Floating city

I share the opinion of @schakel .

I'm not sure what's the reason for your floating city. If the floating cities are for escaping from land due to climate change (for example rising sea level) stop thinking about building a sea city. Steel and concrete produce much greenhouse gasses while manufactured and it's kind off counterproductive to use this materials for "fighting" the climate change.

Btw here in the Netherlands MARIN did research on floating islands with rectangle and triangle shapes.

 

There is a whole website with visuals and reseachprojects.
I know one founder of them. But we had discussion, migration will be better in my opinion.
Ecoboot https://www.ecoboot.nl/ecoboot_new/

Some of the artist impressions on a floating city from the ecoboot site.

 

One issue is that most countries don't welcome most immigrants.

Some countries like Canada do if you are young, healthy, have a skilled profession, and are therefore likely to help support the retired community - they expect that to be a major economic problem - though you might get a better idea of the criteria at
www.cic.gc.ca/english/helpcentre/results-by-topic.asp?st=4.1

USA is quite selective. E.g., see Overview of Immigrant Eligibility for Federal Programs https://www.nilc.org/issues/economic-support/overview-immeligfedprograms/

But a large fraction of people can't meet all the desired criteria.

Certain of the countries you mention have substantial issues with civil rights and the treatment of ethnic minorities.

Some people would have trouble learning a new language and culture.

If the world gets warm enough Antarctica could be settled - supposedly Russia, which has extensive experience settling people in cold climates, is already looking at it, though many other countries, like the USA, have signed treaties which bar doing so.


To the o,p.:

Living at sea is a very attractive idea at first glance. But it may be more complicated than the o.p. might perhaps realize when you look at details.

E.g., while I'm not an engineer, the idea that objects with a horizontal size greater than one wavelength are "stable" is somewhat oversimplified. Waveheights sometimes are roughly comparable or even larger than wavelengths, especially in shallow water regions. Many people would be unable to deal with living on a platform that is constantly pitching one way and another by 45 degrees - e.g., consider the elderly and infirm. And many would have trouble dealing with extended period storms at sea where the windspeed could blow them away if they step outside.

Inland water might be more practical, but there are still issues, and the amount of usable inland water is limited. Some places you can create more, but it would probably be easier to build on the unflooded land.

For young children, you need a wall to keep them in.

You also need to preserve life and property when structures fail, as they inevitably eventually will. That is also a significant possible issue for living under the sea, which people used to talk about a lot.

As kapnD mentions you also need to consider getting basic supplies to the structures, like food & water, as well as electricity. On salt water, the foods you can grow outside on site are limited, and you need to protect them from wind.

There are also sewage and garbage disposal issues, and medical access issues.

There are also dangerous predators in some climates, that might get on board your structures, like large snakes, alligators and crocodiles. Mosquitoes, including those that carry diseases could be an issue, though that is true on the land too.

Another issue is that many of the countries with difficulties relocating people have very corrupt governments. Most of the money spent or given won't go to the right purposes, and many structures will be secretly built in an unsafe fashion. In fact, that was one of the biggest problems with the idea that wealthy countries that contributed to climate change should give massive amounts of money to poor countries that will be affected. While there may be exceptions, the primary reason almost any poor country is poor, is government corruption. The other contributing issue for some countries is war and civil conflict - which could be quite hazardous to floating structures.

You need to anchor your vessels, so they don't float into other people's property, shipping lanes, other floating cities, or another country's territory.

I'm sure other people could come up with other issues.

I don't want to discourage you from looking for solutions. Moderate priced floating communities have existed for thousands of years - e.g., grass mats in inland water.

And then there are mangrove forest islands, which are quite common in tropical climates, like the Everglades, and which "build" themselves. Though they have issues too. (But I wonder if they could be genetically re-engineered or bred for colder climates, out of the range of tropical predators. Of course, they could cause environmental problems if they become too common.)

I really love the genetically-reengineered mangrove forest idea. So I'm certain people here will respond by sinking that idea too.

In fact, I've created a separate thread
www.boatdesign.net/threads/mangrove-forest-island-based-communities.68284

for that, to avoid hijacking your thread.

 

The shape of your boat: It sounds like you want a rectangular block. In some wave patterns, that would tumble end over end. Some whitewater boats are deliberately designed that way, by not having much rocker (bottom convex curvature) at the ends. In other words, somewhat like your shape. Normally ballast keeps a boat stable, but if the leading edge catches the next wave, I'm guessing it might even help initiate the tumble, like leaning forward into that wave in a whitewater boat.

I guess your idea is to try to build boats large enough to live in whose cost is comparable to that of a similar size inexpensive houses on land in the middle of nowhere. So cost is a big factor.

I should have clarified - it isn't often that you get surface waveheights comparable to or larger than wavelengths. Ordinarily, such a wave would definitely break at far less a ratio than that - e.g., I've seen ratios of about 1/7 cited for deep open water as the approximate threshold for breaking. But sometimes surface waves do break. And sometimes, when they interact with bottom topography, and sides, especially with some standing waves that occur in tidal rivers and straights, they undergo cyclic patterns of growth, and breaking. (And one cool thing in whitewater boating, the presence of the boat can sometimes make a wave break. A heavy non-streamlined boat, with no rocker, like you have in mind, might well do that pretty easily.)

