Worldwide DSC Group Call Network

Allan Riches
Allan Riches
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Here is another DSC radio idea that follows on from my recent OCC forum topic of DSC Group and Individual Calling, and the experience of the WCC/ARC rally group getting their DSC HF/SSB radios working and using their assigned DSC Group Call ID to create a mutual support network.

I subsequently considered how to create a similar DSC Group Call system to provide a mutual support network for yachts travelling independently, and to give them access to local information from local boat crews when they get to destinations or as they explore coastal or island regions.

The result is a Group Call ID based on the NAVAREA where the vessel is located.

To make the system work it just needs recreational and marine tourism vessels in that region to enter the Group Call ID in their DSC capable radios, and maintain their radios in a 24/7 DSC watch, so any other private yachts or marine tourism related vessels (live aboard dive, surf, charter and sports fishing boats etc) can conveniently contact each other using the General Receiver in a DSC capable HF/SSB or VHF radio. (This assumes the General Receiver frequency/scan setup in HF/SSB radios has been amended as per the attached documents.)

I have attached a document with more information on what has been named this Worldwide Group Call Network. The document includes the DSC Group Call IDs for 20 of the world 's 21 NAVAREAS.

Setting up to join/create/use this network takes about 20 minutes for an ICOM M802 or M801 radio, and about ten minutes for a VHF radio. And costs nothing. Keeping radios in a 24/7 DSC watch is a quiet experience, because the radio speaker is muted while the radio does the work of listening for DSC calls.

Entering the NAVAREA Group Call ID in the DSC capable radio and keeping the radio switched on 24/7 immediately creates a mutual support network of similarly equipped nearby yachts - known and unknown - which can contact each other for advice, a part, fuel, water, a tow or other assistance.

The more recreational vessels doing this, the more dense the network of nearby small-craft to assist each other. By keeping radios on 24/7 to help each other with information, advice or assistance with minor problems, the radios are also on 24/7 to provide a prompt and nearby response in the unlikely event of a major problem; by contacting each other with a DSC Distress call.

If yachts and other recreation and marine tourism vessels maintain a 24/7 DSC watch for mutual support and advice, they also become accessible to MRCCs or regional S&R centres looking for a nearby vessel to go to the location of an activated EPIRB or PLB. The MRCC or regional S&R centre simply needs to send a DSC Distress Call to make contact.

This Worldwide Group Call Network facilitates what MRCC Australia highlights as the importance of nearby assistance from other vessels when away from the excellent shore based S&R support that is available only around the coasts of UK, Europe and North America and a few limited areas in the rest of the world. Such quick response and 24/7 S&R support simply does not exist in most of the world, including the Atlantic (as demonstrated by Chiki Rafiki), nor in the Pacific or Indian Oceans, nor around most of Australia 's coast or most of SE Asia. (Which is why RHKYC requires DSC HF/SSB radios in all yachts to maintain a 24/7 DSC watch and uses DSC Group Calling for their long distance events.)

MRCC Australia, with responsibility for and experience managing S&R in one of the largest, least populated and low resourced coastal and ocean regions in the world, with low commercial shipping densities, says:

"In the event of an emergency, communication should first be attempted with others close by using radios"

And, "While satellites and satellite-compatible distress beacons have significantly improved the effectiveness of SAR operations, the system is NOT a substitute for carrying appropriate marine or aviation radio."

Because "Even once a (EPIRB) position is obtained, response times then depend on the time for a search and rescue (SAR) unit, such as a helicopter, aircraft or ground party to be readied and transit to the search area. The more remote the location of the distress incident, the longer the response time. In all instances, be prepared to survive."

Therefore, "Depending on the circumstances, your initial distress alert should still be made by radio if possible. You should activate your distress beacon only if contact cannot be made by any other means or when told to do so by a rescue authority." Because the distances are great and the EPIRB battery could expire before an official S&R response can reach the location.

See more details on the Worlwide Group Call Network at this webpage: .

The development of this concept ultimately become a combined Brunei/Australia, USA and UK project and therefore integrates ideas from all three sources.

I hope this is also useful for OCC members planning to cross more oceans and explore distant shores.

