Low cost seastead design requirements: feedback wanted
November 21, 2008 at 12:19 am #754
Hey all. Over the next few months, our engineering consultants are going to wrap up the big seastead design, and we’ll publish all of the details. Hopefully someone will develop a business plan around that design. The consultants will shift to working on small, low-cost designs which we could actually afford to build in the next year or two.
Here is a preliminary writeup of design requirements for low-cost seasteads. Comments here, or on the discussion page, would be appreciated.November 25, 2008 at 12:56 pm #4330
It sounds like a barge would meet the requirements, other than “not a boat”. The competition isn’t really cost or boats. The competition is the ocean. “Beating” the ocean and providing a safe place to live on it is not an easy thing to do. Ships have done it moderately well for centuries.
Barges should be less expensive than “boats” of equivalent displacement since they’re simpler.
Barges have the advantage of not having a driveshaft since they’re usually pushed around by tugboats. Any structure could have an external motor pod, or outboard motor, thus avoiding a shaft through the main hull. Either configuration has advantages and disadvantages.
Houseboats: what would it take to make an ocean-going houseboat? Houseboats are either monolithic hulls or pontoon boats with a big house/cabin on top. Both are arguably too low to the water for the ocean, even with high freeboard, so a catamaran is the next logical alternative.November 26, 2008 at 8:04 pm #4358
I general, I agree, a barge should do the trick. We probably want something that resists the waves a bit more, though.
We have a number design alternatives in the cooker — truss spar, Vince’s Windwalker, a SWATH/catamaran design. We’ll see what the pros and cons are.
In a world wide recession, used boats look mighty attractive too.January 27, 2009 at 7:47 am #4741
This may be daft, but why not build on top of the barge, treehouse style? Are barges liable to flipping? do they sink from taking on too much water? Because if not, then it seems easier to build 20′ high platforms on top of the barge’s metal floor rather than as a freestanding structure. If for no other reason than that the hull will absorb most of the wave’s energy and create the stability, so no long poles or rickety platforms are required. Plus, barges seem surprisingly cheap to buy. http://www.boatquest.com/Barge/1/allcategoryboats.aspx
The price may be a little high for a single family, but the square footage means that a small group of families, say 3, could live there comfortably. Plus the houses could be smaller as there is a field to use when there is no storm, so the house would be used for bathroom, sleeping, cooking and waiting out storms above the wave level. I don’t know, anyone else think that would work?
As for the document, why the need to withstand a 300 year storm? Assuming the ability to move and get the forecast, could the seastead not just move out of the way of anything that big? Also the article make no mention of sustainability. You can have a completely safe large platform that is pretty, but if it requires a constant inflow of external resources, it will never leave the coast.January 27, 2009 at 11:45 am #4742
Yes, barges can sink or flip. They’re like a big metal bowl. Fill a bowl with water or tilt it or splash water into it with big waves and it sinks.
The more mass above the center of gravity, the more likely anything floating is to flip. So putting something tall and/or heavy on top of a barge will only encourage it to roll over (flip) in winds or waves. Vertical spars do the opposite by lowering the center of gravity through putting ballast deep under water. It may be possible to counterbalance a tall structure built on a barge with a spar with ballast far below the surface, but at some point you run out of buouyancy. OTOH some barges are meant to carry very heavy stuff like bulk coal, gravel, sand, etc., so some may have quite a bit of buouyancy.
Another problem with a barge is that it more or less maximizes wave interaction since it has a large waterplane area. It’s pretty much maximal area right at the waterline.
A spar buoy is essentially the opposite design with minimal waterplane area, therefore minimizing wave interaction.
There are very many other possible designs aside from these two extremes.
Many houseboats are built on barges or something like a barge, but they’re meant for protected waters, have little freeboard, etc. There are open ocean barges, but the last thing one should do with one is to put a very tall structure on top of it.
An interesting book that summarizes research and knowledge up to fairly recently is Oceanography and Seamanship, Second Edition by WIlliam G. Van Dorn. It’s used as a textbook by an MIT ocean engineering class, and I found a used copy for about half price through Amazon Market. It includes chapters with overviews of ship design issues. Since it tries to cover so many areas, it can’t be too thorough, but may be a useful introduction into further study.January 28, 2009 at 1:23 am #4743
Aren’t many barges flat topped? In that case, no metal bowl. Alternatively, the bowl could be filled with pumice or some other space filling floating material. I know barges may not be ideal, but it just seems to be such a cost effective solution for the space available. I doubt you could even buy an equal amount of materials for the cost of one. If nothing else, it would work as a base around which to build a wavebreak. As far as top heaviness goes, just drop down a spar below the barge. I wouldn’t stop all motion, but it could counterbalance any buildings placed on top. Also, I have no references beyond a Make magazine article on them, but what about a wave break made from a scaled up phononic filter? As in like a faraday cage made from pipes to block waves greater than can be handled, except that the distance between the poles can be greater than the amplitude of the wave and still block the wave. Unfortunately, there seem to be few free resources on any filters of this type. Has anyone else heard of these?
