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 wide 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, which half of
each column under water.   The bottoms of the floats will make a rectangle about 50 feet wide and 74 long.
From the bottom of each column there will be 
2 cables going to the adjacent corners to hold it in place.
There will also be a cable making a rectangle between the bottoms of all the floats 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 2.5 meter diameter propellers on 4 low speed submersible mixers and solar power to move
at around 0.5 to 1 MPH plus planning to get help from using eddies.  These each can do 720 lbs thrust on 3.2 kw and even
more efficient at lower power levels (so 4 is 2880 lbs thrust and 12.8 kw max).

The question I would like you to look at is if some small windmills to make electricity might make sense.
Our first target market is the Caribbean which usually does have wind.  The extra drag from windmills
would require even more thrust when going upwind but be a help if going downwind.  

I am thinking of a windmill that produces 1000 watts in 20 mph winds.  What would peak rating be for such a unit?
What sort of diameter blade?  What sort of push would that have on the seastead in 20 mph winds and 1000 watt power?

Can we get ones where the blades can be feathered or folded back when not in use so it does not add too much drag?

How long would marine style windmills they last on a yacht? (salt from ocean environment is hard on moving thing)

What would 4 such windmill cost? (assume we source marine/feathering/1000-watt ones from China)  

And what would they weigh? (use lbs)

We could mount one windmill above each leg/float and the legs/floats will have some rubber between them and
the main cabin, so vibration noise transmitting through the structure would have some isolation.

How bad would the noise be for people in the seastead?

What do you recommend?   Is 4 of this size reasonable?  Should be go even larger?  
Should we just have 1 in case it is cloudy for too long for our solar?
Do windmills break so much faster than everything else we will be using that they will be annoying?