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Concrete sphere island?

Home Forums Archive Structure Designs Concrete sphere island?

This topic contains 4 replies, has 4 voices, and was last updated by Profile photo of  Anonymous 5 years, 1 month ago.

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  • #1356
    Profile photo of Elwar

    I’ve been thinking of a design using floating concrete spheres, and making an island out of them.

    You could start with a circle of the floating spheres attached to each other. Then you add a layer on the outside, then a layer underneath and one on top, with the width wider than the depth. You keep doing this until you basically have a floating island.

    The waves would crash over the perimeter balls and break up after making it past a few “rungs”. You’d be up high enough that you never get hit by the waves.

    This would be easily modular as you can start small with just enough to support a person on calm waters, then build it up ball by ball until you can have a small hut on fairly calm waters. Then build it up more and more until you get to the point where you can support a structure. And you can always keep adding to it to make it bigger and bigger. And the bigger it becomes, the more stable it becomes and the more it can withstand higher waves.

    Kinda like this:






    Profile photo of

    Look at the Hexatoons, on here. Prototype has been made. Attatches better, no significant gaps, just concrete the deck, to protect against UV decomposition…



    Never be afraid to try something new…

    Remember, amateurs built the ark, professionals built the Titanic.


    I think that we all are in agreement that building a city sized seastead as one solid piece of engineering is simply not possible as the drydock installation to do so simply do not exist. So if you want to build something city sized you have to do it in modules or parts and assamble it floating on the water – we have called that “raft up modules” . If you think it trough the size of those modules is a critical factor in any “seastead building business plan”. Happens that as Richard Sowa (spiral island) has shown that the base modules can be as small as PET-bottle size. On the other hand making the modules a bit bigger has some advantages. For practical reasons a ideal module size could be in the 1-2 meter diameter range.

    If the module has flat surfaces the connection can be easier – but i imagine that the sphere modules you suggest can have a advantage to stay on their site just by buoancy as they fit into the spaces of the layer above. It might be sufficient to just have a tension cable element around the island to keep it all togehter – somebody should do a couple of experiments on this topic.

    I also agree on your suggestion of an “incremental structural approach” this is something that naval engineers really hate as it does not allow to calculate the island as a solid piece of engineering – the force distribution is quite “uncertain” and there is little where a engineer can engage with his math and computer tools – the whole island will be a amorph thing that works very much as a “foam block” – in practice it will be a completly empiric aproach – if it moves to much you will cast a couple of structural elements on top (reinforced concrete plates, etc) – until it stops to move and supports the structures you want to build.

    It also allows to inject additional buoancy beneath the island if you start sinking too deep under the load of the buildings on top. (see spiral island and the vegetation islands of lake titicaca).

    All in all i think the concept could work fine with relative big islands where you can have multiple layers of modules. I see problems with very small islands in the single layer mode – as the modules would not be easy to fit together in a single layer mode and connections would not be very hog and sag (bending) resistant in waves.



    European Submarine Structures AB

    Profile photo of jack.tinsley

    I couldn’t find a thread on this here, has anyone considered using recycled propane bottles and bracing them together. Here are my thoughts.

    I am interested in building a 100′ by 50′ floating island out of used 500 gal propane tanks. They are 3′ dia x 10′ long and weight 800 lbs. I am planning on using 50 of these, the layout would be: 10 in a row, 5 rows spaced and braced. Total flotation of the system seems to be around 75 tons, I would like to add 50 tons of buildings and equipment. The unit will be self propelled by two modified dozer boats at the ends. Looking to move in fair weather at 1 to 2 knots.

    I live on the Queen Charlotte Islands, Haida Gwaii, in British Columbia. This “eco-island” would ply the waters surrounding the island, maybe only moved 50 miles at a time every month or so. Only on fair weather days and anchored in protected bays.

    My questions are:
    Do you think I am correct in my flotation calculations?
    Is the layout one that would serve best?
    What would be the simplest and lightest bracing, ( 8’spaces between rows )?
    What issues do you think I may run into or haven’t covered.

    Thanks for any comments and thoughts in advance.

    Profile photo of

    Corrosion will be a big problem, with steel tanks. They aren’t really the best quality and the welds will be a severe weak-point, corrosion-wise.



    Never be afraid to try something new…

    Remember, amateurs built the ark, professionals built the Titanic.

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