Is there a maximum size/displacement for ships?

Greenheart

Greenheart

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Silly question, I know. But when we seem to be able to build bigger and taller towers, bridges, etc, I'm curious what technical issues prevent ever-more vast cruise-liners and container ships being built. Aside from the limits of space in docks & canals, is there any limit?

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it's one of the reasons that the Panama Canal is being widened to allow use by vessels up to 160 foot beam, 1200 foot LOA and 50 foot draft. Those are seriously large container ships from China, and US Navy Warships as well.
 
So, if the world's great canals and ports could permit passage/docking, would there be any reason not to build as big as possible? I mean, as far as the economies of scale make it beneficial to stack 18,000 containers aboard the present enormous state-of-the-art ships...

...is there an engineering reason why, for example, a reactor-powered catamaran a mile long and a quarter mile wide, couldn't be flitting around the globe at ninety knots, delivering consumer-durables more cheaply than ever before, and giving us tsunami-wakes to surf on?
 
I read earlier this evening that Shell are having built a liquified gas exploitation ship ('facility') that will be the largest floating object in the world. Fully kitted and fuelled it will displace 600,000 tons, and will be 1/3 mile long. 260,000 tons of steel are to be used in building it.

I don't suppose it will be trying to get through the Panama canal. It is to be stationed 200km off the Australian coast.
 
As far as I can work out, there is no limit in the long term. Materials and construction techniques are probably the limiting factor right now. We're still building ships out of steel. The biggest steel ships today, would have broken apart if built 50 years ago with the engineering techniques used then. Steel has lots of limitations. Ports and water ways adapt to the size of vessels and not the other way round - if they want the business, they accommodate. It's possible that in 50 years time, there could be ships that are so long that they have to have slightly curved keels to allow for the curvature of the Earth and they will probably have to dock in off shore ports, but then it's also likely that ships will fly by then :D
 
Almost all of the very large vessels in last 15 years are built from the keel up to be the maximum size for the ports they have contracted to work at.

Reach across the deck can be a serious problem for bulk carriers as ports that can load bulk cargo can find it difficult to load vessels wider then 60m.

Because bulk material is literally stacked into the holds and comes close to the hatch combing so the cargo can not shift on rough conditions.

Some carry bulk cargo and oil, but not on the same trip. it's a triangle trip, oil from the gulf to Australia, pock up a load of Iron ore for china then back to the gulf for another run and another crew change.

Being a 50 +metre bean and a flat bottom between bow and stern, they often leave port on high tide with a metre of water under the.

If you ever wondered why ships come in and tie up on the port side and the next on the starboard side, it's because the port master has calculated the sailing time and wants the ship going into the tide the mud that the prop's throw up will be carried clear of the channel by the tidal currents.

So in short the answer is depth of water and loading equipment that has enough reach.

I could tell about some scary moments when the Chines purchased a few of the Onasis (sp) tiny 20,000 tonners, back in the days when I was a Loading Master. Good luck and fair winds
 
Predicting the technological future

35mm said:
It's possible that in 50 years time, there could be ships that are so long that they have to have slightly curved keels to allow for the curvature of the Earth and they will probably have to dock in off shore ports, but then it's also likely that ships will fly by then :D
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I have always been a lover of technology so for 60 years have been predicting what the future will be like.
One thing I have learned is that you can not predict future technologies. I thought everyone would have helicopters for commute by now but that is just not so. We thought supersonic air transport would be common place but it has been and gone. We had the moon landings but now no more? Who would have predicted the internet as it is today. At least Dick Tracy has finally got his (well almost) wrist watch telephone. So I am not convinced of ships flying in the future. olewill
 
Perhaps there could be some benefit in 'modular' cargo/container platforms...each one 400m x 50m, so they'd be small enough to be dealt with in existing ports, but they could join them in train, end-to-end for reduced wash, and fuel burned-per-tonne of cargo carried...:rolleyes:
 
dancrane said:
So, if the world's great canals and ports could permit passage/docking, would there be any reason not to build as big as possible? I mean, as far as the economies of scale make it beneficial to stack 18,000 containers aboard the present enormous state-of-the-art ships...

...is there an engineering reason why, for example, a reactor-powered catamaran a mile long and a quarter mile wide, couldn't be flitting around the globe at ninety knots, delivering consumer-durables more cheaply than ever before, and giving us tsunami-wakes to surf on?
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A lot of shippers/importers are against the new generation of containerships.
Bigger ships, less frequent port calls, and slower steaming, means they have to import a larger quantity of goods to keep themselves in stock until the next delivery.

Another limiting factor for the size of ships is the shipyard and drydocks
 
dancrane said:
Perhaps there could be some benefit in 'modular' cargo/container platforms...each one 400m x 50m, so they'd be small enough to be dealt with in existing ports, but they could join them in train, end-to-end for reduced wash, and fuel burned-per-tonne of cargo carried...:rolleyes:
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They already do that with barges in Europe, always struck me as a shame that most British canals are not wide enough or tall enough to take containers...
 
There wil be a limit on length and breadth. The flexing will eventually lead to strain that requires so much metal to support that it cant be done except by using novel materials: diamond if it can be manipulated would be an amazing construction material. I have no idea what the limits with steel would be on boat dimensions.

http://lifeboat.com/ex/10.futuristic.materials
 
onesea said:
They already do that with barges in Europe, always struck me as a shame that most British canals are not wide enough or tall enough to take containers...
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When I was working in the public sector, I regularly heard so called professional planners saying we should move freight of the roads and onto our canal system..

Whilst I am always impressed at the achievements of engineers.. I am always dismayed by the total stupidity of public sector employees... Ho hum .. just keep paying their salaries and gold plated pensions:rolleyes:
 
Tomahawk said:
When I was working in the public sector, I regularly heard so called professional planners saying we should move freight of the roads and onto our canal system..

Whilst I am always impressed at the achievements of engineers.. I am always dismayed by the total stupidity of public sector employees... Ho hum .. just keep paying their salaries and gold plated pensions:rolleyes:
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I think the point of that argument was the very much great energy efficiency (albeit at much lower speeds) of a boat vis a vis road or rail transport. Yes of course our 18th/19th c. canals would hardly have the capacity to replace road/rail.

It also seems to me that the near collapse of capitalism a few years ago suggest that there is no public sector monopoly on stupidity.
 
There are icebergs out there bigger than the Isle of Wight. And they float while intrinsically being stacked full to the brim with heavy frozen water.
 
BlueTwo said:
There are icebergs out there bigger than the Isle of Wight. And they float while intrinsically being stacked full to the brim with heavy frozen water.
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Frozen water is less dense than liquid water.
 
KenMcCulloch said:
I think the point of that argument was the very much great energy efficiency (albeit at much lower speeds) of a boat vis a vis road or rail transport. Yes of course our 18th/19th c. canals would hardly have the capacity to replace road/rail.
.....
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But they could not see that simple fact...

KenMcCulloch said:
.....
It also seems to me that the near collapse of capitalism a few years ago suggest that there is no public sector monopoly on stupidity.
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But the engineers and designers who are building such superships do not display the stupidity of their banking and public sector counterparts... so it can be done...
 
Tomahawk said:
When I was working in the public sector...
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... you must have been totally stupid, if your next paragraph is to be believed.

Whilst I am always impressed at the achievements of engineers.. I am always dismayed by the total stupidity of public sector employees... Ho hum .. just keep paying their salaries and gold plated pensions:rolleyes:
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Where does that leave engineers employed in the public sector?

(All generalisations are dangerous ... this one included.)
 
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