July 7, 2008 at 11:29 pm #646
Wrote up another idea bouncing around in the back of my head:July 8, 2008 at 6:37 pm #3418
That’s a very interesting idea. A while back I had a similar idea, of a fully spherical geodesic done sitting on top of a spar, which would give the whole structure a sort of lollypop shape.
The geodesic design has some advantages, including being a very strong shape, and, as you mentioned, not needing internal supporting walls or pillars, which should reduce the amount of materials required. Also, a sphere has the largest ratio of internal space to surface area of any shape; these facts combined should mean that a lightweight, spacious dome could be created, which would reduce the required size and weight of the spar and ballast, thus reducing the overall cost.
The underside of a sphere might be less vulnerable to large waves than a horizontal platform. A sphere should have high resistance to hurricanes and other strong winds, relative to other shapes.
Geodesic domes are made with triangles inscribed on the surface of a sphere, with the edges of the triangles approximately forming a great circle on the sphere. The struts of the triangles could be made from steel or aluminium, with aluminium or ferrocement plates within the triangles on the underside, and glass plating within the triangles on the middle and top.July 8, 2008 at 7:20 pm #3419
Thanks. Over the next 2 weeks I will be testing several 1/25th scale seastead models. It would be fun to model this one alongside the others. At 1/25th scale this 80 foot wide structure becomes 3.2 feet. Looking around the small island I live on I can not find any 3.2 foot wide bowls so far. If there was a 5 foot diameter ball of some kind that was stiff enough (maybe a ship mooring float) I could cut sections off that. But so far I am not finding anything like that either.
I might be able to frame out the bowl shape with some flexible wood strips and then put a plastic cover around it. This is the best idea I have so far. If anyone has any other ideas on how to model this please let me know.August 1, 2008 at 8:57 am #3521
Perhaps you could create the model out of a nylon fishing mesh/cement composite over a male sand mold?
First, make a large diameter half-sphere out of sand:
1. Use a a string attached to a stake to draw a circle in the sand.
2. Lay down a large piece of cardboard, large enough to completely cover half the circle. Glue several layers together if necessary to make the carboard rigid.
3. Cut out half the circle from the cardboard, leaving the half-circle as a negative space in the remaining cardboard.
4. Pile the sand to the desired height, and shape it to a rough half sphere. Rotate the card board form up and over the pile, smoothing the sand into a uniform sphere. Fill any gaps as necessary.
5. Once you have a satisfactory male mold, overlay it with a layer of nylon cement, as discribed by Bill Birdsall (1)
6. Once the shell hardens, you should still be able to cut out hatches, windows, etc.
7. Create a second shell the same way.
8. You could join the two shells by leaving a layer of mesh exposed extending beyond the edge of one of the shell. Once the shells have hardened, you could put the shell with the lip of mesh on top of the other, and then cement the lip to the bottom.August 2, 2008 at 1:43 am #3527
That nylon cement seems like a nice way to do a number of things. After my other models I think this Geodesic Vessel would be like the sphere and cylinder and be too unstable. But I will keep this in mind and might use it on a future model. Also, I have wanted to make a walkway along a steep hillside on our property and this could help with that project.August 2, 2008 at 4:00 pm #3528
> After my other models I think this Geodesic Vessel would be like the sphere and cylinder and be too unstable.
Thinking I might have been too harsh there. The sphere and cylinder were around 1 foot wide and the Geodesic Vessel is about 3 feet wide. They did not have any shape stability and this does. The tension circle at 5 feet wide and with all the floatation out at the edges was good. So this at 3 feet might just be ok. I might just try this with nylon cement. We have a huge and deep sandbox, bags of cement, just need some fishing net…August 3, 2008 at 12:20 pm #3533
August 3, 2008 at 12:59 pm #3535
- It doesn´t look very inviting IMHO. I don´t feel like I would like to live in a big floating ball with only a tiny balcony as the whole outside area, no matter how safe or efficient it is.
- I think any seastead needs to make people want to go and live there if they are to be successful.
In the same way that there is currently a range of beauty in home architecture, I think we will see a range in seastead beauty too. And beauty really is in the eye of the beholder. To half the world’s population this seastead would probably be a huge step up in their living accommodations. My guess is many of them would want to go live there if there was also a job that let them afford to live in it.
In the same way, I think some people with less money might be more tolerant of seastead movement than some millionaires from silicon valley. So I think there will be a range of acceptable stabilities as well. I just want my seastead stable enough that I could keep focused on working on a computer most of the time.
My dome house has 20 sides of vertical walls and then a geodesic roof. In making a model out of cement, I am now thinking of sort of doing this upside down (or maybe even upside right and turning it over after it dries). So the model would end up with a rounded bottom and a vertical wall around the edge. So it is kind of a round cement boat/barge. At some size this should be stable enough and very cheap per square-foot.March 14, 2010 at 7:50 pm #9853
I like your thinking on this. It is simple and shouldn’t be too hard to construct. I still think you will need some bracing on the inside, but less than is normal in boat construction. I had thought of something similar, except along the lines of a flattened ellipsoid for a boat. But, I think this would be a great design for a stationary seastead. I think you can do without the superstrcture, however.
I am thinking that the top can be mostly polycarbonate to allow sunlight into an agricultural area. That leaves the next deck down for living spaces, and the bottom for mechanicals, storage, and other functions. The curved top however does not make for a good water catchment system, which you don’t need if you are using something more high-tech to provide your peeps with potable water.
Also, you could drop a spar from the bottom and have a large disk at the end. That would provide some leveraged ballast and a motion dampening system to mitigate adverse wave action. then you will only need small thrusters to maintain you N-S orientation for communications and solar arrays.
Good work! Let us know how your investigations are going. It has been almost 2 years since your last post.
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