What is a Cargo Ship?

A cargo ship or freighter is any sort of ship or vessel 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 crane (machine)|cranes and other mechanisms to load and unload, and come in all sizes. Today, they are almost always built by welded steel, and with some exceptions generally have a life expectancy of 25 to 30 years before being scrapped.

Definitions

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 compensation the ship or chartering (shipping)|charterer receives for carrying the cargo.

Generally, the modern ocean shipping business is divided into two classes:

1. Liner business: typically (but not exclusively) container vessels (wherein “general cargo” is carried in 20 or 40-foot containers), operating as “common carriers”, calling 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.
2. 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 Coastal trading vessel|coasters, are often owned by their operators.

Types

Cargo ships/freighters can be divided into five groups, according to the type of cargo they carry. These groups are:

1. General cargo vessels
2. Tanker (ship)|Tankers
3. Dry bulk carriers
4. Multi-purpose vessels
5. Reefer ships

General cargo vessels carry packaged items like chemicals, foods, furniture, machinery, motor- and military vehicles, footwear, garments, etc.

Tankers carry petroleum products or other liquid cargo.

Dry bulk carriers carry coal, grain, ore, and other similar products in loose form.

Multipurpose vessels, as the name suggests, carry different classes of cargo – e.g. liquid and general cargo – at the same time.

A Reefer (or refrigerated) ship is specifically designed and used for shipping perishable commodities which require air conditioning|temperature-controlled, mostly fruits, meat, fish, vegetables, dairy products and other foodstuffs.

Specialized types of cargo vessels include container ships and bulk carriers (technically tankers of all supertanker|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 also carry passengers. A cargo liner that carries 12 or more passengers is called a combination or passenger-cum-cargo line.

Vessel prefixes

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 engine|diesel), “MT” (Motor Tanker, powered vessel carrying liquids only) “FV” Fishing Vessel and “SS” (Screw Streamer, driven by propellers or screws, often understood standing for Steamship). “TS”, sometimes found in first position before a merchant ship's prefix, denotes that it is a Turbine Steamer. (For further discussion, see Ship prefixes.)

Size categories

Cargo ships are categorized partly by cargo capacity, partly by weight (deadweight tonnage DWT), and partly by dimensions. Maximum dimensions such as length and width (Beam (nautical)|beam) limit the canal locks a ship can fit in, water depth (Draft (hull)|draft) is a limitation for canals, shallow straights or harbors and height is a limitation in order to pass under bridges. Common categories include:

• Dry Cargo
  • Small Handy size, carriers of 20,000-28,000 Deadweight tonnage|DWT
    • Seawaymax, 28,000 Deadweight tonnage|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).
  • Handysize|Handy size, carriers of 28,000-40,000 Deadweight tonnage|DWT
  • Handymax, carriers of 40,000-50,000 Deadweight tonnage|DWT
  • Panamax, the largest size that can traverse 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 Deadweight tonnage|DWT loaded, 80,000 Deadweight tonnage|DWT empty.
  • Panamax|New Panamax, Upgraded Panama locks with 366 m (1,201 ft) length, 55 m (180 ft) beam, 18 m (59 ft) depth, 120,000 Deadweight tonnage|DWT^{Cargo ship|[4]}
  • Capesize, vessels larger than Suezmax and Post-Panamax, and must traverse the Cape of Good Hope and Cape Horn to travel between oceans
  • Chinamax, carriers of 380,000-400,000 Deadweight tonnage|DWT up to 24 m (79 ft) draft, 65 m (213 ft) beam and 360 m (ca. 1,181 ft) length; these dimensions are limited by port infrastructure in China
• Wet Cargo
  • Aframax, oil tankers between 75,000 and 115,000 Deadweight tonnage|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 metres (114 ft) high, with a shallow draft of approximately 12 m (39 ft).^{Cargo ship|[5][6]}
  • Suezmax, typically ships of about 160,000 Deadweight tonnage|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), Supertanker|supertankers between 150,000 and 320,000 Deadweight tonnage|DWT.
    • Malaccamax, ships with a draft less than 20.5 m (67.3 ft) that can traverse the Strait of Malacca, typically 300,000 Deadweight tonnage|DWT.
  • Ultra Large Crude Carrier|ULCC (Ultra Large Crude Carrier), enormous supertankers between 320,000 and 550,000 Deadweight tonnage|DWT
    

TI-class supertanker is an Ultra Large Crude Carrier, with a draft that is deeper than Suezmax, Malaccamax and New Panamax. 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 the 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.

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. This level of pollution is accelerating: 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. International standards to dramatically reduce sulphur content in marine fuels and nitrogen oxide emissions have been put in place. Among some 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. If the various requirements are enforced, the International Maritime Organization's marine fuel requirement will mean a 90% reduction in sulphur oxide emissions; whilst the European Union is planning stricter controls on emissions.

Source: https://en.wikipedia.org/wiki/Cargo_ship