DRP #4: Breakwaters
December 23, 2008 at 1:50 am #4539
I have come across a few references about air curtain or pneumatic breakwaters. In this technology, submerged pipes (the depth is dependent on our situation) eject a stream of air, forming a curtain of bubbles. This serves to “fluidize” the water, reducing its local density, and lowering its potential to transmit force, thereby making it a poorer medium for wave propagation. http://www.britannica.com/EBchecked/topic/254888/harbour/72119/Pneumatic-breakwaters
1) This is an active system, requiring constant expenditure of energy. It may perhaps be economical only when waves are of a certain strength.
2) Expanding on this topic, could explosives placed in the water at a distance from the seastead be considered as a last-ditch defence against a rogue wave or huge waves?? Or maybe bags of compressed air which are triggered at just the right moment to break up dangerous waves?December 23, 2008 at 12:16 pm #4543
Very interesting ! The article says it is really the upwards and outwards surface currents induced by the bubbles that counteract incoming waves, and that water jets should be just as efficient. Maybe a mechanical device harnessing wave power to create such jets would be worth a try ? And if that can be made into a purely passive mechanism, then maybe we’re just heading back to the rectangular caisson floating breakwater (which reflects incoming waves to cancel them out)…December 23, 2008 at 9:22 pm #4548
There is a lot of energy and momentum in a wave. If you are not absorbing that energy with a big heavy structure going up and down but trying to do something to it with bubbles, then it is going to take a lot of bubbles. The depth of waves is proportional to their length, not their height. So you really need to go down a ways to fully stop a wave. Pumping lots of air down 50 feet into the water all along the edge of your breakwater will take huge amounts of energy. Running 3 airconditioners on a tropical island got my electric bill to $2,000 US one month this summer (when diesel prices peeked on this island). The compressors for these AC units are tinny compared to what would be needed for this wall of bubbles. I am sure the total costs for a bubble breakwater over the life of a seastead would be far higher than other methods, if bubbles can even be made to work. So I really doubt this is of practical use for seasteaders.
– VinceDecember 24, 2008 at 2:07 am #4554
I was thinking more along the lines of a last defence against a big wave, combined with some sort of passive mechanism. Of course its not worth running at all times.
Extrapolating from this concept, what do you think about the use of explosives for rogue waves? Explosives are also after all a means of adding a lot of gas to the water… just letting my imagination run wild..December 24, 2008 at 2:13 am #4555
As Vince points out below, it’s going to be quite expensive to run…something to keep in the attic of our minds though. Maybe as a last line of defence??December 24, 2008 at 3:48 am #4556
“There really is no such thing as a rogue wave. These larger than normal seas are the result of two wave trains coinciding at just the right moment for their energy to combine. When this happens the higher-than-normal crest is exposed to more wind force and absorbs additional energy. And if the wave happens to be unstable and breaks – because the rotating particles within the wave can no longer make it over the top – there will be a large mass of water falling downhill.”
From "Surviving the Storm" by Steve & Linda Dashew, page 241.
A "confused sea" is when waves are coming from different directions and combining. When this happens an extra large wave can form right next to your boat. This is not a good place for gunpowder. In the video below I don't think a bunch of gunpowder next to the boat would have saved the boat. The easiest thing to do is make your boat bigger, or at least wider, like my WaterWalker proposal. A 100 foot wide WaterWalker would not have had any trouble with the wave in this video.
http://www.youtube.com/watch?v=swdyn713M-Q http://wiki.seasteading.org/index.php/User:Vincecate/WaterWalker http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0645928
Another thing about rogue waves is that they go away as suddenly as they form. Once the component waves are no longer on top of each other (maybe only 50 feet over) the rogue wave is gone. There really is no magic or mystery to rogue waves. No "conservation of energy" or "conservation of momentum" or other physical laws are injured in the forming of rogue waves. - VinceDecember 27, 2008 at 10:01 pm #4583
We are working on designs for several different points in the design space. We initially focused on a 200-guest seastead resort design, which is going to cost at least $50M (perhaps as much as $150M – five star resorts seem to be expensive). That is the design we are patenting and will soon be releasing along with models and engineering analysis.
