Structure designs open thread
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April 22, 2008 at 10:13 pm #1850
That also occured to me: a seastead might be a great way for nuclear scientists to do research. No way of selling to landlubbers though, barring the construction of 200 nautical mile power lines. It would be neat if it were in combination with power intensitive industry, like aluminium or something. We could copy the business model of iceland: cheap power in combination with a transportation hub.
Also, nuclear reactors are possible at the scale of submarines, so they are scalable enough. But thats on a military budget, which we do not have.
Considering that the seasted will need propulsion for pretty much its entire lifespan
I think the only two options for day to day operation are going with the flow or anchoring. Keeping engines of that size running on a permanent basis doesnt sound too attractive to me, financially.
Adding a propeller on a shaft through the spar and a rudder doesnt seem that complicated to me.
Then build us one id say. But if you would ask a professional naval drivetrain manufacturer, id say this situation is sufficiently far enough out of their box so that you wont get it even near the price of a series-produced tugboat with a similar engine. And one tugboats servicing a bunch of seasteads will ofcource get a proportionally higher utilization rate.April 22, 2008 at 11:36 pm #1851
Eelco, I guess everything depends on what stage in the evolution of seasteading we´re talking about. I admit that most of what I proposed won´t be feasible on the experimental/prototype/baystead stage. The situation changes quite a bit if we imagine a time in the future when seasteading has become more or less “mainstream”, with mass production of spar buoys complete with power, propulsion and all the basic facilites most ´steads will need. At that point adding propulsion units might be more economical over the life of the platform, adding all the costs, running and fixed together. Having the possibility to move easily and instantly without relying on external services seems in line with the idea of the dynamic geography, as far as I can tell, anyway. I can´t offer you any finished blueprints of a seasted propulsor unit, but here´s a couple of links anyway: http://en.wikipedia.org/wiki/Azipod http://en.wikipedia.org/wiki/Voith-Schneider I´m not sure those would be ideal for our structure, though. Perhaps one feasible way would be to use two electric motors rather like the Azipod (one on each side of the spar), but they wouldn´t need to be able to swivel. That could both rotate the seastead in place and drive it forwards and backwards. The Voith-Schneider device gives you the ability to move in any arbitrary direction regardless of your present orientation however, but it might need to sit below the counterweight which might give problems with tilting due to the offset between the center of gravity and the propulsive force.
This is Carl Pålsson after registering, FYI.April 23, 2008 at 12:26 am #1853
Thanks for the links and welcome!
Personally I feel that it would be nice if a Seastead could move around or at least stay in one place without using a tugboat. Mooring is extremely expensive so it’s probably not an option (unless in shallow waters of course). Mooring in the SF Bay makes a ship a “floating home”, may be if it keeps sailing we don’t have to pay rent? (see http://www.floatinghomes.org/dnload/fhrl.pdf for information on this).
If Seastead is outside territorial waters, it should not unintentionally drift towards land.
Btw, line breaks are inserted automatically? Just type real enters in the text.
JoepApril 23, 2008 at 2:29 am #1855
Another reason for needing precise maneuvering gear is if you need to move the seasted from within the middle of a grouping of other platforms. I seem to recall that this would be managed by lowering the moving platform so that it clears the superstructures of the neighbors and then navigating out “below” them, so to speak. Using tug boats pulling on ropes for such a critical maneuver appears difficult at best to me.
Thinking some more about possible placement of the propulsors I think they probably could sit below the counterweight /flotation cylinder. After all, the center of gravity would be situated somewhere in this region, if I understand things correctly. I guess in the end only testing will settle this. Anyone know if there has been any actual tests with models (poolstead etc), and where results from this can be found?
That PDF is a perfect example of why seasteads are needed in the first place :-).
I might have used the plain text editor last time, lets see if this will look better…
…nope, line breaks won´t play ball.
/CarlApril 23, 2008 at 7:16 am #1860
Regarding fossil fuels, I still think that Biodiesel brewed from algae http://www.unh.edu/p2/biodiesel/article_alge.html has alot of potential for a seastead, perhaps a solar still/furnace could provide the energy (“free” energy) required for processing.
But on the subject of “free” energy;
I recall seeing an interesting propulsion system many years ago, an inventor from a Norse nation (I cannot recall which one) had retrofitted a row boat with three outboard “dolphin” flippers on outriggers, one at the stern and one each at the sides just ahead of the midpoint. As the bout bobbed on the waves the (neutral bouyancy) flippers pivoted up and down creating forward thrust. Granted it was slow, but it was forward thrust.
I imagine that such flippers could be mounted, at the vertical fulcrum point (of the spar, so as not to “rock the boat”), on outriggers/downriggers attached to the floating dock (as mentioned in the book). Use a good ole rudder to steer and there you have it slow but free long distance propulsion. As long as you have any wave action you have a proportional forward thrust. I would still use manuvering thrusters for precision navigation (docking and the such), but given their limited use I think you could get away with smaller/weaker solar/wind charged electric motors for tight manuvering.
P.S. My line breaks, and html tags, won´t play ball either.April 23, 2008 at 9:28 am #1863
I dont expect to make use of dynamic geography very often, actually. The possibility of it should do most of the work to begin with.
I know mooring can get extremely expensive, but i think we can keep it managable, because there is just so much choice for locations. We can look for shelfs, so line lengths will stay managable. And we dont need exact positioning, like an oilrig for instance, so just one line would be fine, perhaps shared between a bunch of seasteads.
In its simplest form, all we need is a block of concrete/steel/whatever, lined to a buoy. We kick that off the tugboat in the desired location, no mechanism for reeling in or anything, and you can hook up a bunch of steads. That should be constructable at a cost << seastead. Youll need a new one every time you move, but i think it would be a minor cost compared to the whole moving operation even.
