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Monaco floating concrete breakwater 163 thousand tons

Home Forums Archive Structure Designs Monaco floating concrete breakwater 163 thousand tons

This topic contains 17 replies, has 5 voices, and was last updated by Profile photo of ellmer - http://yook3.com ellmer – http://yook3.com 3 years, 9 months ago.

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    This project contains some seasteading relevant elements – a open ocean capeable breakwater built to create a save harbor for cruiseships, containing a connection piece to connect to land (or other breakwater elements) serving not only as breakwater but as parking garage for 400 cars, as shopping mall, and as floating base for a couple buildings. The piece actually made a international 1000 mile voyage from Algeciras to Monaco. Has a maintenance free service life of hundreds of years.

    So basicly there are ALL the elements present we need for a high road seastead in one single project.

    See a detailed video of the making and implementation of this project here (monaco floating breakwater)



    European Submarine Structures AB

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    Interesting find as always Ellmer.

    How do you keep it in place though (in deeper water)?

    edit: Ok, after watching the videos it looks like it could be made reasonably low drag and positioned with thrusters. Make the end more pointed and get rid of the “shelf” under water or at least the “stringers” (or whatever they are called) holding it up.

    It looked like it was quite low in the water though. I suppose it must be to be able to break the waves efficiently. But this might increase the drag and propulsion costs.

    You can’t use ten mooring lines in the deep ocean like they will do in Monaco. I doubt even one line will be cheaper than dynamic propulsion, if you do it right.

    I didn’t understand the cylindrical thing on the end of it. Some sort of ball joint?


    The joint at the end called “rotula” allows movements of 2 degrees it is kind of a ball joint with tension screws around it.

    Normal anchors with chain and cable, suction anchors and moorings, today are handled almost on a dayly base in waterdepth down to 2000m in the oil/gas industry. This was unthinkable just a few years ago but it is “state of the art” today. (history of deep water anchor handling)

    Those anchors are capeable to hold an oil rig or production platform in place allowing just a few meters of movement relative to the ocean bottom. The needs of a breakwater are by far less stringent. So i would say the problem of anchoring is solved already.

    The newest tendency is to replace the chain/cable by buoyant lines which takes chainweight out of the equation and allows anchoring in unlimited depths.

    Pipe laying ships like Solitaire have a capacity to lay pipes in ocean depth of 10.000 feet already. I would suggest a process that takes and combines elements from pipe laying and anchoring.

    Anchoring with polypropylene lines goes back to cousteau who was the first to see that if you want anchor extremly deep, you need a “floating line” or the weight of the chain (cable) itself will break it.

    Also the spooling of kilometeres of chain and cable that is under the tension of hundreds of tons is a monumental task – a task that modern anchor handling ships in the oil industry can handle already.

    For a seastead or a breakwater we will probably not even need those high grade anchor handling ships as the anchor requirements are far less stringent (no need to stay above a specific point within a few meters of tolerance)

    My suggestion is the following : get a plastic extruder mount it on the shore, start extruding a solid piece of tree trunk thick plastic (fiber enforced) and let it float out on the water. Keep extruding until you got a long flexible solid piece of plastic of 4 kilometer of length floating on the ocean surface. Now load a concrete anchor block on a ship, grab the end of the plastic trunk and pull the plastic piece to the anchor location behind your ship. Then connect the anchor block to the end of the plastic piece and toss the anchor block overboard – it goes down taking the end of the plastic trunk with it in a long curve to the bottom. The plastic has enough flexibility to form the 4km radius curve all the way to the bottom. You connect the seastead to the other end and enjoy a relative flexibe mooring, able to take tousands of tons of force, litte sensible to fatigue, ever lasting.

    To install it, you need no winch, no spooling, no big cost no high grade anchor handling ship. Just the cost of raw plastics and rent of an extruder and a small ship.

    You can alternate the sistem by doing a couple of pieces connecting them to a “chain” of a few segments.

    The basics is – when anchoring deep forget spooling and lines – go to long thin neutral floating flexible “anchor elements” instead.

    I assume that the oil/gas industry does not anchor that way because such a simplyfied rig would allow movements outside the few meters of tolerance zone they are working with – but for a seastead or a breakwater the simplyfied (chain free) version of a deep sea anchor would do the job just fine.



