The Suez fiasco shows why ever bigger container ships are a problem

London(CNN Business) The blockage of a crucial global trade route last week by a 224,000-ton container ship has raised questions over whether vessels have become too large for the waterways they navigate.

The Ever Given, which ran aground in the Suez Canal last Tuesday, is in the top 1% globally in terms of vessel size, according to shipping insurer Allianz Global Corporate & Specialty. At 400 meters (1,312 feet), the ship is as long as the Empire State building is tall and can carry up to 20,000 containers.

The largest ships in the world can carry up to 24,000 containers and measure over 61 meters (200 feet) at their widest point — wider than a standard American football field. Over the past 50 years, the container carrying capacity of the biggest ships has increased 1,500%, and doubled over the past decade alone, according to AGCS.

"Obviously, the size of these vessels makes a salvage operation a significant undertaking," said AGCS global head of marine risk consulting, Rahul Khanna. "For some time now, many in the salvage industry have warned that container ships are getting too big for situations like this to be resolved efficiently and economically," he added.

It took salvage teams almost a week to dislodge the Ever Given, enough time for it to hold up over 400 other carriers, including oil tankers and dozens of container ships. While the successful refloating of the vessel on Monday was met with relief, the backlog will take days to clear, according to major shipping lines.

That will compound problems in supply chains, such as container shortages and port congestion, amid an unprecedented demand for goods.

"Even when the canal gets reopened, the ripple effects on global capacity and equipment are significant and the blockage has already triggered a series of further disruptions and backlogs in global shipping that could take weeks, possibly months, to unravel," Maersk (AMKAF) said in a statement on Monday.

Bigger ships, lost cargo

The Suez Canal has had to contend with ever larger container vessels in recent years, forcing it to be widened on several occasions. According to S&P Global Panjiva, the average capacity of ships transiting the canal reached 119,000 metric tons in the 12 months to February 2020, compared with 93,500 in 2015.

The Ever Given ran aground after being caught in strong winds and a sandstorm that caused poor visibility and made it difficult to navigate, according to the Suez Canal Authority.

While the Suez Canal is wide enough "under normal conditions," the bigger the vessel the smaller the margin for error, Andrew Kinsey, a senior marine consultant at AGCS, told CNN Business. "The impact of any misalignment becomes more severe as a function of the increase in vessel [width] and length," he said.

Stacking containers higher on these ships also makes them more susceptible to strong winds, which may have been a factor in recent incidents when cargo has been lost during bad weather, he added.

At least five ultra-large container vessels lost containers during the most recent winter storm season in the Pacific, analysts at S&P Global Panjiva said in a research note.

The largest loss was on the Ocean Network Express Apus during a violent storm in late November, when over 1,800 containers fell overboard. Maersk's Essen and Eindhoven vessels lost or suffered damage to 750 and 325 containers respectively in rough seas earlier this year.

But there are few signs that container shipping operators are ordering smaller boats, said Kinsey. "The drive continues to be for larger and larger vessels," he added.

More efficient or riskier?

Shipping lines argue that ultra-large container vessels are more efficient and environmentally friendly when it comes to transporting large quantities of goods around the globe.

"Ultra-large container vessels have existed for many years and have sailed through the Suez Canal without issues," said Maersk's chief technical officer, Palle Brodsgaard Laursen.

"Waterways such as the Suez Canal are designed for these vessel sizes," added Hapag-Lloyd (HPGLY) spokesperson Tim Seifert, pointing to the fact that almost 19,000 vessels transit the canal annually, or some 50 a day, and there have been about eight incidents a year over the past decade.

Laursen acknowledged, however, that it can be challenging for very large container vessels to transit the Suez Canal. This is because the small distance between the ship and the bank of the canal causes water to flow around the vessel in such a way that risks a "momentary loss of steering," he explained.

"This effect is more profound for the largest [vessels] transiting the canal," he added.

Transiting the Panama Canal, which is narrower than the Suez, is more complex but takes place in a more controlled environment because ships make passage individually rather than in a convoy, said Kinsey.

Germany's Kiel Canal, which links the North Sea with the Baltic Sea, has more frequent incidents, such as collisions and machinery failures, but it doesn't deal with the same size of vessel as the Suez, which significantly reduces the impact, he added. "The Suez is just such a crucial link in the supply chain," he said.

When it comes to the Ever Given, it will be important to determine what caused the ship's grounding, said Emily Hannah Stausbøll, an analyst at shipping association Bimco.

"From there it may be necessary to look at the rules regarding these ships' passage through the canal," she told CNN Business on Tuesday, adding that it is too soon to draw any conclusions.

"Already today we are seeing other ships of Ever Given's size make it through the canal without any problems, as happens the vast majority of the time," she said.