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Thread: Use Your VHF-DSC Radio with Confidence

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    Thumbs up Use Your VHF-DSC Radio with Confidence

    Good Article (even if DSC is not in Alaska) From Boating World magazine:


    Use Your VHF-DSC Radio with Confidence

    Posted: July 1, 2012 |

    It could save your life one day.

    By: Tony Gardiner, director, United Safe Boating Institute


    Marine VHF radios with Digital Selective Calling (DSC) are part of a worldwide upgrade of maritime communications. They allow boaters to make ship-to-ship private calls to other vessels equipped with a VHF-DSC radio, and in emergency situations they allow boaters to send an automatic mayday at the touch of a button over marine Channel 70, which is monitored by the U.S. Coast Guard and large commercial vessels.
    To work properly, however, VHF-DSC radios must be registered and encoded with a unique nine-digit Federal Communications Commission (FCC) identification number — called a Maritime Mobile Service Identity (MMSI) — that functions much like a telephone number. Once the radio is properly registered through the FCC or its designees — BoatU.S., Sea Tow or the United States Power Squadrons — the MMSI number and identifying information about your boat are entered into the U.S. Coast Guard’s national distress database.

    The first three digits of the nine-digit MMSI number denote the geographical area and are followed by six digits. In the United States and its territories, the geographical area begins with the number 3 (i.e., 3XX, with the Xs assigned any digit from 1 to 9). Group MMSIs start with the number 0, immediately followed by the three-digit geographical code, plus five more digits.

    There’s one more step. To take full advantage of the VHF-DSC radio’s ability to send an automatic mayday, you need to connect your radio to a GPS that can transmit your vessel’s location and its identifying information. Properly connected and registered, your DSC radio will transmit your position and, if entered, the nature of your distress to rescue authorities. (If you have a GPS that is not connected to your radio, you can still enter your position manually.) Once activated, your DSC radio will continue to transmit your emergency signal until it is acknowledged.
    If you obtain your marine VHF-DSC radio through a dealer or during a new-vessel purchase, make sure you apply for your MMSI number immediately. As part of the application process, you will be asked to provide your name, address, telephone numbers (yours plus an emergency contact) and the vessel description, including registration number, vessel type, length and passenger capacity.

    Should you need to activate a distress call later, this information, embedded in your MMSI, will be provided to the nearest Rescue Coordination Center (RCC), ensuring that no matter where you are in the world, local authorities will have an excellent chance of finding you and rendering assistance or rescue.

    If you purchased a secondhand boat with a VHF-DSC radio already installed, take the radio to a recognized marine electronics store and have the old MMSI replaced with your new MMSI. Before heading out on the water, take time to input the MMSI numbers of vessels with which you’re likely to have contact in your radio directory. If you belong to a yacht club, Power Squadron or other boating group, chances are that they will have what is known as a Group MMSI, which will let you alert all other members of the group at once. This is useful for cruises and other on-the-water activities, but emergency situations are where it really comes in handy.

    ALASKAN SEA-DUCTION
    1988 M/Y Camargue YachtFisher
    MMSI# 338131469
    Blog: http://alaskanseaduction.blogspot.com/

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    Good article. I just wish folks would learn to use their VHF radios correctly. Yesterday out in Resurrection Bay a couple of nimrods were trying to converse on the VHF, first suggesting channel 28, which is a commercial simplex station used by the marine operators (do they still exist?), anyway they came back after not being able to talk on 28 thinking their radios were bad and went to 22. I waited for the coasties to blast them for using 22 but after several times hearing them talking on 22, but no such reprimand. Please, learn how to use the best safety item on your boat properly - others may depend on it.

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    Member JR2's Avatar
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    I have to admit I don't know what channels your supposed to use for just BS, but I know enough to stay off of 22. I suppose I should learn a bit more about what channels I should use and I know I read it once. Guess I have something to go look up on Google tonight.

    Does DSC not work in AK? I was going to get it all set up as my radio is already wired up for location but I just had not got around to getting the magic number.
    2007 Kingfisher 2825 - Stor Fisk

    Civilization ends at the waterline. Beyond that, we all enter the food chain, and not always right at the top. -- Hunter S. Thompson

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    There actually is no maritime mobile frequency dedicated for use as a "chat" frequency. This website http://www.offshoreblue.com/communications/vhf-us.php gives a good summary of the maritime mobile frequency allocation, each "channel," its corresponding frequency in the VHF band, and its designated purpose. No where in any of it is there a "chat" or "conversational" channel. 9 and 16 are listing as "hailing" channels. The "public correspondence" channels (24-28, 84-88) are for contacting a marine operator at a coast station. The "non-commercial" channels (68, 69, 71-74, 78A) all state that communication must be "about the ship's needs." I doubt that general "chat" would fall into that category.

