How to make a VHF Mayday call

Is it a Mayday?

Mayday is the distress call. It is only for grave and imminent danger to a vessel or a person, when immediate help is needed: a fire, sinking, a man overboard. The word comes from the French m'aider, "help me", and a false distress call is a criminal offence in many countries.

If the situation is urgent but nobody's life or the boat is in immediate danger, it is a Pan-Pan: an engine failure clear of danger, a crew member needing medical advice, or being unsure of your position with no risk of running aground. A Sécurité is a safety message about navigation or weather, such as a hazard adrift. Mayday outranks Pan-Pan, which outranks Sécurité.

Raise the alarm, then speak

A DSC radio has a red distress button under a protective cover, often spring-loaded. Press and hold it until the alert goes out. The alert carries your boat's MMSI, a nine-digit number that identifies her, and if the set is connected to a GPS, your position and the time too. If nobody acknowledges, the set repeats the alert.

Then switch to channel 16 on high power, press to talk, and speak slowly. While you hold the button you can't hear anyone, so finish with "Over" and release it to listen.

The message, in order

The call gives your boat's name three times; the message then follows a fixed order. Some sailors remember the order as MIPDANIO: Mayday, Identity, Position, Distress, Assistance, Number aboard, Information, Over. Give the position as latitude and longitude if you can.

Worked example

Kittiwake, a fictional yacht with four aboard, has hit a rock two miles south of Gull Island light, on the fictional Kerran Sound chart we use in the course, and is taking on water fast. After the DSC alert, her skipper says on channel 16:

MAYDAY, MAYDAY, MAYDAY. This is KITTIWAKE, KITTIWAKE, KITTIWAKE, [call sign], [MMSI].
MAYDAY, KITTIWAKE, [call sign], [MMSI].
Position two miles south of Gull Island light [or latitude and longitude from the GPS].
Hit a rock, taking on water fast.
Require immediate assistance.
Four persons on board.
Preparing the liferaft.
OVER.

The call sign and MMSI come from the boat's Ship Radio Licence. Write them on a Mayday card, keep it by the radio, and practise reading it aloud, never on air.

Sent one by mistake?

You must cancel it. Cancel it on the set if it can, or switch off and on after 10 seconds. Then on channel 16: "All stations, all stations, all stations, this is Kittiwake, Kittiwake, Kittiwake", call sign, MMSI, "please cancel my distress alert of" and the time it went out, in UTC.

What you need to use the radio

In the UK a boat with a fixed VHF needs a Ship Radio Licence from Ofcom, which comes with the MMSI and call sign and stays with the vessel. On a British-flagged boat the operator needs at least the Short Range Certificate (SRC), a course of about two days with an exam. This guide is theory, not a substitute for the SRC.

The full lesson, with Pan-Pan and Sécurité calls, channels, range and DSC, is Module 17: VHF radio & distress calls. What to do next in an emergency is Module 18.