We are working on a seastead design.
This is NOT a normal boat hull shape, but it is a bit like a trimaran in that their are 3 floats.


Above the water there will be a big triangle frame, 80 feet front to back and 40 feet wide.
The triangle frame will be a sort of truss structure that also doubles as a 4 foot high railing to keep humans from falling off.
We will call the 3 points on the triangle "front", "left", and "right".
And the edge between left and right we will call "back".

There will be a floor and roof/ceiling (7 foot inside) the full area of the triangle.
The enclosed living space will be 14 feet wide and 45 long on the centerline but one edge close to the back.
There covered area around the living space make an open porch.  
The living area will have lots of windows in the font and back and some along the side.    

There will be 3 floats/legs/wings that will be the buoyancy.
Each leg/wing will 19 feet long and have a NACA foil shape with 10 foot chord and 3 foot width.
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.
Each of the 3 legs will be attached to the underside of the big triangle near one of the 3 points and going down into the water.
The 3 wings will all be parallel with the blunt or "leading edge of the wing" forward  so it is easy 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 front of each leg on the top half that is out of the water will be a built in ladder.

There will be 6 RIM drive thrusters, one on each side of the legs/wings about 3 feet up from the bottom.
These will be aimed so they can push water past the wing and toward the back of the seastead.

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

Behind the living area will be two supports going over the railing and 2 ropes going down to a dinghy that
is a 14 foot RIB boat with 1 outboard motor that is sideways against the other side of the railing.   
When the seastead is moving the dingy will not feel the wind as the living area will block it.

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 10 foot wing-span, 1 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.
While the thick part of the leg is 4 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.








Around the bottom of the living area we are planning to have a strong frame.
If we make the legs and frame out of duplex stainess steel it might be reasonable to make them
so they bolt on and do not need any cables (so not tensegrity).  I worry that the long legs
might be such a long lever that the stresses at the joint are hard to handle.  
We want to be able to get it fabricated in China and the parts shipped to the Caribbean
and assembled here.  So we want to be able to bolt the frame together and then maybe bolt
the legs on.

Please try to analize the stresses on the joint if the legs were just bolted on and there were no
cables.  How strong a frame would be needed?
Could this work or should we stick with the cables?

If we can get rid of the cables it has some advantages:
   1) Less drag moving through the water
   2) Less to clean / inspect / maintain / replace
   3) No problem with cable vibrations that people might feel or hear

How does the weight and cost of the seastead compare with the cable and no cable versions?