The biggest container ships ever built ply the world's oceans, but will physics and economics set some limits to how much larger these vessels can get?

有史以来最大的集装箱船往返于世界各大洋，但建造更大型的船舶是否受到物理和经济因素的制约？

When the Ever Ace, one of the largest container ships in the world, eased out of Yantian port on 14 August last year and manoeuvred gingerly into the South China Sea, she had embarked upon a record-breaking voyage.

去年8月14日，世界最大的集装箱船“长范”号驶离深圳盐田港，小心翼翼地驶向南海，她开始了一次破纪录的航行。

To date, no other ship has carried such a large volume of shipping containers – the equivalent of 21,710 20ft (6m) containers.

迄今为止，没有任何船舶运载过这么多的集装箱——相当于21710个20尺（6米）集装箱。

The 399.9m-long (1,320ft) and 61.5m-wide (203ft) vessel is a true behemoth, but there are dozens of container ships of a similar size sailing today. Many more are currently under construction. Just two of them stacked vertically would be nearly as tall as the world's tallest building, the Burj Khalifa in Dubai.

399.9米长（1320尺）61.5米宽（203尺）的船舶是真正的庞然大物，但当今类似尺寸的集装箱船有几十艘，还有更多正在建造当中。其中只有两艘采用垂直堆叠的方式，高度接近于世界第一高楼迪拜哈利法塔。
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If you cast your eyes over a list of the largest container ships in the world, you'll soon notice that they are all 400m (1,320ft) in length or just less than that, and about 60m (200ft) wide. It is more or less today's upper limit for these vessels. There is a surprising number of reasons as to why – and also why you're unlikely to see any container ships much larger than this, perhaps ever. But what are they?

如果你浏览一下世界最大集装箱船的参数，会发现它们长度都是400米（1320尺）或者更短，宽度大约60米（200尺）。这几乎是当今集装箱船的尺寸上限，原因多得令人吃惊——这也是为什么你不太可能看到尺寸更大的集装箱船，可能永远也看不到。但原因是什么？
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There are around 5,500 container ships globally and together they are capable of carrying 25 million TEUs, or the equivalent of around 25 million 20ft (6m) containers. That's if they were all fully loaded at the same moment.

全球大约有5500艘集装箱船，总载箱量2500万TEU，相当于大约2500万个20尺（6米）集装箱，这是它们同时满载集装箱的运力。

As George Griffiths, editor of global container markets at S&P Global Platts explains, the global order book for new container ships will increase that total collective capacity by a gigantic 25% in just a few years.

标普全球普氏能源资讯（S&P Global Platts）的全球集装箱市场编辑乔治·格里菲思透露，在短短几年内，全球的新集装箱船订单将使总运力大幅提升25%。

"We're seeing a lot more of the ultra-large container ships being built," he says. "The proportion of new ships that are moving over 14,000 containers is staggering."

“我们看到建造中的超大型集装箱船越来越多”，他说道。“载箱量超过14000TEU的新船比例令人吃惊”。

In the last decade alone, the average capacity of a container ship has grown from less than 3,000 TEUs to around 4,500 TEUs. And there are currently more than 50 ships with a capacity of 21,000 TEUs or more. Practically all of them were built in the last five years.

仅在过去十年里，集装箱船的平均载箱量从3000TEU增至大约4500TEU，现有50多艘集装箱船的载箱量超过21000TEU。事实上，它们都是过去五年来新造的集装箱船。


If ships become bigger, they may not be able to use waterways such as the Suez Canal

如果船舶变得更大，可能无法通过苏伊士运河这样的航道。
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However, these vessels stretch the limits of even the world's largest ports, says Griffiths. To load and unload containers, cranes must reach across the vessels. Container ships also have to turn, pass through locks and canals – including the Suez and Panama canals, which have size restrictions.

