnel planning and supervising the stowage and securing of cargo should have a sound practical knowledge of the application and content of the Cargo Securing Manual, if provided. In all cases, improper stowage and securing of cargo will be potentially hazardous to the securing of other cargoes and to the ship itself. 

Decisions taken for measures of stowage and securing cargo should be based on the most severe weather conditions which may be expected by experience for the intended voyage.

Types of Sweat 

• Cargo sweat 

• Ship sweat