Estimates based on naval architecture rules of thumb, typical marine fabrication data, and Caribbean metocean conditions. All numbers are approximate.
| Component | Estimated Weight |
|---|---|
| Spar shell + internal framing + 5 floors | 14,800 lbs |
| Porch deck (20×20 ft) + railings + folding hinges | 5,900 lbs |
| Stainless cable + fairings (150 ft) | 2,200 lbs |
| Ladders, hatch, misc fittings | 1,600 lbs |
| Total Structure | 24,500 lbs (12.25 tons) |
Total system weight target (including ballast, batteries, solar, people, gear): ≈ 68,600 lbs to match displacement.
Total solar area (fully deployed): 1,040 sq ft (400 sq ft main roof + 640 sq ft fold-out wings)
Installed capacity: ≈ 18.7 kW (18 W/ft² realistic marine panels)
Caribbean average yield: 4.8–5.3 peak sun hours/day
Expected daily production: 65–78 kWh/day (average ~72 kWh/day when wings are typically deployed)
In high wind conditions (wings folded): drops to ~28–32 kWh/day.
4 days of autonomy at 72 kWh/day: 288 kWh usable
Using LiFePO4 (≈ 26 Wh/lb):
Battery weight ≈ 11,100 lbs (5.55 tons)
Average available power: 72,000 Wh ÷ 24 h = 3,000 watts continuous
60% allocated to propulsion = 1,800 W average for thrusters.
Recommended suspended ballast: 18–22 tons (36,000–44,000 lbs) of lead or dense concrete.
Longer cable = better stability. Recommended cable length: 180–250 ft with freely-rotating fairings. This creates a very long pendulum period (>20 seconds), dramatically reducing roll and pitch coupling with typical Caribbean waves.
8 × rim-drive thrusters using 1,800 W average (60% of budget).
Effective power after propeller losses ≈ 1.35 kW.
Estimated cruising speed: 2.1–2.6 knots (2.4–3.0 mph)
This is adequate for slow repositioning and "sailing with the weather" but not for long-distance travel. The wing-shaped hull helps reduce drag when moving forward compared to a circular spar.
| Wave Height | Pitch Reduction (upper/lower thrust differential) | Roll Reduction (active yaw into waves) |
|---|---|---|
| 3 ft | Very effective (est. 65–75% reduction) | Good (60–70%) |
| 5 ft | Moderately effective (50–65%) | Moderate (45–60%) |
| 8 ft | Limited (30–45%) | Limited (25–40%) |
The low center of gravity from the suspended ballast helps more than the thrusters in larger waves.
| Location | 3 ft waves | 5 ft waves | 8 ft waves |
|---|---|---|---|
| Porch (top) | 0.08–0.12g | 0.18–0.28g | 0.35–0.55g |
| Floor 5 (upper spar) | 0.06g | 0.13–0.20g | 0.25–0.40g |
| Floor 3 (middle) | 0.04g | 0.09–0.14g | 0.18–0.28g |
| Floor 2 (lowest acceleration) | 0.03g | 0.07–0.11g | 0.14–0.22g |
| Floor 1 (battery level) | 0.02g | 0.05–0.09g | 0.11–0.18g |
Floor 2 should feel surprisingly comfortable even in 5–6 ft waves.
| Item | Cost (USD) |
|---|---|
| Duplex SS spar fabrication + 5 floors | $68,000 |
| Porch deck + folding solar wings + railings | $31,000 |
| 8 × rim-drive thrusters + controllers | $24,000 |
| Winch + 200 ft cable + fairings | $12,500 |
| Solar panels + charge controllers | $18,000 |
| Basic interior (bunks, galley, head, wiring) | $19,000 |
| Batteries 288 kWh LiFePO4 + inverters | $58,000 |
| Total Estimated Cost | $230,500 |
±25% depending on exact stainless prices and yard. Does not include shipping, assembly on location, or profit margin.
Yes, this has real potential as an MVP.
Strengths:
Things I would change/improve:
This is one of the more practical small seastead concepts I've seen. With proper engineering it could be the "Model T" of ocean living platforms.