We are looking at possible designs for a minimal viable seastead.  
We see the goal of a "seastead niche market" as homes you can easily and cheaply move over the ocean.  
It is a bit different than a boat which is more for getting from one place to another.
For starters we will just target the Caribbean,
and staying outside of the hurricane zone during the months of hurricane season, so the waves are not too bad.
Legally it will be a catamaran yacht and probably flagged in Panama.
With Starlink providing cheap Internet everywhere, tens of millions of tech-nomads, and other possible markets,
I think it is time to try selling a seastead.


When I say "aluminum" anywhere below please read it as "marine aluminum".

An idea I would like your feedback on is as follows.

1) A custom aluminum 40 foot high-cube container that becomes the living area but also hold other parts during shipping.
      It will have steel or stainless steel ISO corners that are either isolated or removed after shipping.
2) It is a catamaran with each hull made from 2 sections, so 4 sections total.
    Current idea is that each section is a truncated cone (frustums) made of aluminum.
    Maybe 2 feet diameter at the small end and maybe 5 foot diameter
       at the large end, 1 cm thick walls (naval architect will pick real number), and maybe 33 feet long.  
       It would be closed off at the small end and open at the large end.
    We could stack all 4 sections together like cups.
    The sections will have flanges welded on at the large ends so they can be bolted together (designed as structural joint).
        Note the small end goes inside other section the flange on the large end is always outside.
        When two section/flanges are bolted together there will be a plate of aluminum so each section is a separate watertight compartment.
        On both sides of the aluminum plate there will be gaskets between the plate and the flanges.
3) There are 4 beams that each go from a top corner of the container out and down to the center of a section of a hull.
     The beams might be at 45 degree angle. 
     Each beam will be one piece that fits in the container, so less than 40 feet.
     The living area is well above the water.
     For Galvanic corrosion these should be aluminum like the hulls.
     The living area might be stainless or aluminum and so might need galvanic isolation.
4) There are cables holding the hulls/legs in and in position
5) The top of the container will be covered with solar panels as well as sticking out 3 feet on left and right sides
   These will ship inside the container and be assembled at the destination 
   There will be attachment points welded on in the low parts of the container corrugation so assembly is easy
6) There will be an electric thruster at the back of each hull and differential thrust will be use to steer.
   The propellers will probably be reasonable large as we are only expecting slower speeds.
7) There will batteries (expect lithium-iron-phosphate LFP) that hold 2 days worth of solar output.
   These will be split into 4 banks and put in the 4 ends of the hulls to increase rotational inertia and stability of the vessel.
   What is the total weight of the batteries is lbs and what is each of these 4 banks?
   There will be a waterproof hatch in hull above each battery compartment for access and something separating the compartment from the rest of the hull.
   Each half hull section will have several air bags for safety.  They provide flotation even if a hull is punctured.  Can be removed for inspections or repairs.
8) Some other stuff probably should also go in the hulls, like water tanks, waste water tanks, emergency term food storage, etc.
9) A pointy cap to go over the flat 2 foot wide end of the hull.  These 4 cones can also pack together like cups.
   If we have trouble fitting the main hull sections they could be made a bit shorter and the point cap a bit longer,
   adjusting the 2 foot diameter to whatever larger size is decided upon.
   The naval architect will make the determination on how long the sections should be and how long the pointy caps should be.
   In any case these are not attached during shipping, only during assembly at the destination port.
   The nested pointy caps can actually fit inside the nested main hull sections during shipping.
   There are more difficult regulations for yachts over 24 meters so we probably want to design the pointy sections so we stay under that.
   The naval architect will decide the final shape, they may want to round out the point some or make it more like the front of a boat or shorter etc.
   Depending how different from a cone it might not fit inside the main hull sections, but it could go on top of the thin part of the main hull with some supports.
10)  Most times hopping to the next island in the Caribbean is not very far.
   If you leave when the sun is coming up with a mostly full battery you can go faster than solar-only for most hops.
   Please make a table with estimates for speed and total distance in the following cases:
       1) typical Caribbean sun 24/7 for days at a time (charging batteries in day and using at night)
       2) Same as 1 but with all A/C turned off
       3) If all batteries were full and we were willing to use them up over 5 hours but no sun
       4) If all batteries are full and we use them up over 10 hours but no sun
       5) If all batteries are full and it is 10:00 am and no clouds at all and we use solar and batteries for 4 hours with no A/C
11) Probably it makes sense to have a center-board / dagger-board /fixed-fins on each hull so a cross wind is easier to deal with
12) There will be ladders down the beams going from living area to hulls.
      There will be flat walkway with railings on top of the hull between the two beams/ladders.
      The ends of the walkway will connect to the two beams.
      So you can get down to water-level on either side for fishing or getting into a dinghy.
13) The target customer is thrifty person who lives on the boat full time.  We expect them to 
      use moorings or anchor, not to pay dock fees.