    European Submarine Structures AB

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    There is a big difference between mooring a tension-leg oil platform and a large breakwater.

    The TLP is designed to have a very low surface area in contact with the waves. The goal is to minimize the effect of the current and wave action, so that the force on the mooring lines and anchors is as low as possible. That’s why a lot of people favor spar designs…minimal surface area in contact with the water.

    A breakwater, on the other hand, is designed for the completely opposite purpose. It has an enormous surface area in contact with the waves, and the effects of the current and wave action on the structure are very large. The force acting on the mooring lines and anchor are going to be many times higher with a breakwater than with a TLP or other semi-submersible oil rig design.

    You are correct that none of this requires any new technology or leaps of engineering. Mooring a breakwater in thousands of meters of water is possible using current off-the-shelf products and techniques. I don’t think anyone doubts that.

    The issue is cost. Do you know how much a single suction anchor that is 30m high and 6.5m in diameter costs? And you will need many of them. Then add in the pre-installation site survey that is required…detailed analysis of the ocean floor where you will do the installation to determine the content of the seabed and suitability for anchoring. I’m sure that isn’t cheap. Then all the labor costs…this isn’t something you just hire off the street for. It requires highly skilled technicians and specialized equipment.

    I have been trying in vain for years to get a detailed cost analysis for a mooring system for a prototype seastead. I have been focusing on VLA systems, but suction anchors are fine too. This would be another great project for TSI to focus on, rather than worrying about business plans. But while the technology might be available that doesn’t mean that the cost won’t be prohibitive.

    Your idea of using an extruder is very interesting. I’d want to see what forces that “tree trunk thick plastic” line could handle, and what the costs would be.

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    Interesting idea with the extruder. I’m not sure why this would be easier than just buying some off-the shelf neutrally buoyant rope though. If you still need to buy fibers for reinforcement you could just buy the fibers in the form of a rope and use that directly.

    Anchoring is still rather inflexible compared to using propulsion. So it will need to be a lot cheaper over time. Ropes can break, anchors can be lost. Maybe you’ll need to move now and then. You might need to buy new lines and equipment then. Dynamic positioning has the potential to be made relatively free from continous expenses, by using solar power for example. Propulsion is entirely unaffected by depth. Park over the Challenger Deep if you like. We already know from sailing ships that you can use the wind to stay in about the same place pretty much indefinitely.

    We need some cost estimates for the various stay-in-place schemes.


    The reason why plastics is woven to ropes is to increase flexibility – if you think it trough this is a quality we do not need to buy as with a 2000m plastic piece the flexibility comes from the length. The price difference between a plastic piece and a woven rope is enormous.

    It is not that you need fibers in the plastic – it is just you might get insurance trouble with structural load bearing plastics due to the little compareable engineering. So a way to work around that is just embed a wire or cable inside the plastics and calculate the the plastics with cero load – so you would have a “normal anchor device” with a “buoyant mantle” around it. This is redundancy as plastic CAN hold the load but a engineer and insurance guy will be happier with a load bearing steel wire (cable) than a never seen before “plastic only” solution. So including the wire may in practice come more economic than leave it away.

    I can not see a economic dynamic positionioning sistem of any kind anywhere – no matter if solar or not – just check on the cost and maintenance of the mechanics/ electrics/ instalation cost/ for a azipod for a cruiseship – i also can not see a “economic sailing sistem” on the market for something that exceeds ship size. Some things that work well for a small yacht – do absolutly not work for a seastead just imagine taking down a 5000 squaremeter sail in a strom.

    Looks to me that all discussed “methods to avoid anchors” are orders of maginitude more expensive and complicated than to put anchors in deep sea.



    European Submarine Structures AB

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    You don’t need a full size azipod as you only need a top speed of perhaps a couple of knots. The same reasoning applies to the amount of solar panels needed. The energy you need to overcome drag is exponential to speed so the power demands drop rapidly when going slower than typical ship speeds.

    Sailing would be done with small rigid wing sails sort of like movable canards on an airplane. Because they are small you don’t need to take them down in a storm.

