词条 | Lightering |
释义 |
HistoryLightering 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' draft sufficiently to enter the port, cargoes ranging from water to ships's 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 have reduced the frequency of the practice in dry bulk shipping after the middle of the 20th century. However, the practice remains in common usage in the oil tanking industry ("wet" cargo trade). Modern processWet bulkLightering for tankers typically occurs in the EEZ, generally between {{convert|20|nmi|km|-1}} and {{convert|60|nmi|km|-1}} 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 bulkIn many developing nations, such as China and especially India, dry bulk vessels still often lighter in order to meet draft restrictions at ports that either do not have natural deep water access or whose channels have yet to be dredged to sufficient depth to allow some of the larger-size bulk carriers to safely transit. In dry bulk, lightering can be undertaken one of two ways. If the vessel to be lightered is geared, 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, although not very common, vessels will sometimes lighter before (or even between) berthings, shifting to shallower berths in order to discharge more quickly and also free up space for larger vessels. See also{{Portal|Nautical}}
External links
References1. ^{{cite web|title=lighterage|url=http://dictionary.reference.com/browse/lighterage|publisher=Dictionary.com}} 2. ^{{cite book|last1=Glanz|first1=James|last2=Lipton|first2=Eric|title=City in the Sky: The Rise and Fall of the World Trade Center|date=2003|publisher=Henry Holt and Company|isbn=0-8050-7428-7|url=https://books.google.com/books?id=yE1Pyui4GpkC&pg=PA48#v}} 3. ^{{cite web|publisher=U.S. National Oceanic and Atmospheric Administration (NOAA) National Ocean Service|title=What is lightering?|url= http://oceanservice.noaa.gov/facts/lightering.html}} 1 : Ship management |
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