9. Classification of cargo ships (Part III)

Liquid cargo

Tankers. Tankers were among the first ships designed to carry only one kind of cargo - petroleum. Their construction is entirely different from that of dry cargo ships; Tankers are one-decked ships with the engine room and superstructure at the stern and a pump compartment often at the bow. The middle part of the tanker consists of a group of identical sections (called tanks) separated by cross walls in the hull. Hence the name of tankers. Tankers are equipped with pipes, valves and pumps to transfer cargo from/to the shore and from one tank to another when necessary. Today, large tankers, often called supertankers.

Supertankers have various economic advantages over smaller tankers. For example, it costs much less to ship a large amount of oil in one supertanker than in many small tankers. But supertankers also have major disadvantages. Their huge size makes them difficult to navigate and increases the risk of accidents. Because of their size, supertankers require deep ports in order to unload. If a supertanker suffers an oil spill, the pollution that results could be disastrous because of the ship's huge capacity.

Types of tankers: CC (Crude Carrier), LCC (Large Crude Carrier), VLCC (Very Large Crude Carrier), ULCC (Ultra Large Crude Carrier).

LPG carriers (Liquid Petroleum Gas carriers) - built to carry liquid gases, either natural gases or products of oil processing (methane, propane, butane), for chemical industry. Gases (which are kept in three conditions - liquid, cooled or under pressure) are held in special reservoirs. Safety measures are vitally important. Ventilation is provided in all of the compartments (containing gas reservoirs) to prevent dangerous chemical reactions through air between gases. Living quarters are located in the stern and are equipped with oxygen-supply devices. Anti-fire systems are installed everywhere.

LNG carriers. (Liquid Natural Gas) are tank ships designed to transport liquefied natural gas.

Ships called ore/bulk/oil (OBO) carriers can serve as either tankers or dry bulk carriers. An OBO ship can haul ore; bulk cargo, such as grain or fertilizer; or oil. Some OBO's do not carry ore.

Chemical carrier - they transport chemicals. Some products require special conditions - for example, asphalt and liquid sulfur need to be warmed so as not to cool down during transportation.

Multipurpose ships are designed to haul several kinds of cargo at the same time. They can have refrigerated space for foods that spoil easily, tank space for liquid cargo, and a deck for automobiles, etc.

14. Say whether the sentences are true or false. Correct the false ones.

1. OBO is used for carrying containers.

2. Large tankers are called supertankers.

3. Large oceangoing vessels are called boats.

4. Car ferries carry only automobiles and cars.

5. LASH ships are huge freighters that carry preloaded seagoing lighters.

6. Barges that operate in coastal waters must have definite size.

7. Multipurpose ships are designed to haul either ore or oil.

8. The main disadvantage of containerization is that there is far less theft of valuable merchandise because the containers are sealed.

9. Roll-on/roll-off ships haul such cargoes as cement, coal, grain, gravel, and sand across harbours, on canals and rivers, and along coasts.

10. Air cushion vehicles provide fast trips for short distances.