Container Ships - how to they stay upwright?

[Chris_Robb]

Looking at the picture of a container ship in March PBO, how on earth - with all that deck cargoe above the watertline does it get its stability. Same with ferries which load everythung above the waterline.

Also - looking at the way the containers are held on: In a stack 10 high, it appears the bottom 2 have some form of cross bracing - and the others are just stacked.

Are these things top heavy - what happens if they get beam on in mountainous seas?

Any experts care to enlighten me (or frighten me)

Chris

<hr width=100% size=1>

 

[tcm]

a client who controls/sells/rents containers aorund the world told us that "at least 50,000" of the things have been lost at sea.

<hr width=100% size=1>

 

[Evadne]

The hold is full of containers as well, and they go down a long way. Also, the Mates have to do a lot of exams entailing stability calculations (how to put the heavy ones at the bottom and the lighter ones at the top) before they get their tickets and are allowed to load a ship for real.


<hr width=100% size=1>

 

[robp]

Yes, have you ever seen news footage when the containers are sliding off into the sea? It seems that insurers' cost for the risk is lower than that of lessening the payload, or increasing the security of the damn things!

<hr width=100% size=1>

 

[maxi]

Re: Dave_White

Sounds simple, Do all the light boxes get offoaded first, with the heavy ones later?
or are routing considerations now out of date?

<hr width=100% size=1>

 

[Rowana]

I have some lovely photos of container ship disasters.

I believe I have to load them onto a website somewhere, then link the photos to this site. I've no idea as to where I could put them, as I've never done it before, so if someone gives me the instructions (In words of one sylable, please), I'll share them with everyone.

Jim

<hr width=100% size=1>

 

[boatmike]

They have a broad beam and flat bottom making them extremely stiff and stable in "normal" conditions. The angle of vanishing stability is however very low. It's like a catamaran in a way. Up to a point very stable. Beyond that point don't even think about it......

<hr width=100% size=1>

 

[Chris_Robb]

PM Jimi - he will be able to help - if hes not got his finger up his rudder hole.

<hr width=100% size=1>

 

[SteveA]

I think to say that they rely on a broad beam and flat bottom is being very simplistic.
Going back to my days in the Merch each ship had a dedicated loading computer with all of the ships stability details programmed. The loading Officer, usually the Mate, would plan how the ship was to be loaded, input this to the computer and this would then calculate whether the loading plan and final stability were acceptable or not.
With regard to lashing of containers I think there is an investigation to improve these being carried out at the moment.

<hr width=100% size=1>

 

[Guest]

Having been the cargo officer for Containers and Ro-Ro's during my time at sea ....... that is ignoring one serious fact !

Many 'fast loading' ships are loaded based on shore calculations / plan. The vessel then inputting to the computer during and after loading to ensure that a mistake has not been made ....... !! Why ? Because the containers / trucks etc. are weighbridged and then docketed by the shore terminal .... the ship only knowing as they come on board. Terrible but true.

Secondly there are ballast and auto-trim tanks that are used in port etc., with auto tanks turned off at sea for obvious reasions. The major part of the ballast being low down in double-bottoms .... and then extending part way up the sides etc.

Lashing of containers - all cnt's are interlocked by corner clamps, as well as cross cables. The top ones often being empty or supposed to be lighter.

Finally there are a %age of containers that are actually empty ......

Oh nearly fogot - I hated container and Ro-Ro ships with a vengeance and was glad to get back to Tankers !!!!


<hr width=100% size=1>Nigel ...
<A target="_blank" HREF=http://www.qqbaltic.com/index.html>http://www.qqbaltic.com/index.html</A> For all those disbelievers ! /forums/images/icons/cool.gif

 

[Guest]

Re: Dave_White - good one !!!!

