Article by Pat Schrawder
IN CASE YOU THINK DSC AND MMSI ARE SECRET CODES……
The most important electronic item on your boat might be considered your communications radio. If you have a problem and need assistance, you need some way of communicating that back to shore. The most popular form of communication for boats today is the VHF radio. If you have problems, you can call the Coast Guard or a towing vessel. When you do, you will be asked to identify yourself, the nature of your problem, your location, etc.
In recent years, a system has been activated to help those in need of assistance and it is referred to as DSC or Digital Selective Calling. All VHF radios manufactured today are required to have this feature. You will often see it on your VHF as a red window that is marked “DISTRESS” OR “EMERGENCY”. Depending on the model, you may also see another button on the radio that is marked DSC. Although broadly referred to as DSC, they actually perform two distinct functions, one being the distress call in an emergency and the other being a means of communicating back and forth between selected vessels.
In order for the system to work as designed, you must first apply to the FCC for your unique 9 digit identifying number known as your MMSI (Maritime Mobile Service Identity). This can easily be done on-line at the following address:
https://svartifoss2.fcc.gov/cores
If you do not currently have an “FRN” (Federal Registration Number), you will be instructed to get one first. It is free and only takes a few minutes. Once you have received it, you can proceed to the FCC License Manager page to get your MMSI?number:
https://wireless2.fcc.gov/UlsEntry/licManager/login.jsp
You may also obtain an MMSI number for free from BoatUS at:
http://www.boatus.com/mmsi/
This number will then need to be programmed into your VHF radio. There should be instructions in the manual that came with your radio telling you how to do this. A simple connection between your VHF and your GPS or loran will complete the electronic and paperwork components for the system to operate fully functional.
Once that is complete, you have both distress and digital selective calling available to you. If you have an emergency, you should lift the cover on your radio marked “distress” or “emergency” and push and hold the button until you hear a confirmation tone that your call has transmitted. Your call is sent over channel 70 to any available DSC compatible radio within range of your vessel. This includes many commercial vessels who are automatically monitoring channel 70. Your radio waits to hear an electronic acknowledgement on channel 70 from a coast guard station. After the acknowledgement is received, your radio automatically switches to channel 16 and you can proceed to talk to the Coast Guard with details of your problem. The improved feature of this system is that the Coast Guard has already automatically been sent your MMSI number, along with your precise location and the information about your vessel. In the event that you cannot communicate for long or at all, the Coast Guard has all the necessary information to proceed with a search and rescue mission. The radio will continue to transmit its data. If you do not apply for an MMSI, but you hook up your GPS to your radio, your set will still function to send a distress call and will indicate your location but it will not identify who you are.
The other feature of DSC that is considered a convenience rather than a safety item, is the selective calling. You can preprogram your VHF with several DSC ID’s along with the names of other boats that you normally communicate with and the VHF channel you wish to use for that communication. They can also be separated into groups of numbers. Using your non-emergency DSC button, you can selectively call one or more vessels. The VHF will use channel 70 just as before but the signal will only go to the boat(s) you select. The VHF will again wait for the received acknowledgement and will then switch to the other communications channel you selected when you programmed that person’s boat into your VHF.
Some VHF’s have the ability to monitor two channels independently so that you can “stand by” on channel 70 for DSC calls while operating on another channel. Using DSC is actually not difficult once you get it set up and understand its operation. For more precise details on setting up and using DSC on your own radio, you should consult your operator’s manual.
One side note here is that DSC is part of a larger program by the Coast Guard referred to as RESCUE 21, which will aid the Coast Guard in carrying out all the missions the Coast Guard performs by providing an advanced command, control, and communications (C3) system that is more reliable, and more capable than the current system. Not all areas have the full system installed at this time. Check with your local Coast Guard to see if they have Rescue 21 implemented and/or if they monitor Channel 70.
Pat and her husband, Larry are owners of L&L Marine Electronics in West Ocean City, MD.
