1. Skip to navigation
  2. Skip to content
  3. Skip to sidebar

size and shape of the seasteading platform

Home Forums Research Engineering size and shape of the seasteading platform

This topic contains 49 replies, has 8 voices, and was last updated by Profile photo of spark spark 9 months, 3 weeks ago.

Viewing 15 posts - 1 through 15 (of 50 total)
  • Author
  • #23112
    Profile photo of Alexei Konasehvich
    Alexei Konasehvich

    What is the minimum recommended size and shape of the seasteading platform in terms of safety and stability on the waves? is there any substantiated calculations?

    ss platform size


    Ramform Banff (FPSO) is used as stationary platform in the open sea with quite good empric outcome.
    It is 395ft long by 175ft wide. This seems to be the smallest package for the open sea in rough conditions like the North Sea. Of course in a protected bay a platform can be smaller.

    The Ramform Banff is a Floating Production, Storage and Offtake (FPSO) system purpose-designed to produce from Conoco’s 60 million barrel and 39 billion ft³ gas Banff field in the North Sea, 200km east of Aberdeen. At the same time, it provides flexibility to reconfigure processing packages, either to fit the changing needs of the reservoir, or to manage a new reservoir with different requirements.

    The vessel hull was fabricated at the Hyundai Mipo yard in Ulsan, South Korea and was the first use of the Ramform wedge-shaped hull design as a floating production system.


    The hull, which has a characteristic delta shape, provides both a large load bearing capacity (up to 16,000t) and a stable work platform. This delta-shaped hull form is more fuel efficient at speeds of about 15 knots than similar specification conventional vessels.

    The double hull design has a storage capacity of 120,000 (onboard) plus 500,000 barrels to be provided by a distant moored Floating Storage Unit (FSU) and later a shuttle tanker. The hull is 395ft long by 175ft wide. The vessel weighs around 10,000t, excluding topsides module and helideck. The load bearing capacity is 16,000t. The octagonal steel helicopter deck measures 22.2m by 22.2m and is suitable for EH101 type helicopters.

    For a protected bay you can certainly use a “pod size” like this…

    General rule : The platform size should be 2-3 times the wavelength in the area of operation or it will track the waves what makes live aboard VERY unpleasent.

    Only exception to that rule: Submerged living space can be movement free even on small scale in big wave ambients.

    Read more about the ramform floating base concept for seasteading in open water:
    Read more about the submerged living space bubble concept:
    Read more why ocean colonization is the next big thing to come:

    Profile photo of

    Ocean waves can have very long wavelengths, 300ft is common, even the largest aircraft carriers are unpleasant in them. If you design for a bay, you still should allow for hurricane surge and waves which can sweep over low islands and amount to 10 to 20ft, rolling even large boats over and carrying them 100’s of feet inland (we were discussing the “SY Legacy” earlier, google it). A hurricane a few years ago was monitored on the continental shelf over 60ft down, and the bottom scour uncovered oil pipelines that had been buried 6ft deep. The scour began as the eye went over and continued for days after the hurricane went inland. Plus in the usa the regs say a submerged vessel must have a boat above with a recovery crew (even one person) in it.
    I do not believe the common boat (ramform, submarine, cruiseliner, etc) is going to be adequate. Before i took my site for seasteading down, i had posted pics of the largest of military ships with bows underwater or damaged by waves, an aircraft carrier being rocked by another boat’s wake, and one of the Disney cruise ships with it’s bow completely underwater. I also showed barges rocking dramatically in fairly calm water, oil platforms leaning, and documents from people on the FLIP ship saying they got seasick when it was in it’s vertical spar position. I had posted pics of the newest and largest of container ships with cargo knocked down from transverse rolling action, even tho they were tolerably stable in head-on bow-to-stern waves. Some people like to mention the ramform hull, but i do not know why. It isn’t being considered any more, the planned sister ships to the Ramform Banff were all canceled.
    However, if you do not build in these ways known to be problematic, you will get a lot of grief from everyone. But i believe a non-conventional approach will succeed.

    Profile photo of OCEANOPOLIS


    I don’t think there is a certain “consensus” regarding seasteading “platforms” shape or size. It will definitely be based on the size of the “wallet” of whoever will build them. I personally draw the bottom line at 60′-70′ LOA (coastal seasteading) and over 200′ LOA and up for offshore seasteading.

    ellme’r Banff it’s a perfect “small sized” offshore capable ‘seasteading like platform”.


    As I always said, everything will rock & roll out there, for now. But size (and tonnage) matters. If somebody will build a 3000’ LOA seastead displacing millions of tons, than a category 3 hurricane will feel like a cool breeze on that one.

    Profile photo of

    Ocean said: “As I always said, everything will rock & roll out there, for now. But size (and tonnage) matters. If somebody will build a 3000′ LOA seastead displacing millions of tons, than a category 3 hurricane will feel like a cool breeze on that one.”, and i certainly agree with that statement. I am only concerned about how long it will hold together when battered by 20ft (and bigger) waves, keeping in mind the Draupner, like all waves, was a huge trough before and after the huge crest, so it’s not only about the crest water coming aboard, but the lack of support under the seastead as the troughs pass under. And studies show recently that the trough, if near to the underside of the vessel, has a huge vaccuum associated with it. Plus a seastead of millions of tons is unaffordable, you may as well take over part of New Zealand, or the Pitcairn islands, or a seamount somewhere.

