A cargo ship or freighter is a
merchant ship that carries
cargo,
goods, and materials from one
port to another. Thousands of cargo carriers ply the world's
seas and
oceans each year, handling the bulk of
international trade. Cargo ships are usually specially designed for the task, often being equipped with
cranes and other mechanisms to load and unload, and come in all sizes. Today, they are almost always built of
weldedsteel, and with some exceptions generally have a life expectancy of 25 to 30 years before being scrapped.[citation needed]
The words cargo and freight have become interchangeable in casual usage. Technically, "cargo" refers to the goods carried aboard the ship for hire, while "freight" refers to the act of carrying of such cargo, but the terms have been used interchangeably for centuries.
Generally, the modern ocean shipping business is divided into two classes:
Liner business: typically (but not exclusively) container vessels (wherein "general cargo" is carried in 20- or 40-foot containers), operating as "common carriers", calling at a regularly published schedule of ports. A common carrier refers to a regulated service where any member of the public may book cargo for shipment, according to long-established and internationally agreed rules.
Tramp-tanker business: generally this is private business arranged between the shipper and receiver and facilitated by the vessel owners or operators, who offer their vessels for hire to carry bulk (dry or liquid) or break bulk (cargoes with individually handled pieces) to any suitable port(s) in the world, according to a specifically drawn contract, called a
charter party.
Larger cargo ships are generally operated by
shipping lines: companies that specialize in the handling of cargo in general. Smaller vessels, such as
coasters, are often owned by their operators.
Types
Cargo ships/freighters can be divided into eight groups, according to the type of cargo they carry. These groups are:
Roll-on/roll-off (RORO or ro-ro) ships are designed to carry wheeled cargo, such as cars, trucks, semi-trailer trucks, trailers, and railroad cars, that are driven on and off the ship on their own wheels.
Timber (Lumber) carriers that transport
lumber,
logs and related wood products.[2]
Specialized cargo ship types
Specialized types of cargo vessels include
container ships and
bulk carriers (technically tankers of all
sizes are cargo ships, although they are routinely thought of as a separate category). Cargo ships fall into two further categories that reflect the services they offer to industry: liner and tramp services. Those on a fixed published schedule and fixed tariff rates are cargo liners. Tramp ships do not have fixed schedules. Users charter them to haul loads. Generally, the smaller shipping companies and private individuals operate tramp ships. Cargo liners run on fixed schedules published by the shipping companies. Each trip a liner takes is called a voyage. Liners mostly carry general cargo. However, some cargo liners may carry passengers also. A cargo liner that carries 12 or more passengers is called a combination or passenger-run-cargo line.
Size categories
Cargo ships are categorized partly by cargo or shipping capacity (
tonnage), partly by weight (
deadweight tonnage DWT), and partly by dimensions. Maximum dimensions such as length and width (
beam) limit the canal locks a ship can fit in, water depth (
draft) is a limitation for canals, shallow straits or harbors and height is a limitation in order to pass under bridges. Common categories include:
Seawaymax, 28,000
DWT the largest vessel that can traverse the
St Lawrence Seaway. These are vessels less than 740 feet (225.6 m) in length, 78 feet (23.8 m) wide, and have a draft less than 26.51 feet (8.08 m) and a height above the waterline no more than 35.5 metres (116 ft).
Panamax, the largest size that can traverse the original locks of the
Panama Canal, a 294.13 m (965.0 ft) length, a 32.2 m (106 ft) width, and a 12.04 m (39.5 ft) draft as well as a height limit of 57.91 m (190.0 ft). Limited to 52,000
DWT loaded, 80,000
DWT empty.
Capesize, vessels larger than Suezmax and Neopanamax, and must traverse
Cape Agulhas and
Cape Horn to travel between oceans, dimension: about 170,000 DWT, 290 m long, 45 m beam (wide), 18m draught (under water depth).[4]
Chinamax, carriers of 380,000–400,000
DWT up to 24 m (79 ft) draft, 65 m (213 ft) beam and 360 m (1,180 ft) length; these dimensions are limited by port infrastructure in China
Baltimax, limited by the
Great Belt. The limit is a draft of 15.4 metres and an
air draft of 65 metres (limited by the clearance of the east bridge of the
Great Belt Fixed Link). The length can be around 240 m and the width around 42 m. This gives a weight of around 100,000 metric ton.
Wet cargo
Aframax, oil tankers between 75,000 and 115,000
DWT. This is the largest size defined by the average freight rate assessment (AFRA) scheme.
Q-Max,
liquefied natural gas carrier for
Qatar exports. A ship of Q-Max size is 345 m (1,132 ft) long and measures 53.8 m (177 ft) wide and 34.7 m (114 ft) high, with a shallow draft of approximately 12 m (39 ft).[5][6]
Suezmax, typically ships of about 160,000
DWT, maximum dimensions are a beam of 77.5 m (254 ft), a draft of 20.1 m (66 ft) as well as a height limit of 68 m (223 ft) can traverse the
Suez Canal
VLCC (Very Large Crude Carrier),
supertankers between 150,000 and 320,000
DWT.
Malaccamax, ships with a draft less than 20.5 m (67.3 ft) that can traverse the
Strait of Malacca, typically 300,000
DWT.
