TWO DSC radios on boat - unique or common MMSI numbers?

[jfm]

Thanks Paul. A few thoughts on all that:

If i also have JFM's MMSI number and do the same, what happens when his tender and mothership VHF sets both receive the position request and transmit their coordinates ? Pretty sure it's not going to work correctly/reliably.

I agree it may not work, but I really don't care. No-one has my MMSI nor do I have theirs. If they got my MMSI I hnestly wouldn't know how to respond on the DSC radio without checking the manual, and life is too short for that. For chatting to mates I use mobile phone or hail on ch16. I cannot imagine using position request EXCEPT to locate my tender from mothership or vv (where it could be useful)

How about if he brings the tender MMSI up in his VHF menu on the mothership and sends a position request ? The mothership transmits the call and it will be accepted by the tenders VHF because it matches the MMSI that the call is being sent to, the mothership cannot receive it, as it's transmitting. The tender then sends it's position, which the mothership alone receives, as the tender is transmitting.

Hmm, i was working through that last paragraph as i was typing. Looks like you're right, that side of things should work. I guess i was forgetting that each set that was transmitting wouldn't be able to receive at the same time.

I reckon that will work. That means I can have a common MMSI, which might be more legal and which gives me ultimate backup if I need to send a mayday, yet still have postion request twixt tender and mothership

It seems to me having read this (and thanks everyone for the advice) that there is no clear cut answer: you can make an argument for having one or two MMSIs. For my own personal requirements, I'm leaning towards having one MMSI but I'll cogitate for a few more days. For sure this is not one of life's more important issues

 

[grumpy_o_g]

One other thought - if you have AIS B and are transmitting on that someone could call you on DSC based on your AIS return I think. Having said that I suspect you don't intend to use AIS-B much, so that probably won't worry you either. Brilliant and fascinating thread - thanks for your time in sharing it all.

 

[mlines]

Get a separate MMSI for each set.

Then form your own cruising club "Rich B*ggers Cruising" and apply for a Group MMSI (for free). Then you can have each radio respond individually to their own MMSI and collectively to the Group MMSI.

Martin

 

[powerskipper]

vhf

different MMSI numbers as it is a different vessel, and for the position request, this will only work if the set you ask a request of,, has a GPS feed.

 

[mjf]

I would be inclined to have each seperate as the Tx/Rx are separate units on separate hulls.

You may sell the mother ship but wish to keep the tender

Also the 'find msii' maybe useful if you suspect the tender has been nicked or gone to some 'do not do there ' place or whatever.

 

[jfm]

different MMSI numbers as it is a different vessel, and for the position request, this will only work if the set you ask a request of,, has a GPS feed.

Yup, both dsc sets will have a gps feed

But is it a different vessel? Do you have some rule in mind governing that point? For many purposes a tender isn't separate: you'd never register it separately, and no foreign state that insists on registration (eg France) would ever insist it be registered separately. See Q+A 3 on thispage for example, which agrees MYAG's comment that atender is basically part of the mothership and that the tender's DSC radio is therefore an additional radio set of the mothership. Confusing isn't it?

 

[jfm]

There's a thread on it here, and they don't know the answer either!

 

[PaulGooch]

There's a thread on it here, and they don't know the answer either!

Looking at it from the other side, what do you gain by having a single MMSI number, that you don't get by having separate ones ?

The only thing i can think of, is if the mothership was unable to send a DSC mayday you could do so from the tender and they would still be looking for a 78ft boat. That's easy to rectify, as you should follow the DSC call up with a traditional mayday on CH16.

 

[BartW]

all interesting stuff on here,

I guess I will have two separate MMSI numbers,
as the tender could (eventually) operate completely independent from the main boat

 

[oceanfroggie]

Let's look at this another way. How well would it work if both a hubby and wife had the same phone number on two separate phones? Comprendee!

 

[Bilgediver]

I am trying to work out whether I should (a) register/license them separately and have a unique MMSI number for each one, or (b) register them both on one licence and so have the same MMSI on both radios.

Not sure where you went with this however if you go and check out your boat on the ITU web site you will see they expect you to have separate MMSI numbers for all craft associated with your boat and they provide the method for interlinking them to the mothership on the data base!!!!

Seems logical....

Same process applies to cruise ships and their rescue craft.


http://www.itu.int/online/mms/mars/ship_search.sh

 

[jfm]

Not sure where you went with this however if you go and check out your boat on the ITU web site you will see they expect you to have separate MMSI numbers for all craft associated with your boat and they provide the method for interlinking them to the mothership on the data base!!!!

Seems logical....

Same process applies to cruise ships and their rescue craft.


http://www.itu.int/online/mms/mars/ship_search.sh

Hmmm. Thnaks - I see your point Bilgediver. Yet more food for thought! I haven't actually done the MMSI programming yet; will do soon

 

[Hurricane]

I agree it may not work, but I really don't care. No-one has my MMSI nor do I have theirs.

AIS ?



Yep - I know what you are going to say.
Switch it off!!!

Just as I did in France - just too many busy bodies were calling me to ask stupid questions - dont seem to get that problem in Spain so I switched it back on again as we left Corsica.