Experimental small hexagonal platform

(Oleksii Konashevych) #1

I have an idea of a small experimental hexagonal platform of 166 sq.m / 1 786 sq.ft.
Preliminary calculations show that the construction of this platform costs 50,000 - 75,000 USD, including unexpected expenses.
This price seems reasonable. It is calculated by current prices of Odessa shipyard (Ukraine). I think the construction such a platform in China might cost even less.

The idea is to create a small “village” of 10-100 of such platforms.
I have also thought that if create a “mother” platform that will be a floating construction yard for such platforms to build these offshore, that could provide the experiment for unprecedented experience and the vision of future bigger concepts.

The costs might be reasonable comparing to 50 by 50 meters platforms that cost 15 mln USD (according to The Floating City Project 2014, p.25)

materials: concrete, steel, polyurethane foam or expanded polystyrene or similar

Landluber's Guide to Seasteading Feasibility
Hexagon Pontoon design and cost estimate

IMHO, these might work for protected waters, under other than stormy conditions. Similar ideas have been proposed in this forum, and in the original forum.

(Chad Elwartowski) #3

That is definitely an option. As we are now focusing on protected waters such platforms will be common and can certainly be done for less than the $50 million price projected by TSI.

I think the idea of building structures from the platforms is a worthy goal for all of us as that will be revenue going into the community, the only outgoing revenue will be for the materials at that point.

Building in Ukraine is an interesting approach and I have considered Eastern Europe due to their cheap labor. But you may want to consider the possibility that French Polynesia will likely be the starting point for a seastead community. China or a coastal Asian nation might be better if considering that approach. A prototype anywhere would be good as well.

(Chris Smedley) #4

Olksii, we are looking at a similar hexagonal platform for our seasteading designs.

Send me a private message and lets discuss how to commercialize this.

Chris Smedley, @ Digital Habitats.

(Jake Rosoman) #5

There is a well written patent for a similar design but it leaves of the bottom. Turns out you don’t need to put a bottom on it since the walls will trap the air inside. This lowers the cost of production and actually provides a form of dynamic stabilisation since as a wave travels underneath the structure the air is able to move to the opposite side meaning the air pressure will remain even throughout the underside of the platform. So it won’t tip as it rides the waves. It will just go up slightly while there is a crest of a wave underneath it and down slightly while in a trough.

In another one of that guys patents he mentions the idea of putting a sump in the platform to provide space for a tree’s roots to grow down. Or any large heavy thing like a septic tank. As long as you fill the sump with something roughly as dense as water it won’t have much effect of the buoyancy of the platform which is neat. A sump made out of glass would make a pretty sweet spa pool especially if you were able to grow a reef on the underside of your platform.

(Theodore M. Amenta) #6

This is brilliant if correct — I am not competent on this topic, — I hope you are correct. The proposed cost of the platforms is not feasible — Your insight might be of huge help. I have drawn a small “pilot” project shared with Randy and Joe — I will share shortly. Ted

(Jake Rosoman) #7

The style of platform proposed here can be produced much cheaper than @konashevich estimated. With roughly 50tons of concrete required I’d expect the cost to be about an order of magnitude less than he estimated.

(Theodore M. Amenta) #8

Jake: I have so much to share! Understand I have already share this information with Seasteading Institute (Randy & Joe) ----(I am not an engineer. I am an architect.) I have come to accept that the optimum size of the platform is 50m x 50m — 250m2. It can be of many configurations. Since the edge is more expensive to construct than the body – the triangle is inferior and the polygon is superior. Please assume for this exchange that I am correct on size and number of edges. This is not the critical issue! The platform “displacement” must be correlated to the built-world to be supported (on top). Seasteading has not released any update of this topic since the DeltaSync work which is flawed in my view — I encourage DeltaSync to correct me. I have provided multiple updates myself. The DeltaSync platform has a “draft” of 16.5 feet. This equates to a displacement of 1,056 pounds per square foot. I calculate the imposed live and deal load for the three level buildings described as possibly 25% to 35% of this. ---- So I conclude the platform is “over designed.” Thus the contemplated “cost” of the platform is not correct — over priced by possibly 50% — In the absence of interaction with Seasteading Institute — (do not respond) — I have reduced the platform cost by 25%. – Keep it up! ted

(Larry G) #9

Place the “bottom” (deck) in the middle of the upright walls and kill two birds (buoyancy and internal space) for the weight penalty of one deck and greatly eliminate the complexity of design and construction implied by the internal structure shown above here. Similar to the linked patent design, but the vertical cross-section would look like an “H” in a cut-away drawing. Internal buttresses coul dbe added to the H design to provide structural strength between the walls and deck.

