The rise of specialist ships
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 The Liquified Petroleum Gas carrier Lincolnshire. © NMM | General cargo ships – now known as 'break bulk' vessels - carry only a small share of today's sea-borne trade.
Some items, such as certain forestry products, still need to be packed in the traditional way, but most other goods are now carried in specialist ships.
Liquid bulk carriers
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| The chemical tanker Stolt Emerald. © NMM |
Giant supertankers carrying huge quantities of crude oil are probably the best known and most recognisable of all merchant ships.
The category also includes vessels designed to carry refined oil products and many other chemicals and vegetable oils.
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| The supertanker Limnea. © NMM |
When crude oil was first shipped around the middle of the 19th century, it was transported in barrels or in special tins.
The first ocean-going tanker built to carry oil in bulk was the Gluckauf (1886). Her large tanks could be filled or emptied using a pump. At 2300 tons she was tiny compared to the modern giants.
The supertankers
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The Limnea. © NMM | In western countries, demand for oil rocketed after the Second World War, and ever-larger ships became necessary to bring crude oil from the Middle East. The first supertanker was the 206,000 DWT Idemitsu Maru (1966).
The biggest ship ever built is the 564,000 DWT Seawise Giant (1979). 485 metres (1591 feet) long, she can carry more than 4 million barrels of crude oil. The giant crude carriers specialize in long-distance trade between the Gulf and the west or Japan. Smaller tankers remain in use for shorter routes.
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| The Liquified Natural Gas carrier Libra. © NMM | 'Product' tankers carry petrol, aviation fuel or paraffin. This category includes LPG (Liquefied Petroleum Gas) and LNG (Liquefied Natural Gas) carriers, with their characteristic spherical tanks, and many smaller vessels used for transporting edible oils.
Dry bulk carriers
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| The ore carrier LA Loma. © NMM |
A basic definition of dry bulk is any solid that is shipped without packing. The dry bulk carrier evolved from the ideas of Ole Skaarup.
He proposed a vessel with its machinery at the stern, and large, clear holds with wide hatch openings for easy cargo handling. The ship, the 19,000 DWT Cassiopeia, was launched in 1955. All bulk carriers since have followed her basic design.
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| The bulk carrier Kaien Maru. © NMM |
Dry bulk carriers, also known as 'bulkers', now play a vital role in sea-borne trade, carrying goods such as coal, grain, iron ore, aggregates (quarried or sea-dredged stone and sand) and scrap metal.
They have grown since the days of the Cassiopeia. Some are almost as big as the supertankers. The 365,000 DWT Berge Stahl, built to carry iron ore, is 360 metres (1181 feet) long.
Container ships
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| The container ship Norasia Pearl. © NMM |
Containerization is the practice of carrying freight in containers of uniform shape and size for shipping.
Almost anything can be stored in a container, but they are particularly useful for the transport of manufactured goods.
Since the 1950s containers have revolutionised sea-borne trade, and now carry around 90% of all manufactured goods shipped by sea.
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| Lowering containers on to the Moreton Bay. © NMM |
The modern container ship evolved from the ideas of Malcolm McLean, a truck operator from North Carolina who had branched out into shipping. He found that containers simplified the loading and unloading of ships.
Advantages of containers
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| The ASEA crane loading the Moreton Bay. © NMM | Several factors made it no longer necessary to pack, unpack or store goods at the port:
- by packing and unpacking the containers at the place of production rather than at the quayside
- by moving containers to the port by lorry or rail
- by using quayside cranes to lift the containers onto and off the ship.
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| The container ship Jervis Bay at Tilbury. © NMM |
The traditional teams of stevedores and porters became redundant, and large quantities of goods could be shifted far more quickly than before.
With fewer workers to be paid and less time spent in the ports, containerization meant huge savings for the shipping firms.
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| Container cells on the Moreton Bay. © NMM |
To make containerization pay, new ships were designed. They were built to carry the maximum number of containers. Their internal layout allowed easy removal of the containers by crane.
RO-RO vessels
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| The passenger ferry Ailsa Princess off Stranraer. © NMM | This is a descriptive name short for 'roll on, roll off'. Perhaps 'drive on, drive off' would be better, because these vessels allow vehicles to drive on or off through a door in the bow or the rear. RO-RO ships have a large car deck instead of a cargo hold.
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| The vehicle carrier Hual Tracer. © NMM | RO-ROs come in two types. Passenger RO-ROs include the familiar Channel ferries. Cargo RO-ROs are mainly specialist trade vehicle carriers, handling imports of cars and other vehicles. They can also carry a small number of containers.
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