It seems interesting because a container has strong points at each of the corners and the beams and cables need strong points at 
each of the corners.  So there is kind of a fit.  The container shape is a bit narrow but it is
wider than some sailboats and so probably ok as a minimal viable product.   

Please try to estimate the weights and sizes of the different parts and check if they should all fit
inside the container ok.  In particular check when all 4 hull sections are stacked like cups how long they will be.

Please try to estimate the cost of having a Chinese Naval Architect firm do each of the following:
   1)  feasibility / design review - check that this can be made to work - give estimates on building costs
   2)  basic design - engineering and structural analysis for complete design
   3)  detailed production design - full details for robots at Chinese shipyard to cut and weld everything
   4)  formal engineering assembly sequence
   5)  compliance paperwork package.  Whatever is paperwork we might needed to at least satisfy 1 to 4 below:
              1) Anything a ship registry like Panama would require
              2) battery shipping compliance
              3) CSC safety approval plate with Allowable stacking weight for our custom designed container - fine if low or zero stackable weight
              4) stability, structural, electrical documentation for entering some country
              5) insurance/regulators  
              6) ABYC/ISO-style compliance
              7) class-like documentation.
   6)  quality control check - after factory makes things to check that all looks good  - is there some option like this?
   7)  total

We also need a Third-Party Logistics (3PL) company in China to keep some inventory of solar panels and other parts to
consolidate with the structural parts so each container has a complete kit, and then send it either to me in St Marten
or to some destination for a kit customer.  It is probably cheaper to use a 3PL in China than having our own wear-house space in St Marten.
And long term we want to be able to ship a full kit directly from China to anywhere in the world (for the first 20
this may not matter).

Please try to estimate the cost for all the parts if it is all made in China.
Estimate unit costs for:
   1)  the first single prototype unit 
   2)  a following order of 20 at a time.
   3)  a following order of 50 at a time.
   3)  a following order of 200 at a time.

We will assemble it at a shipyard in the Caribbean, probably in Dutch St Marten.   
It is duty free there and I live in Anguilla which is a short ferry ride away.
Try to estimate how long that would take and the cost.

Estimate the total cost with the Chinese manufacturing, shipping from China to St Marten, and assembly in St Marten.

We hope to eventually have more volume than a normal yacht, and so maybe less markup than normal,
but what do you think we should sell it for after we have gotten through the first 20?  
    1) Sold as fully assembled and in the water in the Caribbean
    2) Sold as a kit where customer worked with their local shipyard to put it together at their expense

How would this compare to other new yachts delivered to the Caribbean of similar living space or similar price?
I assume some yachts produced far from here could have costly delivery charges.

Customers of this seastead don't need to know how to sail or maintain a diesel engine.
It is also more stable, which can appeal to older couples.  So there can be a niche.

Moving as assembled seastead from land to water would be trouble as tension cables are key to the structure,
so it does not lift as a normal solid boat would.
The final assembly will really be in the water.
The 2 sections of each hull will be assembled on land and then the hulls and living area can
be put into the water.  Then the beams go from the top of the living area to the hulls.
We will have some extra cables and winches used during assembly.
As the cables are tightened the beams push up on the living area so it can be lifted
out of the water once in the right position a final cable is attached.  This can be repeated for different cables. 
Final things like installing batteries, solar panels, etc could be done while it was on the water.
This can save shipyard space rental costs and give the customer the option of doing some of the
work on their own. 

We will keep detailed videos and instructions showing how to unpack the container and assemble the parts on our website.
A prospective kit customer can use this to get a quote from his local shipyard, and the shipyard can use it during assembly.
Customer can also use it for any parts he ends up doing himself.

If there is a "hobby horse" issue we could modulate thrust to help counter it.  Since the thrusters are down low 
and some weight is up high modulating thrust can have an impact.

One AI thinks that we would not be able to ship the LFP batteries with the rest of our kit because our container
is not totally standard (even though we will have a CSC plate).  Do you think this would be a real problem or do you
think it can be shipped as part of our kit?  We plan to use catalog marine LFP packs that already have UN38.3 certificates.
If we have to try more than one carrier that is probably ok.

This design reminds me a bit of Wharram Catamaran that had some flexibility and so avoided stress concentrations. 

Preliminary plan is:
   0) 3D print a froud scale model to test
          1) parts fitting together and fit in scale 40 foot container
          2) test in scale waves
          3) test if we cut one cable if others hold
   1) go through steps with Naval Architects as long as keeps looking worthwhile
   2) build prototype
   3) Do sea trials to see if all works as expected
             1) test with strain gages
             2) handling in waves, cross winds, etc.
             3) solar, battery levels, etc.  
   4) if we need major changes the do those with NA and go back to step 2
   5) If we have a well tested prototype we like and other people do as well, then we can sort of crowd-fund the volume production by taking large deposits
        Depending on the number of deposits and the amount of money we are willing to risk we can pick the next production batch size