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Until the 20th Century, ships generally, were all-purpose cargo vessels, with very little specialisation (with the exception of tank vessels which first appeared in the 1880s). All cargoes were carried in general purpose holds, or on deck. Modern commercial vessels are designed and built to carry specific cargo types. The names we give to the various vessel types reflect the type of cargo for which they are designed and built to carry. For example, A "bulk carrier" is specially designed to carry cargo "in bulk" and the hatch cover and hold design is focussed on the carriage of raw dry cargo goods, such as coal, grain, iron ore and bauxite, which are simply poured into cavernous holds then grabbed and bulldozed out at the port of discharge.
Tankers carry liquid cargo in tanks The most obvious example is the well-known oil tanker, but even within this generic type, each tanker is specially designed to carry a particular type of liquid cargo, not just crude oil. Other liquid cargoes would include petroleum products, chemicals and yes, even wine ! 2 recent hybrid designs of tanker carry Liquified Natural Gas (LNG) and Liquified Petroleum Gas (LPG), both of which need to be kept under pressure and at low temperature to maintain the cargo in a liquified state. A further hybrid is the Floating Production, Storage and Offloading unit (FPSO), which is usually a large tanker (maybe a converted old VLCC, but now brand new specialised FPSOs are being built) specifically designed for the oil industry, working offshore where an onshore facility to process and store offshore oil is deemed impractical.
Container ships (a revolutionary idea in the past 50 years) carry their cargo in standard size containers, normally either 20 ft units (TEU) or 40 ft units (FEU), for speed of loading and discharge. A modern container ship can discharge a cargo in as many hours as it used to take in the equivilent number of days. This "brainchild" of Malcolm McLean, (a former New Jersey truck driver)found no interest among shipowners in the 1940s and 1950s, so he built his own to prove the concept. Within 10 years, the container ship revolution had started. From just a few hundred containers, modern ships can carry many thousands.
Cargo Design for particular cargoes = the vessel type - Simple really, but something the BBC have never really understood. Whenever a vessel (other than a tanker or passenger ship) gets onto the BBC News, it is termed a "freighter". ANY vessel that carries goods for reward is a "freighter", so it just goes to prove what "land-lubbers" the BBC are !
Click on any of the images below
to learn about specialised vessels commonly used in today's maritime commerical world. |
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