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 are really trying to get a lot of solar area, living area, and stability for the weight of the design.
The idea is that costs basically scales with weight.  For stability a small waterline area helps
reduce the impact of the waves and make the stabilizer have a bigger impact.  However, the longer
the legs go into the water the more drag they have, and the slower we will go, and so the
less impact the stabilizer will have.

Please make and run a program or spreadsheet that helps search for optimal tradeoffs between leg length,
waterline area, speed, wave response, and stabilizer effectiveness.  We will tay with the 
size and weight of the above, and the 3 legs.   

We want a table that show what different length/width legs do to stability, cost, and speed.  
And that smaller waterline makes the seastead move less so there is less motion for the stabilizer to get rid of.

It should take into account that the stabilizer works better when going faster.
The force the stabilizer produces depends on the size and the speed.  Then sort of convert
this to feet of stability influence by taking how many feet (or part of a foot) that much force is
for the waterline area and 64 lbs/cubic-ft of seawater.


Please make an interactive html spreadsheet where I can set the values for:
  
Electric Pow to RIMs (Watts - default 10,000)
RIM Efficiency (% - default 40%)
Wave Peak-to-Trough(ft)   (default 5)
Wave Period (s)      (default 5)
Stabilizer wingspang  (ft)  (default 10)
Stabilizer chord  (ft)      (default 1)
Stabilizer Lift Coefficient (CL)  (default 1)


Then for these 3 Leg profiles:
Leg Profile 	Dimensions (Total L, Draft, Chord, Width) 	
   NACA 0040               (keep 10 foot chord and calculate with same volume))
   NACA 0030                 39,  19.5,  10,  3    (baseline)
   NACA 0025               (keep 10 foot chord and calculate with same volume)

I want a simplified model/calculation for wave response.  Lets assume we are stationary to start and just look at the top half of the wave.
So for a 5 foot wave just the water going up an extra 2.5 feet over that part of the wave period (about 1/4th of the total wave period).
Then after we know how much the leg would move without the stabilizer can subtract out what the stabilizer can remove and get a net motion.
So in the 2.5 feet of wave maybe the leg without stabilizer goes up 1.5 feet and the stabilizer subtracts 0.5 feet for a net movement of 1 foot.
The Column headers in the table should be something like the following info:


Waterplane Area (Total Sq Ft) 	

Restoring Force (Lbs per ft water height ) 	

Est. Speed useing  10kW power (Knots) 	

Heave without stabilizer in ft for 5 foot wave (in ft)

Stab Force   (Total Lbs) 	

Stab Influence (Ft Equivalent) 	

Heave WITH Stabizer included, (Final Motion)

Estimated weight of each leg in Marine Aluminum

Estimated cost of 1 leg and 1 stabilizer in Marine Aluminum