Floating geodesic domes of concrete?
August 19, 2011 at 5:50 am #14798
I, for one, don’t give a rat’s posterior about how thin you could make a concrete hull and have it able to float without being crushed by the water pressure alone. There’s more under waves and sky to deal with that static pressure. Wave action is push and pull even more than static pressure. The Edmund Fitzgerald did not sucumb to static water pressure. It succumbed to being tossed about by waves nearly as big at it was. Further, some may be willing to strap a 10 horsepower outboard and putter about from here to there, assuming that smaller engines are more efficient and can reduce overall onboard fuel needs. I have no such desire or understanding. I want to be able to get to where I want to be as expeditiously as possible, and I want engines and motors as powerful as possible, and ample fuel and energy stores, to effect this. Weight, structure, and propulsive force are also going to have to feature in any claim of minimum hull construction.
But finally, there’s the big one. I know the seasteading dream is to cut loose of dry land altogether and never again approach a shore. I want a hull that I know I can beach if need-be and not smash to pieces. I want a hull that can take incidental contact with submerged rocks and outcroppings of coral without feat that a crack will open up.
You can keep your minimal hull specifications. I’m a certified Over Engineer.
Becides, as a spherical ship, it wouldn’t be bad to have a much thicker hull on the lower hemisphere than the upper, not necessarily for durability, but just to help keep the floor pointing downward and the ceiling pointing upward.
I have a thorium reactor under the hood of my car. I get ∞ miles per gallon.August 19, 2011 at 2:23 pm #14802
One of the mayor advantages of seasteading over landsteading is mobility. A sphere or a dome structure sacrifices mobility – why not make a captain nemo float out in a more streamlined shape?
concretesubmarine.comAugust 19, 2011 at 2:58 pm #14803
Ellen, as for the gunnite getting / absorbing some salt from the sand, rather than having to buy clean sand why not use a plastic tarp liner? I am all for cost savings. and as for added weight, I travel allot in an RV and know well what added weight is… take small / mid size diesel generator your looking at 1000 lbs 5kw of solar panels add another 1000 lbs. 1000 gallon water tank 8000,10,000 lbs (use desalinator to make local water) Batteries 40lbs each, x20 so there is another 1000 lbs… It is going to be quite hard to get to 1 million lbs that way.
Elimer, the idea of a 1/2 sphere of concrete is ease of construction, gunnite pools can be sprayed in a day, in fact when they did mine at my house it only took a few hours and it was done, 1 week later we filled it up with water.
How long does it take to make a concrete sub? what kind of materials and $$$ do you spend on formwork?
The simplicity of making a floating dome shaped pool is the ease of construction and the hull loading evenly dispersed.
From what I’ve looked at seasteading, all the concepts seem to use pillars / towers / drilling rig type superstructures… They are not too mobile and cost literallt hundreds of millions of dollars, when you think of the total cost involved, what will that boil down to for a condo type dwelling on it?
my 50′ dome idea would literally give you potentially 5 decks if you used the whole thing, but realistically 2 decks at the sphere 1/2 way mark, that is allot of living space.
allot of my comments can be seen here http://outpostalpha.com/forum/viewforum.php?f=8
GeorgeAugust 19, 2011 at 5:16 pm #14807
i doubth that the paradigmas this discussion is taking for given are right.
In my projects the framework cost are around 1% or less of the project cost as we use reusable framework. Forming a sphere is not easier and not harder not more expensive and not cheaper than making a cube a triangle or a blimp or whatever – once you figure out a adequate forming method. Concrete is liquid you can form it to ANY shape at equal cost so the assumed reasons for picking a “clumpsy shape” does not really exist.
Paradigma 2 building such a clumpsy structure in a drydock or modifiying a beach to do so – is a “minor cost” i would put the dock installations and movement cost for such a structure considerably higher than the building cost of the structure itself.
So i would strongly recommend to give the structure a movement facilitating underside (as you see on the blimp shape in the picture below) from the design phase on – or build it in floating status right away and avoid touching land during the whole life cycle of the structure – modular construction floating on the water as shown in the box sistem below is the key.
The whole discussion about covering concrete with plastic to wateprove it, is innecessary as you can see in the picture below, a wall of only 5cm of concrete unpainted and without any special cover can be waterproof and stay bone dry if performed correctly. Any size from box size (see our tests below) to city size (see condeep structure in black and white) has successfully been performed already.
