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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 3 years, 5 months ago.

Viewing 15 posts - 16 through 30 (of 155 total)
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  • #7873
    Profile photo of David-Walen
    David-Walen
    Participant

    Plan of breakwater module

    David Walen

    Attempting to Leave Living Footprints
    http://tribes.tribe.net/acce

    #7898
    Profile photo of FreedomFighter
    FreedomFighter
    Participant

    David Walen: That’s a really flexible design. How do you build it?

    #7904
    Profile photo of David-Walen
    David-Walen
    Participant

    I am really fascinated by the idea of “printing” buildings.

    So, I imagine a network of seasteads that are on a smooth sea, using armatures to print structures, and on any day, weaving rebar (non metallic (bamboo-hemp)) and metallic, rebars into waterproof kelp foams. And so, I don’t know which designs your mentioning..

    I like the designs at the start of this thread. Hexagonal always is the most efficient. And I also think going partially submerged is a great idea.

    David Walen

    Attempting to Leave Living Footprints
    http://tribes.tribe.net/acce

    #7909
    Profile photo of FreedomFighter
    FreedomFighter
    Participant

    I see several flat whatevers. So they are basically woven mats encased in foam? How do make the foam? How do you get the shapes you want?

    #7910
    Profile photo of SailorTrash
    SailorTrash
    Participant

    From experience, it’s not reef development you have to worry about; it’s the fast-growing “beard” of sea grass, algae, and generic fuzzy organic crud that will quickly accumulate. I have to scrape/scrub our boat about once a month, even with its new coat of anti-fouling paint. Since these structures can’t be hauled out and painted, this will be an ongoing problem. Ocean stuff will want to stick to them and grow.

    #7917
    Profile photo of xns
    xns
    Participant

    Michael, you’ve actually chanced upon one of the larger economies that will develop from my design. Consider for a moment the kind of gunk that occurs around your boat. Heck, take a photo of it next time and show the owner of your local marine aquarium. I think you’ll be surprised at how much some if it is worth… That aside, there are very simple solutions to seagrass and algal build-up; Herbivores. If properly managed, the ecosystem around the island will be very capable of keeping it relatively clean.

    Finally, I’ve run the numbers, each hexatoon will be able to support approximately 1200kg to 1250kg. It’s biologically impossible for enough gunk to build up to sink one… And the bigger these islands are, the higher the volume to surface area will be. So I’m more concerned with being able to sink the bigger ones.

    Oh, a little progress update on my end. I’ll be incorporating Genesis sometime next month. We’ll be selling the first hexatoons to “Kelongs” or floating fish farms. Seems the regional ones still haven’t realized that building them out of Teak and replacing it every 5 years isn’t the smartest thing to do.

    Interested investors can PM me. You’ll be issued shares for your investments. I’ll post the business registration number when I get the clearance.

    http://en.wikipedia.org/wiki/Kelong < --- that's a kelong.

    #8357
    Profile photo of xns
    xns
    Participant

    Spent some time refining my design. So, critique away!

    King Shannon of the Constitutional Monarchy of Logos.

    #8368
    Profile photo of Jeff-Chan
    Jeff-Chan
    Participant

    If all the floatation is on bottom and all the ballast on top, then the center of gravity will be above the center of buoyancy and the natural tendency will be for the structure to flip over (invert). That’s why boats and ships have tons of ballast in their keels (at the deepest point underwater): to move the center of gravity below the center of buoyancy in order to create stability. On the other hand, the underwater portions of the island around the outer edges act like a heave plate and will resist coming out of the water mostly due to surface tension and partially due to the mass of the water above, and that’s a good thing for dynamic stability. So the design may work.

    The larger risk of capsizing may occur during construction when the structure is small, before the ballast lowers the edges under water, etc. Temporary anchoring, or construction in protected waters having smaller waves may help reduce that risk.

    #8370
    Profile photo of bencoder
    bencoder
    Participant

    Jeff wrote:

    That’s why boats and ships have tons of ballast in their keels (at the deepest point underwater): to move the center of gravity below the center of buoyancy in order to create stability.

    In the interests of accuracy, that’s not entirely true. Many boats don’t have a center of gravity below the center of buoyancy, but in fact they are “meta-stable” because as the boat shifts in the water, the center of buoyancy moves, as a different part of the ship is underwater, which makes the center of buoyancy laterally move away from the center of gravity and oppose the tilt. The simplest example of this is the catamaran, where, in the extreme case, if one hull is fully underwater and the other fully out of water, then the center of buoyancy will be located in the underwater hull, lifting that side only and stabilising the boat. This is true of most monohull boats as well, but catamarans are simpler to visualise in this case. That does mean that there is a certain angle where these metastable boats cannot recover from.

    I imagine that the design shown would be pretty meta-stable because of the wideness of it, although i’d change the design so that the buoyancy is more at the edges and less in the middle. As the seastead tilts, more of the seastead on the tilted down side is underwater, opposing the tilt.

