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Modular Island Design

Home Forums Archive Structure Designs Modular Island Design

This topic contains 154 replies, has 35 voices, and was last updated by Profile photo of Ken Sims Ken Sims 4 years, 5 months ago.

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    Profile photo of xns

    The sketch above is for the design of a HDPE Hexagonal Pontoon(Hexatoon) that can be used in the construction of modular artificial islands for the equatorial zones.

    A few things I’ve considered during the design process:

    1) Sized such that they can be easily man-handled

    2) Size also allows them to easily fit into standard shipping containers and trucks

    3) Hexagonal shape increases island’s rigidity since there are less straight lines to flex(Unlike traditional square pontoons)

    4) Rigidity further increased by the web of connecting pipes(PVC or similar non-corrosive material)

    5) Compartmentalized air pockets. Attacks on the Island must do significant damage to a majority of the hexatoons before it sinks.

    6) The layering system eliminates the need for a spar and prevents the island from flipping over.

    7) Layering increases bouyancy. I expect most islands to rest 2-3m out of the water when fully loaded with infrastructure

    8) Layering adds FURTHER rigidity but also causes the island to eventually form a dome shape due to weight.

    9) A concrete 10cm thick “shell” will be poured on top of the island to protect the HDPE from UV light. Increasing rigidity EVEN FURTHER

    10) 1.5m to 2m of soil can be added on top of the shell to allow for plant life to grow

    11) Ponds and Streams can be “sculpted” into the island by using Hexatoons to create paths and collection areas.

    12) Hexatoons at the edges will be made neutrally bouyant with concrete and used to create a sort of “continental shelf” to allow for reefs and beaches to form.

    13) I made all these considerations assuming the eventual island would be approximately 1 sqkm / 247 Acres / 10,763,910 sqft

    Profile photo of sda1950

    How high is your island going to be? While waves in a bay may be only a few feet, I suspect at sea they are frequently more than 20 feet. Interesting concept though, but you may want to increase the size of your hexagons.

    Profile photo of OCEANOPOLIS

    because @ 1sqkm and shaped as shown (a rhombus), your sides will be1.2 km. You will need hundreds of submerged layers (@ 50 cm) to provide for internal strength, and more than 2-3 m on top. @ least 10 m of freeboard (out of the water). Can u elaborate on the joining system? Are these holes and pipes? What is the role of the ring? I am asking because I have designed something similar but using kite shaped modules and I am still researching on the best way of connecting them.

    Profile photo of xns

    @sda, The reefs that I expect to form around the outer, submerged hexagons should be enough to break the oceanic waves. Failing that, one could just make the island bigger and let the waves crash on the beach. As for the size of hexagons, Any larger and they’ll be too large to fit into shipping containers and for a person to easily handle them without specialized machinery. Which puts a serious dent in my plans to manufacture and market these things :p

    @Oceanopolis, Funny you should mention the joining system, I just WTFBBQed myself on the way to work when I realized it was physically impossible to join then as illustrated =( I too am stuck trying to find alternative methods of connecting them while maintaining structural integrity. But yes, the plan is to just use holes and common PVC pipes to cut down costs. The ring in the middle is to help support the middle of the structure. I don’t want the weight of people and vehicles causing a “dent” to form.

    I might build a little styrofoam model over the next few weeks, but I need to figure out another way to join them.

    Profile photo of dArtagnan

    It seems we’re thinking along similar lines with regards to modularity. I have considered using something similar to the latches and posts used in car doors at several points along the hexagon as methods of joining hexagons, while still allowing for quick release in case one wants to move on. The issue I’m considering on these is that they provide little flexibility, thus putting stress on the concrete and rebar around the post. I plan on having the posts actually wired to the rebar to help distribute those stresses. Actual sea trials are needed to determine impact of the stresses or whether greater flexibility needs to be engineered into the joins.

    Another reason I like this idea of the quick-release is that it allows individual seasteaders to put some space (i.e. water) between them and the next neighbor by putting a bridge, poles, etc. between them using empty quick-release posts to anchor, but these can then be quickly moved in order to allow a boat, for example, to pass through.

    I’d be interested in hearing other ideas on joining modular seasteads.

    Profile photo of Melllvar

    How do you expect enough reef to form quickly enough to break waves against the structure? I’m no coral expert, but doesn’t that stuff grow at a rate of like fractions of an inch per year? Also, a surrounding coral reef is going to be really heavy, you would need an aweful lot of ballast to float one capable of breaking worst-case ocean waves. Waves at sea can be 30+ meters (approx. 100 ft), you’re design seems a little small to deal with them, not to mention the tremendous forces they’ll place on your joints and such.

    Profile photo of xns

    @dArtagan: I may be heading in a different direction from you, here’s my idea: Instead of pipes, we use PVC sheets. It solves the problem of having to insert them at odd angles since they can be quite easily bent without permanently deforming the shape. The other part would be to make the inside of the connecting port and the exterior surface of the PVC sheet work like cable ties. Which will allow for a strong, permanent connection

    The thing about my design is that I wanted it to be as simple as possible, and once protected from UV light, it’s supposed to “last forever”(Which is why I’m never fully convinced with the spar buoy designs). I’d thought about a latch/hook system, but my concern there would have been wear and tear. And like I’d said in the first post. Rigidity is key for the island to be able to accommodate tall structures.

    You might be interested to know that Sea trials will be happening in the near future, I’m just waiting on my local port authority to give me a permit. Failing that, we might just dump one outside malaysias’ territorial waters.

