Research Update: TSI Engineering Assessment Report (part 1) released

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Thanks to Eelco Hoogendoorn and a host of valuable community support, our first offical Engineering report is now available for general parusal. You can pick it up from our new (and still in-progress) Research page, or download the PDF directly here.

From the Preface:

This document is a high-level analysis of the engineering challenges involved in homesteading the high seas. The aim is not to provide a detailed design of a specific seastead, but rather to find answers to general questions, such as the cost per unit area of functional real estate.

Note: This is a first draft of this report. It is being publicly released for community feedback. Due to still being in a state of considerable flux and expected changes due to feedback, polishing is not yet high on the agenda. Please send any feedback you might have regarding content to eng@seasteading.org.

15 comments

  1. Thorizan 5:01 pm

     The PDF link doesn’t appear to be functional.

  2. nthmost 8:37 pm

    Sorry about that — the link is fixed now!

  3. Carl Pålsson 12:47 am

    I mostly agree with the sections on mobility and station-keeping.

    I’d like to see a calculation of power requirements for a used cruise- or container ship. Clubstead does not seem like a good candidate for dynamic positioning.

    Knowing the propulsive power and top speed of a ship one should be able to easily calculate how much power would be needed for a loitering speed of a couple of knots, with optimized propellers.

    http://commercial.apolloduck.com/display.phtml?aid=129684

    The drag force equation in your paper seems to me like it depends on the velocity squared.

    If v=14.6 knots and P=9480 kW, then a v of 2 knots would require a P of 178 kW.

    Is this correct?

  4. Jeff Chan 3:22 pm

    The large prestressed concrete LPG vessel is fascinating.  Cost is not mentioned, but we can estimate $9 million+ for the concrete alone based on the 12k cubic yards of concrete used and Eelco’s estimate of $1000 per cubic meter of constructed concrete.  I hope everyone reads the report about it.  Similar constuction techniques could probably be used to build seasteads.  Interestingly the technology is more commonly used to build bridges.  Concrete Technology Corporation in Tacoma, Washington was the builder:

    http://www.concretetech.com/

    The engineers were ABAM:

    http://www.abam.com/

    Who have built a number of innovative floating concrete structures:

    http://www.abam.com/portfolio/pmw/innovative/index.cfm?id=88

    Note that it was built mainly to the 140m wavelength of the semi-protected waters it is buoyed in.  For the open ocean a structure would need to be at least 300m long to deal with the longer wavelengths present.  Therefore, while incrementalism and modularity of single family units is desirable, it may not actually be practical on the ocean.  It may be possible to have small housing uints if a large structure existed onto which individual homes or apartments could be placed, but it frankly seems impossible to create a (rigid) 300m structure from smaller modules.  It’s a great idea, but probably not doable.  At best, it may be necessary for someone to own the "land", even if it’s the deck of a ship or semi-submersible to place the houses onto.

    Lots of folks are finding ways to make housing from shipping containers.  Perhaps one way to start would be to put container-based homes onto a container ship, if we must have modularity.  Both containers and container ships are plentiful.  I believe there’s currently a massive surplus of them due to building cycles started during the boom and lack of business now.  Personally I would like a (converted) cruise ship better.  A far less expensive, better business-modelled Residensea would be fine.

    Your proposals for a flexible structure are certainly interesting and very creative, but personally not too appealing.  I’m not sure how comfortable people would be with "the land moving".  A large cruise ship is probably more comfortable, familiar, and appealing.

    Frankly until someone comes up with something better, it’s hard to beat a 300m ship on the open ocean.  (I think a 300m multi-spar structure like a larger Clubstead or Seadrome could be better than a ship for stability, durablity, etc.)

  5. Eelco 1:54 pm

     I’d like to see a calculation of power requirements for a used cruise- or container ship.

    It isnt included, since it is expected to be so much lower. Station keeping, or moving at a knot or two, shouldnt be a problem for a ship.

    Clubstead does not seem like a good candidate for dynamic positioning.

    Its current form with four blunt pontoons, i agree, but changing that into a twin-pontoon hull would make a whole lot of difference.
     

    The drag force equation in your paper seems to me like it depends on the velocity squared.

    If v=14.6 knots and P=9480 kW, then a v of 2 knots would require a P of 178 kW.

    Is this correct?

