A VHF radio is the single most valuable piece of equipment for emergency situations. Signaling devices are great for getting the attention of boats in the immediate area if they are looking in your direction and the visibility is good, otherwise a VHF may be your only chance for help. Although the VHF's range varies from five to about 25 miles, its most valuable feature is that in areas of Coast Guard jurisdiction, the VHF is monitored 24 hours a day. However, there are other uses for VHFs: telephone calls to shore, obtaining supplies and services such as marina reservations, and boat operations like drawbridge openings and communicating with commercial and other recreational vessels. Chatting is not permitted. The Federal Communications Commission (FCC), which regulates marine radio traffic, dictates that all other uses are secondary to safety.

DSC Update Digital Selective Calling, or DSC, is new technology which will be the equivalent of a "mayday button" on a VHF or SSB. When activated, it will automatically broadcast an encoded distress call that will be picked up by all nearby vessels. If the radio is interfaced with a Loran or GPS, it will also automatically broadcast the distressed vessel's position. While administration of the system has not been sorted out, a few high-end radios now include it as a feature.

How Do They Work? VHF radios communicate via line-of-sight, which means that the signal is sent and received in a straight line. Anything blocking your line of sight will limit your ability to transmit and receive. By law, VHF radios on boats are limited to a maximum power of 25 watts. They must also have a low-power, one-watt switch for short-range transmissions, which is usually all the power you'll need. Using 25 watts won't increase your range, but will enable you to transmit through heavy VHF traffic without being "stepped on." Remember, the distance over which you can transmit is not so much a function of how much power you have, as is the height and gain of your antenna and the quality of your connections.

What to Look For? Most VHFs offer all U.S., International, and some pre-programmed weather channels for a total of at least 55 channels, most of which you'll never use. The basic channels you need are:

6 - ship-to-ship safety calls after contact is made on another frequency.
9 - hailing plus some other functions. In Florida, for example, 9 is the bridge tender's channel.
16 - distress, safety, hailing (Coast Guard monitored)
13 - boat-to-boat navigation
22 - emergency transmissions once directed by the Coast Guard to switch from another channel.
24-28 and 84-88 - a marine operator is available to connect you to a land-based line.
WX-1-3 NOAA weather.

Expansion channels (above 70 numerically) aren't operational until the FCC designates them in the future.

The following definitions will help you understand the specs listed with each radio.

SELECTIVITY Indicates how well a receiver rejects adjacent signals from channels close to the one you're using, usually designated at a negative decibel level. Look for the highest absolute number: -75dB is better than -55dB.

AUDIO OUTPUT Is the radio loud enough to compensate for engine noise?

TYPE OF TUNER/READOUT Usually a keypad or rocker switch with digital readout on high-end radios, and rotary dial tuning on lower-priced models.

SCANNING There are four basic types of scanning. Dual Watch scans Channel 16 plus one other preselected channel. Tri-Watch scans Channel 16 plus two other preselected channels. Memory Scan scans any number of preselected channels depending on the memory capability of the VHF. All Scan scans all available channels.

Handheld VHFs Most handhelds cost slightly less than fixed-mount VHFs and offer many of the same features, but with short antennas and 1-6 watts of power, they can't transmit over the same distances or through heavy VHF traffic. You can expect a range of 5-6 miles at sea-level for boat-to-boat communications. Check water resistance if you're going to use it on deck or in a dinghy.

The single biggest drawback of handhelds is power supply. You can expect to change batteries after three hours continuous use; on 1-watt and intermittent use they'll go all day. Rechargeable Nicad battery packs will give you up to eight hours of use. Several manufacturers now offer Alkaline battery packs which have the advantage of low cost (a few dollars) and long shelf life. If you rely solely on a handheld, keeping spare batteries aboard is essential. Handhelds are adequate as primary short-range systems in certain circumstances, but they're also great for emergencies and abandon ship situations.

FCC Licensing FCC rules require boaters with a VHF radio to monitor Channel 16 continuously when their radio is turned on and not otherwise being used for communications. A FCC Ship's Station License is no longer required for a VHF radio for recreational boats less than 65' operating in U.S. waters. Most boaters do not need FCC VHF call numbers, and may identify by vessel name. VHF radio operating rules continue to apply, and violators can still be subject to fines by the FCC of up to $8,000. The marine band is monitored by both the FCC and the U.S. Coast Guard and both agencies have sensitive radio direction finders that can track a violator, for instance a false "Mayday" caller. BOAT/U.S. is committed to operator education to keep VHF a valuable safety and communication resource. NOTE: A vessel traveling to a foreign port is required to have a license under international rules. In addition, if you have high-level equipment such as an SSB or Inmarsat C you must obtain a license.