ZIM Container ship in Istanbul
are
cargo ships that carry all of their load in truck-size
intermodal containers, in a technique called
containerization. They form a common means of commercial
intermodal freight transport.
History
The earliest container ships were converted
tankers, built up from surplus
T2 tankers after World War II. In 1951 the first purpose-built container vessels began operating in
Denmark, and between
Seattle and
Alaska.
The first purpose-built container ship in the United States was the
Ideal-X , a
T2 tanker, owned by
Malcom McLean, which carried 58 metal containers between
Newark, New Jersey and
Houston, Texas on its first voyage, in April 1956.
Today, approximately 90% of non-
bulk cargo worldwide is transported by container, and modern container ships can carry up to . As a class, container ships now rival
crude oil tankers and
bulk carriers as the largest commercial vessels on the ocean.
Construction
thumb|250px|The "Zrin" container ship has self-unloading capability
Container ship "CMA CGM Balzac" in the port of Zeebrugge Belgium.
Container ships are designed in a manner that optimizes space. Capacity is measured in
Twenty-foot equivalent unit (TEU), the number of standard 20-foot containers measuring 20 × 8.0 × 8.5
feet (6.1 × 2.4 × 2.6
metres) a vessel can carry. This not withstanding, most containers used today measure 40 feet (12 metres) in length. Above a certain size, container ships do not carry their own loading gear, so loading and unloading can only be done at ports with the necessary cranes. However, smaller ships with capacities up to are often equipped with their own cranes.
Informally known as "box boats," they carry the majority of the world's
dry cargo, meaning manufactured goods. Cargoes like metal ores or coal or wheat are carried in
bulk carriers. There are large main line vessels that ply the deep sea routes, then many small
"feeder" ships that supply the large ships at centralized hub
ports. Most container ships are propelled by
diesel engines, and have crews of between 20 and 40 people. They generally have a large accommodation block at the
stern, near the
engine room. Container ships now carry up to (approximately equivalent to 35 100-car double-stack
intermodal freight trains) on a voyage. The world's largest container ship, the
M/V Emma Mærsk has a capacity of 15,200 containers.
In 2008 the South Korean shipbuilder STX announced plans to construct a container ship capable of carrying , and with a proposed length of 450 metres and a
beam of 60 metres. If constructed, the container ship would become the largest seagoing vessel in the world.
Shipyards
Container fleet in 2006
Large container ships (over ) have been built in the following shipyards:
- Hudong-Zhonghua Shipbuilding, Shanghai, China
- Nantong COSCO KHI Ship Engineering, Nantong, China
Risk
Container ship "Rita" loading at Copenhagen with crew on deck.
The ceaseless transit of these containers (at any given time, between 5 million and 6 million units) entails a great deal of risk.
Some of the risks are linked to the loading and unloading of containers. The risks involved in these operations affect both the cargo being moved onto or off the ship, as well as the ship itself. Containers, due to their fairly nondescript nature and the sheer number handled in major ports, require complex organization to ensure they are not lost, stolen or misrouted. In addition, as the containers and the cargo they contain make up the vast majority of the total weight of a cargo ship, the loading and unloading is a delicate balancing act, as it directly affects the centre of mass for the whole ship. In March 2007, a London based container ship capsized in Antwerp, Belgium while loading.
Maneuvers in coastal waters and ports managed in the
wheel house may be dangerous, as evidenced by a container ship hitting the
San Francisco – Oakland Bay Bridge on November 7, 2007.
It has been estimated that container ships lose over 10,000
containers at sea each year. Most go overboard on the open sea during storms but there are some examples of whole ships being lost with their cargo. When containers are dropped, they immediately become an environmental threat — termed "
marine debris".
Modern loading instruments (like
MACS3 with
BELCO,
SEALASH and
DAGO modules) assist to reduce the risks, caused by incorrect stowage of container cargo.
Specifications
Cargo too large to carry in containers can be handled using
flat racks,
open top containers and
platforms. There are also container ships called
roll-on/roll-off (RORO), which utilize shore-based ramp systems for loading and unloading. ROROs are usually associated with shorter trade routes, as they are unable to carry the volume of
crane-based container vessels. However, due to their flexibility and high speed, ROROs are frequently used in today's container markets.
Future
Economies of scale have dictated an upward trend in sizes of container ships in order to reduce costs. One limit on ship size is the "
Suezmax" standard, or the largest theoretical ship capable of passing through the
Suez Canal, which measures . Such a vessel would displace , be 400 meters long, more than 50 meters wide, have a draft of nearly 15 metres, and use more than 85 MW (113,987 hp) to achieve 25.5 knots, specifications met by the
Emma Mærsk.
Beyond Suezmax lies the "
Malaccamax" (for
Straits of Malacca) ship of , displacing , 470 meters long, 60 meters wide, 16 meters of draft, and using more than 100 MW (134,102 hp) for 25.5 knots. This is most likely the limit before a major restructuring of world container trade routes. The biggest constraint of this design, the absence of a capable single engine, has been overcome by the
MAN B&W K108ME-C.
The ultimate problem was the absence of a manufacturer capable of producing the propeller needed for transmitting this power, which would be about 10 metres in diameter, and weigh 130 tonnes. One has since been built for the Emma Mærsk by Mecklenburger Metallguss GmbH in Waren, Germany. Other constraints, such as time in port and flexibility of service routes are similar to the constraints that eventually limited the growth in size of
supertankers.
Largest ships
Busiest ports of call
Note: "TEU" stands for "
Twenty-foot equivalent unit," i.e. a 20-foot
intermodal container. Thus a 40-foot container is , etc.
See also