    Nope; its even better. Power is force times velocity, so there is a cubic relationship between speed and power. For viscous drag that is. The predominant drag on ships at cruise speed is non-viscous, and on the other hand, the efficiency of a normal propellor will suffer greatly at those speeds. Extrapolating like that might not be very meaningfull.
     

  6. Eelco 2:09 pm

     The large prestressed concrete LPG vessel is fascinating.  Cost is not mentioned, but we can estimate $9 million+ for the concrete alone based on the 12k cubic yards of concrete used and Eelco’s estimate of $1000 per cubic meter of constructed concrete.  I hope everyone reads the report about it.  Similar constuction techniques could probably be used to build seasteads.  Interestingly the technology is more commonly used to build bridges.  Concrete Technology Corporation in Tacoma, Washington was the builder:


    Exactly; this is one of the projects that underlies my confidence in concrete barges. Unfortunately, I have not found any direct cost information for such structures, but even at twice that estimate, the square meter price is still very competetive.
     

    Note that it was built mainly to the 140m wavelength of the semi-protected waters it is buoyed in.  For the open ocean a structure would need to be at least 300m long to deal with the longer wavelengths present.  Therefore, while incrementalism and modularity of single family units is desirable, it may not actually be practical on the ocean.  It may be possible to have small housing uints if a large structure existed onto which individual homes or apartments could be placed, but it frankly seems impossible to create a (rigid) 300m structure from smaller modules.  It’s a great idea, but probably not doable.

    I disagree; from what I can tell, based on an admittedly crude analysis, linking a set of concrete modules into a structure long enough for open ocean operation seems plausible. Still, these modules wouldnt quite be ‘single family’, but more like 40x40x50m blocks of concrete, but you could start with one in protected waters near shore, at a budget I am confident TSI could get funding behind, and provide a plausible path to eventual international water operation.

    Anyway, more on this in part 2!

  7. Carl Pålsson 11:34 pm

    A cubic relationship is what I calculated with in the above example. Are you saying it would be better, ie even less than 178 kW required to maintain 2 knots? Assume that we add electric thrusters with propellers optimized for this speed (2kt). I understand the regular props will likely be too inefficient going this slow.

    I am trying to determine whether it would make economic sense to power the dynamic positioning of a ship with something like PV panels.

    Umm no wait strike that. I used a squared relationship. Cubic you say… interesting…

  8. Eelco 1:02 pm

     Miguel, who also spoke at last TSI conference, has done his thesis project on solar powered fishing vessels. He seemed enthusiastic about it.

    Backup power would still be required though, as the dynamic positioning would presumably also be what guarantees individual seasteads dont bump into eachother. But it could help offset fuel costs, if it proves competitive with other means of energy generation. That said, taking into account that there isnt anything like cheap horizontal surfaces on a seastead, I doubt it.

  9. Jeff Chan 5:17 pm

    Has anyone looked into using a (wing)sail for stationkeeping?  In principle you can sail to any compass point except straight into the wind.  (BTW the wingsail seems to be superior to a cloth sail.  Ask Larry Elison…)  I think Vince looked at kites for transit, but it too may be useable for stationkeeping, with some differences.  As long as the current and wind forces can be made to balance out, it ought to be doable and save a huge amount of resources compared to engines or generators.  One could also use windmills to at least partially energize stationkeeping, assuming more wind than current or drag.  Any could be backed up by a diesel generator or run as hybrids.

  10. Miguel Lamas 10:13 pm

    Very interesting report Eelco! And thank you very much for including me in the Acknowledgements.

    * Barges:I had deleted the barge option from the very begining as I thought that Seasteading was not possible in the EEZ. But I can see that you are considering it. This could lower the costs a lot. See for example:

    http://www.dredgebrokers.com/Barges_Work/90214-BW/Barge.html

    And complies with small scale and modularity:

    Price for Barge: Standard Accommodations 32 berths: EUR € 3,950,000
     

    Price for Barge: Optional accommodations 106 berths total and recreational unit: EUR € 5,950,000

    But what about mooring a Seasted in the EEZ? It could be considered an Artificial Island, and as a consequence, not allowed in that waters…Perhaps with DP it could not considered it: you have the barge sailing at low speed from one place to another. Something very important as you say in your report: Inside or outside EEZ is the key!

