SRT #50 油轮种类和航线
2014.12.01
从二战初期到上世纪70年代海上原油运输的船只已由美国的T-2油轮发展到VLCC超大型油轮, 如图
T-2 tanker 16,000-dwt VLCC tanker 300,000-dwt
152.9mx20.7mx13m 333mx60mx27m
因为航线和需求的不同油轮种类大约可分为下列五种:
Oil tankers come in various shapes and sizes and have developed significantly since the early 20th Century to carry vast amounts of oil (and its derivatives) across the globe each day.
Tankers started to increase in size more rapidly just before, and then during World War I, beginning with the licensing of the USS Maumee, a US fleet oiler (14,500DWT). The Maumee was used to refuel US destroyers en route to Britain and also enabled the Navy to keep its fleet mobile for extended periods which proved crucial to victory in the North Atlantic. Between 1916 and 1921, 316 new oil tankers were built with the ability to carry 3.2 million DWT of oil, compared to just 2 million DWT before World War I.
And then, during World War II tankers again increased in size and sheer volume. The T2 (16,600DWT) was the most popular tanker with over 500 built. They were continued to be used as commercial tankers after the war to move oil around the globe.
The size of oil tankers remained fairly static up until 1956 when the Suez Canal was closed during the Suez Crisis of 1956. Up until this point, all tankers were able to fit through the Suez Canal and have a quick route from the east to the west and so long range efficiency wasn’t as important as it became when the Suez Canal closed. At this point, tankers now had to travel around the southern tip of Africa and this increased their journey distance significantly, from areas like Saudi Arabia and India to Europe, as seen below:
After 1956, a new fleet of tankers started to be produced to try and increase efficiency over the new longer distances that needed to be travelled by tankers.
‘Supertankers’, were classified as tankers whose DWT exceeded 250,000 tonnes. This group contains Very Large Crude Carriers and Ultra Large Crude Carriers (VLCC, ULCC). The largest built supertanker was the SeaWise Giant, built in Japan in 1979. It had a DWT of 564,760 tonnes and was over 400m in length.
TYPE DWT__________
General purpose 10,000 – 24,999
Medium purpose 25,000 – 44,999
Large range 1 45,000 – 79,999
Large range 2 80,000 – 159,000
Product tanker 10,000 – 60,000
PanaMax 60,000 – 80,000
AfraMax 80,000 -- 120,000
SuezMax 120,000- 200,000
VLCC 200,000 - 320,000
ULCC 320,000 - 550,000
PanaMax tankers are the largest tankers that can currently pass through the Panama Canal in Central America. They are mid-sized vessels with DWT between 50,000 and 80,000. Because of the locks contained within the Panama Canal, tankers that pass through have strict size dimensions by width, draught and length. The maximum dimensions of a PanaMax are currently a length of 294 metres, a width of 32 metres and draught of 12 metres, and this allows safe passage of tankers through the locks in the canal and under the Bridge of Americas at Balboa. The size restrictions are governed by the Panama Canal Authority who oversee all operations to do with the canal.
As is the case with the majority of waterways used in the transit of crude oil, the authority responsible for its maintenance and operation is always looking for ways to increase its capabilities. In 2009, the Panama Canal Authority set out dimensions for the New PanaMax tankers that could transit through the larger third lock in the canal. The New PanaMax tankers will be allowed a length of 366 metres, a width of 49 metres and draught of 15.2 metres. The Panama Canal Authority are hoping to double the tonnage capacity of the canal in 2014 when the new lock is opened to international maritime traffic.
An AfraMax tanker is a medium sized vessel with a DWT of between 80,000 and 120,000. This DWT converts into around 750,000 barrels of oil on any average AfraMax tanker. The AfraMax name comes from the Average Rate Freight Assessment (AFRA) guide as set out by Shell in 1954, and the tanker size was created specifically to serve waterways and ports that were unable to handle the larger VLCC and ULCC tankers. Because of their nimble size, AfraMax tankers are seen as the workhorses of the ocean, capable of docking at all global ports and able to navigate all major waterways, even with heavy traffic, something larger tankers are unable to do with ease. They are referred to as dirty tankers given that most of the cargo they transport is crude oil as opposed to refined (clean) products.
AfraMax tankers, because of their size are used mostly in small-medium haul crude oil transportation. They are mostly used to transport crude oil from South American oil fields through to the US Gulf region via the Caribbean, from the former Soviet Union republics to Northern Europe via the Black Sea, from North Africa to Southern Europe via the Mediterranean Sea and to the Far East from South East Asia. But more generally they serve all Non-OPEC regions that have ports unable to accommodate the largest super tankers.
