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.   





We would like to be able to put in and out 3 helical mooring screws to be able to experiment with 
having the seastead be a tension leg structure when parked.   We are looking at a prototype 1/2 scale version 
of the above seastead (so 1/8th the weight) but also want a system that works for the full scale.

The design goal for the prototype is a 1000 lbs working load on each of 3 screws.
Lets say 8 feet of water for the prototype.

For the full scale more like 5000 to 8000 lbs and up to 16 feet of water.

The seastead has lots of solar and so we prefer to use electrical powered equipment.
And an electrical motor that can drive the screw at a higher RPM so we finish faster
is probably justified, as some seastead users may want to relocate often.

I want you to help me work on a reasonably low cost and easy method.
Some seasteads may only relocate every 3 months on average, but some may relocate every week or even every day.
It may be that the ones that relocate often might do regular anchoring and not tension leg if it takes too long.

For the prototype single helix 6 inch diameter mooring screws with 8 feet long shaft (so say 7 feet into the sand)
seem strong enough.  For the full scale probably 12 inch diameter and 12 foot shaft can work.

If we have a modular helix mooring system with an above water torquing device it seems we might keep
the costs down and still be reasonably fast.   It could limit us to reasonably shallow water but that is fine, 
at least to start.

The seastead will be able to hold position using GPS and thrusters, and it is big enough that it will be able
to counter the torque from a torquing device (at least for the helix diameters above).  

It seems you could have one section on top of the mooring screw so that the above water torquing device
could spin the screw in and then detach that after it was down and use it on the next screw.

Since the helix will be going into and out of the sand much more often than a typical mooring, we
would like a stainless steel one and not just normal steel with a coating that could wear off.

For pricing estimates, assume we are buying parts from or having parts made in China.

For both the prototype size and for the full scale please describe:
  1)  The parts of the system and their cost
  2)  The procedure for installation and removal and how long the steps would take