I have both a hand held VHF radio and a fixed VHF radio on board the Mary E. Should each radio have it's own MMSI number or should I assign the same number to both radios?
Multiple VHF Radios with the same MMSI Number
- Thread starter MaryEllaRose
- Start date
If you plan on using the handheld radio on different vessels, like we do when chartering, then I would get a MI number (marine identity) for the handheld, and a MMSI number for the base station on your boat.
MI are used for 'AIS-SARTS", "EPIRB-AIS", MOB devices, and other devices not associated with a single specific vessel.
MI are used for 'AIS-SARTS", "EPIRB-AIS", MOB devices, and other devices not associated with a single specific vessel.
Looking deeper it seem that the US hasn't got that implemented yet.
Canada and other countries do.
Quote:
"There are two main types of identities: the maritime mobile service identity (MMSI) and the maritime identity (MI).The MMSI may be assigned to ship stations, including hand-held very high frequency (VHF) transceivers with DSC and a global navigation satellite system (GNSS) operating on board; coast stations; aircraft participating in search and rescue operations; automatic identification system (AIS) aids to navigation; and craft associated with a parent ship.
The MI is used to identify other maritime devices, such as hand-held VHF transceivers with DSC and GNSS not associated with a specific ship station; AIS search and rescue transmitters (AIS-SARTs); man overboard (MOB) devices; and emergency position-indicating radio beacons that use AIS technology (EPIRB-AIS).
BUT.... here is the current USA info from the US Coastguard with the relevant section highlighted:
"Obtaining MMSIs for DSC-equipped VHF Handhelds
A handheld VHF transceiver with DSC and an integral global navigation satellite system (e.g. GPS) not intended for dedicated use on a particular ship (e.g. a diver’s radio) should be assigned a unique 9-digit number in the format 81M2I3D4X5X6X7X8X9. While currently means do not exist within the U.S. to assign such identities, the Coast Guard has been in discussions with the Federal communications Commission and others on implementing them.
In the interim, VHF handhelds used in the United States should use the MMSI assigned to the ship to which the handheld is primarily associated, even if another radio on that ship uses the same MMSI. Non-commercial users of VHF handhelds not primarily associated with any single ship may use an MMSI provided by an organization such as BOAT US, SEA TOW and U.S. Power Squadron (see above). VHF handhelds should not be used ashore absent FCC or NTIA authorization allowing such use."
Glad you clarified, I posted that same quote last year and was pretty sure it had not changed. Net-net, it tells you to use the same mmsi if the handheld is used primarily on one boat, and give it it's own if used on multiple boats or if the device is an sar device.
Note - I consider ANY modern handheld that has DSC and GPS a SAR device. Mine is clipped to my vest, and it has it's own MMSI. I never want to have my DSC mayday/MOB while in the water confused with my nearby boat. Think about it!
Now I understand the logic behind each device having a unique MMSI. I too keep my hand held clipped to my life vest with MOB (me) in mind. I've got a lot to learn about using the radio, DSC, etc. I keep them tuned to the same channel, usually 9. Often times I hear calls on the hand held but not on the fixed VHF or vice versa. Sometimes on both simultaneously. Why is that?
I haven't personally haven't noticed that happening other than when a signal was weak, and the squelch setting and reception on one radio didn't let the call be heard, but other radio's squelch and reception level let it through.
Might be some glitch with the dual MMSI configuration ? For non DSC calls I can't see why that would matter.
Jackdaw: I assumed that the USA had non vessel specific MI implemented. Lord knows why they haven't yet.
The rational behind the MI number is exactly because it can be useful to rescue agencies.
The confusion that could happen when you take handheld on charter holiday and make a mayday or pan pan call, and the MMSI was for another boat, wouldn't be good. Same if you have abandoned to a raft etc.
What I find curious is that while Canada DOES issue MIs for handhelds (and other devices), they don't notify the ITU-R so it's NOT stored in the international MARS database.
Kinda goofy in both cases.
Last edited:
At this point in time, only the hand held has an MMSI. I'll be getting another for the fixed VHF.