By GMDSS rules, ships at sea are expected to maintain a listening watch on
Ch73, whenever practicable - and particularly in congested waters.
Because of this, voice calls between vessels on Ch 73 may not require a
preliminary DSC Call on Ch 70.The examples which follow indicate types of Safety call/message
you might expect to hear, or may have to use, yourself, in certain
circumstances.Example - Clyde Coastguard Announcing & Sending a Gale
Warning
Ch70 DSC All Stations Safety Alert, indicating Ch 10 for subsequent
traffic.
Chl6 (voice announcement, until 31 January 2005 for non-GMDSS
vessels).
'Securite, Securite, Securite - All Stations, All Stations, All
Stations. This is Clyde Coastguard, Clyde Coastguard, Clyde
Coastguard. For a Gale Warning, listen on Channel 10'
Ch 10 'Securite, Securite, Securite - All Stations, All Stations, All
Stations. This is Clyde Coastguard, Clyde Coastguard, Clyde
Coastguard. Gale Warning issued on 22 December 2000 at
1020UTC begins:
Rockall North Westerly Gale force 8 imminent. Malin,
Hebrides and Bailey - North Westerly Gale force 8 expected
soon '
The DSC Alert, received onboard vessels in the area, would
have looked like:
Safety
To Station: All Stations
From Station: 002320022
Subsequent communications: Ch 10
Received on: Ch70 at (date/time of receipt)
Which would mean:• It was a Safety Alert, with subsequent voice communications on
ChlO (where a 'Securite' call and message would be expected).- The alert came from a Coast Station (MMSI beginning with two
leading zeros must be from a Coast Station - see Appendix V). - The receiving vessel's own equipment added the date and time
that the alert was received.
122 THE NAUTICAL INSTITUTE