We are working on a seastead design.

The goal is to design our seastead such that all the parts can pack into a single a High Cube 45 foot container which has:
   width 7.7 ft
   height 8.9 ft
   length 44.6 ft
   max weight:  62,000 lbs  (rated bouyancy at desired waterline is 27,500 lbs and we hope structure is enough under this that humans and their stuff can fit)

Above the water there will be a big equilateral triangle frame, 44.0 feet on a side. 
The triangle frame is also the wall of the living area and will be 7 feet high (floor to ceiling).
It will be enclosed and the whole inside the living area.
Around the whole outside of the wall, except where the dinghy is in the back, will be a 3 foot wide walkway and railing that 
is bolted on and has some diagonal supports from below bracing to the wall (so walkway is 1 food higher than bottom of the wall).
The walkway will have an aluminum grating that would let a wave pass through but you can walk on.
Also two doors on the back side,  one two feet in from left and one two feet in from the right side. 

There are 3 legs/floats/foils/wings/keels that provide the buoyancy, so it is a bit like a trimaran but with a very soft ride.
Each leg/wing will 14.5 feet long and have a NACA 0040 foil shape with 8.5 foot chord except that the last 0.5 feet of
the thinnest part will be cut short, so with foil does not come to a point at the trailing edge and fits within 8.9 feet
hight of container.  But the buoyancy is very close to that of an 8.5 foot chord foil.
Each of the 3 legs will be attached to the underside of the big triangle near one of the 3 points.
The center of the thickest part and going 1.5 feet in all directions from there will be within the area of the triangle,
but within that constraint, each leg will be as close to the point of the triangle as possible.
The legs will go down so that the lower half is in the water.
This makes for a bit of "small waterline area" similar like a small oil platform but one that can move through the water easier because of the foil shape.
It is not an extreme SWATH design as a 1 foot change in water level is about 1/7th of the total buoyancy, so still significant change.
The 3 legs will all be parallel with the blunt or "leading edge of the wing" side facing forward so it is lower drag when moving forward
than a typical cylinder on a semi-submersible platform.  
Each leg will be 50% under the water (so 0.5 * 14.5 feet) and the top 50% out of the water.
On the top half of the front of each leg, so the top half that is out of the water, will be a built in ladder.

The reason for these sizes for the triangle and legs is so they can pack into a container nicely and shipped to 
a shipyard anywhere for assembly.
Imagine the 3 legs end-to-end with thin/trailing-edge of foil up and leading edge down on the right side of the container.
So the right 3.4 feet of the container (width of legs) is used by the 3 legs.
Then the 3 frame/wall sections will be upright (so 7 feet high) next to each other along the left side of the container.  
I am not sure the width of the walls but if they were 10 inches wide then 3 widths is 30 inches and some extra is 3 feet on the left side.
There should still be lots of room in the center of the container for all the other parts.

Connecting the mid points of the walls both at floor and ceiling level will be structural beams that
make another triangle 22 feet on a side.  Then all the remaining spans will be less than 22 feet.
The rest of the floor and ceiling will be small pieces that are bolted in.

On top of the roof there will be solar all over.  With batteries and electric thrusters as the main propulsion system.

There will be 6 RIM drive thrusters of 1.5 foot diameter, one on each side of the 3 legs/wings about 2 feet up from the bottom.
These RIM drives will be all be fixed orientation to provide forward thrust.  It will use differential thrust to turn.
For slow movements in tight areas like harbors it can reverse thrust on one side and forward on the other to turn in place.

There will be a conduit/pipe welded to the back of the trailing edge to take electrical wires down to the thrusters.
There will not be any "through hulls" in the legs.  The legs will also have multiple
airtight compartments each for safety.


Behind the back near the center will be two supports going out and 2 ropes going down to a dinghy.
The dinghy is a 14 foot RIB boat (deflated for shipping) with an electric Yamaha HARMO outboard.  It is sideways against the center of the backside of the living area.
When the seastead is moving forward the dingy is shielded from the wind by the living area.

On the lower part of each leg will be several bolt on heave plates.  These will help dampen the response to waves.

About 25% of the displacement will be for LiPo4 batteries which will be put low in the 3 legs.
Each leg will have its own charge controller and inverter so there is triple redundant power on the seastead.
Also, the thrusters for a leg will get power from that leg's inverter or batteries.  So
the 3 pairs of thrusters will have independent failure modes as far as power.

When the seastead is going to be staying in one place for awhile, we can put down 3 helical mooring screws and give the seastead tension legs 
so it becomes nearly stationary when parked.  Near each corner there will be a pair of helical mooring screws with a motor unit between them.
We only plan to do this in the Caribbean where tides are very small and in protected places where the saves are small,
so pulling down 3 feet will be sufficient to never go slack.


