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DSC alert location finding

Old 08-04-2020, 12:29 PM
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Question DSC alert location finding

The other day the CG was communicating with DSC distress call. If the CG was not communicating with them I wouldn't have known where they were, thinking offshore or CG occupied with other calls or something possibly. Other than AIS do any VHF radios identify the DSC callers location either via the receiving VHF or by showing on a chart plotter/multi function device? Referencing identifying location of a vessel in distress scenario.

Last edited by Carjunkie; 08-04-2020 at 12:44 PM.
Old 08-04-2020, 01:58 PM
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AIS has nothing to do with it,
its the basic functionality of any DSC capable VHF:

If the other vessel's VHF had an MMSI entered into it,
and had the lat/long provided to it,
then it could have transmitted an automatic DSC distress message
which included that data.

If you were within range to receive that transmission,
your VHF would have alarmed,
and displayed on its screen the MMSI and lat/long of the other vessel.

Further, if you had your VHF connected to a chartplotter via NMEA 0183 or NMEA 2000,
the plotter would have automatically displayed the position and MMSI of the other vessel.
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Old 08-04-2020, 02:25 PM
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If I am understanding your question and scenario correctly, what you were receiving was the Coast Guard acknowledging the DSC emergency transmission and issuing an alert to "All Ships". If you had received the DSC transmission from the vessel in distress, and if that vessel's radio either had internal GPS or was connected to a GPS, the coordinates would have been received by your radio and either displayed on your radio, chart plotter, or both. The acknowledgement from the Coast Guard would have had the Coast Guard's MMSI and would have given the coordinates of the distressed vessel, the UTC time of the DSC distress call, and whether the nature of the emergency was defined.

I received a similar transmission from the Coast Guard a few weeks ago. The vessel in distress was in the Charleston Harbor and I was about 60 miles away. I did not receive the distressed vessel's DSC call, but I did receive the Coast Guard acknowledgement of the DSC distress call. As such the distressed vessel's location did not automatically show on my chart. I jotted down the coordinates they gave for the distressed vessel because I could tell by the northing and easting that it was inshore and south of where I was, but I wasn't sure how far. I manually entered the coordinates in the chart plotter and confirmed it was in Charleston Harbor, some 60 miles away. At that point I resumed fishing and continued to listen to Channel 16. A few minutes later, the Coast Guard confirmed it was a false alarm and canceled their Pan Pan.

There may be a way to send the coordinates relayed by the Coast Guard directly to the chart that I am not aware of. I have received a DSC distress call from a vessel before and the vessel's location appears on my chart with their MMSI#. I was within VHF range of the distressed vessel though and I was also able to hear all voice transmissions between the distressed vessel and Coast Guard.

I do wish there was better guidance from the Coast Guard on how to handle DSC emergency transmissions. I've read some of their protocol manuals, which are not written for the general public. Maybe some YouTube videos of actual DSC distress situations, but the few that are on YouTube are not all that great at understanding what is going on and what boaters in the area should be doing.
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Old 08-04-2020, 02:42 PM
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To the OP, if your vessel has a registered DSC radio, it will receive the distress signal from any other registered radio within range. The nature of distress, the location, time, and MMSI number should all show up on your radio. The time stamp and MMSI number are important, there are frequently more than one distressed boat at a time (for instance in a storm or wind event).
The DSC alarm is loud and annoying, you won't ignore it.
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Old 08-04-2020, 02:49 PM
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Originally Posted by From the Helm View Post
To the OP, if your vessel has a registered DSC radio, it will receive the distress signal from any other registered radio within range. The nature of distress, the location, time, and MMSI number should all show up on your radio. The time stamp and MMSI number are important, there are frequently more than one distressed boat at a time (for instance in a storm or wind event).
The DSC alarm is loud and annoying, you won't ignore it.
I wish the CG had the ability to send out DSC messages when they relay coordinates. I am never able to write down and enter them quick enough to know of the vessel in distress is near me.
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Old 08-04-2020, 03:16 PM
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There were actually two calls, one was a mistake per the conversation, the other was nor an emergency. I did something to my radio to silence the alarm when they came in minutes apart. I will need to read up on the radio, I assume when I silenced the alarms (they were rather loud of course) I must have removed the information from the screen. The radio is not networked with the chart plotter as the plotter is new and only speaks NMEA2K while the radio only speaks 183. I do have an MMSI programmed. Thanks for pointing me in the right direction.
Old 08-04-2020, 03:20 PM
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Originally Posted by heatzig View Post
I wish the CG had the ability to send out DSC messages when they relay coordinates. I am never able to write down and enter them quick enough to know of the vessel in distress is near me.
That was my problem, I knew I was near both locations after the CG spoke with them each separately but they both gave generic location information. If either were real emergencies I would have had trouble finding them. This was the first time I heard a DSC distress come in other than relayed by the CG from places too far for my radio to pick up the original call.

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