Digital Selective Calling (DSC) Satellite and digital technology used for several years on commercial ships is now available to the recreational boater. DSC radios allow boaters to make ship-to-ship private calls and the DSC distress channel is currently being monitored by commercial ships.
Since 1996 recreational boaters were no longer required to have a ship's station license issued by the FCC in order to operate a VHF radio. The new DSC radios have to be registered to work properly in emergency situations. They are also encoded with a unique nine digit FCC identification number that allows the ship-to-ship calling feature. This number called a Maritime Mobile Service Identity or MMSI, is much like your cell phone number. Once the radio is registered with the FCC, that information and your boat's information is entered in the US Coast Guard's national distress database.
The major advantage of the DSC radio is its ability to send an automatic "mayday" that identifies the vessel and also, when connected to a LORAN or GPS, can send the vessels location. The DSC radio operates much like an EPIRB that sends encoded "maydays" directly to satellites. The DSC radio will also continue sending the emergency signal if the skipper is disabled.
Another feature of the DSC radio is the ability to place private ship-to-ship calls to other vessels equipped with DSC radio. Basically if you know the MMSI number of the radio you are calling only that vessel will receive you message. Just like using your cell phone.
Commercial ships over 300 tons are now required to monitor the DSC Radio reserved Channel 70 for distress calls, the US Coast Guard is still monitoring Channel 16. There have been recent incidences where commercial ships have picked up the "mayday" calls on Channel 70 and relayed them to the USCG.
The DSC radio is part of the Global Maritime Distress and Safety System (GMDSS).
