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

Building seasteading friendly sub $100K single family Catamarans

Home Forums Research Business Building seasteading friendly sub $100K single family Catamarans

This topic contains 14 replies, has 3 voices, and was last updated by Profile photo of ellmer - http://yook3.com ellmer – http://yook3.com 3 years, 9 months ago.

Viewing 15 posts - 1 through 15 (of 15 total)
  • Author
  • #1750
    Profile photo of nicolas1776


    Looking for collaborators to start an organization providing full time ocean living suitable, small (single family sized) Catamarans, sold for under 100,000 USD.

    Seasteading will likely be enabled by a wide variety of competing and complementary technologies and infrastructures. One such enabler is the light and mobile single family sized vessel. This is an important component of the transition to seasteading, as well as an important component of the realized vision, ensuring their viability from beginning to end, from the days of shipstead business ventures to floating breakwater cities.

    Practical steps must be taken sooner rather than later to enable aspiring seasteaders to take on the coastal and high seas, simaltenously providing mutually reinforcing support to other approaches such as fixed structures or larger narrow focus ships.

    The need

    Familiarity: in the beginning of seasteading, access to land and commonly used infrastructures and services within a well defined legal framework will prove crucial for all but the most determined pioneers. A large liveaboard boater community provides access to both expertise and rapid community building, enabling bolder moves sooner.

    Smooth transitionning: likewise, many candidate seasteaders would benefit from the ability to transition smoothly, both quantitatively and qualitatively, from their current lifestyle to that of a seasteader, easily going back and forth between periods of sea living and land living at a pace and level they are individually comfortable with.

    Versatility: individuality is a key definer of this initiative. A shared but basic and versatile common vessel design should enable varied lifestyles. Including but not limited to, the small business home office, the small scale floating shop or the floating home anchored off a larger seastead (such as the future blueseed vessel) or coastal city’s job pool, all the while minimizing the difficulty of switching from one style to another.

    Affordability: finally, practical mass access is severely hampered by the requirement of a large commitment, and difficult access to credit and insurance. A low price point is crucial to remedying the first two and a familiar proven design should help with the former.

    The market

    Part time seasteaders: individuals and families maintaining strong ties to land via fixed jobs or demanding commitments whose eventual goal is to become full time seasteaders. They aim to achieve this goal over a period of years, starting with a low commitment to temporary periods of ocean living. Some of them might make our product their home, living from a marina, and some might only use it for weeks or months at a time. Ideally, our product would be transportable by land to give access to landlocked lakes as well.

    Full time seasteaders: individuals and families working on larger seasteads lacking accomodations, wishing to provide services to other seasteaders and coastal cities or those being almost entirely self reliant.

    Casual sailors: a secondary market could be found in young retirees or people who can currently not afford the initial purchase of a similarly sized vessel but can support the ongoing expenses of maintaining one. It is unclear how big this market is and it should be considered secondary at best. These customers would also help lower the commitment of our main target customers as they could also enable them to more easily recoup their costs in the event of a desired or unforeseen change of circumpstances.

    The product

    The envisioned product would be a vessel largely similar to existing cruising catamarans but more conducive to long term living at sea. Only a couple variations of the same basic design should be offered, largely customizable by the owner while already on the water.