In fact when I did my tickets - there was little really about specific ships and plenty about Dry-docking etc. Most knowledge was expected to be gained by working on the ships and working up the 'ranks' - understudying the Mate etc. It was only later that authorities started to differentiate bewteen Chemicals and Tankers etc. leading to special additions to a licence.
My Father was with Aircraft and he always remarked about the lack of differentiation between ships for licences against aircraft pilots ......


<hr width=100% size=1>Nigel ...
<A target="_blank" HREF=http://www.qqbaltic.com/index.html>http://www.qqbaltic.com/index.html</A> For all those disbelievers ! /forums/images/icons/cool.gif

 

[Guest]

Its actually a esign factor ...

If you make it so fast and secure - you may create a safety problem for the ship.
Better to lose a container over than risk the ship.

Sorry but a sad fact of pure physics and dynamics.


<hr width=100% size=1>Nigel ...
<A target="_blank" HREF=http://www.qqbaltic.com/index.html>http://www.qqbaltic.com/index.html</A> For all those disbelievers ! /forums/images/icons/cool.gif

 

[kindredspirit]

It's the container recipients who are responsible for insurance of the actual containers not the shipping line. If you're bringing in goods by container and it's lost at sea, its your hard cheese if you haven't it insured, or else paid CIF.

<hr width=100% size=1><A target="_blank" HREF=http://www.begleys.com/kevin/weather.htm>Weather & other useful links for Irish waters.</A>

 

[Mirelle]

Very roughly...

Operating costs rise, more or less, as the square of the length.

Carrying capacity rises as the cube.

Stability rises as the fourth power of the beam.

Big ships don't have much of a stability problem; very little ones do.

As has been said below, every ship's stability characteristics are known and deck officers have to take a serious exam in Ship Stability. Container ships of the larger sort are loaded by terminals using stability data supplied by the ship and weights taken from the weighbridge or from shipper's declarations (iffy - they lie!) but the terminal's planners are ex deck officers who have done the exam.

Containerships use a programme based on the ship's stability characteristics with the known cargo weights to determine what lashings are required - obviously a heavy box at the top of a stack, or a ship with very few boxes on deck and correspondingly stiffer, will require more lashings.

However, do not pay too much attention to the lashings you see; in many trades it is customary for the crew to finish off the lashings after sailing rather than have everything done by expensive port labour whilst the ship is costing US$1,000 per hour whether alongside or en route.

At the moment, if you look at a ship coming up the Channel after loading in China she will have every container full, but full of lightweight stuff like TV sets and computers; going back down Channel she will have between 20 and 50% of the boxes empty and the others will be full of heavy stuff like bathroom tiles.

(The exception to this rule of thumb is Germany, which not only still makes stuff but sends it to China.)

<hr width=100% size=1>Que scais-je?

 

[nicho]

I wondered the same thing when we were on P&O's "Oceana" earlier this year - all flaming 14 decks of it!!. Perhaps they put all the fatties on the lower decks? No, can't be that - WE were on deck 12.....!!

<hr width=100% size=1>

 

[Chris_Robb]

Nicho - youre not fat are you! I imagined you as a wizzkid used car salesman! Maybe this was the image a decade ago!

<hr width=100% size=1>

 

[jimi]

He's the Oliver Hardy to BIGNICK's Stan Laurel. Extra bouyancy had to be added to B pontoon at Hythe as a safety measure and even then when he stepped on the pontoon the displacement flooded the car park .. the fat bastid!

<hr width=100% size=1>.. whit way roon should it be again ..

 

[nicho]

Probably even two!! Semi retirement gives us more opportunities to eat/drink I'm afraid, but I wouldn't swap it!!

<hr width=100% size=1>

 

[nicho]

Ouch, that really hurt! Can't really argue, sadly!! I WILL lose a few lbs when we get back from hols, I promise.........well......maybe!

<hr width=100% size=1>

 

[Chris_Robb]

My God - you can't let Jimi get away with being so rude!! My father would be horrified - but then Jimi probably didn't have one.

<hr width=100% size=1>