    Profile photo of OCEANOPOLIS

    I think that for ANY size seastead, mobility is paramount. No captain will just “sit” there getting pounded by a storm, specially if it’s getting really ugly. You turn around and run to shelter waters full speed with a rolling sea behind you while hoping for the best.

    Sorry to disappoint, but that’s about it,…not to many choices out there.

    Profile photo of

    What you say is prudent. But a oil rig cannot do that. And for 60ft draftvessels, there’s not a lot of choice about where to put in and hide.
    The book i mentioned earlier gives a lot of history on concrete vessels, wharves, piers, tunnels, and other concrete and cement in the ocean. Their eventual point, i think, is it’s possible, and it’s even been done before, to construct in a way that seeking shelter isn’t required, even in a class 3 hurricane. One case i read a few pages back is a floating bridge several miles long, still in service, was damaged durng construction by 97mph winds and waves, but the damage was repaired, and in the 50+ years since it was built it has not been damaged. However, it is not a “traditional” vessel design. I suggest you read it, it may be useful history and insight into how you build your floating cement barges better or easier.


    Ocean, although the run away for shelter is a good strategy for a boat and even for a ship i would invite you to think about the underlaying idea that “seasteading” in its nature is “making a home at sea” the basic idea of a home is “shelter” so if you design a thing from the beginning that it is giving only a “limited shelter” to its occupants, what you design is not a “home” but a “camp”. So as long as the concept of “run away once a year” is part of the concept it falls short for being called a “seastead”. In fact the “stand all what comes” quality is one of the core factors that set a vessel apart from a home that gives you shelter. So solving the hostile climate problem is one of the cornerstones of the idea. Not solving it and declare run away part of the concept instead renders the concept somewhat pointless.
    I agree that a floating platform that can just sit there and take any storm in open sea, is quite hard to achive, it really needs to be a big platform compareable to Ramform Banff at least. So the only option to provide shelter in a family sized unit might be shell concepts like the bubble concept.
    Read more about the bubble concept:

    Profile photo of OCEANOPOLIS

    Everything is “limited shelter” when you are dealing with a Cat 4 or 5 hurricane. No mater what you call it or if it’s at sea, under water or on land.


    concrete shell after the mega storm
    Ocean, no doubth you have a point here – but for all practical purposes – this concrete shell is what stands after the houses and the trees have been destroyed…so there are differences in “tail event wortyness” and this matters…

    Profile photo of Alexei Konasehvich
    Alexei Konasehvich

    I tend to think about the need to choose the larget dimensions of the platform to avoid the need to run away from storms and waves. especially if ones intend to create more than one platform. But the city

    Profile photo of Alexei Konasehvich
    Alexei Konasehvich

    General rule : The platform size should be 2-3 times the wavelength in the area of operation or it will track the waves what makes live aboard VERY unpleasent.

    I was thinking about the same but decided that best rule is to take in account the biggest wave. not close to the shore waves (cos they can be even 85 meters – 279 ft in height) but in the middle of the ocean.

    I found that the biggest “rogue wave” http://en.wikipedia.org/wiki/Rogue_wave
    is 48 m (157 ft):

    “Fastnet Lighthouse Struck by 48 m (157 ft) wave in 1985 [28]”

    So steatead platform should be not less then 48 m (157 ft).
    But the more they are the more comfortable it will be. What is the recommended size? I’m not sure.

    Ellmer wrote: “2-3 times the wavelength”

    why length?

    is it 2-3 times length waves enough not to have seasick?

    if so then I suppose that 48 * 3 = 144 m (472 ft) is best recommended size.

    in addition the best form must strive to round form (we don’t assume to move so we don’t need a boat form), it means that 144 m (472 ft) should be size of length and width

    If length and width has some ratio aspect (3:4, 4:5 …) the short size shouldn’t be not less then 144 m (472 ft)

    What do you think?

    Profile photo of

    I suspect we can disregard the tall waves near shore, such as lighthouses and the Rockall islands. Any wave coming at them is being pushed taller by the bottom rising at the shore, much like a tsunami. A mass of water coming ashore has only one place to go, and that’s back to the ocean, compounding the effects of the next incoming wave.
    Much like the dangers on land are planned for to some degree or accepted to some degree, living on water is going to be a balancing act. I am not convinced that mass/weight or acres of deck space is the cure for bouncing in waves, simply because those things cost money, and whoever owns that huge vessel will control your life the same way any government on land will. You must also remember that any seastead will be built from things carried off from land, and if you are building a million ton seastead from something on land, someone on land is going to interfere.


    ellmers idea is good. That picture with that half sphere shows it. Each room of a city or a flat should be it an sphere or an half sphere.

    Unsinkable becomes an other meaning.


    rescue pod
    what is considered “safe at sea” (after all other structures and vessels have gone to hell) is obviously this. So i think the starting point for “safe living space at sea” should start here. Its key features: can be overwashed and impacted by waves, shelters for UV light, encloses the living space in form of a bubble. The curved walls give it a strenght that a “square house” would never have. It is no coincidence why bunkers and rescue pods are so similar designs.
    But before we enter in the “dark bunker discussion” again – see floating shells here: http://www.pinterest.com/wellmer/oceanic-concrete-shell-building/
    See land based honeycomb concrete shells here:

Viewing 15 posts - 1 through 15 (of 50 total)

The forum ‘Engineering’ is closed to new topics and replies.

Posted on at


Written by