But anyway, were are not yet at a point to start ruling things out, we need to consider all options in more detail.April 24, 2008 at 6:45 pm #1868
The seastead is going to need some amount of station keeping capability to keep it at rest relative to its neighbors. It seems extremely likely that the station keeping task can be powered off of solar/wind/wave power. In addition, the propulsion system that is used for station keeping can also be used for spar relocation to another site. Since I expect relocation to be infrequent, I do not expect people to invest heavily high speed seastead self propulsion. They will either rent a tug or accept slow speed self propulsion. The decision will be an economic one.
-WayneApril 24, 2008 at 6:50 pm #1869
In general, I am a big fan of nuclear energy. The US Navy is largely nuclear and, hence, demonstrates that feasibility of nuclear at sea. However, access to nuclear technology is pretty constrained world wide. While it is possible to obtain uranium from ocean water, it has not been done on a commercial scale yet. If you can not get nuclear fuel, it is hard to go nuclear.
-WayneApril 24, 2008 at 7:20 pm #1870
It is extremely important that seastead be able to maintain a relative position with its neighbors. In addition, because there will likely be some solar panels on top of the seastead for daytime power collection, it is probably a requirement that the seastead not rotate while it is maintaining position. The reason for this is because the solar panels will probably have limited sun tracking capability.
While is is possible to do station keeping with three propellers spaced 120 degrees apart, we will probably opt for 4 propeller spaced 90 degrees apart. No swivel capability or rudder is required, the propellers can be fixed to the side of the seastead. This allows us to separately move the seastead in X and Y (i.e. East-West and North-South). In addition, the 4 propeller system is capable of twisting the seastead as well.
By the way, if you can find the [Input Format] and set it to [Full HTML], then this wacky forum system will insert paragraph tags around each line. The lines have to be entered without any carriage returns though. Anyhow, that I how I can get paragraphs to show up.
-WayneApril 24, 2008 at 9:07 pm #1872
Station keeping/transport: Wayne, 3 or 4 propellers does sound like a simple way of getting full movement in all directions plus rotation. You should be able to do everything with three though, including rotation. I assume you mean to put them on a 90 degree angle out from the structure? You´d lose efficiency when translating with three though, but that´s the only drawback I can see. Nuclear: How about just buying the fuel? Do you forsee political problems? Eelco, yes, the possibility to move will go a long way. But that option needs to be real, and not involve high risk and cost, such as using a tug boat to move a platform from in the middle of a complex of a hundred others without ruining everybody elses day. If there is a non-negligible risk of crashing into another platform, very few will risk doing it, and then dynamic geography will fail. But, like you say reality will settle this matter eventually regardless of our argument.
And, will someone for the love of all that is holy explain to me like I am a four year old how you create line breaks. I have read all your suggestions but I cant find the buttons to push or understand what you mean. Thank you.
-CarlApril 24, 2008 at 10:27 pm #1874
I thought some sort of rigid connection between neighboring steads’ was the preferred method of relative positioning? Anyway, since seacurents arnt not very variable, one buoy should give a rather stationary orientation to your seastead.
What about the powering you mentioned? I can see how solar would work, although its intermittent. But wind? That is going to have to involve rolling out of your bed, wether its a windmill or a sail. And what about waves? You mean some way of using the force of the waves directly, or through a generator? It might work great, but i personally feel we should stick with proven technology as much as possible for v1.0. You can always add features later, but if your prototype is a failure, that might just shatter the movement.April 24, 2008 at 11:25 pm #1875
Though going nuclear would be a nice and probably very efficient option, the advantage that you might get it from ocean water (provided we could afford the machines to get it and know how to do it) is very small. Any Seastead will never be autonomous, having to import lots of things (paper, eggs, clothing, concrete, whatever), so as it will have to import things anyway, importing the tiny amounts of uranium a Seastead would need shouldn’t be the problem.
The biggest problem would, however, be the usage of uranium itself. The loss in public support would be huge, neighbouring states will start accusing us of “helping terrorists ” or at least “endangering civilians”, the country whose flag we fly will start complaining, and the end of Seastead would be within weeks. (Using depleted uranium as balast would be in the same category).
JoepApril 24, 2008 at 11:30 pm #1876
The baseline for power is solar panels with battery storage. This is tried and true but not necessarily cheap.
The next level for experimentation is wind power. It is supposed to be the case that wind turbine coupled to a propeller captures enough energy to drive into the wind. It remains to be seen whether a wind turbine, connected to generator, connected to electric propellers are capable of overcoming the movement due to wind.
Wave power is very speculative.
-WayneApril 24, 2008 at 11:41 pm #1877
There is no technical reason why nuclear power wouldn’t work, but the political ramifications would be difficult. I doubt we will see any nuclear power generation on seasteads in the next 20 years, unless there is a serious technology break through (e.g. polywell fusion.) Given the long time frame for nuclear, I will tend to focus my energies on the more surefire solar/wind/wave technology. Even there, wind and wave power are not really surefire.
-WayneApril 25, 2008 at 5:30 am #1882
Regarding station keeping for the purpose of keeping the sloar panels aligned, it won’t be necessary if you use the amorphous thin film panels. The thin films currently have about half of the peak conversion efficiency as the crystaline panels, but since they can convert at any angle to the sun (and partially shaded, and partially damaged, and regardless of temperature) they have a much greater overall efficiency rate. The bottom line with the thin film solar panel is, if light touches it, it make electricity.
Also great strides are being made in vertical axis windmill generators, they seem to have a greater ability to self regulate in high winds, making them less damage prone.
And I still can’t seem to get paragraph breaks, what am I missing?
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