A SuezMax is the largest tanker with a full cargo that can pass through the Suez Canal. The maximum DWT of a SuezMax changes with the development of the Canal and is dictated by the Suez Canal Authority. There are maximum conditions for DWT, depth, beam but all are interchangeable and the Suez Canal Authority produces tables regarding the conditions for tankers which have specific dimensions. Currently, the maximum DWT is about 240,000 tonnes, the maximum draft of the tanker is around 20.1 metres, the maximum height is 68 metres and the maximum beam is around 77 metres.
A SuezMax offers the relative economies of scale that can be achieved with a VLCC tanker, but because it is slightly smaller in size, it is able to offer more versatility in terms of the routes it can take. To add, a SuezMax is versatile in that it is able to access the majority of ports worldwide, unlike a VLCC tanker which is restricted because of its size.
The maximum dimensions of a SuezMax are limited by a few key factors. Given that the Canal has no locks, the only limiting factors of the Canal are the draft (the maximum depth of water below a tanker’s plimsoll line) and the height of the Suez 义Canal Bridge (also known as the Shohada 25 January Bridge) and to a lesser extent the beam (width of tanker). Since the height of the bridge is unchangeable at 70 metres above the waterline, the only way to increase maximum tonnage of the SuezMax is to increase the depth of the Canal.
VLCC Maersk Nautilus
VLCC tankers will typically have a DWT of between 200,000 and 320,000, so they are capable of carrying a vast amount of crude oil; a maximum of 2,400,000 barrels. The VLCC tankers can have a length of up to 470m, width of up to 60m and draught of up to 20m, but a typical VLCC tanker will have length of 330m, width of 57m and draught of 12m. This typical size allows many VLCC tankers safe passage through the Suez Canal which makes them suitable for long-haul crude oil transit from the Persian Gulf to Europe as well as North America. VLCC tankers are well known for their versatility with regard to terminals and their ability to access many major ports with draught restrictions and this makes them a first choice for many traders.
ULCC TI Oceania
ULCC tankers are the largest of the maritime fleet, with DWT typically ranging between 320,000 to 550,000. ULCC tankers are gigantic in size, typically being 415m in length, 63m wide and having a draught of 35m. However because of their size, they must have custom built terminals and as a result are only able to serve a limited number of ports that have the facilities to accommodate them; this means they are not as flexible as the VLCC tanker. However, ULCC’s prove to be the most economical over long-haul journeys between the Persian Gulf and North America/Europe via the Cape of Good Hope and to the major economies in Asia, assuming they have a fully loaded cargo.
航线:
亚洲国家所需之原油多数来自波斯湾和西非.
1.如从波斯湾进口用的船只都是30万吨的VLCC, 航线是经 Hormuz 和马六甲海峡, 如果超过30万吨即要用路程稍远的 Lombok 海峡.
2. 如从西非进口,数量小的可走苏伊士运河, 数量大的即需经好望甲.
The Strait of Hormuz is the waterway that connects the Gulf of Oman and the Persian Gulf. It is the only waterway that connects the oil-rich nations in the Middle East with the Indian Ocean, which is vital for maritime traffic, as seen belo
The Strait itself is only 21 miles wide at its narrowest point, between the Omani Musandam Peninsula at Oman and Iran. There are 8 small islands within the Strait of Hormuz, seven of which are controlled solely by Iran, and the last one by the United Arab Emirates. Iran has maintained a military presence on the seven islands since the 1970’s. The Iranian Navy has access to the open sea through the ports at Bandar Abbas, Büshehr, and Chah Bahar and with its de facto control of the seven islands in the Strait; Iran has been able to maintain a significant influence in matters concerning the waterway and in the region more general.
To control the flow of traffic through the Strait, vessels follow a traffic separation scheme (TSS), which helps to reduce collisions. There are two shipping lanes, one for vessels moving one way, and one for vessels moving in the opposite direction. The lanes are each two miles wide, and are separated by a 2 mile wide gap in between. This leaves relatively little room for ships to manoeuvre within the TSS zone.
