You may be in the market for a new marine VHF radio or just bought a new boat with a new VHF radio on it. There are a lot of options today in the marine VHF radio market. One of those options that is standard on all new fix mount VHF radios and many handheld radios is DSC or Digital Selective Calling.
What is DSC?
Digital Selective Calling allows you to make ship to ship calls, find a fellow boater’s position, make a distress call with the push of a button and report your own position. DSC is coupled with GPS either through a stand alone GPS receiver, your chart plotter or a GPS receiver in the VHF radio. The GPS connection is a two wire connection using NMEA 0183 protocol. Generally if you have a NMEA 0183 capable chartplotter or stand alone GPS receiver you can hook your VHF radio to it and be able to send your coordinates to other ships or the coast guard in the event of an emergency. If you don’t have a chartplotter or a standalone GPS receiver don’t worry there are DSC capable marine VHF radios with a built in GPS receiver.
A DSC radio is a good investment for several reasons. You can call all the people you normally boat with by putting in their MMSI number and “ringing” their DSC capable radio. This lowers the amount of unnecessary traffic on marine channel 16. DSC transmits data on channel 70 and in a congested area using DSC rather than voice to call friend or to find a friends position is much better than tying up the airwaves and potentially transmitting over a distress call. With DSC and a chartplotter you can see where your friends are on the chartplotter and you can see any vessels in distress near you. In the event of a mayday or distress condition on your boat you can just push the red button on the radio and instantly transmit your boats position, details on the type of boat, name of boat, your name and contact info to the coast guard and any commercial ships near you. Greatly speeding up the time it takes to get help also because DSC is digital not voice you may have a greater transmitting range compared to making a voice mayday call on VHF channel 16.
If you have a new or new to you DSC radio in addition to wiring it to a GPS receiver you will need to enter your MMSI number into. A word of caution! Some radios will only allow the MMSI number to be entered once or twice. If you are buying a used radio make sure it can accept your MMSI number and if you are buying a new radio make sure you enter the number correctly. The MMSI number you register links your radio to your information. It contains your boat name, boat type and brand, size of the boat, color of the boat, your phone number, emergency contact information and your address.
Obtaining a MMSI number is easy. If you only plan on boating in US waters and are registering a private vessel you can visit one of the following three websites:
If you are planning on boating outside of US waters you will need to file directly with the FCC to obtain your MMSI number. The forms can be found here: Form 159 and Form 605
If you are outside of the US visit this site in order to find the proper place to register for a MMSI number.
Connecting your DSC radio to GPS in such an important thing, it is literally a simple life saving step you can take to insure quick and proper notification to the authorities in the event of an emergency.