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  • Concrete spars and printing-in-place?

    First, about me. I'm an aspiring seasteader trying to build on an extremely small / narrow budget, trying to think outside the box. I have some experience with additive manufacturing. I've been thinking...

    XLII used a traditional steel spar, with all the materials, welding and transportation costs that includes. What about other material ideas for spars?

    I was specifically thinking of 3d printing a concrete cylinder and lowering it into the water as it cures to print additional layers. The trick would be to build a stable motorized support to lower the platform into the water to add additional layers, perhaps on cable or chain?

    Infill with poured concrete and/or sand as needed to achieve proper balance of buoyancy.

    People are 3d printing houses with this approach, my question would mainly be whether this is structurally sound and whether concrete will survive long term in immersion in ocean water.

    https://www.youtube.com/watch?v=wtCJKojjxzM


    Eric

  • #2
    National Geographic 2017 - The world's longest cable-stayed bridges rion antirion: Rion-Antirion | M

    https://youtu.be/YLo2_UFyGcQ

    Comment


    • #3
      Concrete cruising yachts realm the oceans for decades and are the cheapest option. No sure about the 3d printing option.
      https://en.m.wikipedia.org/wiki/Concrete_ship

      https://www.ferroboats.com

      Comment


      • Barskor
        Barskor commented
        Editing a comment
        Basalt rebar and fiber cloth could make those Ferroboats better as they can not rust and have excellent strength. Magnesium phosphate cements are stronger and don't have the problems with salt water.

    • #4
      Looks promising. I was thinking the biggest problem would be having to let it dry to cure, but it looks like portland cement can cure while wet, so even totally submerged it should work as long as it can stay straight. The trick to the right buoyancy would presumably be just be the right ratio of air to heavier materials.

      For building the platform on top, I'm been looking into aircrete and I think might be good. Cheap, light, insulating, and in case of disaster, it floats. Unlike XLII, maybe just mount a slab and then build a house on top of that rather than mounting a prefab. Again, I'm really thinking about how to dramatically lower costs.

      Here's a guy with a company teaching people how to make aircrete domes.

      https://www.youtube.com/watch?v=zzCXNlqDW6M

      https://www.youtube.com/watch?v=JR8KiyLUWI0

      Comment


      • skipperzzyzx
        skipperzzyzx commented
        Editing a comment
        Very cool. I hope to see pictures of what you built.

    • #5
      As I posted on Facebook the cylinder is actually the cheapest part of the whole thing. The post production work plus getting it out to the site standing upright is the biggest cost for the spar.

      The house is also a large expense. Our production version will actually go quicker because we will use a mold and be able to knock them out quicker. For the single prototype it was about 5-6 months of labor. Part of it figuring things out. But the quality is that of a boat interior with water tubes and pumps and bilges and framing and making sure the house floats if the spar sinks and all of the electric (solar, marine batteries, inverter, charge controller, etc.). The shell is probably the cheapest part there as well.

      Consider your house. Just some wood frames with flat wood on the roof covered in tar paper. Should be pretty cheap.

      But we are not against concrete and we actually plan on building in concrete for one of our side projects. Building downwards. We can do this because it is a very large structure (about 20k tonnes) with almost no post production necessary.

      We discussed doing the spars in concrete but we believe that steel is safer for a living space. The cost difference for the cylinder would be within a few thousand dollars while being able to work with the steel afterwards is easier than concrete (you can just weld things onto the cylinder). And concrete "leaks".

      I'm not trying to sell the Ocean Builders spar as the best solution, just telling you our thought process.

      They are subsidizing steel in China so it is very cheap. Being in Thailand we are not that far from the Chinese ports.

      I want people to try their own designs. I even worked out the next design so that we can build just the spar with a steel 'plate' for those that want to do their own design. We are pricing those blank slates at about $45k. That's with twice the depth of the current spar with living space inside.

      Just remember, when considering house designs, you want to consider the wind and we made it so that if the spar sinks the platform floats on its own (they are independent). You also need to consider solar panel space and it's really nice to be able to sit on top on the upper deck.

      Also, the reason we do not want them too wide is because we calculated the angle of tilt you would get from one or two people walking to the furthest side of the platform. With our 2 meter wide spar the tilt is 3 degrees if someone is 3 meters from the center. We figure this is within the comfort level of most people.

      Comment


      • Marc de Piolenc
        Marc de Piolenc commented
        Editing a comment
        Concrete is not inherently leaky. Ferrocement hulls as thin as 3/4 of an inch have been built that were watertight ab initio. There are of course excellent sealants that can be used on the outside if you put a little too much water in the mix. Reinforced concrete is a valid material, butt the question is: how do you incorporate reinforcement into a 3-d printed hull? My feeling is you don't need this technology, if you are producing the spars in a low-labor-cost country. I have a lot of documentation on both ferrocement and RC ships.

      • Marc de Piolenc
        Marc de Piolenc commented
        Editing a comment
        Concrete is not inherently leaky. Ferrocement hulls as thin as 3/4 of an inch have been built that were watertight ab initio. There are of course excellent sealants that can be used on the outside if you put a little too much water in the mix. Reinforced concrete is a valid material, butt the question is: how do you incorporate reinforcement into a 3-d printed hull? My feeling is you don't need this technology, if you are producing the spars in a low-labor-cost country. I have a lot of documentation on both ferrocement and RC ships.