    • Mobility: the vessel should be fast enough to outrun most storms it cannot survive, as well as use dynamic positioning when necessary and normal anchoring when not. The base design should be light and streamlined enough to allow for this with minimum expense. Normal expected cruising speed would be low while allowing for a sustainable top speed of around 20 knots or more.
    • Stability: should be at least as stable as existing 45 foot catamarans. While not providing a land like experience under any sea states, this level of stability has proven confortable enough to experienced cruisers (which all aspiring seasteaders will eventually become) as well as to be conducive to performing varied work activities onboard. Heavy or simply rough seas will provide an uncomfortable ride, may prevent income generating activities, cut off Internet communications and require moving unexpectedly to other areas.
    • Size: it is expected that ports will be an important destination of early seasteaders and the vessel should be designed to easily dock and fit into slips. It should also give enough accomodation space for a few people and light commercial or self sustaining activies. Existing 45 foot catamarans should provide a good starting point.
    • Materials: frequent low intensity impacts as well as occasional high intensity ones are expected. Collisions with like vessels, heavier ones, groundings and bumping into fixed facilities should be expected. The vessel should survive most and remain largely unscathed for minor collisions with small vessels, fixed structures and groundings. Insulation should be adequate to minimize energy use to provide a livable environment in the tropics and in cold climates (the emphasis is on liveable – confort in extreme environments may be the result of owner modifications). The hull and structure should require no further work and satisfy the requirements outlined in this specification. Finish however, should be basic and allow the owner to make final touches while at sea.
    • Versatility: the base design should provide for accomodations and extra space for undertermined activities. Modifications to suit various lifestyles and activities should be possible while at sea. Limited vegetable growing, medium fishing, guest food serving, light artisanal manufacturing, mechanical repair work, design, internet or professional consulting etc.
    • Energy: should offer a simple generic design allowing for a wide range of energy sources that can be easily altered. A possible solution would be an all electrical system (motors, stoves, refrigerators…) with no provided power plant and limited battery bank. Such a design would allow the energy to be supplied via any means deemed appropriate by the owner (solar, wind, LENR, waste burning, diesel power generation…).
    • Equipment: should be basic but include minimum sleeping, washing, cooking, storing and navigation equipment.
    • Safety: the hulls should be largely insubmersible in the base configuration, while providing a reasonably safe habitat in most expected sea states and while capsized. Most serious blue water catamaran designs already satisfy this requirement. In addition to the above, carefoul thought should be given to the threat of piracy and theft (both of the whole vessel and inside) at the structural level, while at sea and underway.
    • Price: the vessel should be liveable and autonomously movable as sold (with the exception of the power plant which should be provided by the owner) and carry a price tag of under 100,000 USD.

    The roadmap

    1. Assemble core team.
    2. Gauge interest and refine concept.
    3. Discuss further steps based on our conclusions (potentially partner with or recruit a catamaran designer or catamaran building company to produce a workable design, then take pre-orders, find a shipyard..).

    Getting started

    Edit: people interested in collaborating on this project can join this Google group as a first step (a project management space has also been opened to further organize): https://groups.google.com/group/sub-100k-seasteading-catamaran/


    Hello Nicholas, excellent post ! – No doubth that the next step to seasteading will be just one step away from something that exists and is in use already right now. It is also clear that the ONLY reason that inhibits the yacht segment to develop into a seasteading movement is that only millionairs can handle the cost of yacht seasteading in the current setup.

    So the task left is to get something very similar to a independent yacht on the water that is affordable for a average joe – means in the cost and living space range of an average landbased house.

    Seasteading (i like the term ocean colonization better) will develop along a lot of different axes (see here) and one of the most important of those axes will be catamaran seasteading the base element will be a boat that is percieved by the public just as a long term live aboard specialized catamaran.

    The main reason why yacht living space cubic and squaremeters are a factor 100 more expensive than land based living space cubic and squaremeters is, that yachts use materials (resin, carbon, glassfiber) that are a factor 100 more expensive than the materials used in land based housing (concrete).

    Happens that concrete shell building comes at the same cost for land based applications as for sea based applications. So the logical way to solve the factor 100 living space cost dilemma is to apply concrete shells at sea .

    The catamaran that can handle the specification you are talking about is a honeycomb concrete shell structure along the lines we built in our testsites in cartagena we built a series of small concrete honeycomb structures, among those a catamaran floating element.


    This catamaran floating element could form the base of floating houses or long range cruising and live aboard catamarans of house size and house cost.


    Affordable living space on the ocean that is not limited to the fancy shiny and expensive club and marina atmosphere that is covered by the current yacht industry.


    Profile photo of nicolas1776

    Thank you for taking the time to express your views. I am actually familiar with your designs and unbounded love for concrete.

    Concrete is a wonderful material for many applications and there are enough varieties of it to address a wide range of conditions and needs. The advantages of building marine structures with it are well understood in this community, but as in any design putting lives potentially at risk, it is crucially important to focus on its potential faults. I am quite certain you do agree with this last statement and have already considered this aspect.

    I am mainly concerned with the energy required to move such a structure, reduced maneouverability (which is more important for smaller versatile vessels), its lack of inherent buoyancy when breached, as well as the handling of frequent low intensity collisions. While a thin ferrocement shell can be used to reduce the weight down to acceptable levels, it requires more maintenance and flawless execution during construction. Various composite concretes do exist and I am no expert. I stand to be corrected (and would be thrilled to be so) on all or part of the above. It is important to come to the design table with few preconceptions and a very open mind.

    In short, this is definitely a path to consider and explore, but its promising aspects should not result in a lack of consideration for its very real and worrysome downsides, or in a lack of consideration for other materials. The main issue with what is currently being used in catamaran building is not so much the raw materials cost as it is the labor required to work them into fancy integrated shapes with high building standards.


