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发表于 2020-7-6 04:49:18
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本帖最后由 gaoloumi2035 于 2020-7-6 04:53 编辑
"Suezmax" is a naval architecture term for the largest ship measurements capable of transiting the Suez Canal in a laden condition, and is almost exclusively used in reference to tankers. The limiting factors are beam, draft, height (because of the Suez Canal Bridge), and length[1] (even though the canal has no locks).
The current channel depth of the canal allows for a maximum of 20.1 metres (66 ft) of draft,[2] meaning that a few fully laden supertankers are too deep to fit through, and either have to unload part of their cargo to other ships ("transhipment") or to a pipeline terminal before passing through, or alternatively avoid the Suez Canal and travel around Cape Agulhas instead. The canal was deepened in 2009 from 18 to 20 metres (59 to 66 ft).
The typical deadweight of a Suezmax ship is about 160,000 tons and typically has a beam (width) of 50 m (164.0 ft). Also of note is the maximum head room—"air draft"—limitation of 68 m (223.1 ft), resulting from the 70 metres (230 ft) height above water of the Suez Canal Bridge. Suez Canal Authority produces tables of width and acceptable draft, which are subject to change.[1] From 2010, the wetted surface cross sectional area of the ship is limited by 1006 m2, which means 20.1 metres (66 ft) of draft for ships with the beam no wider than 50.0 m (164.0 ft) or 12.2 metres (40 ft) of draft for ships with maximum allowed beam of 77.5 metres (254 ft).[3]
Panamax and New Panamax (or Neopanamax) are terms for the size limits for ships travelling through the Panama Canal. The limits and requirements are published by the Panama Canal Authority (ACP) in a publication titled "Vessel Requirements".[1] These requirements also describe topics like exceptional dry seasonal limits, propulsion, communications, and detailed ship design.
The allowable size is limited by the width and length of the available lock chambers, by the depth of water in the canal, and by the height of the Bridge of the Americas since that bridge's construction. These dimensions give clear parameters for ships destined to traverse the Panama Canal and have influenced the design of cargo ships, naval vessels, and passenger ships.
Panamax specifications have been in effect since the opening of the canal in 1914. In 2009 the ACP published the New Panamax specification[2] which came into effect when the canal's third set of locks, larger than the original two, opened on 26 June 2016. Ships that do not fall within the Panamax-sizes are called post-Panamax or super-Panamax.
The increasing prevalence of vessels of the maximum size is a problem for the canal, as a Panamax ship is a tight fit that requires precise control of the vessel in the locks, possibly resulting in longer lock time, and requiring that these ships transit in daylight. Because the largest ships traveling in opposite directions cannot pass safely within the Culebra Cut, the canal effectively operates an alternating one-way system for these ships.
Panamax is determined principally by the dimensions of the canal's original lock chambers, each of which is 110 ft (33.53 m) wide, 1,050 ft (320.04 m) long, and 41.2 ft (12.56 m) deep. The usable length of each lock chamber is 1,000 ft (304.8 m). The available water depth in the lock chambers varies, but the shallowest depth is at the south sill of the Pedro Miguel Locks and is 41.2 ft (12.56 m) at a Miraflores Lake level of 54 ft 6 in (16.61 m). The clearance under the Bridge of the Americas at Balboa is the limiting factor on a vessel's overall height for both Panamax and Neopanamax ships; the exact figure depends on the water level.
The maximum dimensions allowed for a ship transiting the canal using the original locks and the new locks (New Panamax) are:[1]
Length
Overall (including protrusions): 950 ft (289.56 m). Exceptions:
Container ship and passenger ship: 965 ft (294.13 m)
Tug-barge combination, rigidly connected: 900 ft (274.32 m) overall
Other non-self-propelled vessels-tug combination: 850 ft (259.08 m) overall;
New Panamax increases allowable length to 366 m (1,201 ft).[2]
Width (beam)
Width over outer surface of the shell plating: 106 ft (32.31 m). General exception: 107 ft (32.61 m), when draft is less than 37 ft (11.3 m) in tropical fresh water.
New Panamax increases allowable width to 49 m (161 ft).[2] Recently expanded to 51.25m
Draft
The maximum allowable draft is 39.5 ft (12.04 m) in Tropical Fresh Water (TFW). The name and definition of TFW is created by ACP using the freshwater Lake Gatún as a reference, since this is the determination of the maximum draft. The salinity and temperature of water affect its density, and hence how deep a ship will float in the water. Tropical Fresh Water (TFW) is fresh water of Lake Gatún, with density 0.9954 g/cm3, at 29.1 °C (84 °F).[3] The physical limit is set by the lower (seaside) entrance of the Pedro Miguel locks. When the water level in Lake Gatún is low during an exceptionally dry season the maximum permitted draft may be reduced. Such a restriction is published three weeks in advance, so ship loading plans can take appropriate measures.
New Panamax increases allowable draft to 15.2 m (49.9 ft),[2] however due to low rainfall, the canal authority limited draft to 43 feet when the new locks opened in June 2016, increasing it to 44 feet (13.41 meters), in August "based on the current level of Gatun Lake and the weather forecast for the following weeks."[4]
Height
Vessel height is limited to 190 ft (57.91 m) measured from the waterline to the vessel's highest point; the limit also pertains to New Panamax in order to pass under the Bridge of the Americas at Balboa harbor. Exception: 205 ft (62.5 m) when passage at low water (MLWS) at Balboa is possible.[citation needed]
All exceptions are typically allowed only after specific request and an investigation, and on a once- or twice-only basis.[citation needed]
Cargo capacity
A Panamax cargo ship would typically have a DWT of 65,000–80,000 tonnes, but its maximum cargo would be about 52,500 tonnes during a transit due to draft limitations in the canal.[5] New Panamax ships can carry 120,000 DWT.[6] Panamax container ships can carry 5,000 twenty-foot equivalent units (TEU); with 13,000 TEU for New Panamax vessels.
Malaccamax is a naval architecture term for the largest tonnage of ship capable of fitting through the 25-metre-deep (82 ft) Strait of Malacca. Bulk carriers and supertankers have been built to this tonnage, and the term is chosen for very large crude carriers (VLCC). They can transport oil from Arabia to China.[1] A typical Malaccamax tanker can have a maximum length of 333 m (1,093 ft), beam of 60 m (197 ft), draught of 20.5 m (67.3 ft), and tonnage of 300,000 DWT.[2]
The term Seawaymax refers to vessels which are the maximum size that can fit through the canal locks of the St. Lawrence Seaway, linking the inland Great Lakes of North America with the Atlantic Ocean.[1]Seawaymax vessels are 740 feet (225.6 m) in length, 78 feet (23.8 m) wide, and have a draft of 26.51 feet (8.08 m) and a height above the waterline of 35.5 metres (116 ft).[1] A number of lake freighters larger than this size cruise the Great Lakes and cannot pass through to the Atlantic Ocean. The size of the locks limits the size of the ships which can pass and so limits the size of the cargoes they can carry. The record tonnage for one vessel on the Seaway is 28,502 tons of iron ore while the record through the larger locks of the Great Lakes Waterway is 72,351 tons. Most new lake vessels, however, are constructed to the Seawaymax limit to enhance versatility by allowing the possibility of off-Lakes use. SS Edmund Fitzgerald, famous for her wreck in 1975, was the first ship constructed close to Seawaymax size. |
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