      • Barskor
        Barskor commented
        Editing a comment
        You can reinforce with chopped basalt fibers and if you know how to make it or can afford to buy it graphene is amazing in concrete here is how to make it cheap https://www.youtube.com/watch?v=MVyl9Jzn-gA you don't need much graphene to get these results https://www.youtube.com/watch?v=rM5o1zQUsnw

    • #6
      Thanks for the feedback, this is really good information. I clearly have a lot to learn and wish I had an engineering degree about now. I'm definitely going to keep trying to figure out the cheapest possible way to build a seastead, as unfortunately I didn't manage to buy a bunch of cryptocurrency before 2018 (still kicking myself). If I'm going to do this, it's gotta be tiny house level cheap all-in. (I'm comfortable being very minimalist). I know you guys have put a lot of work into making them very inexpensive, but I feel like thinking outside the box, there's always something new and unconventional to try.

      In terms of floating on the water, I'm thinking aircrete for the house itself, domegaia is doing workshops on building houses out of aircrete. Anyway, I think this is going to be my all-consuming passion for a while now, maybe I'll audit some classes and do a workshop for the land-based aircrete stuff, then start developing a platform design. It doesn't have to be just a spar, multiple spars joined under water with the center of buoyancy lower might help your tilt issue...

      Comment


      • #7
        Originally posted by destinal View Post
        First, about me. I'm an aspiring seasteader trying to build on an extremely small / narrow budget, trying to think outside the box. I have some experience with additive manufacturing. I've been thinking...

        XLII used a traditional steel spar, with all the materials, welding and transportation costs that includes. What about other material ideas for spars?

        I was specifically thinking of 3d printing a concrete cylinder and lowering it into the water as it cures to print additional layers. The trick would be to build a stable motorized support to lower the platform into the water to add additional layers, perhaps on cable or chain?

        Infill with poured concrete and/or sand as needed to achieve proper balance of buoyancy.

        People are 3d printing houses with this approach, my question would mainly be whether this is structurally sound and whether concrete will survive long term in immersion in ocean water.

        https://www.youtube.com/watch?v=wtCJKojjxzM


        Eric
        Hi Eric, I'm in the same "boat" as you; not much money, no engineering knowledge, but lots of ideas. I'm glad to see some of the ideas Ive had have already been mentioned here, so at least i know I'm not a total dreamer or not completely crazy. For example the basalt fiber rebar, and cement for the spar design. Also the Graphene oxide powder additive for the cement which will increase the strength incredibly. Cement hulls and spars also need much much MUCH less maintenance then steel, with some cement hulls still in existence for more than 60 years! Now add the non rusting basalt rebar in there and i think weve got a winner. As mentioned by Chad the transportation of the spar is one of the biggest expenses ($45k for a spar is the price of a luxury house in my country sheesh man) but i still think that (for now at least) building the spar on land and then transporting it to location is the best way to go. reason being is that cement needs pure water and clean sand and cant be disturbed by the motion of the ocean. Now unless you had an existing platform out there from which to fabricate from, clean ro water etc, then its a different story. .all that said about cement, i like the fact that the steel can be cut, welded , bent, and reused and recycled etc. its a tough choice.
        Not to bash what the Ocean Builders have done, but honestly I was a bit disappointing so far watching the YouTube videos. After 10 years of talking they go out there with this small thing barely large enough for small family. This was their time to showcase everything they have been talking about for all these years. After just a few hours of sketching (and limited tec knowhow)I estimate that you would need about 100 sq meters (6m wide hexagon,3 levels of 2.44 m high each) of space for a comfortable livable area considering all the equipment you need to keep. My question to you is, do you know where can we get a detailed design for a spar that will take the weight of such a load (estimated at 40 tons), or who could design it for us. The small sea-stead of Chads is cute but lets try standardize an open source design, something for all the DIY'ers thats large enough for a family and for growing some greens. cheers mate. trev

        Comment


        • alecm
          alecm commented
          Editing a comment
          Trev, be sure and post videos once you get yours funded, design, and launched.

        • skipperzzyzx
          skipperzzyzx commented
          Editing a comment
          I would like to see those videos as well. Please.

      • #8
        Sarcasm is never constructive, criticism however can be.

        Comment


        • #9
          I would gladly if funded. Lots of talent and inovation in my country ( south africa ) and weaker currency makes it a attractive location to build such structures.
          it's sad though, that the sick politically correct state that the world is in right now has made people so sensitive to others opinions. on this forum some people can't take criticism at all, (which wasn't even directed towards them lol). Don't see my opinion as bashing what Rudy (elwar) achieved. It's truly inspiring and an achievement of note. You guys don't need to stand up for anyone lol grow up please.

          Comment


          • skipperzzyzx
            skipperzzyzx commented
            Editing a comment
            Yes, OK, just please do not forget the videos.

        • #10
          Originally posted by destinal View Post
          First, about me. I'm an aspiring seasteader trying to build on an extremely small / narrow budget, trying to think outside the box. I have some experience with additive manufacturing. I've been thinking...

          XLII used a traditional steel spar, with all the materials, welding and transportation costs that includes. What about other material ideas for spars?

          I was specifically thinking of 3d printing a concrete cylinder and lowering it into the water as it cures to print additional layers. The trick would be to build a stable motorized support to lower the platform into the water to add additional layers, perhaps on cable or chain?

          Infill with poured concrete and/or sand as needed to achieve proper balance of buoyancy.

          People are 3d printing houses with this approach, my question would mainly be whether this is structurally sound and whether concrete will survive long term in immersion in ocean water.

          https://www.youtube.com/watch?v=wtCJKojjxzM


          Eric
          Eric you might want to google up the building of Rion-Antirion Bridge Pylon and watch the building video of this structure. It starts as a plate in a graving dock and is then slip formed and lowererd gradually down...

          Also check on DRAUGEN a big spar platform built on base of a vertical concrete cilinder...

          Kindest Regards | Wilfried Ellmer | nautilusmaker |

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