Describe the SART — what it is, how it is used in a survival craft, and what its limitations are.

A. SART — SEARCH AND RESCUE TRANSPONDER: WHAT IT IS: a SART is a 9 GHz radar transponder carried in survival craft (liferafts, lifeboats). When interrogated by a 9 GHz (X-band) radar, it responds by transmitting a signal that appears as a distinctive pattern on the searching vessel's or helicopter's radar screen — a series of 12 dots in a line extending outward from the target position. HOW TO USE: (1) ACTIVATE: remove from bracket — the SART will automatically activate when it detects a 9 GHz radar signal. Alternatively, some SARTs have a manual ON button; (2) MOUNT HIGH: hold the SART as high as possible above sea level — radar horizon is the limiting factor; from a liferaft at 1m height, the SART's radar signal is visible at approximately 5nm to a ship's radar at 15m height; (3) LED INDICATOR: a flashing LED indicates the SART is being interrogated by radar — survivors know a vessel or aircraft is searching; audible beeper too; (4) BATTERIES: SARTs have a standby life of 96 hours and active transmission life of 8 hours; OOW ON THE SEARCHING VESSEL: (a) Set X-band radar to 6-12nm range; (b) Look for the distinctive SART 12-dot pattern — it appears as a trail of dots; (c) Range to the first dot = range to the SART; (d) As you approach, the SART pattern brightens; LIMITATIONS: (1) Requires interrogation by 9 GHz radar — S-band (3 GHz) radar does NOT interrogate a SART; (2) Line-of-sight — limited by radar horizon; (3) False returns from sea clutter can mask the SART at close range.

B. The SART transmits on 121.5 MHz and is detected by aircraft only. Ships cannot detect a SART signal on their radar.

C. Set the ship's radar to S-band (3 GHz) to detect the SART — S-band has better range for SART detection than X-band due to its longer wavelength.

D. The SART is activated by pulling a painter line when the liferaft is launched. It then transmits continuously for 72 hours without any further action required.

A. DSC DISTRESS ALERT — VHF PROCEDURE: DSC (Digital Selective Calling) on VHF Channel 70 is the primary GMDSS distress alerting mechanism. PROCEDURE: (1) ENSURE POSITION IS UPDATED: the DSC controller must have a current GPS position input (most modern sets auto-update from GPS). Verify the position shown is current; (2) OPEN THE DSC CONTROLLER: navigate to the distress function — typically a protected button (lift cover or press and hold to prevent accidental activation); (3) SELECT NATURE OF DISTRESS: most DSC controllers allow selection of distress nature — UNDESIGNATED, FIRE, FLOODING, COLLISION, GROUNDING, LISTING, SINKING, DISABLED AND ADRIFT, ABANDONING SHIP. If time permits, select the correct nature; (4) TRANSMIT: press/hold the distress button for the required duration (typically 5 seconds with button confirmation). The controller transmits the DSC distress call on Ch 70 — this broadcasts your MMSI, position, time, nature of distress to all vessels in range and to coast stations; (5) SWITCH TO CH 16: immediately after DSC transmission, switch VHF to Ch 16 and transmit the voice MAYDAY message; (6) MAYDAY VOICE: "MAYDAY MAYDAY MAYDAY — THIS IS [vessel name × 3] — MAYDAY [vessel name] — POSITION [lat/lon] — [NATURE OF DISTRESS] — [POB] — [ANY OTHER RELEVANT INFO] — OVER"; (7) AWAIT ACKNOWLEDGEMENT: coast stations and vessels will acknowledge on Ch 16.

B. The DSC distress alert is transmitted on Ch 16. Tune the VHF to Ch 16, press the distress button, and speak the MAYDAY message directly.

C. Voice MAYDAY on Ch 16 must be transmitted first — then the DSC alert follows. The voice call alerts nearby vessels who may not be monitoring DSC.

D. DSC distress is only for MF/HF radio. VHF uses the traditional voice MAYDAY on Ch 16 only — VHF DSC is not a required GMDSS function.

A. NAVTEX — SYSTEM AND OOW USE: NAVTEX (Navigational Telex) is an automated system that broadcasts maritime safety information (MSI) on 518 kHz (international) and 490 kHz (national language) using NBDP (Narrow Band Direct Printing). WHAT IT PROVIDES: (1) NAVIGATIONAL WARNINGS (B messages): hazards to navigation — wrecks, buoy off station, new obstructions, pilot areas, lights changed; (2) METEOROLOGICAL WARNINGS (W messages): gale warnings, storm warnings, weather bulletins; (3) PILOT SERVICE MESSAGES (P messages); (4) ICE REPORTS (I messages); (5) SAR INFORMATION (D messages): distress messages, SAR operations in the area; (6) SUBFACTS and NAVFACTS: submarine exercise areas and other military notifications. HOW IT WORKS: NAVTEX stations broadcast on a schedule. Each station has a unique letter identifier. The NAVTEX receiver is programmed to receive messages from stations covering your sea area. Messages not relevant to the vessel's area can be filtered. OOW DUTIES: (1) Ensure NAVTEX is switched on and printing; (2) Check the NAVTEX receiver is set to receive messages from stations in the current sea area; (3) READ ALL MESSAGES as they print; (4) Bring significant messages (navigational warnings, gale warnings, SAR in the area) to the master's attention; (5) CHART PLOT: plot navigational warnings on the chart/ECDIS; (6) Do NOT ignore NAVTEX messages — they contain safety-critical information.

B. NAVTEX operates on VHF Ch 68 and provides local port information for vessels within 20nm of the coast. It is only relevant when approaching port.

C. NAVTEX is a backup to weather fax and provides only meteorological information. Navigational warnings are only available through the vessel's AIS.

D. NAVTEX messages should be collected and reviewed once per watch. Urgent messages are highlighted in red and require immediate action; all others can wait.