8.2. Radio communication equipment
Communication systems on board for external communication
All external ship communication is executed using either radio transmitters of very high frequency (VHF), high frequency (HF) or medium frequency (MF) or satellite communications (INMARSAT, Starlink, etc.) providing mobile phones or internet services.
The communications for emergencies are defined in the Global Maritime Distress and Safety System (GMDSS), which sets out the standards for radio /satellite communications on board, defining the types of radio equipment which is obligatory to be carried on board and used for free in case of emergencies.
Four sea areas are designated depending on the ship distance from the shore:
- A1 means radio coverage of at least one VHF coastal station with continuous Digital Selective Calling (DSC) alerting within 20 miles from the coast.
- A2 means radio coverage of at least one MF coastal station with continuous (DSC) alerting, range about 40 miles from the coast.
- A3 means the rest areas within reach of an INMARSAT stationary satellite covering from 700 South to 700 North .
- A4 means the remaining areas outside A1, A2 and A3: polar areas of the Arctic and Antartic.
All areas require a ship to have:
1. Emergency Position Indicating Radio Beacon (EPIRB), which transmits the identification and position of the ship automatically to the satellite, if the vessel submerges into the water. The distress signal then is sent to the coastal station;
2. Search and Rescue Transponder (SART), which will activate if hit by the 10 cm radar beam and will show up in the radar screens of the ships in the vicinity as a dotted line;
3. NAVTEX, where meteorological, navigational and safety information is received in the form of abbreviated messages.
Other communication equipment on board a ship depends on the sea area it operates in.
For example, communication equipment for the sea area A1 is :
- One fixed VHF radio telephone with aerials.
- EPIRB, SART, NAVTEX, DSC devices;
- One enhanced group call receiver with aerial;
- Two hand-held self-contained radio telephones.
A vessel operating in the A2 sea area shall carry additionally: an MF radio telephone with 9 and 16 metre high aerials and one INMARSAT-C satellite communication system.
Reference:
Borstlap, R., Ten Katen, H. (2021) Ship Electrical systems. Vlissingen.