Hydrodynamics & Towing Force at 0.25 MPH
Have others built propeller/solar relocatable FADs? Yes. The term eFAD (electronic/smart FAD) is growing. EU Pacific fisheries projects, NOAA, and several startups have tested GPS-tracked, solar-powered FADs with limited propulsion or drift-control. Fully thruster-driven FADs remain rare due to power/drag tradeoffs, but tow-by-USV concepts are actively prototyped.
Drag Estimates
- Typical artisanal FAD: Submerged structure (bamboo, netting, fronds) ~50–200 lbs. At 0.25 MPH (0.11 m/s), hydrodynamic drag is 8–15 lbf. Biofouling increases this by ~30% over months.
- Optimized "Easy-Tow" FAD: Streamlined hydrodynamic keel, minimal frontal area, porous but aligned materials. Reduces drag by ~50% → 4–7 lbf.
- Thruster capacity: 6× Blue Robotics-class units (assuming T200/M-series equivalent) provide ~25–30 lbf peak. At 15–20% duty cycle for 0.25 MPH, you're well within capacity, but propeller slip and current fighting will dictate real power draw.
Fish Behavior & FAD Design
- Will a bare 1:4 seastead work as a FAD? Yes. Any floating structure with shade, hull legs, and stabilizers creates a shadow line, predator refuge, and current eddies. Pelagics (tuna, mahi, jacks) will aggregate within 48 hours. Adding traditional biodegradable streamers increases efficiency 3–5×.
- Thruster operation at 0.25 MPH: Low-RPM thrusters generate minimal broadband noise. Fish are habituated to low-frequency vibration. Intermittent operation (duty-cycling) is recommended to conserve power and avoid habituation.
- Aggregation timeline: Small fish arrive in 12–24h. Mid-large pelagics in 3–5 days. Peak biomass: 7–14 days. Gradual movement ≤0.3 kts retains 60–80% of the school. >0.5 kts causes rapid dispersal.
- Shallow water & drop-offs: Pelagics avoid depths <50–100 ft. Your NE Anguilla drop-off (~5–6 miles out) keeps them in preferred habitat until ~12 miles from harbor. Fish will follow if depth stays >80 ft and current remains stable. Reef species may persist deeper inshore.
- Acoustic classification: Fish do vocalize (swim bladder, feeding, spawning), but ambient noise is high. Hydrophones can detect presence/chorusing and estimate swarm size with ML training. Echosounders (sonar) are far more reliable for biomass, species grouping, and depth tracking. Combine both for best results.
Operations, Rules of Thumb & Legal Context
Artisanal FAD Spacing
3–10 NM apart. Closer spacing causes resource competition; wider reduces search efficiency. 5 NM is standard for open-water artisanal fleets.
Submerged Mass
Typically 50–300 lbs (excludes mooring line/anchor). Materials: bamboo, coconut fronds, biodegradable netting, old tires/plastic buoys.
Biomass & Catch
Peak aggregation: 500–2000+ lbs of mixed pelagics. Typical artisanal catch/visit: 30–150 lbs. Sustainable revisit interval: 4–7 days.
Anguilla Legal & Regulatory Notes
- Exclusivity: No Caribbean jurisdiction guarantees FAD owner exclusivity. Once deployed and unmonitored, FADs are typically open-access unless a formal licensing/registry system is established.
- AIS & Transparency: Expect mandatory AIS for navigational safety. Sensor/fish data can remain proprietary. You may monetize location alerts, biomass estimates, and guided fishing charters, but coordinate early with Anguilla Department of Fisheries to align with local licensing policies.
- Strategic Monetization: Selling real-time "FAD readiness" alerts to charter operators or local fishers is highly viable. Pair with a voluntary "stewardship fee" or data subscription to avoid regulatory pushback.
Interactive Smart eFAD Economics Calculator
Adjust parameters to model weekly profitability. Assumes straight-line amortization, zero fuel (solar), and excludes labor/maintenance overhead.