Engineering Estimates & Performance Analysis
40ft triangular aluminum platform • 3× NACA foil legs • 11.4 kW solar • 6× rim-drive thrusters
Living Area Roof: 12 ft × 24 ft = 288 sq ft
Two fold-down wings: 2 × (8 ft × 24 ft) = 384 sq ft
672 sq ft total solar
11.4 kW installed
(17 watts per sq ft installed — marine-grade panels with 18% efficiency + losses)
| Component | Estimate | Notes |
|---|---|---|
| Triangle frame (aluminum box beams) | 1,200 lbs | 3 × 40 ft sides |
| 3× NACA legs (marine aluminum, 1/4"–3/8" skin + internal framing) | 8,800 lbs | 19 ft tall, 10 ft chord, 2 ft thick |
| Living structure (12×24×8 ft aluminum with windows) | 4,500 lbs | Includes framing, roof, doors |
| Netting, railings, davit, misc | 2,000 lbs | Conservative |
| Total Structure Weight | 16,500 lbs |
Buoyancy at 50% submersion (9.5 ft draft):
29,184 lbs
(Cross section ≈ 16 sq ft per leg × 9.5 ft × 3 legs × 64 lb/cu ft seawater)
Extra buoyancy after structure: 12,684 lbs
Available for batteries, solar panels, RIB, davit, people, stores, etc.
One per leg (3 total). Mounted on trailing edge. Small linear actuator controls tail angle to adjust main wing AoA. Only ~25% of wing chord notched into leg.
| Parameter | Estimate | Notes |
|---|---|---|
| Wing area per stabilizer | 18 sq ft (6 ft span × 3 ft chord) | NACA 0015 foil, marine aluminum |
| Lift force at 5 knots (Cl = 1.0) | ≈ 1,050 lbs | Sufficient to counter 1 ft of heave buoyancy change |
| Estimated cost per unit (batch of 20 seasteads = 60 units) | $2,850 | Fabricated in China including actuator |
| Weight per unit | 68 lbs | Complete with actuator and pivot |
Wave reduction capability: A stabilizer that can remove 1 ft from the crest and 1 ft from the trough turns a 4 ft wave into roughly a 2 ft felt wave.
6× rim-drive thrusters (2 per leg). Estimates include appendage drag from legs and stabilizers.
| Speed | Propulsion Power | Total Power (with 1 kW hotel load) | Hours on 4000 lb LiFePO4 | Range (nautical miles) | Stabilizer Effect |
|---|---|---|---|---|---|
| 4 knots | 2.1 kW | 3.1 kW | 57 hours | 228 nm | ≈ 0.9 ft crest/trough reduction |
| 5 knots | 3.8 kW | 4.8 kW | 37 hours | 185 nm | ≈ 1.4 ft crest/trough reduction |
| 6 knots | 6.4 kW | 7.4 kW | 24 hours | 144 nm | ≈ 2.1 ft crest/trough reduction |
Battery assumption: 4000 lbs LiFePO4 ≈ 220 kWh nominal, 176 kWh usable (80% DoD). Stabilizers add ~300–600W depending on sea state.
Average solar harvest (Caribbean): 5.5 peak sun hours/day
2,650 W
continuous average power
After 1,000 W base load → 1,650 W available for propulsion
Sustainable speed: ≈ 4.1 knots
Extra power for actuators & control: ~450 W average
2,200 W
continuous average power
After 1,000 W base load → 1,200 W available for propulsion
Sustainable speed: ≈ 3.7 knots
| Wave Height | 4 knots | 5 knots | 6 knots |
|---|---|---|---|
| 3 ft waves | 0.6–0.9 ft motion | 0.5–0.7 ft | 0.4–0.6 ft |
| 4 ft waves | 0.9–1.3 ft motion | 0.7–1.0 ft | 0.6–0.8 ft |
| 5 ft waves | 1.2–1.7 ft motion | 0.9–1.3 ft | 0.8–1.1 ft |
SWATH design already reduces motion significantly. Active stabilizers further reduce felt motion by 45–65% depending on speed and sea state.
| Item | One Unit | Batch of 20 |
|---|---|---|
| Aluminum structure + legs + living area | $68,000 | $41,000 |
| Solar array + controllers (11.4 kW) | $19,500 | $12,800 |
| 6× Rim-drive thrusters + electronics | $21,000 | $13,500 |
| 3× Active stabilizers + actuators | $8,550 | $5,200 |
| 4000 lb LiFePO4 battery bank | $26,000 | $18,500 |
| 14 ft RIB + 30 hp outboard + davit | $18,500 | $16,000 |
| Interior, windows, electrical, misc | $24,000 | $17,000 |
| TOTAL PER SEASTEAD | $185,550 | $124,000 |
⚠️ These are rough order-of-magnitude estimates (Q3 2025 pricing). Tooling, certification, shipping, and profit margin not included.