The operation of radar equipment is one of the key facilities navigators use to gather situational awareness about their surroundings. With an ever-increasing need for alwaysrunning logistics and tighter shipping schedules, operators rely more on computerized instruments and their indications. As a result, modern ships have become complex cyber-physical systems in which sensors and computers constantly communicate and coordinate. In this work, we discuss novel threats related to the radar system, one of a ship's most security-sensitive components.In detail, we first discuss some new attacks capable of compromising the integrity of data displayed on a radar system, with potentially catastrophic impacts on the crew's situational awareness or safety. Then, we present a detection system to highlight anomalies in the radar video feed, requiring no modifications to the target ship configuration. Finally, we stimulate our detection system by performing the attacks inside a simulated environment. The experimental results indicate that the attacks are feasible, easy to carry out, and hard to detect. Moreover, they prove that the proposed detection technique is effective.