    #8373
    Profile photo of Jeff-Chan
    Jeff-Chan
    Participant

    Thanks for the clarification about metastable boats. Putting ballast in a keel does lower the center of gravity though, even if not below the center of buoancy.

    As an aside, at the Pampanito museum at Fischerman’s Wharf in San Francsico, there’s a chart showing the center of buoancy (cb) below the center of gravity (cg) when the this World War II submarine is surfaced, but cg is below cb when submerged. That’s because the bouancy tanks used for surfacing are are low and to the lateral sides (abeam) of the sub. When those tanks are flooded the relationship between cg and cb is inverted. Not really related to the current proposal, but kinda interesting and weird that a boat can have both relationships and two kinds of stability (meta stable and stable) in different operating modes (surfaced and submerged).

    #8374
    Profile photo of Jeff-Chan
    Jeff-Chan
    Participant

    bencoder wrote:
    I imagine that the design shown would be pretty meta-stable because of the wideness of it, although i’d change the design so that the buoyancy is more at the edges and less in the middle. As the seastead tilts, more of the seastead on the tilted down side is underwater, opposing the tilt.

    One problem with putting more buoyancy at the edges is mechanical strength. The dome shape with more floatation at the center is probably stronger than a doughnut shape with more floatation at the edges. A good shape may be a dome, which would spread the forces over the curved top, like an arch.

    A doughnut (toroid) shape would be more like a catamaran revolved about a vertical axis. A dome would be more like a rotation of a monohull. As we know, a catamaran needs a very strong deck to bridge the hulls. So by analogy, a toroid would also need a strong center dome to bridge the floatation. May not be practical with the hexagons as a building block. Trusses could work.

    There’s probably some modelling that can be done to determine the optimal distribution of floatation over the resulting shape with regard to dynamic stability.

    Keep in mind that the portion under water at the edges would have a strong resistance to being pulled out of the water due to surface tension and a lot of vertical drag, in addition to the mass of water above. There isn’t really an analog to that effect in conventional ships. Heave plates come the closest. It’s also a feature of HARTH’s underwater hulls.

    #8662
    Profile photo of jgpeyer
    jgpeyer
    Participant

    bencoder wrote:

    I imagine that the design shown would be pretty meta-stable because of the wideness of it, although i’d change the design so that the buoyancy is more at the edges and less in the middle. As the seastead tilts, more of the seastead on the tilted down side is underwater, opposing the tilt.

    Hey Ben,

    It seems to me like the design is attempting to do exactly what you are suggesting, while retaining symmetry. The buoyancy that you are after is a number achieved by drawing a vertical line through the stead, right? So at the center, even though you have more hexagons, you also have the main above-water weight of the seastead, offsetting the added buoyancy from the hexagon layers. The buoyancy of the reef structure is not reduced by stuff piled on top of it (unless you grow infinite layers of coral, I suppose) and may therefore have a higher buoyancy. Your general point, however, is very well taken. Such a calculation would have to be considered. I think logistically though, this design could work as it stands. I like it a lot.

    #8667
    Profile photo of billswift
    billswift
    Participant

    Ideally, you should have the buoyancy at any point exactly equal the load on that point, then you would not need any rigidity or strength in the platform.

    In the real world this is not possible because of changing loading as people or whatever move across the platform, wind loading, waves, etc. But if you keep the principle and ideal in mind, you can probably improve any real design, including reducing its strength requirements. The shallow water border area, probably meant primarily as a breakwater, either is neutrally buoyant or if contributing to the flotation of the center platform will require substantial reinforcement (especially at the border between it and the thicker part of the platform).

    It would probably be better to make an independent ring shaped breakwater that is not rigidly connected to the float.

    The overall shape of the platform is not important if you can keep the loading and buoyancy closely linked, and a more lozenge shaped (very enlongated hexagon) would probably be better for an anchored seastead – less current stress on the anchorage.

    #8946
    Profile photo of greyraven_r
    greyraven_r
    Participant

    Not bad, similar to my preference, but I’m envisioning Hexmods in excess of 10 meters to a side by 1 meter thick, with a complete overlap shift. I also envision a shallow (10-20 meters deep) bay between the “island” shore and a perimeter break water, all of similar Hexmods (which may vary in bouyancy, based on level above of below sea level).

    “When I look into the abyss it stares back at me, but not as the cold
    dark beast you perceive it to be.
    When I am gazed upon by the abyss I see the eyes of a mother, a lover, an old friend.
    When

    #9021

    If we design a platform that is more a “flexible grid” than a “rigid platform” we can get much more platform extension with much less structural material necessary.

    If you have a look at mangroves you see that nature uses that principle of “somewhat rigid” and “somewhat flexible” elements with a lot of waterspace between the structural elements.

    This is a very efficient way to build up big islands that can stand strong storms.

    I would suggest the seastar platform grid as a base for a semi rigid island with distributed buoyancy in the sense of billswifts distributed bouyancy concept.

    Reference : Seastar Platform

    Wil

    concretesubmarine.com

    European Submarine Structures AB

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