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.




If a storm is coming we might want to use a kite to move fast long before the storm is 
near.  This might be a one-string-kite but the keel/legs would let us go some off downwind,
or a two-string-kite and we could have lots of flexibility about which direction we ran.

In really high winds (no kite) the differential thrust will eventually not be sufficient to
go into or across the wind, and we will need to run downwind.
For some level of wind the thrusters and stabilizers will be able to give reasonably control while
running downwind.  As the wind pushes the seastead faster the legs will give much more drag
and the stabilizers will have more control.  The stabilizers can give more drag if we deliberatly
use them to lift up the seastead, not just stabilize, a bit more like a hydrofoil.
How fast might this approach be reasonable?
How thick would the stabilizers need to be to handle the forces from going that fast?  


At some point the wind is probably too high for even just the thrusters and stabilizers
and we will want "trailing drogue on a sliding bridle" or "drogue with adjustable bridle".
We will have a winches at the two back corners each with ropes going out to the drogue.
Then you can let out or in either winch to adjust things.
This lets us adjust the angle the drogue will aim the seastead off of directly downwind. 
How far a range to the left and right of downwind do
you think it could get?  The 3 legs will act like giant keels or daggerboards
and mostly we will move in the direction they are pointing.   With this it seems like we could have
reasonable control even in rather bad situations.  How well do you think this would work?

Say we would like to move like 5 knots even with drogue out so we can try to get out of the way of the
storm.  What size drogues would be good for that kind of speed in 30, 40, 50, and 60 mph winds?

It would be best to have a system where we could adjust the drogue drag level on the fly.
Something like the Jordan Series Drogue could be interesting if we could pull in the 
collapse line to disable some or let it out more to enable more of the cones.
Is this in the right range for our needs?  Or is there something like this that is
adjustable and in the right range for our application?

What about Galerider-style perforated drogues, do they come in the range we would want?

I heard of Adjustable drogue that is a heavy-duty parachute/basket drogue with a collapse line (purse-string) 
lets you vary the open diameter on the fly.   This sounds great.  Could one work for the range we need?

Please analyze these possible methods of running from storms and see when each could be reasonable.
If you have other thoughts on this topic please share them.