ClassNK launches class notation as GPS spoofing hits 5,000+ daily incidents

ClassNK is offering shipowners formal class recognition for vessels fitted with systems that detect satellite navigation interference — a response to an average of 5,131 GPS jamming incidents recorded every day in the third quarter by maritime intelligence firm Windward.

The Japanese classification society has revised its Guidelines for Advanced Safety Measures, publishing Edition 1.1, to allow vessels equipped with systems that identify the effects of GNSS interference and warn bridge teams to receive a new class notation. For owners, the framework creates a verifiable way to demonstrate that their ships carry equipment designed to detect navigation signal manipulation — a distinction that may matter increasingly to charterers, insurers and port authorities as electronic interference spreads.

What does the notation actually cover?

The threat comes in two forms. GNSS jamming prevents or degrades the reception of satellite signals outright. Spoofing is subtler: it feeds receivers false information, potentially making a vessel appear somewhere it is not.

ClassNK's revised guidelines enable the evaluation of onboard detection and alerting systems against these threats. The society has been explicit about the limits, however. The notation does not mean a ship is immune to interference, nor that reliable satellite positioning can be restored during an attack. In other words, the certification covers the ability to detect and warn — not to defend. Owners presenting this as a full solution to navigation interference would be overstating what ClassNK has actually endorsed.

Where is interference happening?

The move comes amid growing international concern over electronic interference in four regions in particular:

• the Baltic Sea
• the Black Sea
• the Middle East Gulf
• parts of East Asia

Earlier this month, Britain's Maritime and Coastguard Agency issued new guidance warning shipowners to prepare for operations without reliable satellite navigation — a striking admission that degraded GNSS is now treated as an operating condition rather than an exceptional event.

The scale of the problem is measurable. Windward's figure of 5,131 daily jamming incidents in the third quarter works out to more than 470,000 potential interference events over a 92-day quarter — a pace that makes manual position verification impractical without onboard detection tools.

The spoofing side has produced outright absurdities. SplashTech has reported four tankers operating in the Black Sea apparently transmitting positions placing them in Lima, Peru — more than 12,000 km away. A position jump of that magnitude would be obvious to any watchkeeper cross-checking radar or visual fixes, but smaller, subtler displacements are precisely what detection systems are meant to catch.

How does this fit existing cyber rules?

ClassNK has separately clarified that existing IACS cyber resilience requirements E26 and E27 do not directly mandate protection against GPS spoofing or jamming. That gap is the commercial logic behind the new notation: owners investing in navigational resilience now have a certification mechanism that existing class and statutory requirements did not provide.

For equipment makers, the revised guidelines create a formal evaluation path — and a potential marketing lever — for detection and alerting products. For shipowners, the notation offers a documented answer to the MCA's warning about operating without reliable satellite navigation, though it stops short of solving the underlying problem. Expect other class societies to watch uptake closely as interference incidents continue to run at record levels in affected regions.

By Marcus Bennett