Buying Tips from the Marine Electronics Journal

How to Buy Marine Electronics

Your Trusty VHF: Don't Leave the Dock Without It

Marine VHF radios come in two general categories: fixed-mount and handheld. Make your first onboard radio a fixed-mount, 25-watt (the legal limit of power output) marine VHF, all-channel radio, factory preset for the following marine VHF services:

• Distress and safety

• Coast Guard liaison channel

• Ship-to-ship calling channels

• Ship-to-shore phone channels

• Port operations and navigational channels including vessel traffic system

• All weather channels with weather alert

• Commercial fishing channels

• Recreational ship-to-ship and ship-to-shore channels

• Digital Selective Calling Channel 70

The most important channel to monitor when at the dock or out on the water is VHF Channel 16. This is the international distress and calling frequency, and the best channel to summon help in an emergency. On any sunny weekend, there may be as many as 100 to 500 VHF radios tuned to Channel 16, standing by for any distress call or listening in as the U.S. Coast Guard or towing companies head out on emergency missions.

All-channel portable handheld radios transmit with a power output of 5 watts. Fitted with small rubber antennas, their transmit and receive range is less than a fixed-mount, 25-watt VHF wired to an outside white fiberglass antenna, but they could also be a lifesaver. Some are fully submersible, so if your daysailer turns turtle, you can call for help. Even with a marine VHF handheld, Channel 16 is where you place voice distress calls.

By international maritime agreements, any vessel from a dingy to ore-carrier must have a VHF marine radio onboard as their primary short-range radio system before any other type of radio can be installed. Even those mega-ton, double-football-field-long cruise ships have marine VHF onboard. VHF Channel 16 has the same importance to them as to the small recreational boater putting around the harbor.

With so many mariners using marine VHF, the channels sometimes become crowded—even VHF Channel 16. Channel crowding might get so severe that the skipper leans over and turns down the volume. No more racket, but no more distress call monitoring, either.

Improving maritime distress and safety communications became a priority of the International Maritime Organization (IMO) 15 years ago when vessels were sinking within sight of shore, yet no one knew they were heading for the bottom. Reminds you a little bit of Titanic, doesn’t it?

Enter DSC

In 1979, a group of radio experts drafted the International Convention on Maritime Search and Rescue, which detailed the development of the worldwide emergency search and rescue plan that all boats have to comply with. This group also passed a resolution calling for the development by IMO of a Global Maritime Distress and Safety System (GMDSS) to provide the communications support needed to implement the search and rescue plan. GMDSS was officially adopted in November, 1988, and implemented some 10 years later. Among its safeguards are an automated ship-to-shore distress alerting system that even small recreational boats can use in case of a life-and-death emergency. It’s called Digital Selective Calling—DSC.

New 25-watt marine VHF radios designed to meet the distress signaling standards are easily identified by a big red plastic cover and a recessed white button that should only be pressed in a life-and-death situation with the emergency message call. In non-emergencies, however, this same button can also be used with menu selections to place an all-ships call for safety purposes, a ship-to-towing-company call, or a directed call to another boat.

Digital Selective Calling is a fancy term for a quick way to get help on your 25-watt VHF radio. Everyone onboard should know the process of lifting the red plastic distress button cover, pressing and holding the button in while looking at the screen of the VHF and, if appropriate, following the screen instructions to press the button again to confirm a life-and-death emergency exists onboard.

What goes out over the airwaves is a digital burst of information on VHF Channel 70. The DSC radio automatically knows where to send this databurst. The digital distress call not only commands every DSC radio within range to switch over to voice monitoring on Channel 16, but also may contain your vessel’s latitude and longitude, along with your unique “MMSI” maritime identity number. The latitude and longitude are coupled into your marine VHF DSC radio by a simple three-wire connection to your Global Positioning System (GPS) receiver.

Your MMSI, an acronym for Maritime Mobile Station Identification, is entered into your DSC-equipped radio by the marine electronics dealer from whom you bought the unit. The dealer will collect your vessel and owner information and obtain the 9-digit MMSI through an agent such as Boat US. There is usually no fee for obtaining the MMSI, and only a nominal charge for inputting it. Keep in mind that if you attempt to input the number yourself, you have only two opportunities to get it right. If you accidentally misenter the number twice in a row, you’ll have to get your radio reset.

Once your MMSI number is entered, the radio’s menu provides a literal phone directory for using this number to contact other boats or services in a non-emergency situation. For example, say you’ve been fishing all day and there’s not quite enough juice in the battery to turn over the engine. You might make a direct DSC call to the local Boat US MMSI number, and your radio will be switched automatically to their working frequency.

