I am working on a tensegrity seastead design.  As part of this there are floats/columns/legs
that are partway in the water and partway out of the water supporting a living structure.
So far I have had these as 30 feet long and 3.9 foot diameter.  This lets me fit 3 or 4
in a normal 40 foot container for shipping.  There are cables that attach to the bottom
of the leg and the combination of pushing on the body, the buoyancy force, and the cables
hold the leg in position.

The only downside is that the leg is not as hydrodynamic as it might be.  If it were
more of an airfoil / wing shape it could move through the water easier.  Probably shorten the chord 
and have thicker wing than normal airplane style was we are trying to get a certain
amount of buoyancy.

If we were to make a wing shape (with the same volume) and stack them such that the front and back of the
wings alternated left and right we could still fit them in a 40 foot container.

Even a "stadium" profile (rectangle with half circles for font and back edges) could move through the water easier
than the cylinder shape (not a full wing shape but closer to that than a cylinder is).

We have thought about using Duplex Stainless Steel or Marine Aluminum and having the
legs made in China / South Korea / Vietnam. 

Cost is important for this seastead (we aim to be both more stable than a yacht
and lower cost per square foot of living space than a yacht while
going slower than a yacht).  We will be solar powered so not being hydrodynamic
means we go slower, not really burning more fuel.

We plan to use two 2.5 meter diameter submersible mixers as electric thrusters.

Kamm-Tail Teardrop features a blunt semi-circular front, tapering back like an airfoil, but the sharp trailing edge 
is chopped off and replaced with a smaller radius semi-circular back edge. It provides 90% of the benefits of an airfoil 
but is shorter, structurally stronger, and easier to manufacture.  Maybe 3.10 wide and 4.90 ft chord.

Please try to estimate the costs of making these legs in different shapes like
  1) cylinder
  2) airfoil
  3) stadium 
  4) ellipse
  5) lenticular
  6) Ovate  - maybe 3.2 ft wide by 4.5 ft long
  7) Kamm-Tail Teardrop
  6) something else more hydrodynamic than the cylinders but also 30 feet long and the same volume

Estimate weight and costs for both for duplex stainless steel and marine aluminum.
Also estimate the drag per leg of each leg type with half the leg in the water and moving at
1 MPH, 1.5 MPH, and 2 MPH. 
Also  estimate the electrical wattage needed if the seastead has 4 legs for each type for each of these speeds.
Also estimate how many legs of each type can fit in a 40 foot container.

The legs need to have hard points on the ends.
When held at the ends they need to handle being pushed through the water in any direction at 4 MPH without buckling.

We have thought some about having a small internal pressure on the cylinders, maybe 10 PSI, to make
it stronger against buckling and to make it easy to detect leaks.  It seems like this might also work with 
the ellipse and lenticula shapes.  Do you agree?