Re: How secure is GPS ?
Inertial navgation is not really usable for long distances when you're on a ship that's constantly rocked by waves, pushed around by winds or even dragged by sea currents.
It works better for submarines in immersion because they only have to deal with underwater currents, which are relatively constant.
What's left for a civilian ship is GPS or automated celestial navigation, both can be unreliable.
Biting the hand that feeds IT