    Still, you would think they would have (should have) allocated at least one channel for that purpose. As a ham, I know that radio spectrum is tightly controlled by the FCC and highly sought after by lots of groups and industries. Directly below and above maritime mobile in the VHF spectrum is the Land Mobile stuff, such as private 2-way radios (for private companies, etc.) and not too far beyond that is air band and commercial television. The FCC would either have to strip someone of RF spectrum to add anything to maritime or repurpose current maritime allocations. I guess letting two sportfishing boats or cabin cruisers talk about the weather, where the fish are biting, or the hot chick on the boat that just passed by wasn't a high enough priority.

    On a side note, the FCC has a a license class called "Marine Radio Operator Permit" (MP License) which is easy to get (24 questions out of 100-ish question pool) that I think every boater should be required to have. Come to think of it, though, no where in my study guide did it ever discuss "chat" on maritime mobile radio.

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    By the way, what's this about DSC not working Alaska? I've never heard of that before. DSC has been around since the 1990's. We were using it in aviation (in the Lower 48 at least) even before that. I find it hard to believe that DSC doesn't work up here.

    (Well I KNOW DSC will work up here; I find it hard to believe that no one is monitoring.)

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    The Coast Guard can not monitor DSC yet I guess, BUT the Cruise Boats / Sightseeing types are required to have DSC, not sure what the term commercial means in reguards to DSC, so even if it's not 100% up in Alaska, it's just another chance to be heard. For example if it does go horrible wrong fast It could be your only shot at getting a signal out before going down, specialy if getting life jackets and dingy deployed.
    Cheap insurance is a ditch bag with a hand held VHF too.
    Be prepared for the worst and never use is way better than wishing once it could save your family lives.

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    Member AKBassking's Avatar
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    The last time I checked (and the USCG guy on this site may chime in) DSC is not yet operational in Alaska due to budget constraints and terrain. However, if you have DSC and activate it, it will broadcast your distress to other boaters with DSC. I also believe DSC is now required on all VHF radios sold in the US.

    ALASKAN SEA-DUCTION
    1988 M/Y Camargue YachtFisher
    MMSI# 338131469
    Blog: http://alaskanseaduction.blogspot.com/

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    Well I guess I will go get the magic number I need to get it all fired up and working... Might as well take advantage of every possible bit of help I can get in case of a problem.
    2007 Kingfisher 2825 - Stor Fisk

    Civilization ends at the waterline. Beyond that, we all enter the food chain, and not always right at the top. -- Hunter S. Thompson

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    Yeah, DSC is definitely an asset in an emergency, especially if you sync it with your GPS unit. My VHF mobile radio had the capacity to take NMEA inputs from a variety of compatible GPS units and a guarded red switch. In an emergency, you could simply flip up the switch guard, hit the panic button, and the radio would automatically start broadcasting a SELCAL distress signal along with your position. Of course, that was back in FL-lots of boats everywhere and the Coast Guard monitoring.

    A note on monitoring, incidentally, commercial vessels of a certain size, known as "compulsory equipped" are required to maintain a listening watch on certain distress frequencies. A lot of that these days is done by automatic electronics that alert when a distress call come in, relieving the crew from constantly listening to the radio. I'm not certain that Channel 70 is one of those compulsory monitored channels.

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    Quote Originally Posted by alaskapiranha View Post
    Cheap insurance is a ditch bag with a hand held VHF too.
    This is true, and a good Marine Band HT's (Handie Talkie or Handheld Transceiver depending on who you ask) can be had new at a price point affordable to anyone who can afford a power boat. However, I'm not certain how effective that HT will be when it all goes south. VHF signals are, for the most part (not entirely) line of sight. This website http://www.qsl.net/kd4sai/distance.html calculates distance to the radio horizon based on VHF antenna height. If you're actually IN the water, your HT may only reach one mile. Of course, that combines with another station's antenna height so 5-7 miles is probably more accurate. I think having an HT in the water would be best for contacting aircraft simply due to their antenna height (altitude).

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