A DSC Primer for Cruisers by Lynn Kaak
MARCH 2013
“Can I get your MMSI number?” This question should be as common among cruisers as “What’s your e-mail address and phone number?” After all, we rely on our radios for communication, yet the utility of Digital Selective Calling (DSC) is incredibly underutilized by cruisers. There are features available that seem to be designed with the cruiser in mind. Before any of the advantages of DSC can be used, you must have an MMSI number (Maritime Mobile Service Identity). This can be obtained from your country of registry or documentation. Fire up your favourite internet search engine and find out how to get one for your boat. Since it varies for each country, we won’t discuss it here in any greater detail, except to remind US vessels that a BoatUS number is not on the international database, and is meant only for domestic use. For everyone else, the information given when you apply for your MMSI is on an international database that can be accessed by maritime search and rescue organizations. The first feature, and certainly most important thing, is for safety. That red “Distress” button on the front of your radio is designed to send out a continuous Mayday call if you press it for at least five seconds. If your radio is hooked up to a GPS, your position will automatically be sent out with the Distress call to every DSCequipped radio within range (radios with an MMSI number). If any of those receiving vessels have their GPS chartplotter hooked up, they can actually see your position on their screens. This certainly makes getting help in an emergency a lot easier and more effective. Trying to clearly give your location is not necessarily an easy thing to do in an emergency. This makes it error free. Then you can go to Channel 16 and do it the more traditional way.
Lynn Kaak is cruising the Caribbean aboard Silverheels III.
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Another feature that is just so useful is the ability to privately “call” or “page” another boat. Let’s be honest, we’ve heard those boats in an anchorage that seem to call each other every five minutes, or the person who tries to call a boat 20 times within five minutes, and you wish you could find a way to get them to desist, or you turn off your radio to limit the chatter. DSC can make everyone’s lives a little easier. Say Cranky Pants wants to call Leaky Tub. They simply can use the “Individual Call” option on their DSC menu, find Leaky Tub in the addresses, and hit a few buttons. Leaky Tub will get a “chirp” of some sort from their radio, which will get progressively louder, to let them know that they are being paged. Leaky Tub hits the appropriate buttons on their radio, and both radios will miraculously be on a working channel so the conversation may begin. (Actually, Cranky Pants will have already chosen the working channel when setting up the call). And no one will know about it unless they scan all of the channels. Granted, it takes the fun out of reading the mail or lurking, but you can’t have everything. And if Leaky Tub wasn’t home, but the radio was on, they will see on the radio that Cranky Pants was trying to contact them. The other day we were coming into an anchorage and we weren’t sure where our buddy boat was, as they had arranged a mooring for us next to them. Rather than call on the radio and possibly bother them while they were dealing with their mooring, we did a “Position Request”. Their radio (hooked up to their GPS) told our radio (and our chartplotter) their position. We saw where they were, and they didn’t have to do a thing. Their radio has the ability to auto-respond to those kinds of requests, as does ours. You can also do a “Position Report” to tell someone where you are. This is nice when buddy boating and also in areas where you might not feel comfortable about giving your coordinates out loud on VHF. Sometimes a group of boats will buddy up to traverse an area where they may not feel comfortable. Maintaining radio contact is nice, and one can create a common “Group MMSI” number for all of the boats in the flotilla, like making a multi-party conference call. You can do positional information to the whole group, or page them, if you wish. Let’s say that you are entering an anchorage and you would like to know if anyone you know (and have in your radio address book) is there. A “Polling Request” will call out to your friends’ VHF radios, and any of them in range will answer, provided that their radio is switched on. At times when perhaps you aren’t feeling well, or are napping, or whenever you don’t want to hear the general calls on the local cruiser calling channel, you can turn down the volume or change to another channel. If someone pages you, or there is a Distress call, your radio will still alert you to those calls. At least this way your friends can get hold of you, even if you may be feeling a little anti-social toward the rest of the world. Get your VHF owner’s manual out and do a little reading on the capabilities and how to use them for your particular radio. Each radio has its idiosyncrasies, and that needs to be checked for yourself. Once you start using the features available through Digital Selective Calling, you may never look back. You, too, may be one of those who include an MMSI number on your boat cards.
CARIBBEAN COMPASS
Your MMSI is on an international database that can be accessed by maritime search and rescue organizations