2019 LOOR Racing Guide

Page 48 Lake Ontario Offshore Racing Guide
What’s a MMSI?
And, why I need one
and how do I get it?
By Graham Dougall,
Race Management, Safety and Technical Committee Chair
The Maritime Mobile Service Identity (MMSI) is a unique numeric identity
assigned to a vessel’s radio to identify the vessel for use in Digital Selective
Calling (DSC) on radio frequency equipment capable of DSC, e.g. VHF-FM
marine radio 1 . Think of it as the equivalent to a phone number for your vessel.
Vessels within range can directly contact and identify each other provided
that both vessels have obtained MMSI numbers and have entered them
into their VHF radios. This functionality is also a way to transmit the identity
of your vessel and position, in the event of an emergency in conjunction
with the standard MAYDAY radio protocol.
A MMSI is free from your vessel’s country of registration. That’s right; a
MMSI is one of those free items in the expensive sport of sailing.
VHF-FM marine radios sold today must be capable of DSC and it is
recommended that you make use of your free MMSI. If you have programmed
your MMSI into your radio, when you push and hold the red button for 5
seconds, the radio will:
1. Transmit a digital MAYDAY signal
2. Include your MMSI number
3. Relay your latitude and longitude position from;
a. an integrated GPS, (many new fixed VHF-FM Marine DSC radios
are sold with an integrated GPS)
b. a GPS cable with or communicating with the VHF-FM Marine
DSC radio aboard the vessel, or
c. You manually inputting your vessel’s position into the radio.
Something that you are required to do every four (4) hours
if the GPS position isn’t obtained from either a. or b.
Any ship or coast radio station that receives the MAYDAY will act on it.
When your VHF-FM Marine DSC radio receives a MAYDAY, it makes a very
loud sound and displays the MMSI with LAT LON of the originating station.
Only a coast radio station, such as the Canadian Coast Guard Prescott Marine
Communications and Traffic Services Centre, can cancel a DSC initiated
MAYDAY. Utilizing the DSC functionality is an extremely fast way to initiate
a MAYDAY. If you do not have MMSI installed and are not connected to a
GPS, you cannot avail yourself of this functionality.
1
There are several situations were devices can be assigned MMSI, e.g., hand-held VHF-FM radio
that moves from vessel to vessel. There is an identifier included in the MMSI to flag these types of
devices. DSC is supported on GMDSS mandated radio communications equipment beyond VHF.