但是，这些船舶突破了世界最大港口的极限，格里菲思说道。起重机必须跨越这些船舶来装卸集装箱。而且集装箱船必须转弯，穿过船闸和运河——包括苏伊士和巴拿马运河，它们对船舶是有尺寸限制的。

It's crucial that vessels avoid running aground, too. In some ports, the largest ships actually sit so deep in the water that they touch the bottom and glide through the silt rather than float above it, says Stavros Karamperidis, head of the Maritime Transport Research Group at the University of Plymouth. Such a manoeuvre must be handled with extreme care.

船舶避免搁浅也很重要。在某些港口里，最大型的船舶吃水太深，以至于在海底淤泥中滑行，而不是漂浮在上方，英国普利茅斯大学“海运研究小组”负责人斯塔夫罗斯·卡拉姆普里迪斯说道。这种操作必须慎之又慎。

To accommodate ships much larger than the biggest in existence today would require a huge overhaul of port infrastructure. And that would be incredibly expensive, notes Griffiths: "Why would you invest in bigger ships if it means you have to invest eye-watering amounts of money in the ports as well?"

要想容纳比现有最大尺寸还要大得多的船舶，需要彻底改造现有的港口基础设施。这样做是极其昂贵的，格里菲思指出：“如果这意味着你还必须对港口进行惊人数额的投资，那你何必投资建造更大的船舶呢”？

Karamperidis adds that the largest ships are also restricted in terms of where they sail because they are so vulnerable to heavy weather. They don't tend to cross the Pacific, for example, which can hurl violent storms at vessels. Medium-sized container ships sometimes lose hundreds of containers in the Pacific.

卡拉姆普里迪斯补充说，最大的船舶在什么海域航行也会有限制，因为它们特别容易受恶劣天气的影响。举例来说，它们一般不在太平洋上航行，因为在那里会遭遇剧烈的风暴。在太平洋海域，中等尺寸的集装箱船有时损失数百个集装箱。

"That's why the [ultra large] vessels come near the coast, so they don't face big waves. It's a matter of stability," says Karamperidis. He adds that most US ports are not big enough to facilitate the largest container ships. Only a handful of ships with capacities approaching 20,000 TEUs have ever called US ports.

“这就是为什么超大型船舶在海岸附近航行的原因，这样能避免遭遇巨浪，关乎船舶的稳性”，卡拉姆普里迪斯说道。他补充说大多数美国港口不够大，无法为最大型的集装箱船提供便利。只有少数载箱量接近20000TEU集装箱船曾停靠过美国港口。

You may be noticing a theme. The limitations on vessel size are not so much to do with the sheer engineering challenges of building really big ships but rather the economics and logistics of operating such giants.

你可能注意到了一个主题。船舶的尺寸限制与建造巨型船舶所面临的工程挑战没有太大关系，而与运营这些庞然大物的经济和物流因素有关。


As ships get bigger, they stress the capacity of even the biggest ports

随着船舶越造越大，甚至最大的港口也会不堪重负。

"Physically, there's not really any limit," says Rosalind Blazejczyk, managing partner and naval architect at Solis Marine Consultants. She does, however, note there are only so many containers that one could stack on top of one another on a ship before the container at the bottom of the pile would buckle under the weight.

“物理上确实没有制约因素”，索厉海洋工程技术咨询公司的经营合伙人和造船工程师Rosalind Blazejczyk说道。但她强调，堆叠在船上的集装箱只能这么多，否则处在底层的集装箱会受压变形。

Containers are also lashed to hold them in place and such systems have upper limits for the number of boxes they could secure safely, notes John Simpson, Blazejczyk’s colleague at Solis.

集装箱还需要被困扎固定，利用这种装置安全固定集装箱是有数量限制的， Blazejczyk在索厉公司的同事约翰·辛普森说道。

Another issue is how these very large and wide ships handle waves. When sailing directly into a sequence of waves, ships can experience a phenomenon called parametric rolling. It happens because, as the waves pass along the length of a very broad container ship, her bow and stern may clear the water whenever the peak of the wave is at the midpoint of the ship. This leaves the upper part of the bow and stern lacking the support of the water below. The variation in this support as waves continue to pass can cause the ship to bob weirdly from side to side.