In order to pass through the Strait of Hormuz, vessels must transverse the international waters of both Oman and Iran. This gives Iran some strategic advantage and often the Iranian elect will threaten to close the Strait over international relations disputes, like the topical question regarding Iran’s nuclear programme. Disputes occur regularly, and most often with the United States, given that the Strait is so important to them (currently), because the state of the world economy depends heavily upon the flow of oil from the oil rich nations in the Middle East to the rest of the world. There is a common fear that Iran could hypothetically close the Strait of Hormuz and cause mass disruption in oil markets and hence the global economy, but research has shown that whilst this may be the case only slightly, Iran doesn’t possess the military or technical ability to do so, and the various economic, political and military forces present in the region today make any real disruption unlikely.
The Suez Canal links the Mediterranean and Red seas together and provides a short route of transit between the East and West. It runs between the Port Said harbour (at the Mediterranean Sea) and the Gulf of Suez (at the Red Sea). The Canal has been constantly developed and improved since 1869 to accommodate larger tankers both in terms of Dead Weight Tonnage (DWT), length, width and draft. In 1869, the Canal was only 164km long but has constantly been lengthened and in 2010, total length is 193km. At its narrowest point, the Canal is 300 metres wide. The Canal has no locks since the height of the Red Sea and Mediterranean Sea are very similar, differing only by around 2 metres at the maximum, and so water is allowed to flow freely between the two seas.
In 1869, there were no bypasses to allow two-way traffic, however several have been created along the distance of the route and the total bypass length as of 2010 is 80.5km. From North to South the bypasses are: 3 bypasses at the Port Said entrance, the Ballah bypass and anchorage site, the Timsah bypass at the Timsah lake and lastly the bypass just north of the Great Bitter lake. These bypasses act as both passages and anchorage sites and allow the safe transition of convoys through the Suez Canal, avoiding any major accidents.
The Ballah bypass has smaller dimensions than the main shipping route and so any convoy that uses the bypass for anchorage or passage will usually contain smaller and often unloaded vessels. The Great Bitter Lake is used for passage and as a waiting area for all convoy sizes as it is much more capable of handling larger tankers.
Capacity
Currently, the Suez Canal allows passage of tankers with a draft of up to 20 metres or 240,000 DWT, and a maximum height of 68 metres above the waterline. The maximum beam that a tanker is able to possess is 77.5 metres. As a result of these restricting conditions, some fully laden supertankers cannot transit with a full cargo and must partially unload their cargo onto another tanker or into a pipeline before passing through the Canal.
The Canal is not wide enough to allow two-way traffic and so tankers travel in convoys and use bypasses in order to avoid collision and optimise traffic flow.
The Strait of Malacca is an important waterway in international oil transportation. The Strait Is situated between the Malaysian Peninsula and Sumatra, the Indonesian island. The Strait is the main shipping lane between the Pacific Ocean and the Indian Ocean; it provides the shortest shipping route between the oil-rich Persian Gulf nations, India and the other major Asian economies (China, Japan, South Korea).
The Strait itself is a narrow but long waterway and is considered to be the most vulnerable oil choke-point because of the dangers derived from its dimensions. The Strait is 1.5 miles wide and 500 miles long as well as being relatively shallow in some parts, having a depth of only 22 metres at its shallowest point, which restricts the size of vessel that can safely pass through it (See MalaccaMax). Many dangers present themselves given the dimensions of the Strait, including collision between vessels in the narrow shipping lanes, grounding due to the shallow waters and piracy given the short distance to land on either side of the Strait. Nevertheless, some 50,000 vessels pass through the Strait each year with 12 million barrels of oil carried each day between the Persian Gulf and the major Asian countries excluding India.
The Lombok Strait is a waterway located between the islands of Bali and Lombok in southern Indonesia and links the Java Sea and Indian Ocean. It is close to the Strait of Malacca and is used by vessels which are too large to navigate through Malacca due to its shallow waters, most notably by VLCC and ULCC tankers.
The Strait is just over 37 miles in length, and is much wider and deeper than the Strait of Malacca. It is 12 miles wide at its southern entrance, 24 miles wide at its northern entrance and around 250 metres deep throughout. This makes the waterway suitable for the very and ultra large ocean-going tankers.
The Strait is also used as the first alternative route through to the major Asian markets of China, Japan and South Korea from the Persian Gulf whenever the Strait of Malacca is blocked because of collisions or as an alternative whenever the fear of piracy in the Strait is high. The Strait of Malacca is particularly susceptible to piracy given its location and its closeness to Indonesian islands on both sides, which means the Lombok Strait, is used regularly by oil tankers who wish to avert this fate.
