A false position can look perfectly ordinary
A yacht’s tracking system does not usually measure its position directly. It calculates one from radio signals sent by navigation satellites. Each signal carries timing information; by comparing when signals from several satellites arrive, a receiver estimates how far away each satellite is and works out a location.
That calculation depends on the signals being genuine. A spoofer transmits counterfeit satellite-like signals that are stronger or otherwise more persuasive than the real ones. If a receiver accepts them, it can calculate a convincing but false position—sometimes one that places a vessel on land.
Why the yacht may not know
GPS receivers are designed to make sense of faint signals, not to determine whether every signal is authentic. A carefully crafted counterfeit can therefore mislead a receiver without producing an obvious warning. The yacht may be navigating with faulty coordinates, while its tracking display reports the same false location to people watching from shore.
This is different from jamming. Jamming overwhelms satellite signals so the receiver loses its position; spoofing feeds it misleading information, allowing it to keep displaying a location that appears usable.
One false dot, several consequences
A landward position on a tracking map does not necessarily mean the yacht has left the water—or that its crew deliberately reported a false route. It may reflect what the receiver was made to calculate. That distinction matters when operators use position data to monitor a vessel, investigate an apparent route, or make navigation decisions.
The practical defense is not to treat one electronic position as unquestionable. Comparing it with independent clues—such as radar, visual observations, or other navigation equipment—can reveal when the coordinates do not fit the yacht’s surroundings. A ship can be miles offshore while its most familiar map insists it is crossing dry land.