There is also a question of what wavelength means. Some patterns of flow create isolated waves, or waves which don't take typical shapes.

As I said, you are going to need to anchor the boat. Maybe I should have said "moor", since it is going to be there indefinitely... In fact, you should have multiple redundant mooring lines and weights. But in deep water, mooring might add significantly to the cost factor.

"Concrete" usually means a combination of "aggregate rock" - a mixture of ordinary rocks and sand - with a (usually) water soluble cement that holds it together, typically limestone. That is pretty cheap. But it isn't clear that a water soluble cement is a good idea for a boat that is going to stay in the water long term. You might want to use a more expensive cement - but that gets back to the cost issue.

Basements are of course normally common concrete (often reinforced with steel or other high tension strength materials, because limestone cracks easily if you subject it to non-compressive stresses). But, in climates where basements are close to the water table, basements tend to eventually leak. They need sub pumps. They should also be lined with non-water-soluble materials. And sometimes they need repairs.

Boats, especially ones built out of potentially leaky, heavier than water materials, should also have multiple compartments, possibly flotation material (in fact, most boats are actually required to have such in many countries), and ways of repairing them, and moderately large pumps. (Small craft sometimes omit the pumps, because it is possible to empty them other ways.)

People compete at building concrete boats. But in such competitions, they don't stay in the water for long. Also, I think they are supposed to be a challenge to build precisely because concrete isn't an entirely optimal material for building boats.

An engineer could probably explain some of these ideas better, and explain better why typical boats aren't made of concrete, and why they have more complex shapes.

 

Those immigrants you refer to wouldn't be able to afford to live on an artificial island. They need to work to barely survive. Your plan is for a luxury only the wealthy can afford.

 

Not my plan.

 

You could use a floating city for land reclamation in low lying areas. Prepare, dam and flood the site, build and position the units, when town, or a new waterfront is made to specifications drain the water, the lot settles on the prepared bottom, or floats, and services are finished off, people start moving in. If sea level rise affects the area too much in distant future, by then the concrete units will be past safe useful life, get filled in with dirt, and voila, coastal green fields above sea level, for new buildings on top. Following on as in archaeology, building a new city on the remains and refuse of the previous one. Wasn't Mexico City a floating city on a marsh, long ago ? Venice is a well known artificial island built on wood stumps on a sand bar, surrounded by water, from memory.

 

That sounds like a cool idea, though it could be bad if one of those concrete blocks leaked while floating.

I guess the basic economic question is whether doing it your way would be cheaper than transporting the building materials to each site by truck.

Also, draining water to create new land is supposed to be quite expensive - or so say descriptions of The Netherlands.

BTW, there is a complex near me that has a lot of "concrete block" buildings. They needed to line them with something not permeable to water to stop moisture condensation (and mildew) on the inside walls.

Do you have any sources saying either of those cities once floated? I can't find anything that says so.

I found something that said Mexico city buildings were built on the lake bed bottom, and some of it was then drained.

www.glassofvenice.com/blog/what-makes-venice-special-top-interesting-facts-about-italys-floating-city implies that Venice was built on a marsh bottom, and floating refers to the fact that its buildings are partially underwater. Wikipedia says Venice subsided after wells drew out ground water, so I guess that caused them to now be partly underwater. It also says that it was initially a miserable place to live, but that the marsh kept out raiders.

Some large ships could be described as small floating cities, because they carry so many people. But they are remarkably expensive per living unit. I do not know if long retired aircraft carriers or cruise ships would be economically practical as housing - the maintenance costs might be pretty expensive too. And the failure modes might be bad.

 

I am reminded of this article I saw a couple of days ago about Royal Caribbean's latest cruise ship which will be starting her maiden cruise soon - she will be the largest in the world, at around 250,000 gross tons.
Icon of the Seas: The world's biggest cruise ship is almost ready | CNN

And this photo really sums her up as a floating high rise city

 

That's correct, and I am planning Norway for an ecape route.
Fishing and vegetable gardens will be main suply of food.

I was partly raised by a norwegian family and they shoot a moose a year.
Cut it into pieces, stow in in old milks packages and stow it in their deep freezing facilities.

I am not looking forward to that but I have a militairy training and shooting a moose is the same as sighting. Only with a gun.
And I seldom miss.

 

Reminds me of this tee shirt:

https://www.amazon.com/Support-Right-Arm-Bears-T-Shirt/dp/B07Z8RJ96S

 

The back end of that ship reminded me of sheep carrying ships - lots of levels packed on top of each other. I bet sheep would enjoy a water slide once they got used to it. I was a farmhand once upon a time, and observed them having fun. Anyway that floating city looks like it will have its share of gastro and rotovirus, and air conditioning bacteria etc., and you have to stay confined to it, or get wet. I'd prefer something connected to land permanently, so I can escape. My (above) words are for illustrative purposes only, I'm no historical expert.

 

If
Government officials refuse to cede ‘an inch of land’ amid rising threat: ‘This is something that we take very seriously’ https://www.yahoo.com/news/government-officials-refuse-cede-inch-213000882.html
is right (which I'm not sure of),

However, based on other Internet sources, the land created with the help of Mangrove trees, may be semi-natural wildlife habitat (e.g., parkland. And perhaps wave break??), rather than long term human habitat, perhaps partly to make up for Mangrove forests and trees that were eliminated to make way for urban expansion.