We are working on a seastead design that will have a 40 by 16 foot living area above the water.
There will be 4 foot diameter legs/floats/columns that are about 24 feet long going out from 
from the 4 corners of living area and down into the water at 45 degrees, with half of
each column under water.   The legs/floats/columns will probably be made from 1/4 inch
thick duplex stainless steel on the sides and 1/2 inch thick on the dished ends.
They will have some modest pressure like 10 psi inside.

The bottoms of the floats will make a rectangle about 50 feet wide and 74 long.
From the bottom of each leg there will be 2 cables going to the adjacent corners.
The boyancy force is lifting up and the leg pushing against the platform leaves an outward
force that the 2 cables pulling in counter, so the leg ends up staying in place.
There will also be a cable making a rectangle between the bottoms of all the legs so we have some
redundancy in case one cable breaks.
The seastead is about 36,000 lbs I think but this is NOT a normal boat hull shape,
it is more like a tiny oil platform as far as drag.

We expect to use 4 low speed submersible mixers with 2.5 meter diameter propellers as 
thrusters, one on each leg/float.  There will be lots of solar and battery.
This should move at around 0.5 to 1 MPH plus any help from careful use of eddies and currents.





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?