另一个问题是这些又大又宽的船舶如何应对海浪。当船舶迎浪航行时，会发生一种被称为参数横摇的现象，因为海浪沿着非常宽大的集装箱船行进，每当波峰位于船体中部时，船首和船尾可能脱离水面，使船首和船尾的上部失去船底水体的支撑。当海浪的继续行进时，这种支撑上的变化会导致船体奇怪地左右摇晃。

"You get very large roll angles with not very large wave heights," says Blazejczyk.

“即使浪高不是很大，也会造成很大的横摇角度”，Blazejczyk说道。

Supersized ships are more at risk of this. And container ships also have very large hatches on their decks, which means their overall structure is weaker than some other vessels and more susceptible to torsion, or twisting.

超大型船舶在这方面的风险更大，而且集装箱船甲板上的舱口非常大，这意味着它们的整体结构比其他船舶更薄弱，更容易受到扭转力的影响。

"They're kind of like a shoebox with no lid," Blazejczyk adds. No problem in calm seas but, again, limiting when or where a ship sails likely also limits its usefulness.

“它们就像没有上盖的鞋盒子”，Blazejczyk补充道。海况平稳时没有问题，但船舶航行的时间和海域受限可能也会限制它的实用性。
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Besides all of the above reasons, there is economic weather to contend with. Griffiths notes that the price of oil is exceedingly high at the moment and the largest container ships require huge volumes of fuel.

除了上述原因之外，经济上也存在制约因素。格里菲思指出，目前油价非常高，最大型集装箱船的耗油量巨大。
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Investing in even bigger vessels might not be the wisest financial choice in the future though, having said that, at the moment these costs are being more than covered by the astronomical freight rates worldwide. Such is the present demand for moving goods around.

从经济角度来说，未来投资更大型的船舶可能不是明智之举。话虽如此，目前全世界天文数字的海运费足以承担这些成本，目前的航运需求就是如此。


Containers have to be lashed onto the deck of ships, which limits the amount which can be carried

集装箱必须被困扎在船舶甲板上，这限制了载箱量。

Karamperidis says that, for container ships with a capacity much higher than 25,000 TEUs to become viable, the economics of operating them would have to change. The Suez Canal will probably always act as a bottleneck for ships travelling from Asia to Europe but it's not impossible to imagine a 30,000 TEU vessel or similar one day traversing a route from China to, for example, a booming African port, says Karamperidis.

卡拉姆普里迪斯说，要想让载箱量远高于25000TEU的集装箱船具有可行性，就得从经济层面改变运营方式。苏伊士运河可能永远是船舶从亚洲到达欧洲的瓶颈。但总有一天，30000TEU或类似的船舶从中国穿越航线，比如到达繁荣的非洲港口，这不是天方夜谭，卡拉姆普里迪斯说道。

"Maybe we'll see those kind of vessels going from Asia to Mombasa," he adds, referring to the largest port of Kenya.

“我们也许会看到那些船舶从亚洲到达蒙巴萨”，他指的是肯尼亚的最大港口。

The 24,000 TEU ceiling on container ship capacity we see globally today is, more or less, a reflection of economic limits as much as it is about port infrastructure, the shape of the world's busiest waterways and engineering.

我们看到当今全球集装箱船的载箱量上限是24000TEU，或多或少反映出经济上的制约，同时也与港口基础设施、世界上最繁忙航道的形状、工程领域有关。

But there's always that possibility that, given the right conditions, someone somewhere with enough money will one day commission a vessel that dwarfs even today’s gargantuan ships. It would certainly be a wonder to behold.

但总有一天，在合适的条件下，资金充裕的某人或某地会委托建造一艘更大的船舶，使当今的巨型船舶相形见绌，这种可能性是存在的，那必将是个奇迹。