Channel 70, Channel 16 and Working Channels

Channel 70 is reserved for DSC signalling and must not be used for voice. Channel 16 carries distress, urgency, very brief safety communications, and initial calling where the procedure requires it; routine conversations move promptly to a suitable working channel. Channel 13 is designated internationally for bridge-to-bridge navigational safety communication and may be useful when contact with another vessel cannot be established on Channel 16.

For a known vessel MMSI, an individual routine DSC call can nominate an inter-ship working channel. When the called set acknowledges, conduct the conversation on that selected channel. If the MMSI is unknown, the MCA small-craft guidance says to make a voice call on Channel 16 using low power initially and move to an inter-ship channel once contact is established; if there is no response, try Channel 13.

Calling a Coastguard or coast station by DSC is not the same as starting a long conversation on Channel 16. Make the appropriate individual call, accept the acknowledgement, ensure the set is on the channel indicated, and wait for the station to call. Harbour authorities publish their working channels and procedures; obtain them during appraisal and monitor before reaching the reporting point.

The skipper should prevent radio activity from becoming a navigation hazard. Prepare the message before keying the microphone, use the correct power, keep the helm and lookout informed, and avoid prolonged head-down menu operation near traffic or danger. If a call is not answered, reassess identity, channel, range, squelch, antenna, and urgency rather than filling Channel 16 with continuous repeats.