Once that is wrapped up, in a month or two, we will be working on designs for single family seasteads, at costs in the $100K – $1M range, hoping to build a prototype (“StudioStead” or “BayStead”) late in 2009.December 27, 2008 at 10:12 pm #4584
I agree that each breakwater will have a single owner. What I meant was whether that owner functioned as a small coordinating authority allowing many different types of governments within it, or as a strong central government.
Agreed that a breakwater measured in wave heights rather than lengths will be much smaller and easier to build.
However, we should not commit ourselves to 50-million “communal” solutions until we are absolutely sure that a cheap one-family breakwater cannot be build.
I agree that one-family modularity is much more desirable, but economies of scale are real. Especially when it comes to a breakwater, I think we will need communal solutions to get those economies of scale.December 27, 2008 at 10:16 pm #4585
I think if you design a generation system cleverly the total cost might not be that much more than a passive wave break. Since it is by definition a very large structure the material cost is always going to be a substantial portion of it. And the tasks go together so well – we need to get rid of excess energy in the water – and we need to produce energy to use for general use – so it seems like a shame not to try.
That’s a good point. And your collector is a nice illustration of the point – adding collection channels and turbines can’t add that much to the cost of these giant concrete blocks.December 27, 2008 at 10:17 pm #4586
I’ve been assuming an incrementally expandable breakwater, where you open the circle and add additional segments.
I think expansion rather than attachment is the way to go, in order to get the 1/R economy of scale.December 27, 2008 at 10:21 pm #4587
I am a bit skeptical, I would think it would take an enormous quantity of bubbles, and thus lots of pipes and pumping costs, to break ocean waves.December 28, 2008 at 3:13 pm #4595
This is very interesting info that belongs on the front pageDecember 29, 2008 at 1:30 am #4597
Thank you for the extra information, Patri. I totally agree with Jesrad that the information is interesting. For those of us who seriously consider seasteading in the coming years it is very desirable to know as much as possible about your plans. It makes it much easier to start to plan how our personal preferences, our existing knowledge, and lives in general can best fit in with your plans.
More detailed knowledge of your plans will also make it much easier to give more detailed feedback to your ideas. And it will be more attractive to spend time improving elements of the design when one can learn the details of the design and therefore make informed judgements about which elements of the design are most in need of improvements.
When you are ready to share the information I would love to get an answer to the questions below (for a start )
> We are working on designs for several different points in the design space.
What is a “design space” and what does the sentence mean?
> We initially focused on a 200-guest seastead resort design, …
“focused” is past tense. Do you not focus on it anymore? If so, why not?
>That is the design we are patenting and will soon be releasing along with models and engineering analysis.
>Once that is wrapped up, in a month or two, …
Does that mean the patent application will be handed in “in a month or two” (instead of december 2008 as mentioned on http://www.seasteading.org/stay-in-touch/blog/3/2008/12/01/november-2008-snippets) and that the secrecy will have to continue till then?
> … we will be working on designs for single family seasteads, at costs in the $100K – $1M range, hoping to build a prototype (“StudioStead” or “BayStead”) late in 2009.
Are you talking about a 1:1 scale prototype?
Is the “200-guest seastead resort design” only a design at present or do you also have an investor and/or actual plans for when and where to locate the first resort seastead(s) and what kind of people do you imagine would use the(se) resort seastead(s)? Will it for example be suited for guests on short relaxation holidays and/or for long term residents in search of a society with better rules?December 29, 2008 at 8:35 pm #4599
Here’s a PDF from Dutch Company Van den Noort Innovations http://www.noort-innovations.nl/Dutch%20Floating%20Breakwaters%20&%20Floating%20Structure%20%20%20%20%20%20Technology.pdf showing a floating breakwater that is supposed to be a very cheap and effective solution.
The normal size is meant for waves up to 2 meters (7 ft) but it can be upgraded for waves up to 8 meters (30 ft). For normal weather, 100% reduction is achieved; in heavy weather 80 to 90%.
I’m not sure if it would achieve the same in High Seas conditions where waves do not come from a single direction.December 29, 2008 at 11:42 pm #4600
Very cool to find an off-the-shelf floating wavebreak that can handle 8 meter waves. Looks like those guys are for real. I think you could use those as sections for a tension circle marina. Would want some large “marine fenders” like they use for cruise ships or supertankers between the sections.
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Written by Wayne-Gramlich