Search and Rescue Radar Transponder (SART) usability for ship

Search and Rescue Radar Transponder (SART) for ship
Search and Rescue Radar Transponder (SART) for ship

A Search and Rescue Transponder (SART) is an electronic device that automatically reacts to the emission of a radar. This enhances the visibilty on a radar screen. SART transponders are used to ease the search of a ship in distress or a liferaft.

All GMDSS vessels up to 500 ton must carry at least one SART. Bigger vessels must carry at least two SARTs. Non GMDSS vessels are strongly advised to carry at least one as well.

A SART has a receiver that detects the signals from X-band radars (9.2 – 9.5 GHz). If the SART detects a signal it immediately transmits twelve pulses on the same frequency. This signal is seen by the radar as “echoes” and will be displayed on the screen as a serie of twelve dots with a gap of 0.6 miles between them. The first dot is at the position of the SART and the others go in a straight line towards the edge of the screen.

Radar screen from a SART on a distance of more than 5 miles
Radar screen from a SART on a distance of more than 5 miles

If the rescue vessel approaches the SART, the twelve dots will become short arcs. These arcs increase in size if the vessel gets closer. If the rescue vessel is very close, the SART will be activated permanentely by the side lobes of the radar antenna. The signal of the SART will then be visible as twelve complete circles on the radar screen. This will tell the search-and-rescue team that they have more or less arrived.

Search and Rescue Radar Transponder (SART) for ship
Search and Rescue Radar Transponder (SART) for ship

A Search And Rescue Transponder (SART) is a Radar based emergency transmitter that is designed to be stored in a liferaft or as a carry on device in the event that it is necessary to abandon ship. When it detects an incoming X-band radar pulse from another vessel or aircraft it automatically transmits a response signal, which appears on the vessel’s radar display as a series of 12 dots pointing to your location.

SARTs are supplied with a mounting bracket and must be manually activated once inside the liferaft. As a Radar SART is designed to only transmit when it detects an incoming radar pulse this dramatically increases the battery life, enabling them to operate continuously for typically over 96hrs.

Since 2010 the AIS-SART (Search and Rescue Transmitter) has been added to GMDSS regulations as an alternative to a Radar SART and has been wheel-marked since 2012. These units include an inbuilt GPS and transmit an alert message along with the vessel ID and GPS position via the AIS (Automatic Identification System) tracking system – this appears on an AIS-equipped vessel’s chartplotter or ECDIS display rather than on the Radar.

A SART forms part of the GMDSS mandated equipment package required by law for all commercial vessels over 300 tons, however many non-mandate vessels and leisure boats also choose to carry a SART to improve safety.

Designed to be stored in a survival craft or as a carry off device, the rugged McMurdo S4 Rescue SART is buoyant and waterproof to a depth of 10m. When it detects a radar signal from another vessel or aircraft, the S4 Rescue SART’s 9GHz X-band Radar transceiver will automatically transmit a response signal which will appear on the other vessel’s radar display as a series of 12 dots, pinpointing your location. An LED and buzzer indicates when the S4 has detected a radar signal and transmitted a response. The S4 will only transmit when it detects an incoming radar pulse – after 15 seconds it will drop to standby mode, conserving battery life and ensuring operation in excess of 96hrs.

Once activated the McMurdo S4 Rescue SART may be suspended inside the survival craft or mounted in an elevated position using the integrated extending pole.

  • Buoyant and waterproof to 10m.
  • Compact, lightweight and rugged.
  • Meets IMO and GMDSS standards.
  • LED and buzzer indicates operation.
  • Inbuilt test facility.
  • Integral lanyard.
  • Over 96hrs operation in standby mode.
  • Replaceable 5 year battery pack.
  • Mounting options – internal/external.

Read more : Search and Rescue Transponder Procedure


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