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Ainulindale, Ainulindale, Ainulindale… this is Zero To Cruising, Zero To Cruising, over…

–>Zero To Cruising, Zero To Cruising… this is Ainulindale, over…

Ainulindale, switch and answer on channel 71, over…

–>Switching to 71.

We both change channels, hopefully having already confirmed that channel 71 is available!

Ainulindale, Ainulindale… this is Zero To Cruising, over…

–>Zero To Cruising… this is Ainulindale, over…

Conversation can now commence. Note that all bored or nosy people can also follow you both over to channel 71 to eavesdrop. There are no secrets on the VHF!

That seems like a lot of steps just to have a brief pow-wow with someone, doesn’t it? Of course, it can be abbreviated, especially by boats which are nearby and speak often, but that’s basically what goes on every time a boat hails another vessel on the VHF radio, unless…

Someone’s radio needs to be cleaned!

Unless both vessels are equipped with DSC radios, are familiar with how to use them and know the MMSI number of the party that they wish to hail.

Wikipedia describes DSC or Digital Selective Calling as “a standard for sending pre-defined digital messages via the medium frequency (MF), high frequency (HF) and very high frequency (VHF) maritime radio systems. It is a core part of the Global Maritime Distress Safety System (GMDSS).

In addition to being valuable as a distress system, DSC allows one vessel to call another almost as easily as dialing a telephone, especially if the vessel to be called’s MMSI number is already programmed into the caller’s radio. Trading MMSI numbers and programming our radios with them is exactly what Kirk on Ainulindale and I did yesterday. It’s ironic too as, after hanging out with one another for the past few months, we only get around to doing this just as Kirk and Donna are getting ready to start heading up island and will soon be out of VHF range.

In order to accomplish this, I admit that I did have to pull out the manual for our Standard Horizon GX2100 Matrix radio as I couldn’t really remember the steps. We got it working though and now all we need to do to hail them is to scroll to their ship’s name in our radio’s directory and push send. On the other boat the radio will start ringing like a telephone does and when responded to, will have already switched to a working channel. It’s pretty cool, and a time saver. It also does away with the busy-bodies switching channels with you to follow your conversation!

There are some other nice things that DSC allows you to do including finding out specifically where your friends are located. Having tied our Matrix radio into our Garmin 546, this is really cool! If you are getting ready to head out cruising, make sure that your boat is equipped with a DSC capable radio and that you register a MMSI number. You’re going to want to have the ability to do all of these things!


Here are some useful DSC related links. Credit to Silverheels 3 for compiling the list.

Canadian MMSI application portal

Americans will find that their MMSI number has been included with their call sign on their 10 year paper FCC radio license for international travel. An American MMSI assigned by Boat US is not recorded in the ITU database. The US government-issued FCC MMSI always ends with a zero.

Log in and fill in your details, one of which will be your radio license. While you are doing this you can also register the rest of your marine electronics. Once you submit this information, you will be provided with a confirmation page with the following details: MMSI, Call Sign and License Number. Your new MMSI can then be entered into your VHF and away you go.

Search here with a ITU three digit country prefix for MMSI to determine a vessel’s country of origin, e.g. 316 would be Canadian.

Once you have the three digit prefix from above you can then:

Information pages for DSC and MMSI:

14 Comments

  1. Mike, do you need to know Mores Code to have this and SSB?

  2. Unless I am hailing an unknown vessel or for navigation or security, I always use cell phones for privacy or for the initial call. If I am going to a marina, I call and advise of my location so they know I am close, then hail on appropriate channel.

  3. That’s great because Ainulindale is a real mouthful. I don’t even know how its pronounced.

  4. DSC = pretty cool. We’ll be fitting one on our new boat (Sunset Chaser, lacking anywhere to mount the thing, will continue to make do with her Uniden Atlantis).

    I do like some of the new networked units that talk to the nav computers over N2K: see a ship on radar and AIS, touch its icon on the chartplotter, click “Call on VHF-DSC”, and the call is made. But you can feed yourselves and your engines for a year with the kind of cash needed for such a system.

    • The radio I linked in the post (the one that we have) does have a AIS receiver built into it. With two little wires I then set it up to plot the AIS hits on the Garmin. I can have the radio call the ships but I don’t have the touch screen that you’re referring to. Then again, that radio is a LOT less expensive!

  5. Are you still on open channels or is this now a private 2 way chat?
    Either way a neat time saver and kudos for spreading the word.

    • To my knowledge it is still an open channel. Should someone be scanning, they would still be able to pick up the conversation I assume. They’d have to be VERY bored to do that though!

  6. Cudos Mike for broaching this subject. You didn’t, however, mention how little it is used. Anybody that bought a radio in the last 5 years has to have DSC built in. They don’t seem to make them anymore without it. From my observation, only about 25% of the yachtie / cruiser population knows about MMSI and DSC. I would guess that 60% of the people who have installed their own DSC radio never bothered to hook it up to the NMEA data stream on their GPS to provide lat/long input to the radio. Therefore, if these people made a DSC distress call on channel 16, the radio would NOT provide their location. I’ve just been to Defender’s website and all of their fixed mount VHF radios are DSC capable while none of their handheld VHF radios are DSC capable. There may be a regulatory reason for this. Maybe the MMSI number is only for the fixed installation in the ship itself and not valid for portables? Self education and actual use of DSC will greatly help to improve people’s knowledge base. Keep spreading the word!

    • Thanks, Wade. It’s a bit hard to tell how much or how little it’s used because we totally miss that radio traffic. I assume that you are right though. I know that even we use it infrequently. In fact, I think Kirk’s boat is the only one we have the MMSi number for in this area.

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