Maritime Communications and Electronic Systems
Maritime Communications and Electronic Systems tests GMDSS, radio procedures, distress alerting and the limitations of electronic navigation aids. The master must know which equipment is required for the ship's sea area and how to use it under stress.
Core rules
- GMDSS sea areas: A1 within VHF DSC coverage, A2 within MF, A3 within Inmarsat or approved HF, A4 outside A1–A3.
- VHF Ch 16 is distress/safety/calling; DSC distress is Ch 70; EPIRB is 406 MHz; SART is 9 GHz radar.
- NAVTEX international is 518 kHz; AIS aids identification, not collision avoidance; ECDIS needs an approved backup.
- False alerts must be cancelled immediately; radio logs and battery tests are survey items.
Worked example
A ship is certified for Sea Area A3 and carries VHF DSC, MF/HF DSC, Inmarsat-C, EPIRB and SART. If the Inmarsat terminal fails, the MF/HF DSC can still provide long-range distress alerting, so the ship may retain A3 capability subject to the approved equipment configuration and redundancy. A VHF-only fit would be insufficient. The reasoning: A3 requires a recognised long-range alerting system, not just coastal VHF.
Traps
Using Ch 16 for DSC alerts; confusing EPIRB and SART functions; assuming AIS replaces radar plotting; and treating NAVTEX 490 kHz as the international frequency. ECDIS alarm overload and incorrect safety settings are also common.