Breakwater Design

(Larry G) #243

I have a library of such things that I have paid for. It’s by no means satisfactory in itself (and the internet is a great resource but has its own problems of sorting and storing and indexing). I have limited means of sharing my resources, despite a willing attitude.

What is the point of TSI? Is it not to share knowledge resources in order to encourage actual construction attempts? Or is it simply to make a noise in the media?


Make noise, and spend donations. IF there was anything SERIOUS behind TSI, otherwise, there would have been the purchase and development of incubator sites, from Thiel’s generous contribution. Since TSI has NO real-world property, they have no intention of building, at least with donated funds, regardless of the intent of the donors. Sell books, make noise, take expensive vacations. THAT is the purpose behind TSI, as opposed to my Gulfsteading site. I plan to be purchasing land and having a potential incubator site, at the very least for my constructs, regardless if anyone joins me, or not.

(Matias Volco) #245

What breakwater questions do you attemp to answer?
We already know breakwaters as they are constitute a macro economic investment.


Robert I think this has been done. If you look at the TSI Link and look at the original Seasteading plan created by DeltaSync. It’s about 65 pages and has many good ideas. It’s what got me interested in the first place.

I did the math, used their notes to make a though experiment. For different reasons, I wrote my little fiction book about libertarian politics “Liberty Awash”. And I was roughly 2/3 of the way through writing it when I realized DeltaSync was full of Banther Fodder.

The size and weight of their caisson design; 18" thick, 50m by 50m would not float like they picture in their study. The actual weight of the caisson would have water washing over the top in even the slightest waves. I tried playing with their design, imagining super-dense concrete that could withstand water pressure at a 9" thickness, and 4" ribbing. The resulting design could withstand a 10’ wave, but not more. Anything taller would wash the buildings off the top.

My view is that engineering has been done, and I presume paid for, and the result did not help. A better position is for TSI to be an idea generator. Let entrepreneurs drive the engineering issues. The idea of seasteading from an engineering standpoint is not practical (see images and discussion above). The idea on which it is based, to create a zone free from international interference, is not legally feasible (see Spratley Islands). Finally, the idea of libertarians living together in peace is downright silly (See Grafton, Free State project, Burning Man, and Sarah Palin.)

So we are here to discuss pretty looking and impractical ideas.

(Larry G) #247

I had a fanciful thought today. I’ve started reading about the caisson breakwaters used for the Normandy invasion (Mulberry Harbors for any who are interested).

Up to this point, I’ve had little inspiration in the realm of floating breakwaters. To be effective they have to be massive, to be massive enough, they are beyond the financial reach of anything much less than a city-state like Monaco or Dubai.

On another thread I was looking at freshwater storage/ballast.buoyancy issues, and placement of such to avoid loading issues when water is being used too quickly to replenish.

I had the thought: what if the mass of a floating breakwater were provided by freshwater, while the rigidity were provided by concrete. Fresh water is about 3.5% less dense than seawater (varies a bit with location and temperature, but call it 25-35 Kg difference per cubic meter.) If you built a big enough concrete enclosure filled with freshwater, you could provide enough buoyancy to float the weight of the concrete, while still having a large mass. and a resource that is serving a secondary purpose.

I know this has been considered using bags of freshwater on the surface, but two problems with that: first, the flexible polymer bags tend to degrade in sunlight rather quickly. Second a bag of water floating in water is not de-coupled from the wave action, it just transmits the wave to the other side. A rigid structure decouples the mass inside, and to a degree, the mass of water on the leeward side, from the wave form.

You still have to have a pretty massive structure to benefit from the minimal buoyancy of the fresh water in sea water. You still need a fairly large structure to have a size/depth/wave height ratio that effectively de-couples from the larger wave form. The engineering for making such a large, relatively flimsy structure rigid and durable may not work. But it’s an idea I hadn’t seen explored before.

