saumanahaii
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I have seen Vince’s work with scale models and even seen the community’s willing to donate cash. I also remember reading about the use of shipping containers as housing. This seems like a good idea, but I can’t find much discussion on it. They are quite cheap: I found a 40′ one on ebay for 1,500$ US on Ebay and slightly higher prices elsewhere. Given how much has been donated towards Vince’s models, that seems to be within the community’s reach. The closest scale test seems to be the short fat pipe spar, which looked ok. Has anyone else experimented with the design?
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Thorizan
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A water tight shipping container, with the right ballast and heave plates could make for quite an inexpensive test of the spar design. If and when I get the 20% pay cut I recently received lifted, I’d gladly donate $100 to a project illustrating this as an option.
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Carl-Pålsson
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Flat walls are bad for resisting outside pressure. A spar needs to be at some depth. So pressure could destroy it or put it at unreasonable risk.
I guess you would have to test this before you could say for sure.
But there is also a problem with using used containers. Sure, they´re cheap, but it is difficult to say what kind of abuse they have suffered during their lifetime, and what weaknesses they may have developed.
Solution: Buy new shipping containers. But because the shape is still wrong (square, rather than circular profile) they will be made of too much steel (compared to a circular tube spar), and all this extra steel costs money. So the gains vs building a spar from scratch go down. Containers might still be cheaper though, but I wouldn´t bet on it.
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livefreeortry
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Containers have another use, as easily assembled housing. There used to be one start-up business park made of shipping containers close to where I work. I went in, it seemed pretty solid. My inexperienced opinion is that containers have potential in assembling cheap habitation (with some extra supports and modifications) on the first seasteads.
http://en.wikipedia.org/wiki/Shipping_container_architecture
Anyway, saumanahaii, do you have a good plan to explore their potential as structural components for seasteads? I could extend about 100-150 US$ to this end.
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Thorizan
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Quik House
This may warrant another thread entirely but there is a growing movement to utilize used shipping containers as housing.
Here is an example: http://www.quik-build.com/quikHouse/QuikHouseBooklet.pdf
Affordable, and probably easily portable. We could get some clamping mechanism to affix something similar to the hull of a larger, multifamily structure, or it could be attached to a smaller single family vessel, which then could be detached, sold, a larger one purchased and attached, and you head back out to sea.
You need not be stuck with the same design while during your entire seasteading existance, and the upgrade costs will be significantly less than those of purchasing an entirely new seastead.
Thoughts?
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saumanahaii
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The way I envision the design is similar to the one put forth in the book, with the addition of a spar below the shipping container. The spar itself would not be made out of the shipping containers. As far as structure goes, because the design is vertical, the reinforcement of the shape to be stronger doubles as the floors for the living space. I also envision keeping the entire structure low in the water so that the waves will just roll over the top and (hopefully) not expend too much energy jerking the structure around. If additional reinforcement is necessary, apply liberal use of concrete.
Now, I currently am lacking large reserves of expendable cash, but I would still like to try some scale tests. Testing the design is easy enough: find a bouyant box and affix a pole with weights and plastic plates. I have no clue how I could model the strength of the shipping container, though. Any ideas?
For visualization of my idea, here is a ugly image of what I am talking about:
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Carl-Pålsson
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For visualization of my idea, here is a ugly image of what I am talking about:
The ballast and heave plates on a truss for extended leverage looks good. But you still have the container probably 30 ft below the surface. I haven´t done the math but I am guessing that means some pretty decent forces trying to implode your spar. Reinforcing will only work so far before the container version becomes more expensive/less efficient than a purpose built spar.
If you spend some money on a custom spar you could perhaps plonk some of those quick houses on top of it:
http://wiki.seasteading.org/index.php/Image:Spar%2Bcontainer.jpg
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saumanahaii
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I thought about that and it would probably work, but I didn’t like the large cross section that could be bombarded by the waves or how much weight would be balanced above the surface. Plus, I think that would make a more expensive seastead. A better, nicer one to live in, yes, but weight can shift far out to the corners and waves have a larger surface to push off of. That would need a bigger spar, or so I think. That would actually be worth checking with a model, though.
Either way we go, we need to know how long the spar must be to still work, and how much stress it will take. Metal is expensive. 4 3″x3″ rolled steel bars 20′ long cost $2,000 US. 1 6″x6″x12′ aluminum bar costs $2,000 US from http://www.metalsdepot.com/. Because of this, I would like the shipping container to do most of the work. Any machinery in it would be shifted to the lowest decks, some ballast would be added (if it proves necessary) to lower its position in the water and make it heavier. Hopefully, then, the price of the spars could be drastically reduced. This is, of course, assuming that using floors to reinforce the interior will make it strong enough to withstand the pressure.
*edit
I googled for pressure at depth calculators and found http://www.gazza.co.nz/waterpressure.html . I typed in 30′ and came up with 28 psi. Assuming that the waves get big and the seastead has a largeish wave roll over it placing the lowest point 60′ underwater, the pressure would be 41 psi. Perhaps we could get a small sheet of metal similar to some in use on shipping containers and place some weights on it to see if it would break. I don’t think it would need to be full size, just big enough for us to test.