Two seasteads will be able to connect together with a walkway, one behind the other, so that while underway 
people can move between seasteads, enabling a real community.  The two computers for the two seastead will both work thrusters
to minimize the movement of the walkway, particularly when warned that someone will be on it.





We will use Marine Aluminum.
The idea is the first seastead should be a a Minimal Viable Product, so just for 2 people. 

Estimate the total "installed watts" and the kwh per average Caribbean day.
How heavy would the batteries be and what kwh?  Assume the cost will be $90/kwh, what would the total cost be?
We would split this weight among the 3 floats, keeping weight wide increases rotational inertia
and so reduces motion from waves.  The weight of the triangle frame is widely spread so also has great rotational inertia.
If we used a days worth of average energy production evenly over a 24 hour period how many watts would we have?


Imagine we are in high winds and turn the seastead to point into the wind.  What sort of 
drag would we have for 20, 30, 40, 50 MPH winds and how many watts would it take for our
propellers to hold the seastead stationary?

Now imagine that we use the 3 legs like keels or dagger-boards and aim across the wind and just a little bit up.
How most of the wind force gets transferred to the wing/keel/dagger-board.
In this way how much wind do you think this design could still keep control in?

Now imagine there are very high winds and we are using the differential thrust from the thrusters
while "running from the storm"
mostly downwind but to the side maybe up to 20 degrees.  How high a wind do you
think this design could still have reasonable control?

For a normal day in the Caribbean estimate the average watts power draw of all electrical components.
How much percent extra solar power do we have?

If we use the "extra power" to run the thrusters what cruising speed could we maintain for 24 hours/day?

Imagine we get a company in China to make the body and legs, and probably get other parts from there as well.

Please estimate weight and cost for each of these:
 1) legs
 2) body
 4) 6 RIM drive thrusters
 6) solar panels 
 7) solar charge controllers 
 8) batteries
 9) inverters
 10) 2 water makers and water storage
 11) air conditioning (AC) - maybe 3 units for 3 rooms but only using 1 at a time 
 12) insulation
 13) flooring, cabinets, kitchen stuff, furniture, bathrooms, bedroom
 14) waste tanks
 15) glass and glass doors at ends
 16) refrigerator
 17) davit/crane/winch to lift dinghy out of the water
 18) safety equipment
 19) dinghy
 20) 2 sea anchors 
 21) kite for propulsion.  Can use as backup, fun, or extra speed - perhaps stack 20 kites of 6 foot each 
 22) 8 air bags in each leg so for extra safety in case of leak in leg
 23) 2 Starlink  - need a backup
 24) trash compactor
 25) 3 heave plates of 20 sq-ft each
 26) electric incinerating toilet
 27) anything else to finish it out

Also totals for weight and cost.  

Each leg with have 20 square feet of heave plate at the bottom.
Estimate the Natural Roll Period for tolling side to side and also for pitching front to back.
Estimate how much damping this shape gives per roll side to side and then also pitching front to back.

Please estimate for both 4 and 5 knots:
   1) how much the body would tip in terms of feet higher or lower between front and back of living area
   2) Gs felt due to waves in living area spot located at the center of the triangle 

for the following types of waves:
  1) 3 feet 3 second period
  2) 5 feet 5 second period
  3) 7 feet 7 second period

both if the wave is coming from the front and also if it is coming from the side.

What length catamaran would have comparable inside square footage to this seastead?
About how many times the cost would that catamaran be compared to this seastead?
Would you agree that this seastead will pitch and roll less in 7 foot waves than a 100 foot catamaran?


If we start with full batteries but on a very cloudy day with no solar, how much range could
this have at  3, 4, 5 MPH?   What if we start with full batteries on a typical Caribbean
sunrise and have solar?   What if there is 20 MPH wind and we are headed into the wind?

In flag of convenience countries like Panama and Liberia could we register this as a "trimaran yacht" or
would it be harder than that? 

FEEDBACK
Also feel free to give any general feedback on:
  1) viability of current concept as a profitable business product
  2) how concept might be improved
  3) how big a market niche this first product could become
  4) Do you think this is fast enough that with weather forecast accuracy in 2028 we should be reasonably
     safe from storms in the Caribbean if we are at the southern edge during hurricane season?
  5) Are there single points of failure that you think need to be further addressed or is what we have good?

Summary section.
  For a summary at the end please list:
    1) estimated total cost for first unit and cost each if we ordered 20
    2) average solar produced, average solar used not counting propulsion, average power left for propulsion
    3) lbs extra buoyancy for customers and their personal stuff
    4) speed in MPH this design can average 24/7 in Caribbean