GMDSS Principles, Sea Areas and Carriage Requirements
What the exam tests
GMDSS is a distress-and-safety system built on two ideas: a ship must be able to alert shore-based SAR from anywhere, and the alert must identify the ship and its position. The exam asks you to map sea areas A1-A4 to equipment and to distinguish SOLAS carriage rules from Italian non-SOLAS practice.
Sea areas
- A1: VHF coverage of at least one coast station with continuous DSC alerting, roughly 20-30 nm offshore.
- A2: MF coverage, excluding A1, roughly 100-150 nm.
- A3: Inmarsat geostationary coverage (about 70°N-70°S), excluding A1/A2.
- A4: the remaining polar and remote areas; HF is the backbone.
Carriage logic
A1: VHF DSC on Ch 70, VHF voice Ch 16, 406 MHz satellite EPIRB, SART, NAVTEX if in a NAVTEX area, two-way survival-craft VHF. A2 adds MF DSC 2187.5 kHz and MF voice 2182 kHz. A3 adds Inmarsat or HF. A4 requires HF DSC, NBDP and voice. Reserve battery capacity and a float-free EPIRB are part of the fit, not optional extras.
Worked example: a 500 GT cargo ship on an A2 voyage carries VHF DSC/voice, MF DSC 2187.5 and voice 2182, a 406 EPIRB, one SART (two if over 500 GT under the usual SOLAS scale), NAVTEX and two-way VHF. It does not need Inmarsat for A2; adding it is a commercial choice, not the minimum. The reasoning is to match the outermost sea area to the alerting path.
Traps
Do not say A3 begins where VHF ends; A3 is Inmarsat coverage. A1 is defined by DSC coast-station coverage, not by VHF voice alone. A 406 EPIRB is not a substitute for a SART. Do not confuse GT thresholds with length overall.