High-Frequency (HF) radars are operated in the 3–30 MHz frequency band. For oceanographic applications low transmit power HF radar systems have been developed, which use surface electromagnetic wave propagation along the salty ocean surface. The WERA HF radar system transmits a power of 30 Watts but achieves detection ranges up to 200 km. Hence the radar system can be used for many applications in coastal monitoring. The measured radar data were analyzed together with simultaneously available Automatic Identification System (AIS) information, which shows current ship position, speed, course and type. This paper presents the target reflectivity measurements as signal-to-noise ratio (SNR) to estimate the radar cross section (RCS) of cargo ships.