Container ships

[Catso]

This Napoli (or whatever it's called) that has beached, had containers stacked up on its deck, perhaps 4-5 high. There's nothing (apparently) holding them on. A quick look at container ships on the net reveals this is the standard way of doing things. Some stack even higher.

Why don't they just fall off in heavy seas? Surely the ship would roll enough to lose some?

[Birt]

Im fairly sure they have locking devices on the bottom of the boxes. The first box locks to the deck and the next box on top locks to that etc

[rojash]

This:

"Containers occasionally fall from the ships that carry them, something that occurs an estimated 2,000 to 10,000 times each year. For instance, on November 30, 2006, a container washed ashore on the Outer Banks of North Carolina, along with thousands of bags of its cargo of tortilla chips. Containers lost at sea do not necessarily sink, but seldom float very high out of the water, making them a shipping hazard that is difficult to detect. Freight from lost containers has provided oceanographers with unexpected opportunities to track global ocean currents."

From here: http://en.wikipedia.org/wiki/Containerization

[kempie]

Containers are anchored to the deck and each other using twist-locks.

http://www.makersan.com/OVRO_PR_containerlock. htm

[Catso]

kempie, those locks are the ones you see on trucks, aren't they? IE They're for locking a container to a fixed object. I acn see that those on the ship's deck would work, but what about containers on top of the first one?

As rojash quotes, in fact it seems they DO fall off, all the time.

Thanks, all, for your answers.

[kempie]

I didn't choose the correct link to illustrate the type of twistlock used for stacking containers. This is a better one...

http://www.tandemloc.com/0_securing/S_AD54000A .asp