SART

A Search and Rescue Transponder (SART) is a self-contained, waterproof transponder intended for emergency use at sea.

The radar-SART is used to locate a survival craft or distressed vessel by creating a series of dots on a rescuing ship's radar display. A SART will only respond to a 9 GHz X-band (3 cm wavelength) radar. It will not be seen on S-band (10 cm) or other radar. Shipboard Global Maritime Distress Safety System (GMDSS) include one or more search and rescue locating devices.

The SART may be triggered by any X-band radar within a range of approximately 8 nautical miles (15 kilometers).