The displacement under the deck can still be EPS. If the walls extend above the deck (bulwark) and below the water line (hull) then you get a starting place for building out living and working space.

You could even deliberately scuttle for stability in shallow enough locations, using the below-waterline hull walls as legs. Could possibly design for initial towing to final placement as a gravity structure. Enclosing the bulwarks above the waterline allows for in-filling as a true artificial island, if you abandon the floating requirement.

(Larry G) #11

A tool for thinking about hexagons:


(Larry G) #13

Why live in the ocean?
(.) #14

I was considering octagons, but hexagons seem better.
I guess it is sacred geometry.

(Larry G) #15

Octagons might have better structural integrity from smaller spans of straight wall. But more corners equal more cost of construction. I figure evolution has things figured out pretty well and bees use hexagons.

I guess somewhere in there between squares-> hexagon -> octagon there is a sweet spot of reasonable structural integrity, reasonable cost of construction, reasonable solution for connecting/expanding, and reasonable livable utility. Probably won’t max out any dimension of those qualities without serious compromise on the others.

The specifics on the hex uses (residence, mixed-use, marina) above is only notional as a point of discussion.

(.) #16

My ideas are difficult to picture, even for me.
The three dimensional design is not easy for me, and I guess it is same for others.

Long hexagonal tubes with a geodesic half sphere on the top.
It would be like the flip ship. Vertically positioned hexagonal tubes could be connected
by their side. The connection would form a structure. That could be ballasted up and down.
The spheres would be wave resistant like those fishing net balls.
I would arrange the hexagons in a circular shape. Ballasting down would open waterways
to the enclosed area. Putting more hexagons around the circle would stagger the domes.
Waves would break gradually, not at once. Hexagonal tubes could be individually made in
vertical position like the Rion-Antirion bridge pillars, and could be transported in vertical
position to assembly. Large flat surfaces of the hexagonal wall under water would give the
possibility of strong connection. It would be modular, and more circles could be added.
There could be horizontal hight difference of the hexagonal tubes. The inner circles would be
higher. Each outer circle would be lower to make wave breaking gradual.
The geodesic dome would be slightly smalled diameter than the hexagon.
I would consider concrete and biorock and the combination of the two. I would consider
biorock formation out of seawater with help of electrodes and solar electricity between hexagons.
This way the structure would grow stronger with time.

my 2 cents


(.) #17

Just guessing out of nowhere: octagons cannot be put together in any shape to form a
continuous structure, as hexagons can be.

(Larry G) #18


A flat plate floor system is a two-way concrete slab supported directly on columns with reinforcement in two orthogonal directions (Figure 1a). Primarily used in hotels, multi-family residential buildings, and hospitals, this system has the advantages of simple construction and formwork and a flat ceiling, the latter of which reduces ceiling finishing costs, since the architectural finish can be applied directly to the underside of the slab. Even more significant are the cost savings associated with the low-story heights made possible by
the shallow floor system. Smaller vertical runs of cladding, partition walls, mechanical systems, plumbing, and a large number of other items of construction translate to large cost savings, especially for medium and high-rise buildings. Moreover, where the total height of a building is restricted, using a flat plate will result in more stories accommodated within the set height.

The thickness of a flat plate is controlled by the deflection requirements given in Sect. 9.5.3 of ACI 318-05. Minimum slab thicknesses for flat plates with Grade 60 reinforcing bars, based on ACI 9.5.3, are summarized in Figure 2 as a function of the longest clear span between supports.

Flat plate systems are economically viable for short to medium spans and for moderate live loads. Up to live loads of about 50 psf, the deflection criteria usually govern, and the economical span length range is 15 ft to 25 ft. For live loads of 100 psf or more, punching shear stresses at the columns and bending moments in the slab control the design. For these cases, the flat plate is economical for spans between 15 ft and 20 ft. A flat plate floor with a live load of 100 psf is only about 8% more expensive than one with a live load of 50 psf, primarily due to the minimum thickness requirements for deflection. Floor panels with an aspect ratio of 2 would be about 30% more expensive than panels with an aspect ratio of 1; the thickness of the rectangular panel is governed by the greater span length, resulting in a loss of economy.

On average, the formwork costs for flat plates represent approximately 46% of the total floor cost. Concrete material, placing, and finishing account for about 36% of the cost. The remaining 18% is the material and placing cost of the mild reinforcement.

Bottom line: 8 meter (24 ft) sides on hexagons greatly reduces complexity and cost of building the deck, going bigger probably needs a waffle joist built into the deck, which means very complex forms and more expertise.

(Larry G) #19


(.) #20

Thank you. That is exactly what I meant.

(.) #21

Although, it might not need to be continuous.

(Oleksii Konashevych) #22

There are a couple of weaknesses here because of the strong lever.