(Matias Volco) #248

Yes, these last months it appears everyone is reaching the same conclusions from different paths or saying it in slightly different ways.
You may fill the breakwater with air or oil for that matter and make the concrete thin and buoyant itself.


@thebastige - Consider this: For a floating breakwater, what’s the difference between a concrete breakwater 90% below the surface, and a coated Styrofoam breakwater 90% above the surface?

I don’t really have a definitive answer. But I think this starts getting to the question; what is a breakwater for? Is it shelter from wind? Wind waves? Ocean swells? Tsunamis?

A related question - why not have living space on the breakwater?

(Larry G) #250

In a word, effectiveness. Even heavy boats get waked in the marina. Stuff that is buoyant and primarily above water doesn’t do much to gentle waves, it just floats on top of them. It has to affect a majority of the wave height to do that. So to be effective it’s going to have to extend both above and below mean water level to some degree.

No, that would be a wind break. Which might be worthwhile but is an entirely different requirement.

The question comes down to how much parasitic space can be tolerated after the primary purpose of the structure is achieved. In a boat, you have a certain amount of space in the hull. Obviously, the more heavy stuff you load it with, the less buoyant it is. Living space is primarily empty to allow movement, so it does double duty as buoyancy pretty easily. It doesn’t do much for mass-based wave damping.

(Matias Volco) #251

Living space, warehouse space, liquid storage space, contained inside honeycomb floating structure


Another issue with the comparison of the 90% above vs 90% below the surface is structure and buoyancy. Think iceberg… The bigger it is, the more stable it beces, but the bulk is below the water-line, due to the nature of materials. In order to lift that mass higher, you need more structure, more buoyancy and it grows emormous quickly, to do so. Size rapidly increases costs and cost-effectiveness.


This would make sense for a fixed breakwater. But for a floating breakwater, doesn’t increased mass increase the likelihood of damage to the contained vessels?

The Condomine Port Extension (pictured above) is fixed to shore on one end, and tied down tight at the other end. It is my recollection that it does NOT go up and down with tides. So it is “floating” only in that it is a semi-bouyant structure that is fixed into place.

To truly have a floating breakwater, I think you would need to rethink mass in conjunction with wave dynamics. Waves hit hardest just below the surface. If you sit above the surface you avoid the main force of the wave, but you don’t shelter boats inside well. If you sit more than 50 feet below the surface, waves will not affect you much. But that top 50 feet is where all the action is, combined with the weight of the water.

I still keep coming back to “floating breakwater” is a solution that is looking for a problem. Why does a floating city need a breakwater at all? For instance - floating near French Polynesia. As I recall in that location the dropoff is so steep, that if you docked your city 1 mile offshore you would need 0.5 mile anchor cables. You have to dock outside the dropoff to avoid damaging coral beds.

(Larry G) #254

So it’s a tension leg platform, which is what prevents it from rising with tides/waves. The tension works against buoyancy, so it can’t rise as natural, and it’s deep enough to not sink when the tide’s out because it was already submerged further than natural buoyancy would allow.

It’s definitely floating, either way.

Multiple things to solve for. The force of the wave only matters if it’s hitting something that resists the force of the wave. A tiny piece of styrofoam floating on top of the wave experiences little destructive force, but it does experience drastic movement and abrupt acceleration, neither of these are particularly desirable in a living platform. So it’s not just that the platform doesn’t shelter a boat well (doesn’t damp the wave form), it’s also not useful for living on- furniture has to be bolted down, Dramamine must be consumed, place settings at the dinner table migrate to the floor, and anything with a long moment arm needs to be braced so as not to snap off when abruptly accelerated in the opposite direction.

If you have a massive object, inertia exerts resistance to the movement of the wave, and therefore the object must also be sturdy enough to take a pounding and damp the energy of the wave. One can have massive but fragile objects that would be easily broken when the weight of the water exceeds tolerance, OR when the wave causes it to sag or hog.

You can have something that is massive and flexible, but then it is not de-coupled from the wave form and may transmit the wave through the object and therefore damps the wave less effectively.

