Marine Radios DSC and GPS

Safety is a vital concern to boaters and most would agree that incorporating GPS into marine electronics has been a real benefit. Combining your marine GPS devices with the Digital Selective Calling feature of a marine radio pays even bigger dividends and may well save your life. Here’s how it works:

Digital Selective Calling, or DSC, is an alerting signal that you can send directly from your radio to the United States Coast Guard and other vessels in the area. The USCG is busy deploying Coast Guard 21 across the country. Coast Guard 21 allows the USCG to receive automatic pop-up alerts on their monitoring systems that not only signal a distress call but provide vital information about the boat in distress, including its precise location if the DSC radio is hooked up to a marine GPS device.

Simply press the DSC button located on the front panel of your radio and the USCG receives an automatic alert with the following information:


  • Name and description of boat in distress mccoy marine 50
  • MSSI Number and Registered Owner
  • Precise GPS location
  • Date and time of the distress call
  • Emergency contact information
  • Nature of Distress (if entered on your radio)

Once a distress call is received the USCG can initiate a search and rescue mission.


Your marine radio encodes your GPS location in the DSC signal and broadcasts it over channel 70. Once the USCG (or anyone else capable of receiving DSC) acknowledges the signal, the channel automatically switches to channel 16 so that you can communicate. The USCG receives all the information from your MSSI registration in the alert.

For DSC to work correctly, it must be configured with a marine GPS device. This usually involves hooking the devices together in a simple configuration requiring two wires. Check in your marine GPS device manual for more information.  You must also properly enter your MMSI number into the DSC radio (you can get an MMSI number from www.boatus.com/mmsi). Without a 9 digit MMSI number the USCG cannot acknowledge your call. Once you are assigned a number, check with your marine radio manual to see how to enter it into the radio.

To recap, in order to be able to send your precise GPS location in a distress call, configure your marine radio to send alerts to the USCG over channel 70 by following three easy steps:



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