    This is my hypothesis at least! I’ve done some simple cost estimates in the past that didn’t discourage me. I was guessing about the exact drag figures of a slow-moving ship though. So some more data like that would be interesting.


    A interesting idea to use rigid wing sails. The most important factor would probably be that the wind attack surface of the structure is not much bigger than the surface area of the wings. Deeploading the structure would be a way to reduce wind attack surfaces and enable a structure to sail with relative small wings.

    For a boat that floats high on the water the required power to move against the wind is some 3 HP per ton of displacement. A deeploaded hull can bring the nose into the wind and move against it, with just 10 watt per ton of electric power. I tested that with my 20 ton prototype.

    Deeploaded Structure little wind attack surface low propulsion need. High floating structure big wind attack surface big propulsion need.

    Happens also that a whale needs 5 times less propulsion to move submerged than it needs on the surface (where wave resistance occurs).

    So go for a low profile deeploaded seastead would make particular sense when dynamic station keeping by solar power or wing sails is part of the plan. The power requirements for dynamic positioning for something like the freedom ship or clubstead are certainly a project dominating cost factor.



    European Submarine Structures AB

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    Good points about going against the wind, Ellmer. I suppose you will be doing this most of the time. With ocean currents perhaps only making minor contributions to the overall vector of your ship propulsion notwithstanding.

    I’m not sure I agree about your take on the scaling of dynamic propulsion with bigger vessels though. I think the per capita cost of propulsion power will decrease with size.

    I agree Clubstead would probably be a terrible design for dynamic propulsion. It is not at all designed with low drag in mind.

    I have this theory though, that all ships and/or seasteads will benefit from having a low drag design, even anchored ones as long as you can control the heading.


    Displacement: 100000t

    Total forward propulsion: 60MW

    For a top speed of: 22.6kt

    Using your figures of 3hp per ton we would expect to need 223MW just to move against the wind.

    Let’s do a very pessimistic linear calculation ignoring the exponential relationship between sped and drag:

    We’ll divide the speed with ten and get a speed of 2.2 knots. For this we’ll need 60MW divided by ten which is 6000KW.

    As it happens she takes 6000 passengers so that is 1kw per passenger. Most normal houses use more power than that.


    Carl, your point that the 3HP/ton figure will not scale up linear is probably correct.

    The question how much propulsion you need to get the nose into the wind and go against it also depends on the structure and its wind profile. A typical ship will orient the bow away from wind (parallel to waves) and needs a engine creating a force to keep it in the wind. I can think of designs that would orient automaticly with bow into the wind having much less propulsion need.

    The figure of 1kw per passenger looks like a real issue. If you see it in housing terms we are talking about a car engine running 24 hours a day to position a family – for most families the energy fuel and maintenance cost of a car engine that runs just a few hours a month (the typical family car) is a serious budget issue already.



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    Four kilowatt, that’s a car engine on idle perhaps.

    One kilowatt per person, four persons, 24 hours a day, 365 days a year = 35040 kilowatt-hours.

    Here in Stockholm Sweden, a ballpark electricity bill for a typical house (electrically heated) is perhaps a bit less, 20-30000 kwh per year or so. Now this is obviously more than houses in warmer climates consume. But the point is that it will not be extremely expensive (keeping in mind that we used a pessimistic estimate of the propulsive power needs). A DP seastead apartment will probably have a bigger electricity bill than the average apartment in some city, but you will by no means need to be a multi-millionaire.

    Of course there are many unknown variables. Exactly how much DP energy will you need in any given location? What is the cost of the competing anchoring system and how long does it last? How high is the economical penalty for being limited to areas with a maximum ocean depth?

    Balancing the nose against the wind should be easy with limited power as long as you won’t deviate too far towards either side (I have limited experience with driving big boats though so take this with a grain of salt). And if you do it is conceivable to have more power on tap temporarily to bring it back in line.

