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The SEASTAR PLATFORM

Home Forums Archive Structure Designs The SEASTAR PLATFORM

This topic contains 30 replies, has 12 voices, and was last updated by Avatar of OceanPhoenix OceanPhoenix 4 years, 4 months ago.

Viewing 15 posts - 1 through 15 (of 31 total)
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  • #1134

    One of the big issues with family seasteading is that small platforms do not behave as “comfortable” in waves as big ones would.

    So i will postulate a design need: “Make small platforms behave as quiet in waves as big ones”.

    The catamaran design makes a small boat behave like a much broader flat barge, waterwalker brings buoyancy at the end of long legs.

    I would suggest to bring waterwaker down to the surface so the legs would float on the surface, still stabilize the platform against rolling movements, but allow a much heavier construction as it would be supported by buoyancy.

    I call it SEASTAR DESIGN – the objective is make a small platform of maybe 10m diameter (house size) behave like a platform of 50m diameter which would be the diameter of the “seastar like stabilisation arms”.

    It would be a lens shape concrete shell structure like this in the center of the “seastar”.

    Adding arms to the design we get a wave stability relevant diameter of 50m what would create a stability in waves that can be compared to the Nkossa barge which is a 46m flat structure floating 60km off coast .

    So we would get “nkossa barge stability” without really need to build a nkossa barge size platform. This would mean a single family seastead would be perfectly stable in open sea.

    We would also get a perfect connectibility of family units – as we can link single independent seasteads to seastar grids connecting them on the arm tips by concrete cast joints.

    This would create calm breakwater protected water spaces within the grid – serving as marina space for boats, or as growing spaces for floating vegetation islands.

    The seastar concept would keep the next neighbour on a “sociable distance” of at least 50m sharing only harbor, and lagoons, and some connection points.

    It would allow to connect platforms of different sizes makes and styles in a irregular matter, maintaining freedom to leave the grid, maintaining options for closing the water spaces with concrete plating, additional floats for parks, larger structures depending on needs that come up and budgets that are available.

    The structure would be relativly flexible and structurally sound at the same time due to the support by buoyancy.

    The concept as such is already proven and in function as we speak in floating breakwater marina designs.

    The arms can serve as connetion ways and build up calm water very efficiently as visible in the picture below of the wave behavior on a floating concrete segment.

    The whole concept is also highly efficiently buildable in modular design to be asembled floating on the water surface.

    Last but not least the arms can be used to span out nets for open water aquaculture purpose like tuna rearing and similar activities to complete the marina, hospitality etc…activities.

    Let me hear your thoughts…

    Wil

    concretesubmarine.com

    European Submarine Structures AB

    #8977
    Avatar of
    Anonymous

    I would make them 3, 4, or six pointed for tileability.

    #8981
    Avatar of vincecate
    vincecate
    Participant

    I would suggest to bring waterwaker down to the surface so the legs would float on the surface, still stabilize the platform against rolling movements, but allow a much heavier construction as it would be supported by bouyancy.

    I call it SEASTAR DESIGN – the objective is make a small platform of maybe 10m diameter (house size) behave like a platform of 50m diameter which would be the diameter of the “seastar like stabilisation arms”.

    It is an interesting idea. The problem with heavy concrete is you need a lot of steel inside to make things strong enough for all that weight. In the end you can easily use more steel than a design that was just steel alone. If the arms where steel cones or tubes, or box beams, or even trusses, I think it would be more reasonable. I think aluminum is nice for single family seastead sized things in the ocean.

    If a wave hits a solid leg it could put a huge force at the end of the long lever where it connects to the center. So an open truss could help with that. Another option is if the legs are only flexibly connected to the center.

    Having the living area down in the water means big waves can hit it and put big forces on it, again stressing the joints to the legs.

    The floats on the waterwalker could be sort of boat shaped, so they move through the water easily. Even sort of a triangle keel so they could work for sailing or kite power. Having big heavy concrete legs down in the water makes moving much harder.

