MAYDAY and Distress Signals
Mayday Distress Call using GMDSS – Digital Selective Calling (DSC) VHF Radio
See for more details http://www.mcga.gov.uk/c4mca/gmdss.pdf
Using DSC for Mayday enables an automatic transmission of both the Mayday signal and your present position, providing your DSC set is interfaced with a GPS.
Just lift or slide the safety latch and press the red Mayday DISTRESS button . Some sets allow you to specify the type of distress eg ‘Sinking’.
Wait about 15 seconds for a DSC acknowledgement from the Coastguard or a ship station. On Ch16, on receipt of a DSC acknowledgement or after about 15 seconds, send a voice Distress call:
Mayday, Mayday, Mayday
This is ‘ YACHT NAME……………..’, spoken three times
Mayday – YACHT NAME and ‘MMSI* or call sign’, spoken once
My Position is…………….
Nature of Distress………………
Number on board (total crew + skipper)……..
* MMSI = Mobile Maritime Service Identity – 9 digit number assigned to the radio
If no DSC acknowledgement is received, and offer of assistance is accepted from another vessel, cancel the DSC alert to prevent it automatically retransmitting.
See here for a guide to VHF Radio Mayday Guide and DSC Procedures VHF skills chart
Acknowledgement of a DSC distress alert
When a DSC controller receives a Distress alert it will sound an audible alarm.
Immediately cease any transmission that may interfere with Distress traffic and continue a watch on CH16. Acknowledgement of a DSC alert by use of DSC is made only by coast stations and vessels fitted with Class A or B DSC controllers. There is no facility on a Class D controller to acknowledge a distress alert by DSC. If there is no DSC acknowledgement after a short interval, acknowledge by voice on CH16: