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.   





Now imagine that the top of the tailing on the port and starboard sides and curving around the front between them is 
has something like the top of an I-beam and that a little robot with 4 grooved wheels that can move along while flying 
a 2 string kite stack.  With proper control the kite can pull
off to the side of downwind.  If the robot moves toward the front of the seastead it can pull that more downwind,
and if it moves toward the back it can pull that part downwind, much like a windsurfer leaning the sail forward or backward to turn.
The 3 floats/legs/wings will act like 3 giant dagger-boards.  So if the robot can tack to gradually go upwind and
easily go to the side or downwind, like a sailboat.   This kite robot is completely independent of the
normal thruster method of control and propulsion, so it has independent failure modes and so would be a great 
backup propulsion system. 

We will have 3 electrical power systems and we could run an extension cord from any that was working
to the kite robot.  It might be fun though to have the robot have batteries that could charge from having the kite
pull it back and forth along the track (though this is more costly and complicated than a power cord). 

The kite will always fly on the downwind side of the seastead so the kite ropes will not go near the living area structure
but out over the open water side of the railing.

The track for the kite robot will curve around inside the point at the front of the seastead enough that there is room on the other side for a 
person.  The kites will really be "stack of kites" where the individual kites can be attached or detached quickly (maybe 20 to 50 kites).  
The robot will fly directly above while 
aiming the seastead downwind so there is minimal movement and pull from the kites when person attaching or detaching the kites.

If the kite stack is very powerful it will cause significant lean.  We could use the stabilizers to combat this and 
also limit the number of kites in the stack so the lean was acceptable.

Do RIM drives have a "spin freely" mode to reduce the drag from them?

What do you think of the kite idea?