How often have you been called using your MMSI?

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Ric

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I am considering whether it is worth getting a DSC radio. I have active AIS, so other boats could conceivably call me using my MMSI. But how often does this happen in practice?

I am not a big user of VHF and rarely make calls myself, and the big red mayday button on DSC sets is not a "must have" for me. However, occasionally I have been called by fishermen at night if I am blundering towards their nets. My main interest in getting a DSC radio is so that they could "ring me up" rather than calling "le voilier a position blah blah" etc which is not so readily discernible. But do people actually tap in the MMSI to call other boats? Or is it more normal to make a conventional call on CH16?
 
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I've never been called by DSC, but since I don't have AIS transmit and nobody knows my MMSI number (well, I put it in the contact details for forum events, but other than that...) it's not really surprising.

I wouldn't expect to need to call an unknown yacht, but if for some reason I did and you have AIS to make it possible, then yes, I probably would. Easy to do, ensures I have the right person, and doesn't broadcast the communication to every random person listening on 16 :)

I would certainly use DSC to call a ship if I needed to.

Surprised they need to identify you by position though - your name should come up on the AIS. So perhaps this indicates that the fishermen don't have (or use) AIS receivers anyway, and having DSC won't help?

Pete
 
prv said:
Surprised they need to identify you by position though - your name should come up on the AIS. So perhaps this indicates that the fishermen don't have (or use) AIS receivers anyway, and having DSC won't help?

Pete
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I didn't have the AIS then! Should have made that clearer, sorry. I just got AIS this winter, not tried it offshore yet.
 
Very rarely - as in once, I think! I have been trying to encourage its use amongst the other marina residents - if we all used it, it would remove a lot of the background chatter on 16. If you have a working non-DSC radio, it is probably not worth ripping it out and throwing it away. If you need to buy a new radio, the price difference between DSC and non-DSC is sufficiently small that you may as well have it.
 
Ex-SolentBoy said:
Never, 10 years with DSC.

Oops, I said in another thread that my radio was nearly always off!
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Your not the only one in that boat...

Once and they where told never to do it again, my phone is in my pocket & the VHF is below. Single handed in close quarters situation with two other cruising boats, all trying to go faster than each other :D. Then my DSC alarm goes off, not happy...
 
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I have recieved one call, once, I was in such a flap I nearly missed making a response before the caller decided I wasn't on air.

I use my DSC radio like a standard VHF, except I have now linked it into the GPS so IF I did have to hit the red button I would gain the benefit of DSC.

I should really get the manual out and learn how to use it properly.
 
Only ever recieved a DSC call as part of a training exercise.
However, I was impressed to see an alarm on the plotter with the casualty shown at their position on the chart having received a Mayday DSC Alert. (VHF connected to plotter.)
 
laika said:
Don't you need a DSC radio to obtain a MMSI in the first place? And no MMSI, no transmitting AIS surely...
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There's nothing to stop you requesting an MMSI without owning a DSC radio - just does not serve much purpose - and MMSI numbers are in short supply, so it is a bit irresponsible.
 
maby said:
MMSI numbers are in short supply, so it is a bit irresponsible.
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I guess it would be if someone were frivolously requesting lots of them. But the MMSI is just as necessary for AIS transmission as it is for DSC, so there's nothing odd about the OP requesting one for that purpose.

Pete
 
prv said:
I guess it would be if someone were frivolously requesting lots of them. But the MMSI is just as necessary for AIS transmission as it is for DSC, so there's nothing odd about the OP requesting one for that purpose.

Pete
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I guess the number of people using an AIS transceiver without owning a DSC radio is very small. If it were to increase significantly, it might make sense to introduce a rule that the AIS should be programmed with a dummy MMSI - zero, possibly?
 
maby said:
I guess the number of people using an AIS transceiver without owning a DSC radio is very small. If it were to increase significantly, it might make sense to introduce a rule that the AIS should be programmed with a dummy MMSI - zero, possibly?
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So what happens when two boats with apparent MMSI zero come into range? The poor receiver will get very confused about this boat that's travelling several miles in between each position broadcast!

The MMSI number isn't just a field of arbitrary data like the vessel name, it's tied into how AIS works. Each station needs its own unique number, MMSI is entirely appropriate for the purpose. It's not purely a DSC VHF thing, though that's how most of us encounter it, it is the Maritime Mobile Service Identifier, applicable to any maritime mobile radio service.

The OFCOM page linked above says they issue it for DSC or satellite equipment. I'm sure if somebody prodded them about it, and they had a bit of bureaucratic thinking time, they'd update it to include AIS on the list too. You have to put AIS transmitters on your radio license; it wouldn't surprise me if the act of doing that (assuming no existing DSC) triggered the generation of an MMSI in the same way that adding DSC does. I don't want to confuse things by trying it out on my license, though :)

As you say, in practice the issue rarely arises because most people fit DSC before AIS.

Pete
 
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