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Floating Breakwater feasibility

Home Forums Archive Structure Designs Floating Breakwater feasibility

This topic contains 39 replies, has 11 voices, and was last updated by Avatar of wohl1917 wohl1917 3 years, 7 months ago.

Viewing 15 posts - 1 through 15 (of 40 total)
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  • #1406

    Floating breakwater discussion is back again -

    Let me post a few thesis for discussion:

    1) Floating breakwaters in open ocean are possible.

    2) Connections between floating breakwaters in open ocean are possible.

    3) A breakwater lagoon is the most simple and cost effective way to allow a come together of ships, boats, houseboats, floating islands, in open sea.

    Is any of those points still in discussion? – why?

    ————————————————————————-

    Related topics for background info:

    Apply concrete shell seasteading – size of modules

    What kind of modules has been performed already

    Floating real estate development

    seaworthyness of concrete rafts

    Monaco harbor floating breakwater

    ————————————————————————-

    Wil

    concretesubmarine.com

    European Submarine Structures AB

    #12082
    Avatar of
    Anonymous

    It would make sense to have the breakwater generate electricity from wave energy while creating a calm lagoon for the boats.

    #12085

    ssteve wrote:

    It would make sense to have the breakwater generate electricity from wave energy while creating a calm lagoon for the boats.

    A field of pelamis wave generators would bring up a similar wave dampening effect as an ice field, a kelp field, or a mangrove jungle – althoug a “single unit” is not a impressive “breakwater” when standing allone, the accumulative effect of many of them is very impressive.

    On the other hand when we talk about a breakwater for a lagoon seastead we are talking probably about floating concrete breakwaters like those below protecting what is basicly a floating real estate development type floating marina.

    Wil

    concretesubmarine.com

    European Submarine Structures AB

    #12107
    Avatar of i_is_j_smith
    i_is_j_smith
    Participant

    1) Floating breakwaters in open ocean are possible.

    Again, as I said in the other post, there is an enormous difference between “possible” and “practical”.

    I am all for a breakwater design…I think a large breakwater surrounding the seastead is critical. But we haven’t seen any real-world examples of large floating breakwaters working in the depths that we will be looking at for seasteading (300m to 2000m).

    The issue, as I said before, is that anchoring a large breakwater in those depths might be prohibitively expensive…maybe even impossible. While anchoring TLPs or semi-subs in those depths is routine, their structure is designed to minimize interaction with the water and thus cuts down dramatically on drag and wave forces. A breakwater is designed to maximize interaction with the water so the forces acting on the anchor cables will be many times greater.

    A thorough meta-ocean analysis of the location of the breakwater will have to be done to calculate potential forces acting on the anchor lines. Wave action, currents, wind forces, etc must all be taken into account. It might turn out that the number of anchor lines needed, and the material required for those lines, would make anchoring unfeasible.

    That’s why I believe we need to focus on seamount areas first. Anchoring a floating breakwater in 300m of water is far easier and cheaper than doing so at 1300m.

    But anchoring a floating breakwater is not as simple as building a few wide barges and throwing a few anchors with chains over the side…

    #12108

    i_is_j_smith wrote:

    1) Floating breakwaters in open ocean are possible.

    Again, as I said in the other post, there is an enormous difference between “possible” and “practical”.

    I am all for a breakwater design…I think a large breakwater surrounding the seastead is critical. But we haven’t seen any real-world examples of large floating breakwaters working in the depths that we will be looking at for seasteading (300m to 2000m).

    The issue, as I said before, is that anchoring a large breakwater in those depths might be prohibitively expensive…maybe even impossible. While anchoring TLPs or semi-subs in those depths is routine, their structure is designed to minimize interaction with the water and thus cuts down dramatically on drag and wave forces. A breakwater is designed to maximize interaction with the water so the forces acting on the anchor cables will be many times greater.

    A thorough meta-ocean analysis of the location of the breakwater will have to be done to calculate potential forces acting on the anchor lines. Wave action, currents, wind forces, etc must all be taken into account. It might turn out that the number of anchor lines needed, and the material required for those lines, would make anchoring unfeasible.

    That’s why I believe we need to focus on seamount areas first. Anchoring a floating breakwater in 300m of water is far easier and cheaper than doing so at 1300m.

    But anchoring a floating breakwater is not as simple as building a few wide barges and throwing a few anchors with chains over the side…

    [/quote]

    I have to disagree.

    My experiences with anchoring large 90% submerged structures (as my prototype) in real world conditions point in exactly the oposite direction.

