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  1. #1

    VHF Radio and MMSI

    Hopefully this is going in the proper area.... I have purchased a new portable VHF that is equipped with GPS positioning and DSC. My questions regards the MMSI registration. Since the unit is a handheld, I have full intentions to use this on both my recreational boat as well as my PWC. When you register for the MMSI it is required that you include your vessel info, yet does not allow you to list mutiple crafts.

    As I understand it, the DSC system when used for distress situations, sends a digital signal to all equipped DSC radios (including USCG) that provides exact GPS position as well as vessel / craft info.

    There may be an issue if they are looking for a 24' SeaRay but I am on my FX SHO.

    Oh - and according to the radio's OM, I only have one opportunity to program the MMSI info. If a mistake is made the manual states that I will have to return to them for reprogramming - so, want to make sure I do this correctly.

    Sorry for the long winded post and thanks in advance for any advice you may be able to provide.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Do you have the Standard Horizon HX850S or HX851S?
    I have the HX850S, and encountered the same question.

    Long story short - the MMSI+DSC system was designed for ships and large boats, and the focus was on permanently installed radios.

    The rules assume (as you have discovered) that handheld DSC radios were simply in addition to the permanent VHF DSC radios, and would stay with the ship. On a ship, every VHF radio would be programmed with the same MMSI ship code.

    The MMSI/DSC system is the result of international agreements, and is not easily revised.

    There is no provision in the MMSI system for moving a radio from one boat to another on a frequent basis.

    This is compounded by the radio manufacturers strictly limiting the number of times the MMSI code can be changed in the radio. On many radios, you can enter the code only once. On some others, you can change it once or twice.

    As far as I can tell, there is no requirement in the MMSI/DSC system for restricting the number of times the code can be changed. It seems to be something the radio manufacturers thought would be a good idea

    It seems that the only way to properly move the radio from one boat to another is to notify the MMSI registry authority of the boat change, and have them update their records. However, they do not seem to be prepared for frequent, rapid changes of MMSI records.

    Another sticking point is that all DSC radios refuse to activate the DSC capability until you program an MMSI number into the radio. That means the Red Emergency button may not work until you program the MMSI into the radio.

    Without the MMSI code, the radio will work as a regular VHF radio, none of the Digital Selective Calling features will work.

    It seems the best you can do is complete your MMSI application with the most useful information you can, and hope the rescue folks can make sense of it in the event you need to push that Red button.

    Be sure you provide contact information for people other than yourself. If you are in trouble on the water, it is unlikely you are going to be able to answer your home phone or mobile phone.

    The contact people you provide should also know what to do if they get a call from the Coast Guard. You need to brief them ahead of time with all the important details about you, your boat(s) color, size, passenger capacity, and so on.

    The contact info should include people who are probably not going to be on the water at the same time you are.

    I think the best you can do is code your MMSI into the radio, and learn to use the selective calling capabilities.

    In the event of an emergency the red button will summon help to your location (once the GPS has a satellite lock, which can take a minute or more if the radio was just turned on). Even if they are looking for a different boat, they will still be looking in your area.

    Once the DSC radio has signaled your emergency location, it will automatically switch to voice mode on channel 16. If you can hear and speak to the Coast Guard, then you can provide correct info regarding the current boat you are (or were) on.

    One thing many do not realize is that once their friends also have DSC radios (with or without GPS), you can call each other directly, without first using channel 16. It works something like a cell phone speed dial
    Last edited by K447; 04-03-2010 at 10:40 PM.

  3. #3
    I have the HX851 - just picked it up and I believe that it is pretty new on the market. So far it seems to be a very good quality radio, includes a strobe light that will flash SOS or continuous (progarmmable), is floating and waterproof, includes a transluscent gasket so it glows in the dark and allows for navigation between waypoints.

    I think what I may do is register the unit MMSI with my PWC info as it is a smaller imprint on the horizon. I am sure that if the CG is looking for a PWC and finding me in my 24' boat would be much easier, better than the other way around I guess.

    Maybe down the road there will be some changes made to allow for portable radio registrations.

    I appreciate your input on the registration completion, what you say makes perfect sense!!

  4. #4
    AaronQuade's Avatar
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    If you just say " Coast Guard " on channel 16. you will get a answer if you are within radio range of your radio. The word help is also a good one. They are going to look for 5 main things. we call them the "Big 5"
    1. Position
    2. Persons on board
    3. Nature of Distress
    4. Description of Vessel
    5. If you have life jackets and if they are on.

    Then depending on the situation they will dispatch a boat/ switch you to another channel/ offer a "MARB" Marine Assistance Request Broadcast.

    Those are some of the basics on if you need help on US waters. I cant say much for other nations waters but thats how ours basically work.

    Remember Channel 16 and Coast Guard.

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by AaronQuade View Post
    ...
    1. Position
    2. Persons on board
    3. Nature of Distress
    4. Description of Vessel
    5. If you have life jackets and if they are on.
    ...
    A properly configured VHF radio with DSC+MMSI code and an internal GPS will provide 1, 3, 4 with the press of the red emergency button on the radio. Even if you cannot speak, or even hear them.

    When trouble happens, you may not be able to report your location accurately, or at all. In some cases, it may be someone else who is using your radio, possibly for the very first time.

    Also, DSC works even if channel 16 is busy with other radio traffic. You don't need to listen and wait for a clear channel to send a DSC call. The radio does it automatically, and DSC uses channel 72 to deliver the initial distress message to the Coast Guard.

    It will continue to deliver the DSC emergency signal until it receives an acknowledgment that the message has been received.

    All the regular channel 16 and Coast Guard calling protocols are still available. DSC just adds another level of capability.

    DSC is also useful when calling another boat, non-emergency. If both boats have DSC radios, you can digitally call the other boat and establish a voice link without ever touching channel 16. You can even digitally transfer GPS positions directly between the radios.

  6. #6
    AaronQuade's Avatar
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    I know from my experience that verbally calling on channel 16 is faster.

  7. #7
    I just purchased a Standard Horizon HX851 Handheld and registered the MMSI number with SeaTow's web site. The radio only allows the number to be entered once, but the MMSI profile on the SeaTow site allows me to update my profile any number of times. I can change my name, boat information, emergency contact information, etc. at will. I assume this information is accessed realtime by the Coastguard in the case of an emergency.

  8. #8
    giguchan's Avatar
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    I was just reading this and found it pretty informative.. One more thing i would like to add is getting Sea Tow Membership. I have one for my jetski. It's peace of mind. you dont want to know what a tow in will cost you without a membership. I too keep a VHF onboard just to have another voice with me.

    Everyone be safe and enjoy the water!

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by kingtut33556 View Post
    ...I assume this information is accessed realtime by the Coastguard in the case of an emergency.
    Don't assume.

    Find out how quickly updates you make on the web site become available to the rescue services.

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