A VHF radio is the one piece of equipment on a boat that works when everything else has failed, and it is also the one most people have never actually transmitted on. Ten minutes of reading now is the difference between calling for help competently and freezing with the microphone in your hand.
The channels you actually need
- Channel 16 — distress, safety and calling. You monitor it whenever the radio is on, and you use it to start a call, not to hold a conversation.
- Channel 13 / 12 — bridge-to-bridge and port operations in many areas; this is how you talk to a ship or a harbour.
- Working channels — once contact is made on 16, you both switch to a working channel and continue there.
- Channel 70 — reserved for DSC digital calls. Never transmit voice on it.
Channel numbering and permitted use vary by country: check the local allocation before you transmit in unfamiliar waters.
How to make a routine call
Press, pause, then speak — the first fraction of a second gets cut off. Hold the microphone a few centimetres from your mouth and speak across it, not into it.
The format is the name of who you want, then who you are:
"Marina Bay, Marina Bay, this is Sailing Vessel Aurora, Aurora, over."
When they answer, propose a working channel: "Switch to channel 68." Say "over" when you expect a reply, and "out" when the conversation is finished. Never "over and out": they mean opposite things.
The three emergency calls, in order of severity
MAYDAY — grave and imminent danger to a vessel or a person. Sinking, fire, person overboard you cannot recover, serious medical emergency.
PAN-PAN — urgency, but no immediate danger to life. Engine failure drifting towards rocks, a serious but stable injury.
SÉCURITÉ — safety information. A hazard to navigation, a container adrift.
The MAYDAY format, worth memorising
On channel 16, at full power:
- "MAYDAY, MAYDAY, MAYDAY"
- "This is [boat name, three times]"
- "MAYDAY [boat name]"
- Position — latitude and longitude, or a bearing and distance from a known landmark. This is the single most important line.
- Nature of the emergency — what is happening
- Assistance required
- Number of people on board
- "Over"
Then release the button and listen. If nobody answers, repeat. Anyone hearing a MAYDAY who can help is obliged to respond, and if you hear one and are not involved, stay off the channel.
DSC: the red button
A DSC-equipped radio has a distress button under a cover. Pressing it sends a digital alert with your identity and — if the radio is connected to a GPS — your position, on channel 70, to every DSC receiver in range and to the coastguard. It is faster and more accurate than voice.
Two conditions must be met beforehand, and both are commonly neglected:
- The radio must be programmed with an MMSI number, obtained from the relevant authority. An unprogrammed radio sends an anonymous alert.
- It must be connected to a GPS source, otherwise the alert carries no position and rescuers know only that someone, somewhere in range, is in trouble.
Use DSC first, then follow immediately with a voice MAYDAY on 16. And check both conditions now, tied up at the dock, not on the day you need them.
Two habits that cost nothing
Keep the radio on and monitoring 16 whenever you are underway — it is how you hear the warning meant for you. And practise the routine call once, on a working channel, calling a marina to ask about a berth. The first time you press that button should not be the day something is wrong.
Domande frequenti
What is the correct MAYDAY format?
On channel 16: MAYDAY three times, your vessel name three times, then MAYDAY and the name again, followed by your position, the nature of the emergency, the assistance required and the number of people on board. Position is the most important line.
What does DSC need to work properly?
Two things that are commonly neglected: the radio must be programmed with an MMSI number obtained from the relevant authority, and it must be connected to a GPS source. Without them the alert is anonymous or carries no position.