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.





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.