    The forces on the anchor rig are SURPRISINGLY low – much lower than they are for a structure of similar size that is floating high in the water like a ship or a boat.

    The idea that anchoring a breakwater is a more severe load case than a oil rig does not look very acertive to me and i can not confirm it in scaled down real world experiments.

    Oil rigs have narrow tolerances for movements in all directions. On the other hand breakwaters can be anchored with wide tolerances and flexible anchor rigs. Anchoring oil rigs in 2000m is already a standard operation.

    I would invite to rethink the idea of wave forces on the anchor rig – a anchor rig is forced by the waves mostly if designed wrong – (not flexible enough). I also would strongly invite to rethink the idea that the breakwater transforms the waves inherent energy into something the anchor has to hold.

    A breakwater should interact with waves to convert their engegy into something that cancels out mutally not into forces on the anchor rig.

    When doing too much “wave energy math” and insufficient field testing the order of magnitude of forces on the anchor rig can be estimated terribly wrong.

    I would suggest a couple of scaled down “bath tube” experiments measuring the real forces on the anchor chain while hooking different structures to it and compare the data.

    Looking for seamounts limits seasteading to places where no business is happening – it is economic suizide.

    Wil

    concretesubmarine.com

    European Submarine Structures AB

    #12110
    Avatar of Altaica
    Altaica
    Participant

    i_is_j_smith wrote:

    I am all for a breakwater design…I think a large breakwater surrounding the seastead is critical. But we haven’t seen any real-world examples of large floating breakwaters working in the depths that we will be looking at for seasteading (300m to 2000m).

    TLPs are PERMANENTLY anchored. Name one permenatly achored deep water(out other wise middle of no where) platform that doesn’t have a nationality?

    the only successful eastead I know of, Conch shell Island, isn’t even 5 miles off the coast of Gonâve Island

    i_is_j_smith wrote:
    The issue, as I said before, is that anchoring a large breakwater in those depths might be prohibitively expensive)

    The Republic of Minerva has shown that being hounders of miles off shore gives you no more advantage than beting just over the horizion. these is lots of shallow water 12 naughts off the coast it should be easy to find some that over the horizion from sea traffic.

    ouk emou alla tou logou akousantas homologein sophon estin hen

    #12111
    Avatar of Alan
    Alan
    Participant

    Seasteads will need power, so I rather like the idea of harnessing wave energy and providing power at the same time.

    How big a field of wave generators would we need to keep the area around the seastead reasonably calm?

    Would this provide less than the energy required for a seastead, roughly meet the requirements, or would it provide much more?

    If the last, would it make sense to use the power to separate hydrogen from water as a fuel source and ship it as an export?

    And, if the last, would it make more sense to anchor the seastead near the intended market, or to seek out high seas for maximum production, in some place with lots of waves like the Antarctic Ocean?

    #12118
    Avatar of Carl-Pålsson
    Carl-Pålsson
    Participant

    Wave energy does not seem very compatible with the preferred (mostly calm) state of the ocean in which to put a seastead.

    A breakwater has sort of the same problem. If you place your seastead where the sea is usually calm you will rarely need the breakwater. It could be cheaper to move the seastead out of the way when the rare storm hits, and spend the breakwater money on something more useful, like a second seastead.

    For very big seastead communities a breakwater might pay for itself, through scaling. Probably not for the pioneering seasteads though.

    Either way, if you try it, the breakwater should probably itself be a seastead. A ring of rectangular concrete barges with hinges on either end and the whole inside used as real estate is the obvious solution.

    Perhaps you could make the hinges between the segments hydraulically dampened – and run generators off the hydraulic fluid. Essentially a ring of Pelamis units that you live inside.

    But, I question whether such a scheme would make enough energy to pay for itself.

    I made some Sketchup images of such a thing and put them up on the Wiki a while back but I can’t find them right now.

    Most hydrogen today is made from oil, I believe, suggesting that electrolysis of water is too expensive. Schemes to make synthetic fuel from hydrogen and CO2 typically suggest using nuclear power because it is cheap and reliable. Also, with next-gen high temp reactors (1000 degrees C or so) splitting water becomes easier. Wave power is rather untested as far as economics goes, I think.

    How much energy does a seastead need?

    How long is a piece of string? :-) Will your seastead be full of manufacturing industry or some sort of eco-collective? Power needs could be pretty much between zero and infinity.

    #12119
    Avatar of i_is_j_smith
    i_is_j_smith
    Participant

    My experiences with anchoring large 90% submerged structures (as my prototype) in real world conditions point in exactly the oposite direction.

