Seastead Wind Energy & Drag Analysis

Based on the parameters of your 36,000 lb seastead, the 45-degree angle columns, and the maximum thrust of 2,880 lbs from your 4 submersible mixers, here is an engineering and practical breakdown of incorporating 1000-watt wind turbines.

1. The Push (Drag) of a 1000W Turbine

To generate a true 1000 electrical watts in 20 mph (8.9 m/s) winds, physics dictates you need a rotor diameter of at least 10 feet (~3 meters). Small turbines extract energy by slowing down the wind, which inherently creates aerodynamic drag (thrust load) on your structure.

Drag per turbine at 20 mph: Approximately 65 to 75 lbs of push force.
Total drag for 4 turbines at 20 mph: Approximately 260 to 300 lbs.
Impact on Propulsion: Your mixers provide a max thrust of 2880 lbs. Going directly upwind in 20 mph winds, the 4 wind turbines would consume roughly 10% of your max thrust capability due to drag. Going downwind, they act as sails and provide roughly 300 lbs of free forward push.

2. Feathering and Drag Reduction

Can you get turbines that fold or feather to reduce drag?

True folding blades: Extremely rare in wind turbines (unlike sailboat propellers) because the centrifugal force makes it mechanically complex to fold them while spinning.
Mechanical Furling: Most 1kW turbines use a "furling tail." In high winds, the tail hinges, turning the blades sideways to the wind. This drops drag significantly.
Electromagnetic Braking: Standard marine turbines come with a switch that shorts the stator, electronically locking/slowing the blades to a crawl. However, a locked 10-foot rotor still creates the aerodynamic drag equivalent of a solid disc about 1/3 its size.

3. Cost & Weight (Sourced from China)

Warning: Many Chinese sellers aggressively overstate wattage. A physical turbine small enough to be "lightweight" will realistically only output 300W-400W at 20mph, regardless of the "1000W" sticker. To get a true 1000W turbine, you are looking at substantial hardware.

Weight: A true 1000W marine turbine head (generator + hub + blades) weighs between 60 to 90 lbs. (Total payload of 4 would be ~300 lbs, not counting steel mounting masts).
Cost: True 1kW marine-grade units from reputable Chinese suppliers (like Sunning or similar) cost roughly $600 to $900 each. Add charge controllers and dump loads, and you should budget about $3,000 to $4,000 total for four setups.

4. Marine Lifespan & Reliability

The Caribbean salt, humidity, and occasional squalls are brutal on moving parts.

Quality Marine Brands (e.g., Silentwind, Primus Air): Last 10-15 years, requiring blade replacement and bearing repacking every 4-5 years.
Standard Chinese Imports: Typically last 2 to 4 years before saltwater breaches the generator seals, bearings rust and seize, or UV degradation ruins the blades. Applying Boeshield T-9 to components before installation can extend this slightly.

To answer your question directly: Yes, windmills break much faster than solid-state systems like solar. They require regular maintenance and their failure rate will be a nuisance compared to solar arrays.

5. The Noise Factor

Small wind turbines generate two types of noise: aerodynamic "whoosh/chop" and mechanical alternator whine.

Vibration Isolation: Your plan to use rubber isolation mounts between the legs and the living cabin is excellent. This will effectively kill the low-frequency mechanical hum transmitting through the hull.
Airborne Noise: You cannot isolate aerodynamic noise. Four 10-foot rotors spinning at 400+ RPM near a 40x16 foot living space will sound like a loud, persistent localized storm. In 20 mph winds, conversation near the exterior will be difficult, and light sleepers inside may be disturbed.

Recommendations & Conclusion

Should you use 4 turbines?

No. Four 1000W turbines are overkill, too noisy, too maintenance-heavy, and create a cluttered aesthetic. Furthermore, mounting 90-pound vibrating turbines on tall masts at the ends of 45-degree angled legs creates massive lever-arm (bending moment) stresses on your underwater columns during a storm.

Should you go larger?

No. A single turbine larger than 1000W introduces severe gyroscopic forces that make mounting on small platforms dangerous in high seas.

The Ideal Solution: Just 1 (or 2 small ones) as Backup

Lean heavily on solar. Solar panels create zero noise, zero moving parts, and have zero active maintenance. They lay flat (low drag) and are highly reliable. Invest the money you would spend on 4 turbines into more LiFePO4 batteries.
Install exactly ONE high-quality marine wind turbine. Scale down to a premium 400W-600W marine turbine (like a Silentwind or Primus Air Breeze). Mount it on an independent, heavily braced mast at the aft or rear corner of the seastead.
Purpose: Use this single turbine strictly to trickle-charge batteries during long, cloudy, multi-day tropical depressions, and to run passive nighttime loads (refrigeration, anchor lights, sensors).