Maritime Communication
Terms from DSC to VHF Radio, each linked to related terms and to the desks that work with them.
Entries updated May 2026
Related desks
Terms in Maritime Communication
11 termsDSC
Digital Selective Calling, a semi-automated method of establishing a radio call using digital codes transmitted on VHF, MF, and HF radio frequencies.
Flag Signals
A system of communication using coloured flags flown from a vessel's mast or signal halyard, each representing a letter of the alphabet, a numeral, or a specific meaning.
LRIT
Long Range Identification and Tracking, an international system for tracking vessels globally, adopted by the IMO as an amendment to SOLAS.
Mayday
The internationally recognised voice radio distress signal, spoken three times at the beginning of a radio distress call to indicate that a vessel, aircraft, or person is in grave and imminent danger and requires immediate assistance.
Morse Code
A communication system using sequences of short and long signals (dots and dashes) to represent letters and numbers.
NAVTEX
Navigational Telex, an international automated medium-frequency direct-printing service for delivery of navigational and meteorological warnings and forecasts, as well as urgent maritime safety information to ships.
Pan-Pan
An internationally recognised urgency signal, spoken three times at the beginning of a radio message, indicating that there is an urgent situation on board a vessel but no immediate danger to life or the vessel.
SAR
Search and Rescue, the coordinated effort to locate and recover persons in distress at sea, involving maritime rescue coordination centres (MRCCs), coast guard units, naval vessels, and commercial ships.
Securite
An internationally recognised safety signal, spoken three times at the beginning of a radio message, used to broadcast important navigational or meteorological warnings to all vessels in the area.
Ship Reporting
Mandatory or voluntary systems requiring vessels to report their position, course, speed, and other information to shore-based authorities when entering or transiting designated areas.
VHF Radio
Very High Frequency radio, the primary means of short-range voice communication between ships and between ship and shore in the maritime environment.