I agree that for a city sized structure mobility looses importance as the city becomes the focus of business in itself. On the other hand for a single family sized structure mobility is one of the most important success factors – so i would not give it away to spare some 0.03% of the total project cost in formwork.
Basicly the way you bring concrete in place (spraying, forming, gunnite, cast) does not really influence much – as long as you can avoid the common concrete engineering pitfalls. Cast method has proven to be the safest to get excellent results this is why 99% of the performed concrete worldwide uses cast methods and the alternative methods are generally seen with slight mistrust due to their suceptibility to failure introduction and not used for structural parts.
General development axes for floating concrete construction and ocean colonization are:
The catamaran float / The plate float out / The real estate squaremeter deal / The Captain Nemo float out / The bubble hotel / The current turbine / Breakwater lagoon marina / Oceanic port city design /
concretesubmarine.comAugust 19, 2011 at 9:44 pm #14816
Dont get me wrong I love the idea of a concrete submarine im not trying to belittle anyone elses ideas.
I want to design a structure 50′ diameter that is 1900 sq’ of livable deck space on the centerline
You made a comment about how it could cost as much as the entire structure to rent a drydock, I really do not know, that Is why I was thinking of building right next to a river or body or water, where I could excavate my hull shape in the dirt, line with sand then plastic, spray the concrete on the plastic to build up my shell thickness like a swimming pool.
A swimming pool if emptied and you flood allot of water on the ground next to the pool it WILL pop out of the ground like a boat as the water pressure building up around the pool will make it float. Just like in Louisana they bury people above ground in crypts as caskets work thier way to the surface with the high water table.
once my hull is cast in place as a single monolithic pour, no cold joints to worry about, flod the sand layer with water and let it float / pop up on its own, then with a excavator or backhoe dig a trench to the water just as large as needed to get the hull into the water. no drydock to rent…
You mention framework only costing 3% how do you cast a million pound structure in a sphere or 1/2 sphere without spending allot on framework? I calculated a 50′ 1/2 sphere 1′ thick would use about 150 yards of concrete at $150 per yard yeilding $22,500 USD so your figure of 3% is way off as that is only $675, here that would buy you 20) 4′x8′ sheets of plywood yeilding 640 sq’ the surface area of a 1/2 sphere 50′ in diameter is 3926 sq’ of surface coverage and that is not going to hold 500k lbs.
So if you could give me some insight how your casting process is so cheap I’m sure the world will want to know especially me as a casting requires inner AND outer mould.
As for a clumsy shape well I guess beauty is in the eyes of the beholder, and transporting if you are moving at a slow speed does not need a hull of any particular design and I believe it would have better fluid dynamics being towed into position than a barge and far more structural integrity.August 19, 2011 at 11:05 pm #14821
I understand perfectly – what you describe is known as a “graving dock” (shown in second picture second row above for a 70m diameter disk rion-antirion pylon). You might want to investigate the cost of such a dock especially the cost of earth moving and wet dry cycles – i get from your statement that you assume that making a hole in the ground is much cheaper than making formwork – i would say the contrary is the case. Also you seem to assume that “one shot pour” is the only thinkable way to do it – if you want to do it that way the formwork cost will indeed be monumental – you might want to investigate techniques of reusable partial forming – better known as “slipform” or continous forming.
concretesubmarine.comAugust 20, 2011 at 1:29 am #14822
elimer – How do you slipform in a sphere with no cold joints?
as for a hole in the ground, I dug a hole with my bobcat in a little 32 hrs in HARD ground for a 30′ wide hole 12 feet deep for a underground concrete dome house
you may find this link interesting, here is the construction of the hole for the dome as well as a pull along concrete mixer I made totally from scratch out of welded steel that I designed and welded.August 29, 2011 at 5:55 am #15044
I've done some design work with freaquency 5 icosahedral spheres with an internal diameter of 20 meters, but I want to put mine underground rather than underwater.
OMG! a gurl! and she shares my interest in underground construction! and she's smart! and she reads slashdot!
[Don't say anything stupid! Don't say anything stupid! Don't say anything stupid!]
