The maritime sector is facing a continuous shift towards digitalization. A ship built during the last decade shows all characteristics of a comprehensive information system, combining information and operational technologies. While industrial programmable logic controllers are used for engine and power management, the bridge is now highly relying on digital sensors, networks and displays for navigation. Meanwhile, over the last few years, many cyber attacks targeting maritime assets and made publicly confirm a real interest of criminal and non-state actors in this critical sector for our globalized economies. In this work, a concept designed to detect and visualize advanced navigation cyber attacks on maritime systems using contextual NMEA data analytics is presented. A strategy is built to enhance the detection of navigation spoofing attacks, assess possible physical impacts onboard and support decision makers.