We are working on a seastead design.

Above the water there will be a big triangle frame.  The
left and right sides will be 70 feet long and the back part of the triangle will be 35 feet wide.
The point opposite the 35 ft side is the front.
The triangle frame will be a truss structure that is 7 feet high (floor to ceiling).
It will be enclosed and the whole inside the living area.  Lots of glass to see out.

There are 3 legs/floats/foils/wings that provide the buoyancy, so it is a bit like a trimaran but with a very soft ride.
Each leg/wing will 19 feet long and have a NACA 0030 foil shape with 10 foot chord and 3 foot width.
Each of the 3 legs will be attached to the underside of the big triangle near one of the 3 points (but the total top of the
leg will be inside the triangle) and going down so that the lower half is in the water.
This makes for a "small waterline area" similar like a small oil platform but one that can move through the water easier because of the foil shape.
The 3 legs will all be parallel with the blunt or "leading edge of the wing" side facing forward so it is low drag for the seastead to move forward.
Each leg will be 50% under the water (so 0.5 * 19 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.

There will be 6 RIM drive thrusters of 1.5 foot diameter, one on each side of the 3 legs/wings about 3 feet up from the bottom.
These RIM drives will have the flat sides toward the front and back of the seastead.

On top of the roof there will be solar all over.

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 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.
Also behind the back on the left and right of the dinghy will be a deck that is 5 feet wide extending beyond the back of the triangle.

There are 3 stabilizers that look like a little airplanes, one attached near the back of each main seastead leg.  
The little airplane has a 12 foot wing-span, 1.5 foot chord, the body 6 feet long, and the elevator has a 2 foot wing-span and 6 inch chord. 
A small actuator makes the elevator angle up or down so it can adjust the angle of 
attack of the main wing of this stabilizer without needing a large actuator.
This is really the "servo tab" idea.
While the thick part of the leg is 3 feet wide the back where the airplane will attach is very thin.  And to get the airplane's
center of lift to balance on the pivot a notch into the front/center of the wing only has to go about 25% of the chord of the wing.

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.

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.   






In really high winds the differential thrust will eventually not be sufficient control.  

Think we 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?

We would like to move like 6 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?


Another idea is to just let the wind push the seastead faster and use the stabilizers
to lift up, not just stabilizer, a bit more like a hydrofoil.  The the legs and stabilizers be lots of drag at high 
speeds, and the stabilizers will have huge control at that point, so maybe a drogue is not so needed.  
Even if we just had half the weight on the foils
it could drop the resistance from the legs and make going fast work reasonably well.
How big would each of the stabilizer wings need to be to take half the seastead weight at 12 knots?
How thick would the stabilizers need to be to handle the forces from going fast?  
Please analyze this possible method of running from storms and see if something along
these lines could be reasonable.

We are planning to have the bottom of each leg sloped such that when moving fast they
provide some lift as well.  The very bottom of each leg becomes a bit like a water-ski, though way underwater.
At slow speeds it will not make any difference.  At 12+ knots it should contribute significant lift.

Also, 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.