How do you make a Mayday call on a VHF radio?

On VHF channel 16 at high power, say "Mayday, Mayday, Mayday, this is" and your boat's name three times, then "Mayday" and the name once, your position, what has happened, the help you need and the number of people aboard. End with "Over" and wait.

A Mayday is for grave and imminent danger to a vessel or to life, such as sinking, fire, a person overboard or a life-threatening injury. Use VHF channel 16, the distress, safety and calling channel, on high power. In New Zealand it is monitored by Maritime Radio and Coastguard.

If your radio has a red DSC distress button and is connected to a GPS, press it first (usually by lifting the cover and holding the button for a few seconds). It sends an automatic distress alert with your position. Then make the voice call.

Speak slowly and clearly:

1. "MAYDAY, MAYDAY, MAYDAY."
2. "This is [boat name, boat name, boat name]."
3. "MAYDAY [boat name]."
4. "My position is [latitude and longitude, or a distance and bearing from a landmark]."
5. "[What has happened], and I require immediate assistance."
6. "[Number of people on board]. [Anything else that will help, such as injuries or abandoning to the liferaft]."
7. "Over."

Then release the transmit button and listen. If no answer comes, repeat the call. If you still get no reply, try again and keep trying; other boats may hear you even if the shore station cannot.

Some practical points:

• Keep a card with the format and your boat's name and call sign next to the radio, and show the crew how to use it in the safety briefing. In a real emergency it may be someone else who has to make the call.
• Give the position first if you are short of time. It is the most important information.
• A handheld VHF has much less range than a fixed set with its aerial at the masthead. Carry a second way of calling for help, such as a phone in a waterproof bag, and an EPIRB or PLB if you go further from shore.

In New Zealand you need a marine VHF operator certificate to use the radio for routine calls, but anyone may use it to call for help in an emergency.

More in the book: Chapter 11, Safety on board