The GPS layer at sea is no longer a single-layer bet

Maritime bridges have stopped treating the satellite navigation layer as a given, and 2026 is the first year the operational cost of that shift is countable. The threat has been in the news; the bills are now in the data.

Quantum Computing Report's Q1 2026 figure of 978,000 jamming and spoofing incidents is the denominator for the threat surface ships actually sail through. Q-CTRL's Coral Sea trial is the matching numerator on the answer side. A 29-meter vessel running the Ironstone Opal stack held bounded 1-nautical-mile positioning across 83 km with no satellite signal, roughly 10 times tighter than the navigation-grade inertial baseline it was measured against.

The pattern is older than the quantum part. Resilience here is a passive, map-matched fallback that does not need a transmitter and does not announce itself: cold-atom interferometry lowers long-term drift, classical accelerometers cover the short term, and a reference gravity map supplies the absolute fix. The vendor owns the first two layers and rents the third from satellite derivatives, which is where the resilience story stays honest.

GPS was never free. It was insured by a single transmission pattern, and the insurance is running out.