    Well it is not for ist worrysome downsides that concrete is mankinds most used building material – it is more for its amazing overall advantages. For every structure that is big enough to host humans inside built in steel – there must be about 1000 being built in concrete. And for every structure in 20m size built in resin and fiber there must be 10.000 structures built in concrete.

    The discussion of collision resistance for marine application was on in the early thirties – but is over now – there is no ongoing discussion among civil engineers that concrete is a perfectly suitable material for any kind of floating structures.

    What you might have heard in this direction is obsolete and originates in old obsolete texbooks written before the latest generation of floating marine structures went into production and performed perfectly. (check here)

    It is for a good reason why protective shells for nuclear reactors are made from concrete, and military bunkers built for giving shelter from artillerie impact are made from concrete.

    There is no such thing like “untested aspects” or “potential faults” in modern concrete shell building.

    Also the idea that concete is heavy is a “wrong popular perception” nothing else.

    Concrete has a specific weight of 2,4 aluminium of 2,5 this makes concrete actually lighter than aluminimum.

    The popular perception comes from the fact that concrete is seen in everyday use in meterthick walls while aluminium is seen in thin profiles.

    You can not build concrete in shells thinner than 5 cm – so you need a house sized structure to make it a leight weight shell compareable to a lightweight yacht – but it can be done with no problem especially if you use honeycomb building – check here.

    If you do not go for concrete shell – in what other material you could build a house sized floating structure with house sized living space – at house sized cost? – wood? – fiber resin – steel – aluminium – titanium ??

    The reason why concrete has no real rival for building living space on land is there is no other material that gives you compareable bang for the bug – (living space per cost) – oil industry has figured that out already and has about 50 large sized concrete floating structures in the high seas in the north sea alone as we speak… (check here)

    If floating concrete structures are still in doubth for you you might want to start reading here.


    Profile photo of shredder7753

    i understand where Ellmer is coming from, and I love his unbounded love for concrete. but i do see where it would be nice to have maneuverable surface floating single family seasteads available. the types of seasteads that people might find uses for is unlimited. thats why i like Nicolas’ ideas to use catamarans. many people, like Octavian, do not feel comfortable submerging permanently or even during a storm. so what im trying to say is, if anyone is willing to buy a catamaran and make a go of it – we salute them. as long as we dont have reason to believe that their project will fail miserably, why not support their endeavor.

    eventually there may be millions of people living as Ellmer imagines, or in my Bergsteads. but a fleet of catamarans permanently at sea – that sounds like an awesome start!!! especially if they have some hydro or wind turbines to make unlimited power! I would even join if i had any money.


    Inventor of the “Bergstead”

    Profile photo of nicolas1776


    At this stage it seems a bit early to settle on one specific material. For example, other unconventional and manufacturing friendly options include polymer materials as in use by the Trymph boat company. Many plastics (and combinations of plastics in different states) could offer the required properties at an affordable price, assuming that a low labor requirement can be maintained using simple tools (which seems to be a major hurdle). Similarly, alluminium is expensive and slightly heavier as you point out, but the comparison is somewhat misleading as different quantities of it would be used and production is more readily automatable. There are a vast number of traditional and less traditional materials and manufacture processes to be considered.

    While I am aware that you do have extensive experience building concrete floating structures, I am not aware of proper testing that has been carried to address the specific issues arising from the use of (non-reinforced?) concrete in the proposed product. For example, can a 45 feet catamaran be built with a 5cm thick concrete shell, with a roughly 5 ton weight and able to wisthand repeated low speed direct hits from the sharp end of a similarly built vessel, without cracks or structural damage?

    The material discussion, however fascrinating and necessary, can only be seen in the context of a specific product. It is therefore important to first settle on the main desired characteristics and design angles, production goals and timeline. There may be some back and forth with specific goals having to be modified in light of difficulties finding a material suitable to all (as an aside, aiming low and defining what can be sacrificed seems as important as stating what must be achieved).

    For this reason, at this time, I am mainly interested in finding like minded collaborators to get the ball rolling on these aspects and settle the material and production questions next (most likely enlisting the help of experts such as at least one catamaran designer…). Eventually, one unit will need to be sea trialled and put in destructive danger before preorders can be taken.

    As a first step, I am planning on opening a project management space today to get things going and organize.


    You are certainly correct that many different approaches should be encouraged and tried, and that different customers with different priorities will favor different designs.

