Article by Capt. Steve Katz
Red "Distress" Button
In 1999, the Federal Communications Commission required that all marine VHF’s sold in the USA to be equipped with DSC (Digital Selective Calling). This was the roots to the red distress button found on the face of today’s modern marine VHF radios. The overall purpose of this distress button (often under a cover to prevent accidental use) is to automatically contact the USCG and nearby boaters to your emergency. The automatic feature is important, because it can allow an inexperienced person to trigger an emergency USCG call, and it can also allow an experienced skipper to initiate an emergency call while preforming other tasks during an emergency.
What happens when you press the distress button?
Many VHF radios require the operator to lift the distress button cover, press and hold the button for 3 seconds and then release the button to initiate the automatic distress feature. Please check your own VHF radios instructions to be sure you know how your specific radio operates.
After activating the distress features, your VHF radio will AUTOMATICALLY digitally transmit the exact location of your boat (latitude and longitude) as well personal information and a description of your boat. Until a coast station acknowledges the DSC alert, the vessel’s VHF radio will continue to broadcast the alert approximately every four minutes. Once the distress call is acknowledged by the USCG, the boat’s distress alert is automatically stopped and the VHF radio is simultaneously switched to channel 16, all automatically by the USCG. At this point, the boat’s radio operator can begin transmitting a standard voice Mayday call and message to start the detailed conversation needed with the search and rescue coast station.
This distress call is also broadcast to nearby DSC equipped VHF radios, so even if the USCG is unable to hear your automated distress call, other nearby boaters may receive the automatic distress call and know your position and may be able to render assistance.
Note: In the event of an accidental false distress alert:
-Turn off the VHF radio
-Turn on the VHF radio and tune to Channel 16
-Make a voice broadcast to "All Stations" giving the ship's name, call sign and DSC number, and cancel the false distress alert.
There are a few key pieces of information in the above procedure that you need to be sure are working properly for the “distress” function to be accurate.
Vessels Position
Your VHF needs to know where your vessel is located- there are two ways for this to work:
Most common – An on-board GPS receiver used for the vessel’s navigation is interconnected to the VHF radio using the NMEA 0183 or NMEA 2000. This interconnection shares the vessels latitude and longitude from the GPS with the VHF radio.
The second method is becoming more popular is a VHF radio that has a GPS receiver built-in, therefore often eliminating the need to connect the VHF to the ships GPS system. Proper GPS operation requires a good signal strength from orbiting satellites. When installing one of these new GPS VHF radios, you will need to consider the physical location since the VHF needs to receive a strong GPS signal from the orbiting satellites, if not the VHF would need to be interconnected to the ships GPS navigational system. Most VHF radios will show the latitude and longitude on the VHF display if working properly or an error if no GPS position is received.
The second key piece if information is the MMSI number/personal information. Each boat owner needs to register to obtain a MMSI number from an issuing agency, such as BoatUS, US Power Squadron or other agency. If your boat falls under specific Federal guidelines or is used outside US waters, then the USCG will issue the MMSI number.
The MMSI number is like a phone number for your VHF, and the registration requires personal data about the boat and operator. Once you have acquired your MMSI number, you will need to enter that 9 digit number into your VHF.
When should a distress call be issued?
A distress call to the USCG involves a serious life threatening on-the-water event or potential event, such as: possible loss of life, fire, man overboard, taking on water, capsizing, sinking, or experiencing a serious medical emergency or other incident deemed an emergency.
Reminder from USCG:
“In general, any vessel equipped with a VHF marine radiotelephone(whether voluntarily or required to) must maintain a watch on channel 16 (156.800 MHz) whenever the radiotelephone is not being used to communicate.”
Once your VHF has a good GPS signal and your MMSI number has been entered your system now has the data needed to broadcast in an emergency. Be sure to regularly review the operation of these systems while at the dock so if needed in an emergency you and your crew will know what to do and will be confident that the VHF “distress” system is working properly.
Until next time...
Stay Grounded!
