DSC GMDSS Primer

DSC/GMDSS Primer

What is DSC/GMDSS? Actually it is two separate things that are can now be linked together.

The Global Maritime Distress and Safety System (GMDSS) has been in place since 1988 and has been all but invisible to the boater. A “mayday” call on your VHF radio, a signal from an EPIRB, Search and Rescue Transponder (SART), or a phone call (cell or satellite) to the Coast Guard will all trigger the “Distress” segment of the system. The “Safety” side allows the user to access weather and safety related broadcasts.

Being on the Great Lakes, we don’t need to tap into many of the features but offshore cruisers and professional mariners are well aware of the system.

What is new to the average recreational boater is the application of Digital Selective Calling (DSC). Each DSC radio is assigned an MMSI – Maritime Mobile Service Identity. Call it a telephone number. Knowing you friends MMSI allows you to contact them by dialing them up and having the radio “phone” them. You punch in the working channel and the radio automatically switches over to that channel for you. You then carry on your conversation as you would under the traditional system.

The other feature is that your GPS can also be linked to the radio. Along with the automatic dialing feature, your position is also broadcast at the same time. The advantage is that you now can make contact without tying up the already congested calling and distress channel 16. (DSC calls are made invisibly on Channel 70.)

By now, the link to GMDSS may be becoming apparent. DSC radios have a little button hidden beneath a red cover with the word “Distress” printed on it. Lifting the cover and holding down the button ends out a VHF Distress / Mayday signal to “all stations” including the Coast Guard and all DSC radios in range.

Adding to the “safety set”, all commercial and mandatory equipped vessels are already required to be DSC equipped and will receive that distress signal. They will also automatically know your position (remember that GPS link) and will be more readily be able to assist in a response.

Another advantage is that the radio will continue to broadcast that signal until it is acknowledged, allowing the skipper to continue with his or her efforts at bailing, fire fighting, or searching for the crew overboard.

Is any of this mandatory for the recreational boater? Yes if you are sailing offshore into international waters. No if you are planning on staying on the Great Lakes.

Does it make sense? Most certainly if you are in areas with limited coverage. Another of the changes is that those mandatorily equipped vessels are no longer required to monitor channel 16. That freighter passing by a half mile to starboard may not hear your mayday. A DSC distress signal is announced on an alarm on the radio and cannot be silenced until acknowledged (by the Coast Guard.) They cannot ignore a channel 70 digital distress call.

There was a plan that the Coast Guard would also be allowed to discontinue monitoring channel 16. That suggestion has been reversed and the Coast Guard (US and Canadian) have advised that they will continue to monitor both channels 16 and 70 for the foreseeable future.

Back to that DSC / GMDSS link. DSC is intended to be the major link between all boaters (recreational and commercial) and the GMDSS safety net both inshore and offshore. You don’t need a special license your old ROC (M) is all you need but taking the course and obtaining the DSC endorsement will give you a better understanding of how it all works.

Any new licenses issued after January 1, 2005 are required to have the DSC endorsement. Any new radios approved by Industry Canada (or the FCC in the US) are required to be DSC equipped. (Previously approved radios can still be sold without DSC.)

For more information or to register for the full VHF course or the DSC endorsement, contact Ray Kirkham Training Officer 905 523 9721

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