Louis Zezeran
8. jaan 2026
Maritime navigation has become so reliable that it often fades into the background of daily operations. Ships leave port, follow planned routes, and rely on digital systems to provide accurate position, speed, and timing. But what happens when those systems are wrong—and worse, when they appear perfectly normal?
In this CyberCast episode, host Louis Zezeran is joined by Rob Gillette (NAL Research) and Stefan Grefsgaard (SGM Technology) to unpack a growing and often misunderstood threat: GPS spoofing and jamming in the maritime domain. The conversation explores why GNSS systems are vulnerable by design, how interference manifests in real-world operations, and why this issue has become a critical concern for safety, security, and commercial shipping.
Why GNSS is vulnerable
At the core of the discussion is a simple but uncomfortable reality: GPS was designed decades ago for reliability and openness, not for adversarial environments. The signals received on Earth are extremely weak, making them easy to overpower or imitate with relatively modest equipment. This means attackers do not need to break encryption or hack onboard systems; they simply need to transmit a stronger or more convincing signal nearby.
The episode clearly distinguishes between jamming—where GPS signals are overwhelmed and lost—and spoofing, where false signals are introduced that look legitimate to navigation receivers. Spoofing is particularly dangerous because vessels may continue operating normally while unknowingly navigating based on incorrect data.
Why maritime operations are especially exposed
Maritime navigation presents unique challenges. Ships operate far from physical landmarks, often in poor visibility, and depend heavily on electronic positioning. In many cases, GPS has become the primary reference, with other systems acting as secondary confirmations rather than true independent checks.
The discussion highlights how this dependency creates risk. When GNSS data becomes unreliable, the consequences can range from operational inefficiency and insurance disputes to serious safety incidents or geopolitical complications if a vessel appears to enter restricted waters.
When theory becomes reality
The episode draws on real incidents to illustrate why this problem is no longer hypothetical. In one case discussed, authorities struggled to establish a ship’s true location during a crisis because its navigation data could not be trusted. These moments expose a critical weakness: when trust in navigation breaks down, coordination, response, and accountability all suffer.
This is where cybersecurity meets physical-world impact. Manipulating navigation signals can influence where a ship goes, how it is perceived by others, and what evidence exists after the fact.
Beyond “fixing GPS”
Rather than framing the problem as something that can be solved by improving GPS alone, the conversation explores broader resilience principles. These include using independent sources of position and timing, validating GNSS data against alternative references, and designing systems that can alert operators when something doesn’t add up.
The guests discuss how newer satellite constellations and alternative signal sources can serve as verification mechanisms—not to replace GNSS entirely, but to help crews understand when it may be compromised. The emphasis stays on concepts and operational thinking, not on any single product or vendor.
Testing in the real world
A particularly engaging part of the episode covers testing environments such as Norway’s Jammerfest, where interference scenarios are simulated under controlled conditions. These tests reveal how navigation systems behave under stress and how quickly data can become misleading. In some cases, vessels appear to move at impossible speeds or travel across land, underscoring how confidently wrong systems can be during interference.
These examples reinforce the need for bridge crews and shore teams to understand what interference looks like and how to respond when trusted data suddenly becomes questionable.
Insurance, accountability, and “proving where you weren’t”
One of the most practical insights from the episode relates to insurance and liability. When navigation data shows a vessel in the wrong place, proving otherwise becomes difficult. This has implications for claims, compliance, and legal disputes, especially in politically sensitive regions.
The conversation makes it clear that navigation trust is not just a technical issue—it’s a business and governance problem as well.
Key takeaways for operators and stakeholders
Listeners come away with several clear lessons:
- GNSS should be treated as a vulnerable system, not an unquestionable truth
- Spoofing and jamming have different operational signatures and risks
- Independent verification of navigation data is increasingly important
- Resilience comes from diversity, validation, and clear response procedures
- Navigation trust is now part of the broader security and risk conversation
Why this episode matters
For maritime professionals, cybersecurity teams, insurers, regulators, and anyone involved in critical infrastructure, this episode provides a grounded, non-sensational look at a problem that is already affecting real operations. It reframes GPS interference as an issue of trust and resilience rather than exotic technology.
🎧 Listen now to understand why navigation data can no longer be taken for granted—and how maritime organisations can start thinking differently about trust at sea.
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