MMSI number on tender’s USA radio

Should I get my 16’ fishing boat/tender's VHF radio it own MMSI number or should I use the mother ship’s MMSI number? If I get a separate number for the tender, can I use the BoatUS site, or do I have to get/buy another FCC station license for when the US registered boat is in Canada? It’s only 16’ and only has a VHF w/o GPS.
Thanks

If you are not using the 16' boat except as a tender, use the same number, just as if it were a second radio on your big boat. You will be able to make and receive DSC calls between the tender and big boat, just as if they had different #'s. At least that is the way it works with my ICOM / Standard Horizon radios.

Interesting. I would recommend the opposite. It's a separate boat, and can be in a different place. And it has a different description, registration number, etc. I got a separate MMSI, and separate SA license for mine. If you install AIS, you really have to have separate MMSIs so you don't get two conflicting ship positions reported.

twistedtree said:

If you install AIS, you really have to have separate MMSIs so you don't get two conflicting ship positions reported.

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I don't think that is true. The dinghy's AIS will transmit its position with name (perhaps T/T Big Ship) and other info., including an MMSI number. The fact that BigShip's AIS is showing the same MMSI number would seem to be of no consequence. Every other receiver will see both targets and could place a single MMSI call that will be received by both and may be answered by either.
If either VHF is used to create a DSC emergency call, that VHF will reports it's location.

Now you got me wondering, and I found this from the USCG.

http://www.navcen.uscg.gov/?pageName=mtMmsi

My read is:

1) tenders are supposed to use an MMSI that is a derivative of the Ships MMSI, but there is now provision for issuing them, so they are not used.

2) you may use the ships MMSI. Note the word "may", not "shall".

3) use a different MMSI if you use AIS

So it seems both ways are OK under certain circumstances

I used the same #, thinking the hand held is a back up to the big boat, and also part of my ditch bag contents.

MYTraveler said:

I don't think that is true. The dinghy's AIS will transmit its position with name (perhaps T/T Big Ship) and other info., including an MMSI number. The fact that BigShip's AIS is showing the same MMSI number would seem to be of no consequence. Every other receiver will see both targets and could place a single MMSI call that will be received by both and may be answered by either.
If either VHF is used to create a DSC emergency call, that VHF will reports it's location.

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Interesting question how different display devices would handle the same MMSI coming in with different reports in different locations, let alone different names. The MMSI is supposed to be unique to a single ship. I'd bet $100 that at least one product would choke on it.

Sealife said:

I used the same #, thinking the hand held is a back up to the big boat, and also part of my ditch bag contents.

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I think MYTraveler is right that this is fine for handhelds associated with mother ship. See the document linked above for the CG guidelines on the various situations.

The Handheld VHF radio should have a separate MMSI # for the following reasons;

1. It is very easy to change the descriptor information associated with the MMSI number. You just need to log in and edit the form. So if you use it on other boats, dingy while cruising, or a daysailer, or the fishing boat, it is easy to update.

2. In the remarks section, you can state this is a handheld VHF radio associated with a mothership MMSI # and its description. The USCG will see the description. Very important in an abandon ship distress situation. This is also why it so important to keep the information current.

3. If either radio is sold in the future you can cancel your registration of the MMSI # allowing the new owner to obtain the programmed MMSI# in the unit. Example; You sold your main vessel with the permanently mounted VHF radio, You can then cancel your registration so the new owner can sign up for it. You can take your handheld VHF radio with you to the next vessel, just edit the registration form. If you do not cancel the MMSI# registration the new owner will incur the cost of reprogramming the VHF.

4. If someone on the main vessel wants to contact you on the dingy using DSC they can do so using the individual call selection. Then you can have a conversation without hailing on VHF 16 or another channel. This is not possible if both radios have the same MMSI#. You can also just ping the LAT LON for the handheld to find out were the kids really are.

Brian Adams said:

1. It is very easy to change the descriptor information associated with the MMSI number. You just need to log in and edit the form. So if you use it on other boats, dingy while cruising, or a daysailer, or the fishing boat, it is easy to update.

Click to expand...

Which form, please? Link?

-Chris

Chris,

Via the Boat US web site for MMSI registration.

Once an MMSI number is assigned you can go to "my account", select the MMSI# to modify, click edit, then scroll down to "vessel details". This is where you can update the details of the vessel description. This is also where you can state this handheld MMSI# is related to a mothership and give its MMSI#.

I tried to attach a link directly to the vessel details, but you need to be signed in to access the page.

Hope this helps, Brian

Thanks, Brian... thought at first you meant that was for the FCC-issued MMSIs.


-Chris