VHF radios are your link to vessel tracking features that make boating safer and more convenient.
By Glenn Law
Some skippers call them situational-awareness tools; I think of Digital Selective Calling (DSC) and the Automatic Identification System (AIS) as VHF features that, ultimately, make coastal cruising safer and more enjoyable.
DSC, a function found on many VHF radios, has been around for a while, but boaters have been slow to embrace its non-emergency capabilities. For instance, with DSC, your radio can direct-dial another VHF (via its MMSI number) and relay your boat's latitude/longitude. Or, your radio can simply "ping" another. Are you wondering what that means? Well, imagine your kids have just gone off exploring on the tender. If you dial the DSC-equipped radio you sent the young ones off with, the dinghy's position will be displayed on your chart plotter. This feature is technically known as position polling. When cruising with friends, it's a handy way to keep track of everyone. For fishermen, it's a discreet way to let your good friends know where the bite is.
"It is also a really good rendezvous tool," says Raymarine's Jim McGowan of position polling. "Or, if you're broken down and make a call to SeaTow, they can send you a poll request and drop your position as a waypoint on their plotter."
AIS is the latest vessel tracking system for recreational boaters. Essentially, it's a packet of information about your boat that can be transmitted to another vessel. AIS broadcasts your boat's size, speed and MMSI number, among other things, and it can receive the same information about another boat equipped with an AIS transmitter. AIS also allows you to communicate with an unfamiliar boat, one whose MMSI number is not stored in your VHF, such as a big ship. (AIS is required on commercial vessels.) AIS also allows any boat with a receiver to monitor the movements of an AIS-equipped boat. Because the information is carried over VHF, it's not limited by line-of-sight, as is radar.
AIS for recreational boats comes in three versions. Class A is used by commercial ships. It broadcasts extensive information and refreshes every three seconds. Class A requires a dedicated display and a way to input information. Furuno's FA150 ($4,495) is a full Class A system.
Class B AIS operates at a lower power and has a refresh rate of 30 seconds; it's available as a "black box" transceiver. According to Bill Haynes, a product manager at Furuno, professional mariners (ferry pilots in the Northwest, for instance) are not wild about Class B. "They don't like to see the proliferation of this class of AIS because the report intervals are too long," Haynes says. "However, Class B is still a valuable option for recreational boats." Furuno's Class B AIS transponder, the FA50 ($1,800), is a black box that receives both Class A and B transmissions, but transmits only Class B. The Class B transmission can be turned off if you don't want to be seen by other boats with AIS receivers.
Strictly for monitoring, the Furuno AIS Receiver FA30 ($1,100) displays both Class A and B information, but does not transmit. ICOM's MXA-5000 (about $500) is also strictly a receiver.
Navico offers a black box Class B AIS 300 ($1,149) that can be coupled with chart plotters from Lowrance and Northstar. The Simrad AI50 by Navico ($1,627) has its own display. The unit also lets you direct-dial a target vessel on the VHF through the MMSI number imbedded in the AIS packet of information I mentioned earlier. This data is displayed on the monitor. "Once you identify a ship, you can initiate a DSC call directly to it from the display," says Navico's marketing director, Paul Comyns. "If you're in a small boat calling out to 'the big green tanker on my port bow,' you may not get an answer. But when you contact that ship through its MMSI number and say, 'MV Ranger, what are your intentions regarding the powerboat crossing your bow?' you are more likely to get a reply."
Raymarine has the AIS500 transceiver ($1,399) and the receive-only AIS250 ($1,120). Each has specific advantages, depending on where you cruise. "It's more important to be on the receiver side if you're in coastal waters with commercial traffic," says McGowan. "But out on the ocean, where commercial ships are running on autopilot, a transponder will put your boat on the radar and plotters of those ships. Anything you can do to call attention to yourself is going to benefit you."
As more recreational boats adopt AIS, we could see some overload on the plotter screen. A work-around, Comyns says, is to establish a safety zone around your boat and display only vessels that come within that perimeter. Raymarine's AIS units have a naming feature. With it, known vessels — ferries or boats belonging to friends — can be tagged with a familiar name, and all other AIS signals can be filtered out of the display. Other than that, though, there is little filtering available.
Electronics experts are quick to note AIS is not an automatic system; rather, it's another informational system. It's only going to provide safety and situational awareness in direct proportion to the attention the skipper gives it. Says McGowan, "It is really an exciting technology, and as more and more people adopt it, a host of features will be developed."
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Other New Electronics featured this month:
- More Electronics from past issues.
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