    The forces on the anchor rig are SURPRISINGLY low – much lower than they are for a structure of similar size that is floating high in the water like a ship or a boat.

    Of course the forces are low! The forces acting on the mooring system are due to wave drift forces. Since 90% of your structure is submerged it isn’t reflecting any wave energy thus the drift forces are minimized. Something floating high in the water, like a ship or TLP, reflects or absorbs a lot more wave energy thus is affected more by wave drift forces. TLPs try to minimize their exposure to the wave energy by presenting a minimum surface area to the waves, thus mooring them in depths of 1k to 2k is possible.

    A breakwater is the exact opposite of your submerged structure example. A breakwater not only sits high in the water, it maximizes the surface area exposed to the waves. Its entire purpose is to absorb or reflect a maximum amount of wave energy. Thus the forces acting on the mooring system will be many times greater than those of a TLP, and many many times greater than those of a submerged structure.

    The idea that anchoring a breakwater is a more severe load case than a oil rig does not look very acertive to me and i can not confirm it in scaled down real world experiments.

    It’s all about wave drift forces. There is no doubt what-so-ever that the wave drift forces acting on a structure that has a large waterplane area will be much larger than those acting on a structure with a small waterplane area. That is just physics, not opinion. Thus the larger the wave drift forces acting on the structure, the stronger the mooring system needs to be. The stronger the mooring system needs to be, the more expensive it will be.

    Oil rigs have narrow tolerances for movements in all directions. On the other hand breakwaters can be anchored with wide tolerances and flexible anchor rigs.

    It has nothing to do with the positional tolerances…it has to do with strength. Once the wave forces push the breakwater to the extent that its flexible anchor rig will allow it will continue to strain the lines. The anchoring system needs to be strong enough to handle the predicted maximum forces, and that is where the expense comes in.

    A breakwater should interact with waves to convert their engegy into something that cancels out mutally not into forces on the anchor rig.

    ANY interaction with waves is going to cause forces acting on the anchor rig. As soon as the wave hits the breakwater it imparts its energy to the structure. You can’t cancel out anything. You can only minimize the forces by minimizing the interaction with the waves, and a breakwater isn’t designed to do that.

    Read Eelco’s great blog entry on wave drift forces. He makes the point very well.

    Looking for seamounts limits seasteading to places where no business is happening – it is economic suizide.

    Sorry, but just like the first civilizations and cities formed around rivers and fertile areas…areas where it was easy to settle…the first seasteads will need to choose areas that are easy to build in. This means either an EEZ or a seamount.

    Now if your idea of a seastead is a cluster of smaller, mostly-or-fully-submerged single family structures then you have more flexibility. You might be able to anchor in extreme depths with a manageable cost.

    #12121
    Avatar of i_is_j_smith
    i_is_j_smith
    Participant

    Altaica wrote:

    TLPs are PERMANENTLY anchored. Name one permenatly achored deep water(out other wise middle of no where) platform that doesn’t have a nationality?

    What does nationality have to do with anything? I’m talking about whether it’s possible to moor a floating breakwater in very deep waters.

    Altaica wrote:

    The Republic of Minerva has shown that being hounders of miles off shore gives you no more advantage than beting just over the horizion. these is lots of shallow water 12 naughts off the coast it should be easy to find some that over the horizion from sea traffic.

    The Republic of Minerva was a publicity stunt. If he was really serious about the attempt he wouldn’t have left the place abandoned. A few people with cheap firearms could have easily defended the place from the Tongan thugs with sticks.

    There is a HUGE difference between 200nm and 12nm. The Minervans would have been well within their rights to defend themselves on the reef. They would have no such option if they were 12nm off the Tongan coast.

    It’s international waters or nothing…

    #12120
    Avatar of Melllvar
    Melllvar
    Participant

    Let me post a few thesis for discussion:

    1) Floating breakwaters in open ocean are possible.

    2) Connections between floating breakwaters in open ocean are possible.

    3) A breakwater lagoon is the most simple and cost effective way to allow a come together of ships, boats, houseboats, floating islands, in open sea.

    Is any of those points still in discussion? – why?

    Regarding actual breakwater feasibility, and ignoring the cost of the structure itself (which could be offset by making it dual purpose, as Carl suggested above), it really seems like a question of where anchoring technology is currently at, and where it will be anytime soon. If it requires being in shallow water, it isn’t really a solution for seasteading, just a temporary solution for certain situations. Dynamically positioning something that is both very massive and by definition meant to absorb wave energy is not very likely to be cheaper than anchoring (over the long run), even in the deepest of places.