    I have attempted to outline the needs of one such potential group of customers and what can be attempted to address them. I am thrilled to see the variety of designs that have been proposed and researched in the seasteading community.

    The value proposition of a sub 100k catamaran will go up as other types of seasteads are made available to offer complementary opportunities. A very concrete (no pun intended) such example is the proposed blueseed vessel, allowing smaller crafts to anchor in its wave shadow for purposes of trade, supply and transportation to and from land, internet sharing…

    Profile photo of nicolas1776

    People interested in collaborating on this project can join this Google group as a first step (a project management space has also been opened to further organize): https://groups.google.com/group/sub-100k-seasteading-catamaran/


    I would be the first who likes to hear about “other options” and see a realistic business plan on that…

    Do you have global basic figures of cost per ton of stucture building in the “other options” – you postulate. I would like to hear it. I mean you postulated a 100k pricetag for a house sized structure – my question is how many tons of material do you plan to construct into this structure.

    What is your general idea in cost per ton of structure …

    I can assure you that “traditional boat building” in resin and fiber is NOT among the options, and traditional naval steel building is also NOT among the options – those techniques come into the “frame of options” if you add a couple of ceros to your postulated price tag…

    So what is the “base of the miracle” that you can postulate a pricetag that is a way outside of what we see on a dayly base.

    Saying we will build somthing “along the lines of tradition” but we will end up with a price tag outside the lines of tradition is like making wine out of water… if you do nothing different the pricetag of the outcome will be nothing different –

    So the question is what will you do different that allows you putting such a different pricetag on it?

    Profile photo of nicolas1776

    Indeed things need to be done differently to reach a different result. This is not being disputed, and identifying what needs to be done differently, keeping an open mind, is a main component of this endeavor.

    Similarly, the use of concrete is not being rejected in any way. There is no need for such a vigorous defence of a material that is not under attack in this thread. There are also inovative building methods (such as those used by the Trymph boat company) using different materials (polymers only in this case) which should also be looked at and compared as they produce what seems to be adequate hulls at a much lower cost. Traditional boat companies target a different market with different needs and different volumes, and therefore have designs and cost control procedures adapted to it.

    You seem very confident in the likelihood of a concrete based approach to compare favorably to others and I would be similarly thrilled if it did. Other methods will also be looked at (such as injection molded plastic hulls) and perhaps quickly discarded. Even within the realm of concrete building, the options are many and need to be compared to one another. Please feel free to detail the exact type of concrete and the specific building methods you deem appriate to a surface vessel such as the one described here.

    The different materials and construction methods should be analyzed against all proposed targets (which is the reason the targets must be properly identified as a first step).

    Profile photo of shredder7753

    Nic heres another idea that might be a lot easier. Why not start a used catamaran dealership that specializes in buying and retrofitting low-cost catamarans. and then you would jus cater your business toward the seasteading market.

    Here, look about 2/3 of the way down this page:


    and find “Cruising Catamaran For Sale by owner – Catalac 12M” – 12m long, and its been sailed across the Atlantic. They want $120K for her.


    Inventor of the “Bergstead”


    You get me wrong if you think i am a kind of concrete missionary or have any interest to convince anybody of anything – i was just going to focus things a bit on the core problem which is structure building cost.

    I visited the (http://www.triumphboats.com/) website and can not find a USD 100 K pricetag for a house sized structure in polymers anywhere – do you have a pointer that confirms that kind of claim?

    Again i am not pro or con of anything – just asking for the name of the saint and the circumstances of the facts, when somebody is declaring a miracle… it is open minded scientific interest – nothing else.

    I was just assuming that you have crunched the basic numbers on some kind of base – i found your numbers interesting so i was asking for the base…

    The only reason i mentioned concrete honeycomb and shell structures was because i assumed that it is clear for everybody that this is the only realistic way to get into the cost and endurance frame that ocean colonization requires.

    Looks that it is not – if you want to repeat the discussion of the last years – to (hopefully) come to the same conclusion that anybody who does serious ocean engineering has come to in the early seventies… the only long lasting maintenance free ocean capeable structures known to mankind that have a remote chance to meet “colonization specifics” are concrete shells.

    This is not a opinion – it is a fact in any case i will not bother you further with comments if you want to discuss imaginary alternatives – finally it is your thread – for me this kind of discussion is a waste of time – time that would be better used checking existing projects of outstanding floating concrete shell structures and take it from there.