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    I am amazed how often we run to energy problems around here.
    1, We always need more energy.
    2, We are constantly being pounded with energy we didn’t ask for in the form of wind, waves, currents extreme temperature changes and relentless sunlight.
    Consider a field of small wave generators tethered to each other so that they encircle an area. Call it the wave attenuation zone. They would milk some of the energy out of the waves and convert it to a form we could make use of. Could they possibly generate enough to provide for their own position control? I don’t think I am trying to “sail into the wind” here, the waves are formed by action of the wind over a large area of water and all I am doing is using the motion of a small object bobbing up and down to generate electric current. The electronics to provide automated position control are cheap these days. If you connected them in groups with some semi-rigid strut only one positioning motor per group would be necessary
    Imagine units small enough for one man to lift into a boat and spaced about a half meter apart. Place enough units outside the breakwall and you can have several chances to get some free power and dampen the waves between the raw sea and the breakwall.
    Disadvantages: the whole thing would need to be reeled in before a big storm or found and untangled after one. Since they are all connected to one with a motor you could send them a radio command to “come inside”
    . The individual generators would have to be pretty maintenance free but wave generators with 1 moving part are possible.
    Some of the EM field would leak into the surrounding water and seacrete might want to form on the outside of the generators.
    What else have I overlooked?

    I am not sure if we can talk of a “big difference” between anchor a oil platform and a breakwater – especially i doubt that anchoring a oil/rig with its huge wind attack surface by the drill tower and its narrow movement tolerance is a “less severe anchor case” than a deeploaded breakwater – the wind and current attack surface is the major factor, the severeness of heave should count little at the end of a 2000m long anchor chain maybe this is a bit different for a tension leg suction anchor – but you can get the best of all worlds by having a long thin mooring buoy that works without much heave – and connect the breakwater then by a short chain to the buoy.

    What concerns cost of anchor handling in the oil industry i would expect some 80.000 USD per day for a high grade anchor handling ship. But for this you get a job done that holds a 200.000 ton structure in place at 2000m water depth. Add the cost of the anchor rig and you should have a global estimate. (Oil rig anchor chain for sale: here)

    The structure cost is US$560 million – for a 50.000 tons platform – so the anchor cost is not a big deal at the end compared to the other costs of building the structure, in general terms anchoring at 2000m will be in the range of a “few percent of the total project cost”.

    I agree totally on your statement that anchoring in deep sea for seastead sized structures is a mere routine operation handling “off the shelve” parts that needs no quantum leap in engineering of any kind.

    I also spot big savings possible compared to the oil/gas industry anchors as our anchor rigs can be A LOT less rigid which makes them much easier to deploy.



    European Submarine Structures AB


    Farmer wrote:
    Consider a field of small wave generators tethered to each other so that they encircle an area. Call it the wave attenuation zone. They would milk some of the energy out of the waves and convert it to a form we could make use of. Could they possibly generate enough to provide for their own position control? ….

    The energy needed for position control can be extremly low if your structure reduces the surfaces exposed to the wind.

    (part) submerged seasteads, or low profile plate seasteads, would be a solution…

    Sticking out a wingsail from a submarine yacht ( supported by the snorkel) works just fine – tested that. – Yes you can sail against the wind…and you can pull comfort electrics from using the propeller as stream generator.

    I assume that sticking out wingsails from the plate depression of a plate seastead would work similar – as long as the wing sail area is bigger than the dike wall wind attack surface.

    Dynamic station keeping at the end is not a question of feasibility it is most of all a question of economics. Seasteading as society relevant movement will not happen as long as housing costs at sea do not match the housing costs at land.

    So what we are searching for is ultra low cost, ultra low maintenance need, structures and solutions – this might exclude pretty much the dynamic position concept and limit seasteading to simplyfied and cost reduced anchor sistems. No matter how you put it dynamic positioning will always be orders of magnitude more expensive than anchoring.

    Energy generation can not be done without cost (even sailing costs a LOT if you include wear and tear into the calculation) – but anchoring once established is cost free.



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    I am surprised that there has not been much discussion on kites as a dynamic positioning system. They are more economical than sails on the scale needed for a seastead. One person (or computer) can easily control whatever size kite you want, as long as you are positioned in clean wind.

    The kites used in kiteboarding are very powerful and can easily launch a person into the air, or pull them very quickly across a surface. Even the 3.5 meter trainer kites can easily pull a person off the ground. If you are making figure eights you can also get some lift with only a 2 meter kite. Sorry, no video but I have done that myself.

    Kites are even being successfully tested on large ships to cut fuel costs.

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