At a meeting with 250 boaters last year, I asked for a show of hands: “How many of you have registered your DSC radio and have an MMSI number?

Seven hands went up.

“Keep your hands up if you can tell me which buttons to push on your radio to report a man overboard or flooding.”

All hands went down. In a room full of boaters, not one of them really knew how to use their radios to signal a distress. My guess is that you may not, either.

Digital selective calling has been built into every VHF marine radio for more than 15 years, yet most boaters I talk to don’t know what it is; fewer still understand its capabilities or its value. It is likely the most under-utilized piece of safety equipment on the water, and frankly, I’m tired of this (literal) disconnect.

If your boat has a radio, chances are you have the ability to, with the push of a few buttons, tell the Coast Guard who you are, the name of your vessel, your exact location and the nature of your emergency while simultaneously sending a distress message to every vessel within line of sight. Your EPIRB can’t do that. Your satellite phone can’t do that. AIS can’t do that.

And that’s not the full extent of DSC’s value.

Your radio can also query other boats and get their positions. It can selectively call another vessel, or group of vessels, or shore stations, and auto-tune their radios to respond.

DSC-equipped radios:

  • continue sending distress signals even if the captain is incapacitated 
  • allow inexperienced users to send, with the press of a button, a distress message 
  • privately hail another DSC-equipped vessel or shore station 
  • can “ring” other boats without having to constantly monitor the radio 
  • free up channel 16 for hailing and distress 
  • can call “groups” of other vessels or shore stations 

You can code the nature of your distress by pushing a few buttons, then get back to work fixing things, confident that help is on the way. These distress types include:

  • fire or explosion 
  • flooding 
  • collision 
  • grounding 
  • listing 
  • sinking 
  • disabled and adrift 
  • abandoning ship 
  • piracy/armed robbery 
  • man overboard 

But your radio won’t do any of this if you haven’t properly set it up. Here’s how to do it.

First Things First

Step 1: Make sure your radio was manufactured in the last 15 years.

Look at the buttons on the radio. If one of them is marked “distress” (usually protected by a red cover), you have a DSC-enabled radio. If you don’t see it, check the back of the mic; that’s where the button is on older radios. If you can’t find the distress button, you need a new radio. Get one.

Step 2: Get an MMSI number.

MMSI stands for Maritime Mobile Service Identity — think of this as a phone number for your boat. You must have registered an MMSI to take full advantage of your DSC radio. The good news is getting one is usually free. If you boat just in the United States and you aren’t a commercial operator or otherwise required by law to have a radio, all you have to do is register at one of the following sites to obtain the 9-digit code that will make your VHF a super-radio.

  • Sea Tow: mmsiregister.seatow.com 
  • BoatUS: boatus.com/MMSI 
  • U.S. Power Squadrons: usps.org/php/mmsi_new 

Step 3: Follow instructions.

Find the owner’s manual for your radio. Lost it? It’s online. Contained therein will be a section on using the DSC functions, which will include how to program your MMSI number. Read and follow the instructions.

Step 4: Connect your GPS

Also in your owner’s manual will be instructions to connect your vessel’s GPS. It’s just a couple of wires and won’t require advanced training, but you can always ask for help from a professional.

If none of this surprises you and you know all about DSC and how to use it, congratulations. You’re a rare boater, indeed.

Most DSC alerts come from unregistered radios that aren’t connected to a GPS. It’s maddening. Next to the helm is a way to hail your friends, find out where they are and ask the world for help if you need it. And chances are, you had no idea it was there.

Mario Vittone is a retired Coast Guard rescue swimmer who also worked on patrol boats and as an accident investigator.

This article originally appeared in the May 2018 issue.