Lightering (also called lighterage) is the process of transferring cargo between vessels of different sizes, usually between a barge ( lighter) and a bulker or

oil tanker An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk cargo, bulk transport of petroleum, oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quant ...

. Lightering is undertaken to reduce a vessel's

draft Draft, the draft, or draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a v ...

so it can enter

port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Hamburg, Manch ...

facilities that cannot accept large fully-loaded ocean-going vessels. Lightering can also refer to the use of a lighter barge for any form of short-distance transport, such as to bring

railroad car A railroad car, railcar (American English, American and Canadian English), railway wagon, railway carriage, railway truck, railwagon, railcarriage or railtruck (British English and International Union of Railways, UIC), also called a tra ...

s across a river. In addition, lightering can refer to the process of removing oil or other hazardous chemicals from a compromised vessel to another vessel to prevent an

oil spill An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...

History

Lightering was practiced for all types of cargo for centuries. Prior to the 19th century introduction of steamships too large to enter some of the ports they intended to serve, in which case lightering became necessary to reduce the vessels'

sufficiently to enter the port, cargoes ranging from water to ships' stores (food, livestock, misc. supplies), to gunpowder and shot, were carried from dockside to sailing ships moored in harbors and roadways. Dredging, advances in dock construction, and

containerization Containerization is a system of intermodal freight transport using intermodal containers (also called shipping containers, or International Organization for Standardization, ISO containers). Containerization, also referred as container stuf ...

have reduced the frequency of the practice in dry bulk shipping since the middle of the 20th century. However, the practice remains in common usage in the oil tanking industry ("wet" cargo trade).

Modern process

Wet bulk

Lightering for tankers typically occurs in the EEZ, generally between and from the shore, and can be performed while the ships are at anchor, drifting, or underway. The product is typically transferred using specialized hoses which offload cargo from the larger vessel to the smaller. Fenders are used to separate the two ships moored to each other and prevent damage while the cargo is being transferred.

Dry bulk

In many developing nations, such as China and especially India, dry bulk vessels still often lighter so they can meet draft restrictions at ports with no natural deep water access or without channels dredged to sufficient depth to allow safe transit. In dry bulk, lightering can be undertaken one of two ways. If the vessel to be lightered is geared (i.e., supplied with cranes), then it can discharge cargo to smaller, ungeared vessels (typically barges). If the vessel to be lightered is gearless, then floating cranes are often used to transfer cargo to another vessel or barge. A roll-on/roll-off discharge facility, a floating platform, can also be used to connect the vessels. Also, though not very common, vessels will sometimes lighter before (or even between) berthings, shifting to shallower berths to discharge more quickly and free up space for larger vessels.

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