The size of the object for any passive breakwater measure is inevitably going to be related to the size of the wave in order to be effective.

(Matias Volco) #255

My earlier post attempted to answer that question. It’s not an issue.

Then you guys began discussing the mooring of the floating breakwater of Monaco. This brings to mind that the most expensive and technically complicated aspect of that project was the joint attachment to the continent, to incorporate the floating building seamlessly to the rest of the city. This extra cost and complication would not exist in an offshore city.


What about seaweed? The sargasso sea acts as a breakwater. So mass - when light individual objects distributed over a broad area - can act to dampen waves.

A breakwater that costs $500 per square foot is not tenable for a city where housing is $200 per square foot. It’s in the DeltaSync report that their pictured breakwater exceeds the city cost by 4 times (my recollection). This is why a floating breakwater will never be built.

Moving beyond breakwaters is solving the problems they solve, without the mass and cost.

For one, the city itself will act like a sargasso breakwater if the pieces are numerous and light. Yeah, the ride will be rough for folks on the edges. That’s why it’s the low-rent district. But if people can sleep on a 30 foot sailboat, then they can sleep in a 30 foot platform at the edge of a floating city. Also, platform edge design could be such as to break the waves using planar or pointy modeling at the water level.

A lot of this is location based. The location I favor for planning is near STI’s new friends in French Polynesia. On the equator there are no hurricanes, wind and current are steady. Prevailing seas run 1-meter to 3-meters. So the ocean is relatively calm. The other locale in my book, the one pictured in the DeltaSync report, is the Gulf of Fonseca. There’s no need for a breakwater in the gulf.

(Wilfried Ellmer) #257

The key is to aim for solutions where the walls that are the real estate of the city are the bow and the breakwater too in a double funktion - we call that a “ramform city design”.

One deployment of building material 3 functions achieved

• housing space
• bow splitting the waves (instead of breaking)
• seawall behind a bow leading the “rest of the wave” smoothly far from the city without “fighting and breaking” it (what is expensive and creates brute impact forces hard to control ).

That is the genius of @Matias design approach… (ramform on turett mooring)

That this is the best and most feasible way was already clear when this picture was created …

…so there is not really a ongoing debate among knowledgeable marine engineers about the design principles of a floating ocean base…they are cristal clear for at least a century.

It would be nice if the thread participants would finally decide to ABSORB this simple piece of marine design knowledge instead of “debating so much about it”…

It is a bit unsettling for knowledgeable people to hear so much debate on that kind of “basic issue”… learning (from @Matias who is spoonfeeding the relevant info for years now) is probably more indicated than “debating” on this…another 255 pages…


Specifically, YOU call it a ‘Ramform City’, despite the fact that the design meets none of the design criteria to be a Ramform vessel.

(Matias Volco) #259

I call it Ramform City, not vessel. Yes spoonfeeding is accurate.


Then perhaps you need to be spoonfed that “Ramform” is a trade marked name for a specific hull design, from Roar Ramde’s name, once again…

You BOTH tend to assail me, abusing that term, in a tag-team effort, for defending the legallity of using Ramform, but consider if YOU had the TM on, say Volcoform, or Elmerform, for instance, and only 10-15 such vessels existed, and people called anything they wanted to, by your term, but nonody defended you and your legal claims, while knowingly and wilfully misusing it…

(Matias Volco) #261

legal claims? are you kidding me. There is a difference between a technical nickname and a brand.
I hope everybody realises that this is Jeff’s way of admitting he was skeptical about the ramform base for years and then he adopted it as his own (inspired by the ram-shape WHY yacht), thus helping the consensus that a triangular platform with a bow is a good idea for seaworthy surface bases. This was already the consensus a few decades ago when dhingies were outfitted with outboarder motors but it’s always good to have reassurance.


Interesting footage of a breakwater (non-floating) doing it’s job in Taiwan this week.

First 40 seconds of this video 0:00-0:40 or so