Boating Tips


Posted 9/13/2011

EPIRBs and DSC/VHFs – Technology to the Rescue

Although boating is a lot of fun—serene sundown cruises, fishing for the next record catch, or doing whatever you like —the reality of being on the water is that if something goes wrong, situations can deteriorate rapidly.

When you’ve done all that you can to resolve the problem, and the time comes to call for help, there are a couple of electronic devices that can send a MAYDAY distress message for you. 

The most common is Direct Selective Calling (DSC), a federally mandated feature on newer fixed-mount VHF radios. Pushing the DSC button transmits a distress signal to every other DSC-VHF radio within receiving range, including the U.S. Coast Guard. This allows you to focus your attentions to handling things on board.

The DSC is easy to install, particularly if your boat is rigged with Yamaha’s CommandLink® Plus LAN (local area network information system). No need to string wires to the fuse box or buss bar – just connect to one of the 12-volt accessory pigtails integrated into the Command Link Plus cables.

Interfacing a DSC-VHF radio to your GPS receiver (chartplotter, sonar/fishfinder, etc.) is necessary to enable would-be rescuers to know your location; otherwise, no one will have a clue where you are. To allow your DSC-VHF radio to receive information from the GPS, simply fasten the appropriate wires from each device together, following the radio and GPS installation instructions. Once a successful DSC/GPS connection is established, an indicator should appear on the radio’s display screen. Conversely, if the DSC isn’t recognizing the GPS satellite, an error message should pop up on the screen.

On some DSC-VHF units, you can manually enter your position (latitude, longitude) before pressing the DSC button; however, this can waste precious time in an emergency – defeating the purpose of the DSC’s automated distress calling capabilities.

In addition, you need to take a few minutes to obtain and program your Maritime Mobile Service Identity (MMSI) number into the DSC-VHF. The MMSI is nine-digit number unique to your DSC-VHF that transmits your vessel’s identity when using DSC (or other boat-to-boat MMSI communications).

A DSC-VHF is a great choice for coastal areas, but its range is limited to about twenty miles, within reception distance of shore-based rescue operations and other vessels that could lend a hand.
The DSC-VHF has plenty of positives, including the functionality of your VHF radio to communicate what the problem is to rescue operations. Hopefully you’ll be using the VHF as your standard communication device on a daily basis, and never need to push the panic button. One major downside of a DSC-VHF radio is if a catastrophic event disables your boat’s electrical system, neither the radio nor the GPS will work, further limiting your options.

DSC-VHF fixed mount units cost as little as $150 (plus antenna), so there’s no excuse for not having this handy lifesaver on your boat.


An EPIRB (Emergency Position Indicating Radio Beacon) has a single function, to send a satellite signal to emergency responders anywhere in the world that you need help. EPIRBs can be activated manually by the user, or automatically by being under water for a few minutes. It is mandatory that you register your 406 EPIRB/PLB with NOAA SARSAT, so they’ll have your emergency contact and other pertinent information on file.

Basic EPIRB units transmit a signal to LEOSAR (low earth orbit) satellites orbiting the globe about every 100 minutes, and can calculate the EPIRB’s position to within approximately two nautical miles. GEOSAR (geostationary) satellites in high stationary orbit also get your message, but lack position capabilities. Because these beacons must wait for a LEOSAR satellite to pass overhead, it could be an hour or more before a land-based rescue center receives your call for help.

GPS/EPIRB combination beacons fire off a signal with your exact location to LEOSAR and GEOSAR satellites. Rescuers get your distress call in minutes, because the GEOSAR satellite picks up the signal immediately, forwarding the information (including your position within one-hundred yards or so) to the rescue operators.

The upside to an EPIRB is that it’s self-contained (independent of your boat’s electrical system), and it tells the whole world that you’re in trouble. The downside is the EPIRB has no provision for voice communications to clarify the nature of the problem with the rescuers.

Installing an EPIRP is straightforward, fasten a bracket in a suitable location, and insert the EPIRB.

There are two types of EPIRB mounting brackets. Category I brackets release and activate the EPIRB when submerged in as little as 3 to 14 feet of water. Category II brackets require that you remove the EPIRB manually. Both bracket types allow manual activation, whether the EPIRB is in the bracket or not.

You can have a full-featured Class I (auto release/activation) GPS/EPIRB for under $1,000, a small price to pay for offshore peace of mind.