    If you want a discussion how to apply the experience of those large sized industrial projects for house sized catamarans that meet seasteading specs – you have my attention – if you want to discuss a ” wide array of imaginary materials” you lost me…


    Profile photo of shredder7753

    uhh this was a neat idea. but the more i read and watch videos about sail-cat-yachts, i see that you dont get very far with $100K. the first thing about living at sea, is that you cant spend your entire day and night worrying about sailing the actual vessel. the vessel has to take care of itself if u want to do other things, like make money. just because you can collect electricity and fish for all the food u need doesnt mean u can survive without any financial income.

    im backing out of this idea.


    Inventor of the “Bergstead”

    Profile photo of nicolas1776


    With the building methods I am looking at, the structure is only about half your costs if professionally built (and assuming a motor only vessel, within our low speed specs). For most yachts, the structure is actually even less than half the costs and closer to one third or less.

    Since you seem quite experienced with concrete prototyping, you may be able to fill in some blanks. For a Catamaran roughly 12 to 14 meters long (and 7 wide) with all windows, hatches and doors, how much time would the construction of a concrete prototype require (as well as the rough cost)? A very rough estimated range would be interesting to get and you seem to have experience with it.

    This is a rough reference design (two habitable hulls with center saloon space and deck): http://www.lagoonpower.com/UK/frameset_uk.html
    If based off of a different design, please let us know.

    Lastly, please allow me to clarify one thing: I am not trying to build a house sized structure but a liveaboard vessel. It is about the size of a small apartment, all the while allowing for more activities (in less confort perhaps – although that is up to you to judge and except for space and motion, most everything can be customized to feel like a home on land) with mobility thrown in for good measure.
    It will probably not attract buyers looking for a house sized structure, land like confort (little wave motion, lots of space..) who do not care much about structure mobility. This is a different market better served by other ideas.

    Since you offered to explore the use of concrete honeycomb, I would love to get your feedback on cost and build time for the structure of a prototype for the kind of catamaran I have in mind.

    Profile photo of nicolas1776


    I was skeptical of a sail option early on but now that the project is further along, I have ruled it out entirely. Power only seems to be the only way to go here.

    I agree a modern sail catamaran is not achievable with a 100K budget. Nor is it really desirable for at least the following reasons:
    1. too expensive with reasonably efficient sailing apparatus.
    2. extra systems to learn, operate and worry about (we cannot get rid of the motors, generator or any other systems just because we have sail power). Learning curve is higher, so is maintenance.
    3. switching from ocean to river environments require demasting.
    4. more lightning prone in marinas or packed anchorages than power only vessels.
    5. requires too much attention while underway (for both safety and performance).
    6. forces some design constraints leading to both loss of volume and loss of load capacity.

    Now, on to the only real advantage of a sail option… wind propulsion is free (maintenance excluded). However it is highly unreliable and not practical for anchorage or port maneuvers. Unless we foresee the vast majority of early seasteaders moving about on long passages all the time, the cost advantage isn’t that compelling.

    I tend to think early seasteaders will spend 99% of their time in anchorages close to land or in port with a few passages every now and then (diesel, cheap kites and other options will help).
    The vessel I am designing will most likely (at this time I am heavily leaning towards this option) allow for multiple inputs such as Shore electricity, Solar, wind, diesel and (later) LENR to realize the best fuel economy possible as budget and technological advances allow. On a high budget, it is theoretically possible to get unlimited cruising range on solar only (there are already a couple such catamarans of similar size and cruising speed). As seasteaders earn more income, they will be able to add more and more alternative energy generation devices and burn less and less diesel over time… perhaps going from diesel only to full solar panel over a few years.

    Being fully self reliant is not an option and won’t be for many more years. Nor is it particularly attractive to many people (myself included). Making money will therefore be crucial. I agree sailing the ship is not something we want seasteaders to have to focus on. But most liveaboard cruisers of today spend more time working, exploring, resting and playing than actually sailing. Many don’t even live port very often. If you have a land based job, chances are there is a marina, mooring, anchorage or tie up area not so far from it that allows liveaboards. Rivers, lakes and oceans are all suitable for this purpose, and the craft is being designed to be movable (although not cheaply) over land should you be in a landlocked area and need access to the ocean later. This could be your first step waiting for other opportunities to move your home.


    You might want to check (http://concretesubmarine.activeboard.com/t43963819/catamaran-concrete-floating-elements-base-for-ocean-living/) – especially the application of the “Navegante Cholon” – floating house built on catamaran base.

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

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

Posted on at


Written by