Container Ship - Structural failure

[Fittster]

http://gcaptain.com/mol-box-ship-suffers-broken-ba...

Well that's a bit of a disappointment for a 5 year old ship.

How do they make sure containers are correctly loaded? Weigh each one in advance of loading would surely be impractical.

[MercuryRises]

Fittster said:

http://gcaptain.com/mol-box-ship-suffers-broken-ba...

Well that's a bit of a disappointment for a 5 year old ship.

How do they make sure containers are correctly loaded? Weigh each one in advance of loading would surely be impractical.

I know with the stuff we do (Offshore supply) you get a manifest of the containers which includes weight, as well as contents if it's considered to be a "Dangerous Goods" container. I would assume it's the same for container ships, mind, it'd be a hell of a long list.

[anonymous-user]

"Articulated" ships, whatever will they think of next........... ;-)

[Simpo Two]

It begs the link to this: http://www.youtube.com/watch?v=3m5qxZm_JqM

[sherman]

Fittster said:

How do they make sure containers are correctly loaded? Weigh each one in advance of loading would surely be impractical.

I thought they weighed them when the cranes took them off the lorries and stacked them up on the dockside?

[The Hypno-Toad]

Simpo Two said:

It begs the link to this: http://www.youtube.com/watch?v=3m5qxZm_JqM

Never seen that. Bloody hilarious!!

[davepoth]

sherman said:

Fittster said:

How do they make sure containers are correctly loaded? Weigh each one in advance of loading would surely be impractical.

I thought they weighed them when the cranes took them off the lorries and stacked them up on the dockside?

Usually they'll do a weighbridge calculation - weight of the truck on exit minus weight of the truck on entry equals weight of the truck.

Containers are specified to have a maximum weight (about 30500kg all up) so the designers should have been able to calculate everything properly. That makes it all the more puzzling.

I think I have some boxes on that ship. It's going to be an interesting day tomorrow...

[sherman]

davepoth said:

Usually they'll do a weighbridge calculation - weight of the truck on exit minus weight of the truck on entry equals weight of the truck.

Containers are specified to have a maximum weight (about 30500kg all up) so the designers should have been able to calculate everything properly. That makes it all the more puzzling.

I think I have some boxes on that ship. It's going to be an interesting day tomorrow...

Hopefully nothing major.
I thought it was either that or the other way I said. I just went for the wrong one.

[dudleybloke]

a couple of ratchet straps, a few bungees and lots of duck tape should do the job.

[carreauchompeur]

Jeez, it does look well loaded though. Quite amazing that the broken off sections seem to be floating still.

[tank slapper]

Loading isn't the only consideration as a cause of failure. They will also look at manufacturing techniques and material. It is quite possible that residual stresses from construction reduced the effective strength of the steel, or that a minor welding defect went unnoticed which has since propagated and then failed through brittle fracture. The quality of steel used could also seriously affect the behaviour under different loading conditions.

It will be interesting to see what the outcome is, as failures like this have been known about for a long time. In WW2 when welded ship construction was new, several Liberty ships were lost due to breaking in half like that.

[davepoth]

carreauchompeur said:

Jeez, it does look well loaded though. Quite amazing that the broken off sections seem to be floating still.

It's quite deceiving really. MOL Comfort runs from Europe to Asia and back again, and because there's a big imbalance of trade, a lot of the containers on there are likely to be empty. Look how high she's riding, even after snapping in two.

Looking at the pictures there seems to have been a bit of a fire, I wonder whether it was before or after. It's not uncommon for containers to become accidental bombs in rough weather if the people packing them have not paid attention.

[yellowjack]

It looks a little short to me. Aren't container ships usually longer than that?

"Yes"




How much longer are they, usually?





"Oh, about that much longer"

[maffski]

This actually makes great sense, one big ship for the trip from China then when it gets to Europe it can split up and visit all the ports at the same time rather than calling at each in turn. Genius. Unless they load your container across the join obviously.

[MartG]

Could be down to a screwup with the ballasting

[SLCZ3]

tank slapper said:

Loading isn't the only consideration as a cause of failure. They will also look at manufacturing techniques and material. It is quite possible that residual stresses from construction reduced the effective strength of the steel, or that a minor welding defect went unnoticed which has since propagated and then failed through brittle fracture. The quality of steel used could also seriously affect the behaviour under different loading conditions.

It will be interesting to see what the outcome is, as failures like this have been known about for a long time. In WW2 when welded ship construction was new, several Liberty ships were lost due to breaking in half like that.

More likely a fatigue fracture, from whatever initiated it, with final failure being the brittle phase, and the reason for liberty boat failure was hydrogen cracking, caused by the high hydrogen entrapment in the welding process and no subsequent hydrogen release treatment.

[spitfire-ian]

Article said:

The MOL statement said that damage was “extensive”

Little bit of an understatement

[tedmus]

davepoth said:

Usually they'll do a weighbridge calculation - weight of the truck on exit minus weight of the truck on entry equals weight of the truck.

Containers are specified to have a maximum weight (about 30500kg all up) so the designers should have been able to calculate everything properly. That makes it all the more puzzling.

I think I have some boxes on that ship. It's going to be an interesting day tomorrow...

Also the haulier will have the tare weight of the container plus the gross weight of the goods inside.

[castex]

While reading the report my toasted sandwich suffered a similarly catastrophic structural failure. There followed a different kind of "hogging" incident.

[Popeyed]

doogz said:

Could be as simple as corrosion in a tank that's been poorly painted/coated, causing a reduction in strength/thickness/I/Z of the material.

Will be interesting to find out what caused such a massive failure in such a new ship.

On a five year old ship, highly unlikely that corrosion is the cause of such a catastrophic failure.

More probable that the vessel was operating close to the limit of the seagoing shear force and/or bending moment envelopes for the hull.

This coupled with inaccuracies in container weights (it happens all the time and they are often under declared), and excessive speed causing high "whipping" and "slamming" forces in the hull in poor weather, along with a change in the framing system at the forward engine room bulkhead led to the "MSC Napoli" breaking in two in the English Channel.