Container Ship Breaks In Two, Sinks

Cliff Stoll writes "Along with 7000 containers, ship MOL Comfort broke in half in high seas in the Indian Ocean. The aft section floated for a week, then sank on June 27th. The forward section was towed most of the way to port, but burned and sank on July 10th. This post-panamax ship was 316 meters long and only 5 years old. With a typical value of $40,000 per container (PDF), this amounts to a quarter billion dollar loss. The cause is unknown, but may be structural or perhaps due to overfilled containers that are declared as underweight. Of course, the software used to calculate ship stability relies upon these incorrect physical parameters."

Comments

Declared underweight?

[Spy Handler]

so they operate on an honor system?

One would think they'd weigh the container themselves and charge accordingly. But then I'm not in the shipping business so I dunno...

Re:Declared underweight?

[mrchaotica]

I think a quarter-billion dollar claim might cause the insurance company to raise their premiums just a tad...

Re:Declared underweight?

[Anonymous Coward]

Perhaps they could paint a line on the side of a large vessel floating in water and see if the containers displace enough water to submerge the line.

Eureka!

Re:Declared underweight?

[Beardo the Bearded]

Moments, how do they work?

If you load the shit out of the topmost containers, it gets tippy as fuck. As an example of "huh", there's a thing that's going on the mast of a ship that I've worked on. The thing doesn't weigh that much -- although it's being loaded by crane, I could lift it by myself.

To compensate, way more ballast than I can lift is going in the hull.

Re:Declared underweight?

[Rockoon]

The *rational* thing to do is make sure your ships are safe so that you don't waste a quarter billion dollars.

It is almost certainly the case that the insurance companies already factor in the risk of overloading, because they've been insuring these ships and their cargo for a long time. I don't see anyone suggesting that overloading (or incorrectly loading) ships is something new. The insurance companies are armed with actual numbers that go back literally centuries to the East India Company and so forth.

The ship sank. Its not an indicator of a failure of free market, nor is it an indicator that the insurance company isnt assessing the risks correctly. Its just an indicator that that particular ship at that particular time experienced a structural failure leading to its sinking.

In all likelihood, the amount of oversight, construction rules, and so forth on the shipping industry is already very near optimal from a cost/benefit viewpoint.

Re:Declared underweight?

[evenmoreconfused]

The usual tariff is based on a concept called "weight-measure", which works like this:

- For cargo less dense than water, a given tariff is per cubic meter.
- For cargo denser than water, the tariff is per metric ton (one cubic meter of water weighs one metric ton).

If you think about it, this makes perfect sense, because anything heavier than denser than water has to be accompanied by enough air (i.e. empty space inside or outside the container) to make the average density of the shipment equal one, and anything lighter than water takes up just as much space in the ship as heavier cargo would. The result is that if you have e.g. a 2000 TEU ship, and each TEU is 35 cubic meters, a full ship will always generate 70,000 tariff units, whether it be laden with cotton candy or iron pellets.

Of course, shipping companies play both ends against the middle and can, with optimization, get better than 100% billing (e.g. by using fluffy stuff like household goods to provide the airspace needed to compensate for containers full of car engines).

In a previous incarnation I was a Systems Designer at a major container shipping company.

the front fell off

[johnsnails]

https://www.youtube.com/watch?v=WcU4t6zRAKg

Re:So do those containers sink or float?

[dk20]

oddly enough there are special rules around this: http://en.wikipedia.org/wiki/Maritime_salvage

Should've just paid the ransom

[AEton]

I guess the Da Vinci virus wasn't playing around. Bummer.

Hogging

[M0HCN]

It looks to me more likely the problem was excessive weight at the bow and stern rather then midships, the effect is called hogging and is a known way to snap a container ship (or oil tanker) in half, both have occured in the past.
Basically the keel (The BIG beam running all the way from bow to stern down the bottom of the hull) can only take so much sheer stress and if the weight distribution does not match the localised boyancy implied by the current displacement you can very easily bend the ship.

If and how it came to be loaded that way will be one of the things on the investigators list.

There is of course software used to look at this stuff but it cannot realistically be run on the dock during a very tight turnaround, so the declared weights are used as the only data available in advance of starting loading. Not only does that mess of linear algebra have to give a fully loaded ship with the centre of mass and moment of inertia in the right regions (Important for stability and handling), it must also ensure that the total cargo mass per linear meter is roughly the same as the boyancy of that meter of wetted hull at all times during the loading.

Further shippers will sometimes pay a premium for say not having a can of high value goods put in a corner on top of a stack where it is somewhat more likely to be lost, and some of those cans may be 'reefers' (Refridgerated containers) requiring both power and ventilation to remove waste heat, the problem swiftly becomes complex, doubly so as the ports stacking order also feeds into this if you want loading to go smoothly.

A nasty accident, but nobody died, and the hull and cargo will have been insured, so a better outcome then is sometimes the case.

Hope that explains why it is not just about total weight.