What Are VHF Radio and DSC?
The phone and distress button at sea - a life-saver where mobile signal drops out, and often the more reliable option even where it does work.
A VHF marine radio is the phone and distress button at sea. A mobile phone calls one person; VHF calls everyone nearby at once, which is why in an emergency the nearest help is often the boat next door. DSC is the digital side of modern VHF sets: one press of the red button sends the boat’s identity and GPS position.
The table below sets out the main channels and call signals. Channel 16 is sacrosanct: it is not for chat, you make contact there and then move to a working channel.
Main channels and calls
Channel / signal | Use |
|---|---|
Channel 16 | International calling and distress channel |
DSC red button | Sends identity + position in one press (distress) |
MAYDAY | Life-threatening emergency, highest priority |
PAN PAN | Urgent but not life-threatening situation |
SECURITE | Navigational and safety broadcast |
The most critical installation detail is linking the GPS position to DSC; this is the cable most often missed, and if it is not connected the radio cannot use its most valuable feature. The MMSI (boat identity) must be entered correctly, and the antenna and connectors should be checked once a year for range.
Crew training matters just as much: everyone on board, not just the skipper, should know where the red button is and the MAYDAY format. On the best boats, there is also a card by the VHF reminding crew of the who, where, what and how many people format.