Article by Capt. Steve Katz
MMSI and DSC
If you guessed that the government was involved with the above acronyms, you are correct!
MMSI - Maritime Mobile Service Identity
DSC – Digital Selective Calling
Why are these important to safety on the water?
This is related to the VHF (Very High Frequency) radio maritime mobile band of 156-174 MHz, your typical marine VHF radio. In our area, much of the VHF radio communication is about fishing, though the VHF radio is also one of the best safety tools on board your boat, especially when combined with an MMSI number and DSC.
MMSI
A MMIS number is a nine-digit number that uniquely identifies a marine ship station or coast station. You can think of it as a “phone number” for your boat. The MMSI number is programmed into on-board communications equipment and transmitted digitally via Digital Selective Calling (DSC) through a VHF radio or transmitted as part of an Automatic Identification System (AIS) hardware. A vessel should have only one MMSI number.
How do I get a MMSI number? Well, that depends on where you are using your boat. If you ONLY use your boat within the waters of the USA, then you can apply for and obtain a MMSI number from a few different private sources in the USA such as Boat US or the United States Power Squadron. There is often a nominal one-time registration fee. You will need to provide personal contact information and vessel information during the application process. Please be sure this information is correct and updated as necessary.
If you plan on using your boat OUTSIDE of the waters of the USA, you will need to apply for and obtain your MMSI number from the federal government – the FCC (Federal Communication Commission) issues MMSI numbers in conjunction with a “ships station license”. While it’s true that your boat may not be required to have a ships station license, as most pleasure boats are granted an exemption if they do not fall into a compulsory required use category. Your boat can be considered a “voluntary ship” and you can obtain a ships station license. A ships station radio license is often required by foreign regulations when operating your boat in foreign waters, including the Bahamas. Note- if your vessel is registered or “flagged” in a county besides the USA, then you would obtain the ships radio station license and MMSI from the country of registration. When you apply to the FCC you will have two choices - “Voluntary Ship” or “Compulsory Equipped”, in either case you will receive not only the license for your marine communication equipment but also a MMSI number. If you need this type of license, look for FCC form 605, it requires similar personal information and boat information as with the private registration process above and involves a nominal one-time fee.
For reference - Here are the types of boats REQUIRED to have a “ships station license”
-Cargo ships over 300 gross tons navigating in the open sea
-Ships certified by the U.S. Coast Guard to carry more than 6 passengers for hire in the open sea or tidewaters of the U.S
-Power driven ships over 20 meters (65.6’) in length on navigable waterways;
- Ships of more than 100 gross tons certified by the U.S. Coast Guard to carry at least one passenger on navigable waterways
-Tow boats of more than 7.8 (25.6’) meters in length on navigable waterways; and,
-Uninspected commercial fishing industry vessels required to carry a VHF radio.
-Ships required to carry an Automatic Identification System (AIS) transceiver by the U.S. Coast Guard regulations enacted pursuant to the Maritime Transportation Security Act of 2000.
Ok, now you have a MMSI number, now what?
If you have a VHF that is 1999 or newer, it has the DSC (Digital Selective Calling) feature as required by the FCC and most other countries too. These VHF radios allow you to program your MMSI number into the radio (often a one time feature). Once this is complete, you can make a DSC call to other DSC equipped radios on other boats but more importantly you can make a distress call that will include your MMSI number and therefore information about you and your ship to rescue authorities. This distress call can be made automatically by pressing the distress button under the protective cover on most modern VHF radios.
Another piece to this system is the location of your vessel, this is needed to fully complete a DSC emergency call. Traditionally, the user would need to connect the VHF radio to the boat’s global positioning system (GPS) using NMEA0183 or NMEA2000 wiring but now some VHF radios are self-contained with their own GPS receiver. This connection also provides the time of the radio transmission. The Coast Guard urges, in the strongest terms possible,” that you take the time to interconnect your GPS and DSC-equipped radio”, doing so may save your life or someone else in a distress situation!
Why is all this important? The USCG monitors these distress calls and with GPS and MMSI information from boaters, they can respond with speed and accuracy in the event of an emergency. Remember a distress call on the water is not only for your vessel, but you may need to report an incident on the water involving other boaters or emergencies. The often long drawn out process of talking to the USCG and providing them the required information can be drastically reduced when your information is digitally transmitted to their system. The USCG uses an automated system, along with USCG personnel called Rescue 21. Rescue 21 is a modern communications system designed to be more robust, reliable, and capable than the legacy system by using a modern radio system coupled with a TCP/IP network, and digital communication using VoIP.
Two little known benefits to a DSC distress call:
The distress call is automatically broadcast to nearby boaters, their VHF radios will automatically tune to the distress message, possibly allowing nearby vessels to respond quickly to the emergency.
DSC calls can have a longer range than a traditional voice call on the VHF radio Because a DSC signal uses a stable digital signal with a narrow bandwidth and the receiver has no squelch.
There are not any drawbacks to configuring your VHF radio with GPS and your MMSI number. While you may never think you will need it, this feature may be useful to help another boater or during an on-the-water emergency.