Comments, questions and sea trials please.

Allan Riches
GlobalGroupNetwork-PurposeUse.pdf (352 views, 438.00 KB)
ICOMDSC-EMERGFrequencies.pdf (319 views, 409.00 KB)
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This is a very good initiative. Maintaining a 24 hour watch given the significant power consumption of HF transceivers is its key issue IMHO. I have posted a summary of my understanding of the initiative and my thoughts about the power issue at
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Group MMSI (US VHF perspective)

We should choose an OCC group MMSI for use in Digital Selective Calling (DSC)-capable radios. One number should be used so radios do not ever have to be reprogrammed. I suggest using the OCC Commodore’s MMSI, adding an initial zero, and dropping the final zero.

(Reminder: Every DSC-capable VHF radio should be connected to a GPS and have a unique 9 digit MMSI number programmed into it.  An MMSI is like a telephone number for radio digital calls (DSC).  Every DSC radio has a directory to enter the MMSI numbers for boats that are called frequently, and a separate directory for group MMSI numbers. For information on obtaining your own MMSI, go to

One does not need to change your MMSI or a separate license to use group MMSI calling.  Group calls allow radio calling to all members of a group that have the group MMSI call entered into their radios ' group directories.
Please enter the OCC Group MMSI into your VHF radio 's group MMSI directory.  This will allow one DSC call to go to all OCC members in an area limited to VHF radio range of about 25 miles.  

Boat-to-boat VHF DSC calling creates significant day-to-day benefits.    

1. VHF radios can be left on 24/7 with volume turned down.   The radio and not the crew is doing the work of listening for all general and emergency DSC calls.

2. Using a group MMSI, yachts traveling together can provide quick mutual support, coordinate a cruise, or get advice about weather, anchorages, sailing conditions, technical problem etc.   This semi-private multi-party conference call is a perfect solution for a OCC cruise.   This allows allow quick, nearby support, advice or assistance from other cruisers, before it becomes an emergency.  The advantage of this on a cruise is that a group call to every OCC boat rings on every OCC boat on the cruise within VHF range and switch everyone 's radio, when acknowledged, to a group working frequency. 

3. We might consider making a daily time (1700 local) for all OCC boats to turn on their VHF radios to initiate or respond to a group call.  We could call it something like the Daily OCC Communications Hour where members can voluntarily chat, coordinate rendezvous points, exchange cruising and navigation info, help each other or just listen to the conversation.

4. The U.S. Coast Guard group ship station call identity is 036699999.  Calls to any and all local U.S Coast Guard ships within 25 miles can be made by entering  036699999 in the INDIVIDUAL directory and then placing a DSC call.   This MMSI goes in the individual directory, rather than the group directory, since we are not group members and don’t wish to receive Coast Guard DSC calls.

5. The U.S. Coast Guard DSC group coast station identity is 003669999.  Calls to any and all local U.S Coast Guard coast stations within 25 miles can be made by entering  003669999 in the INDIVIDUAL directory and then placing a DSC call.  For boats in the US, we suggest adding these two group MMSI numbers in the INDIVIDUAL directory. This MMSI goes in the individual directory, rather than the group directory since we are not group members and don’t wish to receive Coast Guard DSC calls. This will allow discussions of a routine, Securite or Pan-Pan nature to take place with the Coast Guard easily before a situation becomes a Mayday.  

The RescueMe MOB1 made by Ocean Signal is a combined personal AIS and DSC alarm to use to alert your boat if you fall overboard.   It is small and portable.  IN THE US, BOTH your boat’s DSC and the OCC group MMSI are easily programmable into the MOB1 by use of a downloadable program from Ocean Signal to your PC computer. From Ocean Signal:

“Only one MMSI and one Group number is able to be entered into the MOB1.  The group number is available to US owners only, but can be any country number.

Please note that the Group call is only sent after 30 minutes and does not send position as per the RTCM specification the MOB1 complies with in the US.”  

Thus the DSC alarm with alert your boat and any OCC boat in the vicinity.  This will make it much easier to coordinate rescue of anyone overboard. 

The use of a OCC group MMSI adds safety, convenience and pleasure to any cruise or gathering.

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