    The only other alternative (to anchoring), which I can’t think of a way to do right off-hand, would be to not anchor it and simply let it get pushed around ad infinitum. Most likely that ends with it eventually crossing major shipping lanes or running aground, which probably won’t work. There might be some design to overcome that problem (particularly the running aground part, since if it functioned as some kind of rest stop/refueling platform for the shipping industry then crossing lanes might not be such a bad thing). One idea might be to use engines infrequently to switch from one system of currents to another, so that it cycles indefinitely, but that’s just a (questionable) idea for cost reduction rather than a reasonable solution.

    #12122
    Avatar of i_is_j_smith
    i_is_j_smith
    Participant

    What I’m trying to research is if there is any difference between the energy imparted on a breakwater that causes waves to break rather than just a solid flat structure that takes the full brunt of the wave force.

    My design for a breakwater is an angled ramp that causes the incoming waves to break, just like a beach. It’s possible that this will cause less horizontal force on the structure, and thus less force acting on the mooring system.

    If any engineers or physicists out there have any insights I’d be glad to hear them…

    #12125
    Avatar of Altaica
    Altaica
    Participant

    i_is_j_smith wrote:

    It’s international waters or nothing…

    My point exactly

    i_is_j_smith wrote:

    There is a HUGE difference between 200nm and 12nm. The Minervans would have been well within their rights to defend themselves on the reef. They would have no such option if they were 12nm off the Tongan coast.

    Make up your mind already. 12+ nm is just as much International Waters as 200+ nm so what is there “HUGE difference between” International Waters next to some State and International Waters way out in the middle of nowhere?

    ouk emou alla tou logou akousantas homologein sophon estin hen

    #12126

    i_is_j_smith wrote:

    What I’m trying to research is if there is any difference between the energy imparted on a breakwater that causes waves to break rather than just a solid flat structure that takes the full brunt of the wave force.

    My design for a breakwater is an angled ramp that causes the incoming waves to break, just like a beach. It’s possible that this will cause less horizontal force on the structure, and thus less force acting on the mooring system.

    If any engineers or physicists out there have any insights I’d be glad to hear them…

    I see from your post that you take for a given that in practice there is a tremendous horizontal force acting on a floating structure caused by the waves – i suggest you consult seamen instead of engineers or physicists on that behalf.

    I already commented when i read from elco that “the horizontal forces caused by waves on a structure can reach the magnitude of the structure weight” – if that is so – why i can not see any ship that has an anchor, anchor winch, anchor chain, which is desigend to hold forces of that magnitude.

    I will not dismiss that in THEORY this could happen (comet impact in mid pacific ocean, oil tanker surfing down the resulting tsunami) – what i try to point out is that in PRACTICE anchor rigs and moorings are designed for MUCH MUCH lower forces – and when i look at anchor rigs in practice i see that those apperaently underdimensioned anchor rigs (to hold structure weight) do work just fine to hold ships and other structures in place.

    Structures at drift (like icebergs) tend to follow the current and wind directions what indicates that those are the dominant horizontal forces. Waves just move the structure in small circles but leave it basicly on the same spot.

    This is consistent with the anchor rig designs you see everywhere – the anchor rig holds basicly against the forces of wind and current . (As long as you give enough chain).

    The idea of tremendous horizontal forces on structures at sea – introduced by waves that makes anchoring impossible is a seasteading.org forum myth – There are tremendous forces at work when lifting up a ship and put it down again – no doubt – but those forces deliver the structure on the same place where they took it up – so as long as your anchor rig is flexible NO component of that force needs to be hold by your anchor.

    Just look at the SIZE of those anchors compared to the size of the ship – do the designers expect them to hold the ship weight? – i doubt it. But they seem to work just fine in practice (they are only using the right anchor in this case – it is just working fine).

    Wil

    concretesubmarine.com

    European Submarine Structures AB

    #12128
    Avatar of i_is_j_smith
    i_is_j_smith
    Participant

    Altaica wrote:

    12+ nm is just as much International Waters as 200+ nm

    Totally incorrect. Even the image you supplied shows “International Waters” starting outside the 200nm EEZ. You cannot build a permanent installation inside another nation’s EEZ. You cannot harvest resources, such as fish or seabed minerals, inside another nation’s EEZ. All you can do is “pass through” on your way to somewhere else.

    The EEZ…and in many cases even the continental shelf…is NOT international waters. You have to be 200nm or even more before you can begin to claim any freedom of your own.

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