ULCC (Ultra Large Crude Carrier), enormous supertankers between 320,000 and 550,000
DWT
The
TI-class supertanker is an Ultra Large Crude Carrier, with a draft that is deeper than Suezmax, Malaccamax and Neopanamax. This causes Atlantic/Pacific routes to be very long, such as the long voyages south of Cape of Good Hope or south of Cape Horn to transit between Atlantic and Pacific oceans.
Lake freighters built for the
Great Lakes in North America differ in design from sea water–going ships because of the difference in wave size and frequency in the lakes. A number of these ships are larger than Seawaymax and cannot leave the lakes and pass to the Atlantic Ocean, since they do not fit the locks on the
Saint Lawrence Seaway.
The earliest records of waterborne activity mention the carriage of items for trade; the evidence of history and archaeology shows the practice to be widespread by the beginning of the 1st millennium BC, and as early as the 14th and 15th centuries BC small Mediterranean cargo ships like those of the 50 foot long (15–16 metre)
Uluburun ship were carrying 20 tons of exotic cargo; 11 tons of raw copper, jars, glass, ivory, gold, spices, and treasures from
Canaan,
Greece,
Egypt, and
Africa. The desire to operate trade routes over longer distances, and throughout more seasons of the year, motivated improvements in ship design during the
Middle Ages.
Before the middle of the 19th century, the incidence of
piracy resulted in most cargo ships being armed, sometimes quite heavily, as in the case of the
Manila galleons and
East Indiamen. They were also sometimes escorted by
warships.
Piracy is still quite common in some waters, particularly in the
Malacca Straits, a narrow channel between
Indonesia and
Singapore /
Malaysia, and cargo ships are still commonly targeted. In 2004, the governments of those three nations agreed to provide better protection for the ships passing through the Straits. The waters off
Somalia and
Nigeria are also prone to piracy, while smaller vessels are also in danger along parts of the
South American,
Southeast Asian coasts and near the
Caribbean Sea.[7][8]
A category designation appears before the vessel's name. A few examples of prefixes for naval ships are "USS" (
United States Ship), "HMS" (
Her/His Majesty’s Ship), "HMCS" (
Her/His Majesty's Canadian Ship) and "HTMS" (His
Thai Majesty's Ship), while a few examples for prefixes for merchant ships are "RMS" (
Royal Mail Ship, usually a passenger liner), "MV" (
Motor Vessel, powered by
diesel), "MT" (Motor Tanker, powered vessel carrying liquids only) "FV"
Fishing Vessel and "SS" (
Screw Steamer, driven by
propellers or screws, often understood to stand for
Steamship). "TS", sometimes found in first position before a merchant ship's prefix, denotes that it is a Turbine Steamer.
Famous cargo ships
Famous cargo ships include the 2,710
Liberty ships of
World War II, partly based on a
British design. Liberty ship sections were
prefabricated in locations across the United States and then assembled by shipbuilders in an average of six weeks, with the record being just over four days. These ships allowed the
Allies in
World War II to replace sunken cargo vessels at a rate greater than the
Kriegsmarine's
U-boats could sink them, and contributed significantly to the war effort, the delivery of supplies, and eventual victory over the
Axis powers. Liberty ships were followed by the faster
Victory ships. Canada built
Park ships and
Fort ships to meet the demand for the Allies shipping. The
United Kingdom built
Empire ships and used US
Ocean ships. After the war many of the ships were sold to private companies. The Ever Given is a ship that was lodged into the Suez Canal from March 25 to 28, 2021, which caused a halt on maritime trade.[9][10][11][12]
Pollution
Due to its low cost, most large cargo vessels are powered by
bunker fuel, also known as heavy fuel oil, which contains higher
sulphur levels than diesel.[13] This level of pollution is increasing:[14] with bunker fuel consumption at 278 million tonnes per year in 2001, it is projected to be at 500 million tonnes per year in 2020.[15] International standards to dramatically reduce sulphur content in marine fuels and
nitrogen oxide emissions have been put in place. Among some of the solutions offered is changing over the fuel intake to
clean diesel or marine gas oil, while in restricted waters and
cold ironing the ship while it is in port. The process of removing sulphur from the fuel impacts the
viscosity and lubricity of the marine gas oil though, which could cause damage in the engine
fuel pump. The fuel viscosity can be raised by cooling the fuel down.[16] If the various requirements are enforced, the
International Maritime Organization's marine fuel requirement will mean a 90% reduction in sulphur oxide emissions;[17] whilst the
European Union is planning stricter controls on emissions.[18]
MARPOL 73/78—related to pollution: "Amended Regulation 14 concerns mandatory fuel oil change over procedures for vessels entering or leaving SECA areas and FO sulphur limits."
^"British Order Sixty 10,000 Dwt. Cargo Steamers". Pacific Marine Review. Pacific American Steamship Association/Shipowners' Association of the Pacific Coast. Consolidated 1941 issues (January 1941): 42–43. 1941. Retrieved August 12, 2014.
^Mitchell, William Harry & Sawyer, Leonard Arthur (1990). The Empire Ships (2nd ed.). London, New York, Hamburg, Hong Kong: Lloyd's of London Press Ltd.
ISBN1-85044-275-4.