Design Overview
Your seastead design is innovative, featuring three wing-shaped floats (NACA foil profiles) providing buoyancy for a triangular platform. Each leg is 19 ft long with a 10 ft chord and 3 ft width, partially submerged (50%). The design aims to combine spacious living area, solar power capacity, and efficient movement through water.
Unique Aspects:
- Wing-shaped legs: NACA foil profiles instead of traditional cylindrical floats
- Small waterline area: Only 50% of each leg submerged (9.5 ft)
- Parallel orientation: All legs aligned with "leading edge" forward for streamlined movement
- Active stabilizers: Mini "airplane" stabilizers on each leg with adjustable elevators
- Multiple thrusters: 6 RIM-drive thrusters for propulsion and maneuverability
Drag Coefficient Estimation
The wing-shaped legs have a chord length of 10 ft and thickness of 3 ft, resulting in a thickness-to-chord ratio of 0.3. This is significantly "fatter" than typical NACA airfoils used for aviation (usually 0.12-0.18).
Estimated Drag Coefficients:
- Wing-shaped leg (NACA-like, thickness/chord=0.3): Drag coefficient (Cd) ≈ 0.04-0.06 at low speeds (4-6 knots)
- Round cylinder of similar volume: Cd ≈ 0.8-1.0 for smooth flow, potentially higher with turbulence
- Comparison: The wing-shaped leg should have 5-15% of the drag of a round cylinder with similar frontal area
Sample Calculation at 6 knots:
Velocity: 6 knots = 3.09 m/s ≈ 10.1 ft/s
Frontal area per leg (submerged portion): ~30 ft² (3 ft width × 10 ft chord)
Water density: 62.4 lb/ft³
Drag force per leg ≈ 0.5 × Cd × ρ × Area × Velocity²
With Cd=0.05: Drag ≈ 0.5 × 0.05 × 62.4 × 30 × (10.1)² ≈ 480 lbs per leg
Total for 3 legs: ~1440 lbs drag at 6 knots
Comparison to Traditional Hulls
| Vessel Type | Similar Length (80 ft) | Similar Weight | Estimated Drag at 6 knots | Notes |
|---|---|---|---|---|
| Your Seastead (3 wing legs) | Platform: 80 ft × 40 ft | ~20-30 tons (estimated) | ~1400-2000 lbs | Low drag due to streamlined legs; wave-making drag minimal at low speed |
| Trawler (displacement hull) | 80 ft length | ~40-60 tons | ~4000-8000 lbs | High wetted surface area; significant wave-making drag even at low speeds |
| Catamaran (two hulls) | 80 ft length | ~20-30 tons | ~2000-3500 lbs | Lower drag than monohull but still substantial wetted area |
| Round cylinder floats (comparison) | Same volume as your legs | Same buoyancy | ~8000-12000 lbs | High drag due to blunt shape and separation drag |
Historical Context & Innovation
I have not seen this exact combination implemented before. The concept merges:
- Semi-submersible platform technology: Used in offshore oil rigs for stability
- Small waterline area (SWA) vessels: Like SWATH ships, which minimize wave response
- Streamlined struts: Similar to racing yacht foils but applied as primary buoyancy elements
- Mobile seastead: Unlike stationary platforms, designed for propulsion
The most similar existing concepts might be:
- SWATH ships: Have submerged hulls with streamlined struts, but struts are typically not the primary buoyancy elements
- Some trimaran designs: Use narrower floats but not typically wing-shaped
- Foiling vessels: Use hydrofoils for lift but not as stationary buoyancy providers
Conclusion
Your wing-shaped leg design offers a significant drag reduction compared to traditional cylindrical floats—likely 5-10 times less drag at low speeds (4-6 knots). Compared to a similar length trawler or catamaran, your seastead should experience approximately 50-70% less drag at these speeds, primarily due to:
- Small wetted surface area (only half of each leg submerged)
- Streamlined shape that minimizes flow separation
- Alignment with direction of travel (all legs parallel)
This low-drag design enables efficient movement with relatively low-powered thrusters, potentially allowing for solar-electric propulsion. The combination of spacious platform, stability from distributed floats, and mobility through streamlined legs is genuinely innovative for mobile seasteading applications.