    — Vince

    #8987

    admiral doty – i do not like the term “tilability” because it implicates that everybody must have the same standard platform design – a seastar design allows to connect to a beach, to a industrial facility, without having “standard connection points” if you can connect one or two arms you are strongly connected – but not too rigid – due to the flexibility of the arm. The number of arms can be any number adding and desconnecting arms is easy. For protected water you can go for cero arms. You need the arms only to increase the wave movement relevant size of your (small) platform when you feel it is rolling too much in the waves of the open sea. In a seastar platform community arms could be traded and rented. The arm grid can be intensified and covered with plates when structurally necessary or thinned out to create lagoons and harbors for vulnerable boats within the seastar grid.

    vince – the general idea of seastar is that bouyancy is the primary structural support. The structure rests on the surface with no forces to take at all. The arms should be ballasted deep (like on the photo above) to ensure that monster waves go over it (wave piercing mode) instead of lifting it or moving it around this should keep forces to the central island very moderate and without extreme peak loads. In case of a millenium wave hitting the structure arms should be able to break away with no damage to the central island. So i agree it might be an opton to make them extrem light at first and create heavier transitable floating beams in a second phase when the platform is within the grid.

    The center island is a concrete shell structure much stronger than the ” thin composite” of modern yachts – so the capacity of the center island to take wave impacts will outrank a typical yacht in the 20m size class.

    I agree that waterwalker can be designed almost to behave as a fast, light, high mobility, catamaran – seastar not. I see the both concepts as complimentary designs each with its advantages and disadvantages. Waterwalker is a light design for materials like alu, composite, wood. Seastar is heavy with great tank volumes, big store capacity. What they have in common is the principle of getting the stability benefit of a big platform for a small one using horizontal extensions.

    Wil

    concretesubmarine.com

    European Submarine Structure

    #8989
    Avatar of vincecate
    vincecate
    Participant

    vince – the general idea of seastar is that bouyancy is the primary structural support. The structure rests on the surface with no forces to take at all.

    Not sure I understand this. However, “resting on the surface with no forces to take at all” sounds like flat water, not waves. One of the big stresses on ships is when the wave lengths are the same as the ship length and supporting the two ends or just the middle. Your ship must not crack in half when supported just at the ends.

    http://en.wikipedia.org/wiki/Hogging_and_sagging

    I don’t see how you can plan on the arms being “wave piercing” since with several arms the waves are hitting some from the side.

    If the arms are an open structure, like a radio tower, that waves could pass through, then it might work.

    Oh, maybe I understand. If the central area has bouyancy to hold itself up, then the legs just need to have enough bouyancy to keep it from tipping. So they are kind of like outriggers on a cannoe. I like it.

    Not sure what photo this refers to: “The arms should be ballasted deep (like on the photo above)”

    — Vince

    #8996

    vince, for a 50m diameter structure “big waves that can dynamicly push the structure around” will start at a wave size that does not really exist on the oceans. Some 30m is considered maximum possible. For tropical locations with selected good climate 4m waves is heavy sea. As soon as you reach a certain size all water is kind of flat water compared to the structure size.

    No mega tanker can be built or designed for being supported only on the ends or only in the middle without breaking. Big ships get deeploaded with water ballast to avoid excessive hogging and sagging.

    A wavecrest at the tip of the arm of the seastar design will not lift the whole structure on this tip. There is not enough bouyancy in the tip to do so – it will just go under and let the wave wash over without changing the horizontal position.

    If you look at a floating tree trunk you will get a good picture of the “wave behavior of long thin low bouyancy objects” – they do not change position in waves, they do not get hogg and sagg, they stay on even keel they do not get pushed around, as long as wave size is not considerably bigger than the object size – and that will not happen.

    The idea of “stabilisation by low bouyancy outriggers” is present and tested in philippine outrigger designs for centuries. Seastar just gives the long thin low boyancy outrigg stabilisator a double funcion as connection arm and walkway.

    The picture of a floating conrete breakwater/walkway below is just to explain the principle, i agree that the arm could be thinner, more flexible, the bouancy you need for stabilistation reasons is only very small.