Also, I googled the book. Pretty cheap. Do you know if there are any appreciable difference between the 1984 edition and the 1993 one? Because the 1984 one is on Half.com for 75 cents.January 28, 2009 at 4:17 am #4751
Also the article make no mention of sustainability. You can have a completely safe large platform that is pretty, but if it requires a constant inflow of external resources, it will never leave the coast.
All regions and countries of the world requires a continous inflow of external resources. This is just trade. Yes, it will cost more to ship goods to a lone platform out in the sea, but we are expecting this (the “ocean tax”).
On barges, one idea is to us them as flotation elements for something like Vince´s WaterWalker.February 1, 2009 at 11:12 pm #4795
The shape is different.A barge is rectangular,flat bottom,low freeboard.I designed a modular floating structure shaped as a kite(a quadrilateral polygon).The bottom is not flat but more like a v-hull(so it can be ballasted) and the freeboard is much higher than of a barge of similar lengh(for ocean going,thus wont take spay over the bow).Several kite shaped modules can be rafted up, not only to create a variaty of seastading shapes, but ad infinitum.As we speak I am working on a scale model of my project involving “kite modules”.I will post some pictures soon.Give me a buzz for more infos,Tavi.February 1, 2009 at 11:45 pm #4797
In the other topic I threw out the idea of using an extremely buoyant material like a hydrophobic aerogel and although that is completely impractical in the short term due to the expense, it relates to another hull design concept. The advantage a chunk of material like that has over a simple hull is that it cannot fill up with water and sink.
I think you can get a similar level of “unsinkability” just by using hull designs that are highly compartmentalized.April 6, 2009 at 6:21 pm #5450
The hull shall be built of steel-reinforced, kiln-expanded shale or micro-sphere embedded concrete constructed to current ACI standards to better prevent spalling of the steel sub-structure. The outside dimensions shall be 45ftx75ftx450ft. The interior shall be divided by 5 transverse bulkheads, 1 longitudinal bulkhead and 3 decks dividing the hull into 36 large water-tight compartment accessed by hatchways and manholes. Cover the deck with solar panels and windmills and at the watter line put a walkway and access stairs to main deck so that visitors have some place to tie up.May 9, 2009 at 3:47 pm #5916
In his book “Utopia or Oblivion: The Prospects for Humanity” proposed vertical-tetrahedral cities of vast proportions large enough to house a million people, 300,000 families each having balconied ‘outside’apartments of 2000 square feet each! He speculated that the foundation floats would be 200′ in depth and several hundreds of feet in width giving them enough draft to go below the turbulence level making them, in effect, floating tetrahedronal islands or triangular atolls. Obviously, only Macro-nation/states have the infrastructure or even the will to build something like that but the idea of it on a small scale could be made to work in sheltered waters like Pamlico Sound NC, Chesapeake Bay or San Francisco Bay etc.,. I propose that the pontoons be constructed as described above, only smaller (4.8x8x48) and sealed except for inspection ports, making them small enough to be built and trucked without special permits anywhere to anywhere to be assembled on-site. The ‘Community’ could be assembled and held together with electromagnets and repelled from each other the same way like Tom Swift did with his ‘Ocean Airport’…May 9, 2009 at 6:57 pm #5919
There’s your swath, Patri … and they’re trying to give it away!May 10, 2009 at 3:55 am #5924
Here we go again. OUR money @ work…..I want my dollar back. Oh,…wait is gonna become an exibit in Mr. Lennon museum,… wow, but wait,…there is more. Full size wax statues of the geniuses politicians who appropriated the funds will be featured on deck of the “stealth thing”. A photo opp. is available for only $ 20.99 a shot. One mil. here one mil. there (actually it was billion), pretty soon we are talking serious money. Hey, no worries, will print some more.May 10, 2009 at 10:27 am #5927
My sentiments exactly, Ocean.
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