    @Melllvar: A little on my background, I was a professional aquascaper for about 6 years. So to the question of getting a reef to form quickly you’d need a few things: Calcium, Light, and small amounts of nitrates. All of which will be found in abundance around the island. I’m expecting growth to be in the range of 2cm per year for the slower ones and 15 – 25cm a year for the faster, branching species.

    Also, in the locations I intend to put the islands I don’t expect waves larger than 10ft, even during tropical storms. I’ve been sailing since I was 10(23 now) and the only time I saw anything that large was during a storm when we were approximately 4km from land. So in my mind, a small band of reef and a large section of beach should be enough to protect the interior of the island.

    Profile photo of Melllvar

    Gotcha. Best of luck then, can’t wait to see how it turns out.

    Profile photo of

    xnsdvd, I’ve sent you a private message regarding this project. Please check your inbox.

    Profile photo of trodoel

    What are your hexagons made of?

    Profile photo of FreedomFighter

    I just got into this site, so forgive me if these things have been discussed already.

    Your hexagon design is (I think) the best first try. The blocks need to be far larger though. Big enough to house and support a family of 4. I propose that they be submersible ferroCement living modules that are more like submarines.


    They could be powered by Brown’s Gas fueled Stirling Engines



    The modules can be designed to lock together like Lego blocks and have common utility connections. Each module should have strong removable glass panels on top that can be used to make domes over the growing city or grow hydroponics on board using ocean water while separated.


    The modules would create, support, and power the city. The city would be able to move under it’s own power, albeit slowly. It would really only need to get into the ocean currents to move. Since each unit would be the increasing mass to the city, and it can already support it’s own mass, it would be a near self-balancing equation.

    Should the citizens decide that things are not going to their liking, they could always leave with their own things in their own module and join or form another city. This would control a lot of the social issues.

    With the use of robotics and concrete submersibles, raw materials could be economically accessed from the ocean floor. Research modules could be brought in and out and intergrated into the city or operated within support range of the city. These could provide an income for the city.

    I would think the only thing to watch out for would be early city sizes that are succeptible to ocean swell or rouge waves. A storm of significant magnitude could be avoided, or in the worst case, the city could be broken up and reassembled later. It would only cost all topside investments.

    The modules could be replaced when worn-out, defective, or obsolete.

    Profile photo of xns

    @ trodel: Rotomoulded HDPE. I’ve no idea how thick we want it to be though, still have to run structural integrity tests…

    @ FreedomFighter: You raise some very interesting points that I’ve considered myself.

    For instance, the original design for the hexagons were 35x bigger and meant to accomodate a small home. But then I realized it was too big to get from the factory to the dock. Along with the fact that we’d have to invent our own rotomoulding machine since no one made anything that big. Then there’s the problem of having to use heavy machinery at sea when we set up. Finally, it’d be an engineering nightmare to design the internal structure such that it could support it’s own weight in the middle, let alone a house. That and.. well, we wanted something that floated, not submersible.

    Our thoughts on propulsion are similar as well but with electric turbines. You see, my co-designer(Read: Wife) had come up with a water-based air-conditioning system. If you’ll notice the diagram, the vertical joints run right through the island. What we’re planning to do is pipe cold water from below the island up into the buildings and then use that to cool the air. It was then that we realized that thrust from outlets would allow us to steer the island very very slowly. Which was all well and fine since moving too fast would destroy the coral reefs around the thing.

    Profile photo of FreedomFighter

    I’ve just finished reading through most of this site and it sounds like their are two camps. One, let’s get everyone’s input into the perfect design for a uptopia – rebuild civilization. Two(much smaller), let’s get something in the water and see what we need to deal with then – grow civilization. I’m in camp Two.

    A mobile block of submersible concrete would solve more problems than it creates. HHO power works (don’t flame me on this I have one) but needs to be developed. Hydroponics work in the ocean water and the resulting water is pretty clean. I can’t think of any survival systems that aren’t addressed here.

    Coral reefs take a long time to build and the first couple of steads aren’t going to last that long anyway. So let’s build something cheap, reuseable, reconfigurable, and clean. I’m willing to be that the old addage “no plan survives contact with the environment” will show that 90% of what everyone’s focusing on will be moot.

    Case in point: My wife and I decided that a leaking bath tub was just not a good thing and set about design a haven from the kids. We ended up sequentially dealing with so many little issues like crooked walls and concreted in broken plumbing, I am gutting and rebuilding what was there just to have the kids out of my own bathroom.

    I just finished modeling hex’s and they don’t lock together as well as octogons, so here’s my updated suggestion.

    The platforms can be whatever shape they need to be and the pods can be used for whatever.

    Profile photo of

    I’m very excited about this, as the modular studies I have been doing are perfect for this discussion.
    I had volunteered to render a nice image of breakwater city at this time, I have only completed the outline of the model and am realizing i can’t export it into 3Dstudiomax, nor complete a rendering by the end of today. i think i could finish something using my photoshop3d cs3 tools by monday.. but isn’t it needed this weekend? i really am sorry..
    I imagine the breakwater wall/islands around the outside and around the inside, creating a rotating puzzle to let ships and seasteads in and out.
    see attached rough plan and perspective
    this is the link I found on TSI blog about the tires as a floating breakwater.
    I imagine that they would be filled with sealed and air filled plastic bottles and etc trash, these then encased in an organic kelp closed cell spray and expand foam!
    the white structures around the breakwater ring s are concretes etc and paths


    David Walen

    Attempting to Leave Living Footprints

    Profile photo of

    David Walen

    Attempting to Leave Living Footprints

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