    #9003
    Avatar of vincecate
    vincecate
    Participant

    vince, for a 50m diameter structure “big waves that can dynamicly push the structure around” will start at a wave size that does not really exist on the oceans. Some 30m is considered maximum possible. For tropical locations with selected good climate 4m waves is heavy sea. As soon as you reach a certain size all water is kind of flat water compared to the structure size.

    You seem to be confusing wave height with wave length. While 30 meters is crazy high for waves, 50 meters is not very long for waves.

    A wavecrest at the tip of the arm of the seastar design will not lift the whole structure on this tip. There is not enough bouyancy in the tip to do so – it will just go under and let the wave wash over without changing the horizontal position.

    [...]

    The idea of “stabilisation by low bouyancy outriggers” is present and tested in philippine outrigger designs for centuries. Seastar just gives the long thin low boyancy outrigg stabilisator a double funcion as connection arm and walkway.

    Ok, good. But hitting a concrete arm from the side will be a huge force.

    The picture of a floating conrete breakwater/walkway below is just to explain the principle, i agree that the arm could be thinner, more flexible, the bouancy you need for stabilistation reasons is only very small.

    That concrete breakwater is in a somewhat sheltered bay. It is also not firmly connected to anything at either end. If you tried to connect that long wide thing firmly at the end it would break off in not very big waves.

    The idea of using a small amount of bouyancy on a long lever like an outrigger is good. But I think you will find that concrete is not good for that long lever. Concrete is good for arches and buildings but not so good as a long lever.

    — Vince

    #9014
    Avatar of wohl1917
    wohl1917
    Participant

    Ellmer I think with reguard to ‘over ‘ designing things! An example: once oppon a time if a hand truck rated to carry 200lbs it could carry 200lbs and a bit more and you could drag it up/down stairs over curbs etc., and not tear it up. Not so today because engineers have designed things ‘down’ to just meet specifications to save money in production costs. Over design my seastead thank you!

    < http://ocr.wikia.com/wiki/Oceanic_Citizens_Republic_Wiki>

    vince, we may not have a “unified opinion” on how to optimize the outriggers – this is not surprising – the good thing is there is a viable way of experimenting until you get a design that works well for the sea area you plan to live in.

    I will start building the center island in a protected bay – so i can already live on it before i come up with an outrigger design of any kind. Once i move it gradually out to less and less protected waters i might well find that the stability of the center island itself is comfortable enough.

    If i find that some additional stability would be good, i can add a few arms – and experiment with different designs until i am satisfied with the movement of the island. The good thing is the design is scaleable as well in weight size length, bouyancy of the outrigger arms, a failure means a arm break away – i would to have to repair a cast joint – maybe replacing it with a flexible ball joint. Maybe add masts and tension cables to stabilize the arm tips.

    Even learning by break away failure would not put the center island at risk – so we have a wide field of experimentation to do to find out what is doable, better, expensive, economic, – this focus on real world experments is definitly something about what we we would be on the same page.

    Looks like we would be designing for an average wave height of 1-2 m here in the caribbean – so one point to watch would probably be, not to “structurally overdesign things”.

    It is a bit like land based construction. If you focus on the “worst possible millenium event” you just can not get a reasonable building code. Building anything in California for surviving a millenium earthquake without anything breaking is just not possible. So you need to keep it somehow reasonable, cost efficient, doable.

    This means in the caribbean – especially outside the hurricane belt – waves of 7-8m can be allowed to do “some damage” but not to sink the platform completly. What makes seastar platforms safe is that they are still big and comfortable rescue islands after all arms have broken away.

    #9041

    wohl1917, i did not communicate this right. The center island – the unit where people finally will be sheltered during a storm, will have a kind of “unsinkable bunker quality” it will be a chambered concrete shell structure, hundreds of times stronger than anything used for traditional light yacht building.I would not doubt to host my family there in conditions where traditional yachts get rolled over at the most minimimal handling error. The center island It would even be capeable to survive ship collisions with some arms chopped off but the core intact.

