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August 28, 2012

Radio Revamp

VHF offers more than a means to make idle conversation

 The VHF radio has increasingly become an essential part of the electronics suite, certainly for core safety communications. Also, the growing integration with plotters and GPS has yielded an expanded role in situational awareness.

 Garmin led the way on VHF integration with NMEA 2000 capabilities in both VHF radios and AIS transceivers. For a couple of years, the company had the only system that could initiate a VHF call directly to a specific vessel from the identifier on the plotter screen, eliminating the need to manually enter a vessel’s MMSI number (essentially its VHF phone number). 

Ease of use and the design for integration put Garmin ahead in the market, but other manufacturers are catching up fast. If it has been a while since you reviewed the VHF component in your boat, it’s probably time to give it another look. 

The integration of VHF hinges on two features: DSC (Digital Selective Calling) and AIS (Automatic Identification System). DSC enables your VHF radio to initiate a call that also communicates your GPS position. In an emergency, this feature tells the Coast Guard, as well as other boats, where you are. In non-emergency situations, DSC allows for discreet communication — say, for sharing fishing information you don’t want to broadcast to everyone with a radio or for keeping track of your friends on the plotter. AIS is an identification system that transmits vessel data, such as size, type, speed and bearing, to anyone with an AIS receiver, and it also provides the MMSI of a vessel.

DSC Versus AIS

“A lot of people don’t realize that DSC and AIS are two different things. We have to explain what the technology does,” says Dave McLain, national sales manager for Icom. “And AIS is catching on a lot quicker than DSC.” AIS allows vessels that may be blocked by geography to appear on a plotter screen, as it sees around corners that radar cannot, a huge benefit. “It’s caught on well around Seattle and the Pacific Northwest, where mountains often block the effectiveness of radar,” he says. 

In high-traffic areas, such as shipping lanes, whether you are trolling or fishing at night, the warning of an approaching vessel offered by an integrated AIS alarm system can save your bacon. One of the challenges in using AIS crops up when the targets it displays clutter the plotter screen, but an AIS with a stand-alone display, so ship icons can be switched on and off on the plotter, solves that problem. 

Icom’s new MXA500TR stand-alone AIS ($899) can be tied into chart plotters via NMEA 0183. It also allows you to initiate a VHF call to a vessel by pushing a button, without manually entering the MMSI number. 

This alone is an important feature, and one that is rapidly becoming standard on AIS systems. 

“AIS provides you with, among other things, a ship’s name, as well as its MMSI number,” says Jason Kennedy of Standard Horizon. “Instead of hailing it on channel 16 and saying ‘Hey, big freighter,’ you call them by name and they’ll respond.”