A Search and Rescue Transponder (SART) is a self-contained, waterproof, battery-operated device designed to locate ships or survival craft in distress. It acts as a radar transponder, responding to nearby 9 GHz (X-band) radars by creating 12 distinct dots on the screen, guiding rescuers within roughly 5–8 nautical miles.

Key Aspects of a SART:
Purpose: Essential GMDSS safety equipment for locating liferafts or vessels, providing bearing and range to search teams.

How it Works: The SART remains in standby, activating only when it detects a 9 GHz X-band radar signal. It then sends back a signal that appears on the searcher’s screen as 12 dots. As rescuers get closer (1 nautical mile), these dots change into arcs or concentric circles.

Operational Requirements: Must operate for 96 hours in standby, plus 8 hours when being interrogated.

Usage: Portable, it can be mounted on a lifeboat/liferaft as high as possible for maximum range (around 5–10 nautical miles, up to 40 for aircraft).

Difference from EPIRB: An EPIRB alerts satellite systems over long distances, whereas a SART helps nearby rescuers pinpoint the precise location.