    So a seastar platform would be several times safer than a traditional yacht from whatever angle you look at it. What should be allowed to take some damage in extreme weather is the connection GRID – not the HOUSES – this would be a parallel to the floating vegetation islands of the uru tribe some of those “floating vegetation elements” in the border zones might break away and drift apart in extreme conditions – the island can easily be repaired later. It is also a parallel to the mangrove – some roots may come loose – the strength is in the tissue, its redundancy, its quick repair, not in the structural overdesign of every single part of the connection grid.

    One of the big advantages of a flat tissue, or grid design, or flexible design, is that every single element can fail with no catastrophic consequence for the rest of the seastead. So overdesign is less mandatory as failure has no (fatal) consequence.

    Wil

    concretesubmarine.com

    European Submarine Structures AB

    #9052
    Avatar of vincecate
    vincecate
    Participant

    wohl1917, i did not communicate this right.

    Forums are like people chatting at a party, once the conversation is done it is often forgotten. Wiki pages let you organize and clean up information so that it can be used as a reference over time. It can be linked with related pages and advance the seasteading knowledge base. Please make a wiki page for your seastar idea.

    — Vince

    #9389
    Avatar of J.L.-Frusha
    J.L.-Frusha
    Participant

    The hardest problem for a long ferrocement floating structure is the multiple rolling-moments that twist on it. Designing to reinforce the ‘spine’ of the structure becomes of utmost importance. In a ‘bow-on’ wave action, it is seen as a moving flex, along the length of the structure. Naval ships of both World Wars, made of ferrocement, were designed for both of these conditions. One patent uses both compartments along the bottom of the hull and a hollow wall, of sorts, from stem to stern. These ships ranged from about 250′ to over 350′ in length. Examples are still afloat…

    http://www.concreteships.org/ships/powellriver/

    Later,

    J.L..F.

    If you can’t swim with the big fish, stick to the reef

    #9745
    Avatar of Altaica
    Altaica
    Participant

    One of the big issues with family seasteading is that small platforms do not behave as “comfortable” in waves as big ones would.

    So i will postulate a design need: “Make small platforms behave as quiet in waves as big ones”.

    The catamaran design makes a small boat behave like a much broader flat barge, waterwalker brings boyancy at the end of long legs.

    I would suggest to bring waterwaker down to the surface so the legs would float on the surface, still stabilize the platform against rolling movements, but allow a much heavier construction as it would be supported by bouyancy.

    I would suggest you learn how catamarans work.

    Οὐκ ἐμεῦ ἀλλὰ τοῦ λόγου ἀκούσαντας ὁμολογέειν σοφόν ἐστι, ἓν πάντα εἶναι.

    #10028

    Thanks to swanberg and his link http://inhabitat.com/2010/02/08/the-gyre-a-floating-upside-down-eco-skys

    Thread: seasteading.org/interact/forums/engineering/structure-designs/found-some-awesome-designs

    This source provides some really nice pictures for the concept of seastar design.

    Seastar design not only for a single family seastead but also for a futuristic oceanic skyscrapper….use of the arms as docking space for cruiseships, netting below the arms for aquaculture, long submarine extensions as docking area for submarines, for OTC energy solutions …. compared to a tile platform the connection points for the seastar grid can be organic (no standard) – you can connect a single family seastar arm to a bigger structure, to land, to a industrial facility, whatever need comes up.

    Wil

    concretesubmarine.com

    #10031
    Avatar of OCEANOPOLIS
    OCEANOPOLIS
    Participant

    Its a nice design. But it will have structural weakness in the 4 floats in heavy seas. I would reduce the length of those 4 flots to a 1/4 (of the shown length in the picture) and reeinforce below. Also the draft is high if mobility is involved since it wont be able to get into shallow waters. If intended to be stationary offshore, I guess its ok. Lets build it @ a smaller scale, 100′-200′. I have secured an idustrial area here in West Palm Beach Florida where I can build and store up to 300′.

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