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This document describes our goals, requirements, non-goals, and ideas for the conceptual design stage of engineering. It is a revision of our previous design criteria, described in User:Patri/ConceptualDesignProposal2008.

Please do not edit this unless you are TSI Staff. Feel free to add comments on the talk pages, though!


TSI's mission is to build permanent settlements on the ocean. Our current focus is on SeedStead - a seastead for 50 residents, with commercial space, to be built by 2015. The design should be able to scale up to a city of 20,000 (or at least have a good upgrade path). We don't yet know the depth, wind, & wave conditions - that will come out of our oceanographic research. In general, proposed locations include the Baltic, Mediterranean, and 200 nm off CA.



  1. Size. Target size is SeedStead - 50 people.
    1. Ideally, scale down well to BayStead.
    2. Must scale up, ideally to a city of 20,000.
  2. Safety. People survive in a bad storm. A 300-year storm may damage the structure so severely that it needs to be replaced. That is what insurance is for.
  3. Comfort. Platform movement/seasickness - People are relatively comfortable for 95%-98% of the time. The remaining 2%-5% they can be uncomfortable. They may need to relocate to the center buoyancy to avoid puking their guts out. Even then, some people will puke their guts out anyhow.
  4. Cost. Driving down costs is paramount. Comfort vs. cost trade-offs are permitted. Specifically, we'd like costs to be roughly comparable to an expensive first world house ($150 - $400 / ft^2). Less than that would be even better (comparable to a rural vacation home). Seasteads that can be purchased by individuals are extremely desirable. (Note: cost per ft^2 here is by interior space, not the footprint of the entire platform, so 3 decks of 1,000 ft^2 is 3,000 ft^2 of space) We will compare cost to ClubStead, and we'd like to get lower, definitely at its size, and ideally at SeedStead's size as well.
  5. Modular. Must be built in a modular fashion, so that it can be expanded incrementally and rearranged. It must include/support a SeedStead-sized module. It must support assembly at sea (perhaps only in calm conditions). Modularity is for several reasons:
    1. Primarily to let us start small and grow big, from 50-person SeedStead to 20,000-person city.
    2. But also to support dynamic geography. An individual section with its buildings should be able to be removed from the whole structure without enormous difficulty or cost.
  6. Cargo. We need to be able to transfer tourists and provisions in 90% of weather conditions. We hear this can be difficult out in the deep ocean. We need a solution of some sort.
  7. Anchored. We believe that anchoring makes life much easier and cheaper than dynamic positioning, and that the first seasteads should be anchored. Free-floating deep-ocean is for the far future.
  8. Draft. The structure must be constructed & deployed in a low-draft configuration so it can be built & launched from a shipyard on land. It can have deep draft when fully assembled/deployed, if such assembling can be done at sea. For large structures, this assembly can be hard to reverse or even permanent.


  • Different sizes play nice w/ each other.
  • Prototypeable at BayStead size.
  1. Standards. Should comply with as many marine safety and engineering standards as possible/practical (ABS Classification, IMO, SOLAS, etc).
  2. Mobile - We definitely need to be able to move units from land to the offshore settlement. Also the settlement itself may occasionally need to move, it's ok if this is very slow and moderately expensive.
  3. Draft. Ideally, deployed modules can be converted into low-draft configuration to return to harbor. Extra-ideally, modules have low-draft even in full deploy mode.


  1. Mobility. Options:
    1. No mobility - cluster & individual seasteads are not easily moveable.
    2. Individual mobility - individual seasteads can move, but the group cannot. ie Tugs
    3. Cluster mobility. Likely slow & expensive.


The ClubStead spar platform design is our basis for comparison, although the smaller size of SeedStead may mean that its costs per unit area are higher. But we'd like to beat it on cost and motions.


  1. Pretty. The resulting structure has to have some appeal that people would want to live in it. We want to avoid a prison cell floating in the middle of the ocean design. (NR b/c this is engineering design, we believe we can add prettiness to any skeleton)
  2. Self-sufficiency. We do not require self-sufficiency (ie enough area for growing all food.)
  3. Defense. This is not a fort that needs to defend against a determined navy. Fighting off pirates is important, but a real navy or air force can easily sink us.
  4. Green. We do not need to be carbon neutral.
  5. Construction at Sea. We prefer designs that can be constructed at sea, but do not expect that to be economical, so land based construction is OK for now. But ideally there would be a long-term path for construction at sea, once our sea-cities are big enough.

Specific Design Proposals