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Patri
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A certain large tech company had a project for awhile to build datacenters in shipping containers. The project was rumoured to have ended when a shipping container broke during transit, spilling all of the servers. The engineers said that the shipping containers were not meant for repeated use, and were not strong enough structurally to deal with frequent use.
A shipping container might be usable for a DIY seastead, but I suggest you reinforce it. I can imagine there someday being a standard category for shipping-container based seasteads. Or maybe not – perhaps there will be economies of scale in mass-producing small seasteads via other methods. (Something that can be done w/ a mold, for example).
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Al3x
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I for one wouldn’t want to live in a shipping container 
Seriously though houses that have solid metal walls tend to get super hot in summer and cold in winter even with proper insulation
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DM8954
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Of course I find this thread only after posting something related in another thread…
On the topic of being structurally sound, I would certainly agree that buying only new containers would make the most sense, for safety’s sake. The rectangular shape is also not ideal for resisting the crushing pressures of the sea at the required depths. However, I think you’re considering the shipping containers being used underwater as you might consider a submarine. The structure must withstand the full force of the water in order to maintain survivable internal air pressures. I propose that these shipping containers should be filled with air to a pressure equal to that of the water of their intended final depth. If the container is at equilibrium with the water around it, there would be almost no pressure acting against it at the structural weak points.
You do lose some buoyancy because of the increased density of the air but it’s somewhat minimal in comparison to the weight of water being displaced.
With this solution, the problem is reversed during construction. If they can only be pressurized before installation, there is potential for them to explode under the pressure before they are installed at full depth. If the can be pressurized on site, as their depth is increased while weight is being added above, there’s no issue, you simply monitor their depth and maintain the appropriate internal pressure for equilibrium. If not, a potential solution might be to fill them to half the pressure they’ll be resisting. That wouldonly have to contend with half the explosive pressure above water and half the compressive pressure at depth, making it much more likely that they’ll be able to stand up to either.
Patri wrote:
…The engineers said that the shipping containers were not meant for repeated use, and were not strong enough structurally to deal with frequent use. …
Shipping containers are often stacked 10-20 high in ships and at port, so their strength should be sufficient in an equilibrium condition like this. I’d be curious to know how many trips across the ocean constitute “frequent”/”repeated” use. Though they probably pay for themselves after only a trip or two, I wouldn’t expect them to be discarded after less than 1-5 years of continuous use. [uneducated guess] I think that placing the containers at a depth below the action of waves (wavelength divided by 2), the stresses would be less than those they were designed for.
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Thorizan
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I think hypothesising about shipping container-like structures gets us to a good point in this plan. If we consider plunking down the amount of money that you suggest to ($3500 per container, 12- 40′ containers) there may be other structures that could be built that would be better suited for this purpose. Something that would not oxidize, perhaps, maybe made of some kind of cement. It should be able to withstand the pressures we would require of it. Isn’t 12′ of water equivilent to one atmosphere? So, 60 feet down would be 5 times the pressure on a structure as normal… and if it is pressurized during its descent, there would be no concern with explosive decompression.
Basically, shipping containers COULD be a good call here, but they were designed for an entire different purpose. If we can find something remotely close to the same cost that was actually designed for what we are trying to get it to do, I think that would be a better move.
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Carl-Pålsson
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You can only equalize the pressure inside against a particular depth. So everywhere but there the pressure would be too high or too low.
And going through airlocks just to go outside doesn´t sound like fun to me. Also, if there is just a small leak and you lose pressure, your house implodes.
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Thorizan
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pressurized shipping container that you live in = bad… yes, One used for buoyancy only, or something like it, has more merits.
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DM8954
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With mass production, a similar sized device could be produced to fill the position more efficiently… but until then it would be cheaper to modify something that is already in mass production that might suit our needs. The extra $500-$1000 in that $3500 would be for additional reinforcing, presurization, anti-corossion coating, etc. Similar amount of materials would be used in a custom designed adaptation of this idea but costs would be much higher because new staff and infrastructure would need to be put in place.
Of course, if there’s something similarly well-suited to this type of application, I’m all ears. That’s the whole reason I put the idea out there.
Carl:
I wasn’t suggesting that we live in the sub-surface modules. The 36psi(2.5atmospheres@50ft.) required to maintain equilibrium would not be very comfortable for occupants. (it would be the same pressure as if you were scuba diving at that depth, except you’d be dry) There would be no airlocks involved. The entire habitable space would be 15 or more feet above the surface, in order to avoid most waves. This is a completely separate flotation device only. Pressurized or not, a vessel that requires air for buoyancy will sink if there is a hole. Pressurizing the device in question to match the surounding water would actually make it less likely to fail, short of a violent collision of some sort, because there would be very little force for the containers to resist..
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