The Moving Target Problem
Fresnel zones, saltwater, and 180 metal boats as RF obstacles
The Challenge
180-berth Mediterranean sailing marina generating €90,000/year from Wi-Fi fees (€15/day), but sailors complained constantly: strong signal, frequent disconnections, unusable speeds.
Marina had spent €25,000 two years prior on "professional marina Wi-Fi"—8 high-power shore-based APs trying to blast coverage 80-200m across water to pontoons. It never worked properly.
The Unique Problem: Water + Motion
Fresnel Zone Intrusion
Yacht masts swaying 2-3m in wind constantly interrupted RF line-of-sight. 20m masts moving through Fresnel zones = periodic signal blockage and packet loss.
Saltwater RF Absorption
5 GHz over saltwater at 150m+ = 30-40% signal loss. Salt spray and humid marine air further degraded signal. Waves created variable attenuation.
Metal Reflections
180 yachts = 180 large metal reflectors creating constantly shifting multipath. Boats arriving/departing changed RF landscape hourly. Tides altered signal paths.
The Solution: Distributed Coverage
Bring the APs to the clients. Use lower power. Accept the complexity.
- 16× point-to-point wireless backhaul links from shore to pontoons (5 GHz, 300+ Mbps per pontoon)
- 24× mesh APs on pontoons (4 per pontoon, IP67 rated, low power, 2.4 GHz primary)
- Marine-grade enclosures (stainless steel, IP66, corrosion-resistant)
- €18,500 equipment + €6,500 labor (6 days installation)
Results
Wi-Fi Usage
+320%
Increased adoption and satisfaction
Rating Improvement
2.1 → 4.3/5
On Noonsite and Navily reviews
Coverage
98%
Berths with usable signal (-65 dBm or better)
Total Investment
€25,000
2.5-year ROI from Wi-Fi revenue
Key Lessons
Physics beats marketing specs
- • Fresnel zones matter: Long-distance links over water require clear zones. Obstacles moving through = intermittent connectivity.
- • 2.4 GHz over saltwater: Slower but penetrates moisture better than 5 GHz. For marine: 2.4 GHz primary, 5 GHz bonus.
- • Lower power, more APs: Better than high power, few APs in reflective environments.
- • Corrosion is real: Marine environment destroys electronics. Budget 10-15% annual replacement due to salt damage.