    * Solar powered vesels: one example here:

    http://www.inhabitat.com/2009/07/06/auriga-leader-cargo-ship-gets-power-from-solar-panels/

    For a cargo vessel is not suitable, but for a Seastead it could be a good real option as you do no need so much power!!

  11. Eelco 1:25 pm

    Hey  Miguel!

    With regard to barges, I think we are wielding subtly different terminology. By ‘barge’, I mean all elongated structures less hydrodynamic than a ship, like the Nkossa barge for instance. Thus I dont mean to imply a relatively small size or shallow draft. The kind of barge I have in mind is intended to be scalable to international waters operation.

    Eelco

  12. vincecate 1:29 pm

    That cargo boat is maybe 1/5 covered with solar cells and gets around 10% of its power.  So maybe if fully covered it could get 50% of its power.  But because power needed goes up with the cube of speed, you don’t really need to slow down too much to get to half the power usage. 

    So if you look at 13 knots the power is proportional to 13^3 = 2197  but at 10 knots you are proportional to 1000, or less than half.

    So a cargo boat  could probably go solar  by just slowing down by 25% or so.

    I am sure solar works for single family seasteads because the surface area to weight ratio is better, and because we can go much slower (even 1 or 2 MPH if we need to).   Also see PlanetSolar:

    http://www.theage.com.au/technology/giant-solarpowered-boat-unveiled-20100226-p6ca.html

      — Vince

  13. Eelco 7:12 pm

     Vince:

    The way im reading that, it doesnt include the main drivetrain; I doubt thats electric, or reconcileable with the 400kW mentioned. 400kW is a beefy car, not a cargo ship. Thrusters refers to the small thrusters used for manouvring, im guessing.

    For any SFS that is not some kind of boat (spar, semi, or anything else I can think of), surface area to drag coefficient will be far far worse. A catamaran is probably optimal in this regard.

    But yeah, lower power makes a huge difference. Although as I argued above, the cubic relation doesnt extend all the way from slow speeds to cruise speeds, so scaling from one extreme to the other may give serious deviations.

    Eelco

  14. vincecate 10:58 pm

    > The way im reading that, it doesnt include the main drivetrain; I doubt thats electric, or reconcileable with the 400kW mentioned.

    I think you are right.  It says, "A boat the size of the Auriga Leader needs about 400 kilowatts of energy while at port,".  So at port would not include main drivetrain.

    Here is a cargo ship that can hold 191 containers of the 20 foot size.   The main engine is rated at 1850 kw.

    http://newvesselsale.com/multipurpose-container-vessel-4000-dwt.html

    So if solar could get 200 kw on that ship top then it would be about 1/10th the power of that engine so ship would have to go a bit less than 1/2 the speed (since 1/2^3 is 1/8th).

    Anyway, I am sure we will see more and more solar on cargo ships.  If they start extending beyond the deck surface, they can get even more solar. 

       — Vince

  15. Miguel Lamas 10:13 am

    Hi Eelco, I have checked in rules what it is written about the term "Barge"

    BARGE: DNV for example defines Barge as follows: 

    "Barges and pontoons are defined as vessels without sufficient means of self propulsion for their service area. Assistance from another vessel during transit or transportation service is assumed. In vessels with limited means of self propulsion an upper limit for barges/pontoons may normally be taken as machinery output giving a maximum speed less than V = 3 + L/50 knots, L not to be taken greater than 200 m."

    That means they could be self propelled but at very low speed. So you could install a DP system and it could still be considered a "Barge". Examples of Accommodation Barges:
    * Not self propelled: see http://www.barges.com/
    * Self propelled with DP: see http://www.bhoffshore.com/ 
     

    CONCRETE BARGE:  there is already a standard for that in some classification societies. For example, in DNV: DNV-OS-C502 Offshore Concrete Structures. See:
    http://exchange.dnv.com:6389/dynaweb/offshore/os-c502/@ebt-link;cs=default;ts=default;pt=13637?target=%25N%14_5748_START_RESTART_N%25
    It can be used for "Floating concrete structures for production of oil/gas. The structure may be of any type floating structure, i.e. Tension leg platform (TLP), Column stabilised units and Barge type units".

    But no idea about the price of Concrete Type Barges. Steel Barges, as Accommodation Barges in the examples, should be a cheaper option, but of course it should be compared to maintenance costs of underwater hull.

    Something to investigate more in detail !! I am agree with you that it is a good option

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