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.   





I am thinking to have a dingy,  a tender, and a canister liferaft.
Probably they only have to hold 4 or 6 people.
We are only going to be in the Caribbean and not in the hurricane season.

I think the Chinese boats have very good prices.

For the dingy I am thinking 14 foot (some places get bothered if your dingy is larger) with a 
Yamaha Harmo electric motor.   We can charge the dingy battery from the seastead solar so
not have to worry about running out of fuel for this.

It would also be good to have a tender that was bigger and could go 
further and faster and handle the open ocean better.

In Anguilla most people think a boat going into the open ocean should have two engines,
in case one breaks.   So two smaller outboards on the tender seems better than one large one.

If we are still 10 miles from an island and the weather is nice some people might hop
into the tender and go ahead to visit the island when the seastead was still going to
take another 10 hours at 1 MPH to get there.

Or of someone needed medical attention, something faster would be good to have.

If there was a storm coming that the seastead could not move fast enough to avoid we could 
get into this tender/lifeboat and head to some safe location.   Then the seastead
could be controlled remotely and hopefully make it through the storm and then we go 
back to it.

So the tender has somewhat of a survival function as well.  

Now we are hoping to have the whole seastead sell for maybe $500,000 or $600,000 so 
we are trying to keep costs down.

What would you recommend as far as:
   1) dingy 
   2) tender
   3) liferaft

Please explain the choices, give costs, weights, speeds, and links.