Hi Ellen! ♪♫
[Wait! something's wrong! There are no gurls on the internetz. What have I done?]August 29, 2011 at 6:29 am #15045
This is a pretty good thread, and it’s nice to see some new members who apparently came here via Slashdot – a site I have kept up with off-and-on since the late ’90s.
I have been thinking of the spherical structure a lot lately, but still find it problematic in several respects, including mobility and practical use of space. Perhaps begin with a sphere and stretch it out: a cylinder with hemispherical end caps, for instance – but even so, there are probably better shapes that would not be much more difficult to construct.
But one thought I can give: when considering ballast, keep in mind that it might be a good idea to have several tanks filled with fresh water. These can also serve as ballast. No need to make the concrete extra thick just for ballast: cheaper ballast can be found, and has the advantage of being more easily exchanged for different ballast. That said, I agree with Ellen’s sentiments about over-engineering. I don’t want to be out in the middle of the ocean when I discover that a mistake was made in the construction and the perfectly designed structure is not quite perfect enough to stay afloat.
I work in construction, so I know there will be errors in the construction. The only question is how many and how serious.November 10, 2011 at 8:29 pm #16313
I’d like to invite contributors to this thread to comment on the content of the following thread – https://picasaweb.google.com/107515127316298264488/Dellipse2?authuser=0&feat=directlink – I’ve spent some time calculating a spreadsheet to return the coordinates of a spheric/elliptic shape given the input of height, depth and radius. (There should be a video sequence)
I would like to build such a structure from hollow, rotomolded blocks, solid concrete blocks or thin, curved sheets possibly welded over an underlying ringed lattice.
The purpose would be to have the structure float or be located on the ground. Possibly such a structure could be used as a refuge in areas prone to flooding or in a tsunami.
The inherent strength is I would think, easily apparent…….. Anyway. good thread. Any comments? (Any backers?)
GilboeNovember 11, 2011 at 3:46 pm #16340
look up geo dome building tools on the web there are some good ones check out http://www.goe-dome.co.uk there is a tool on ther to help you design a dome and it works out all the panel sizes for you all you do is asemble them in the right order you canot get this wrong it is foolproof and it is a well designd tool. im all up for helping you with this one sounds like a great idea i have many ideas to do with the goe dome princapal ii is one of the best ways forward as it can be prefabricatedNovember 11, 2011 at 8:12 pm #16346November 12, 2011 at 1:43 pm #16364
thanks didnt spot the spelling mistakeJuly 3, 2012 at 10:34 pm #20797
I was thinking about this myself. But instead of using concrete, wouldn’t fiberglass or carbon fiber work better? The bottom half could be fully made from composite materials and the top half could be made similar with windows also.
Personally the free floating dome is a great idea. I would add a deck around it that has freedom to move independently from the sphere and could be interconnected with other platforms. They could range in size from a small home to a large greenhouse. Then small domes could be built as desalinization plants, wave power and tidal power plants.
These floating geo spheres would be best utilized in salt water, but with light enough materials I’m sure they could be effective in fresh water, like the great lakes here around Michigan. It would be nice not to have to pay property taxes, and there would be an abundant supply of food around. (If I can catch the fish. Hehe.) But to be sustainable, you definitely would need more than one geo sphere. A large greenhouse, and a home.
It would be pretty interesting to see one of these built. I would like to experiment with this, but unfortunately money is an issue, and carbon fiber is not cheap.July 4, 2012 at 6:19 am #20798
One thing is clear, the next step will be just one step away from what is “out there today” to have a better discussion base we should update the group knowledge with learning what is actually already there, how is it built, how does it perform, why concrete is used and not other materials, how is it formed, why and how waves break things etc…
Let us start with learning about the 50 most outstanding concrete floating structures in the world:
( http://concretesubmarine.activeboard.com/f541915/oustanding-floating-concrete-structures/ )
Then lets have a clear idea what a Draupner Wave does and means to a Seasteading venture.
Finally lets have a clear idea that geodesic domes, monolitic domes, and all that fancy names – are just subchapters in a much bigger engineering field called “concrete shell building”
Let’s also have clear that all floating concrete structures out today are either shell structures or honeycomb structures.
A important subchapter are tubular floating structures. (subchapter of shell).
Finally no sea city will ever be built from a different material than a land city – for economic reasons.
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