It would be tempting to hope the recent stranding of the 1,300-foot, 220,000-ton Ever Given container ship in the Suez Canal was a one-off — just a case of a very big ship getting stuck in a narrow waterway.
But more than 100 ships of similar size are plying the world's waterways, and even bigger ones are being built in Asia, creating logistical challenges and concerns about more mishaps in the future.
Capt. Andrew Kinsey, a senior marine-risk consultant for Allianz, a global financial services firm, says with heavy weather in the North Pacific Ocean over the past year, a lot of containers are going overboard.
"We have seen some ... spectacular losses of cargo, with vessels losing a lot of containers," he says.
Part of the problem is the way the ultra-large ships — capable of carrying 10,000 or more cargo containers — handle at sea with towering stacks of containers, especially in strong winds.
Kinsey says one of the more high-profile cases occurred in November, when a Japanese-flagged vessel, the ONE Apus, lost more than 1,800 containers, holding cargo worth an estimated $200 million, northwest of Hawaii during high winds.
Some container lashings failed, Kinsey says, and the cargo, bound for the U.S. from China, went over the side. Other containers stacked up on board collapsed and "tumbled like a house of cards," he says.
Investigations into the incident continue, and the ship is now back at sea.
Alan Murphy, chief executive of SeaIntelligence, a container-shipping research and advisory firm in Copenhagen, Denmark, says it's difficult to gauge whether there has been an increase in the number of containers going overboard or if trans-Pacific container losses over the past year have just received more attention.
In a November report, the World Shipping Council, an interest and lobbying group for the shipping lines, found the number of such incidents to be falling in recent years, although the report does not cover 2020.
There is no central, mandatory database for reporting container losses, so it's not known exactly how many containers fall overboard, Murphy says.
"We have to wait for the shipping line to tell us," he says.
Murphy says container ships are often loaded at capacity nowadays, as demand for consumer products — everything from televisions to exercise equipment to washing machines — has skyrocketed during the coronavirus pandemic.
"In the past, these mega-vessels have never really tried to be loaded as full as they are now," he says. "Obviously, the more full the vessel is, the greater the risk of an incident happening. If you're only half-full and you can stow every container below deck, you're not dropping any container in the ocean."
One reason the Ever Given was so hard to move out of the Suez Canal was that it was packed with 20,000 20-foot equivalent units, or TEUs, the standard measure for cargo containers. Murphy says that when he started in the shipping industry 20 years ago, vessels could hold about 6,000 TEUs.
"I remember people talk about the absolute madness," he says. " 'We've gone mad,' you know. 'Why on Earth are we building these behemoths? Will we ever be able to fill them?' "
In fact, some container ships can carry about four times that number, or 24,000 TEUs.
Allianz's Kinsey says concern about ever-larger ships has been increasing among marine-risk analysts for some time. The stranding of the Ever Given in the Suez Canal is "a warning," he says, "but it's also, we've been trying to raise the issue for a very long time. We've been bringing up the issue of this size, both in our annual safety and shipping review, as well as speaking and in papers for over five years."
Mike Schuler of gCaptain, a maritime industry news site, says bigger ships can cause bigger problems. For example, if they hit a swell in bad weather, container ships can be subject to parametric rolling.
"It's an intense rolling," he explains.
Schuler says he has seen videos of ships rolling by as much as 40 degrees or more.
"And the top of the container stacks on these ships, it's something like 150 to 200 feet in the air," he says. "So you have all these forces with the ship rolling that in some cases knocked the cargo overboard."
Carrying more containers requires bigger and wider ships — like the Ever Given — which means they're more challenging to sail through narrow waterways like the Suez Canal and harder to move when they get stuck.