Or maybe you want to find out how the action is where a friend is fishing. If he has a DSC radio that’s turned on, just call his phone number. It’s even possible to designate what channel you want his radio to switch over to. Standard Horizon has taken DSC to the next level by offering a matching color or monochrome chart plotter that takes detailed C-Map NT cartography linked into their marine VHF. Using DSC, you can call your other pals who have the same equipment and actually see their position on your LCD screen. This is called position polling.

Many Coast Guard Auxiliary stations are equipping themselves with this equipment for the position polling function. In a recent Coast Guard Auxiliary test out of Los Angeles Harbor, the base station was able to instantly see where all of their patrol boats were by just pressing a few keys on the radio.

DSC is also improving marine radio signaling. In the Gulf region, for example, ships may signal ashore for automated telephone connections. Farther from shore, the DSC radio may signal a MariTEL station for automated phone service.

For the foreseeable future, Channel 16 will remain the international distress and safety channel. It is monitored 24 hours a day by the Coast Guard, and will be until the Coast Guard is able to provide continuous DSC monitoring—and perhaps beyond.

When transiting through large commercial ports, listen for traffic service on VHF Channels 12 or 14. Much like air traffic control, you will hear a vessel traffic shore station directing big commercial ships in and out of a harbor with traffic advisories. Tune in, but don’t transmit unless you absolutely have to. These two port operations channels are for obtaining traffic reports.

Single Sideband

Beyond the range of VHF—typically 20 miles off shore—marine single sideband is your additional radio system that goes in place for worldwide radio calls. Marine SSB requires FCC licensing, and you may file for your federal radio license by following the instructions at www.shakespeare-marine.com/new-fcc-license-steps/index.html (all lower case).

As a public service for NMEA dealers and their customers, Shakespeare offers step-by-step instructions for electronic filing of a marine station license required for single sideband radio equipment. You also need an FCC license if you plan to use your marine VHF in foreign ports, too. No license is required for your VHF if you just cruise locally in domestic waters.

The sideband equipment consists of a big black box that mounts out of the way, close to the battery. The small head mounts up in your wheelhouse or NAV station, and a very flexible wiring harness lets you position the SSB head just about anywhere you would like.

The sideband feeds signals into coaxial cable that will drive an automatic antenna unit (ATU) mounted either in the lazaret of a sailboat, or in the flying bridge of a power boat. The job of the ATU is to take the radio energy and deliver it into the airwaves from the insulated backstay or big white fiberglass, non-resonant whip. The tuner is also coupled with 3-inch-wide copper foil that extends down to the bottom of your hull to the ground plate or bronze underwater through-hulls. No extensive grounding labyrinth of wires or copper screen is necessary. The sea water will do it all!

On marine SSB, there is a specific DSC distress channel for automated calls, several long-range U.S. Coast Guard channels, many recreational ship-to-ship and ship-to-shore channels, plus capabilities to receive weather facsimiles. There are also numerous SSB long-range channels for e-mail, and the hook-up between your lap-top and new SSB radio is a smart little (and expensive) silver box called a terminal node controller. It magically pulls data signals out of the airwaves and puts them into readable text on your computer screen. When you compose an e-mail message on the screen, this same box turns it into wireless text that is delivered onto the airwaves with your new marine SSB. While the signaling speeds are not fast enough to handle surfing the web, you can nonetheless pull out e-mails directed to your ship station, and send e-mails to the gang back home telling them what a great time you are having out at sea.

This same terminal node controller will tie your marine SSB into worldwide weather facsimile reception. Powerful shore stations throughout the world transmit satellite and hand-drawn weather facsimile charts, and the terminal node controller faithfully reads your sideband reception of the signals and turns them into crystal-clear charts.

Pumping Up your Cell Phone

Not going out as far as SSB long-range reception, but you need to squeak a few more miles out of your little cell phone? Several manufacturers offer white fiberglass marine cellular phone antenna systems that boost the gain of your cellular signal well beyond what you might experience with just the little cellular stubby antenna on your phone. The range-boosting antenna clears up dropped cellular calls so hardly a word is missed when you’re at the extreme of at-sea cellular coverage. The antenna manufacturers offer a variety of phone pick-up cables so almost any type of cell phone may be adapted to their marine cell antenna set-up.

But all of this SSB and cellular radio range, plus long-range capabilities of satellite phone systems, are secondary to the local coverage you can obtain with a marine VHF. If you’re within 20 miles of shore, using sideband, satellite, or cellular to call for help only confuses matters. For local calls for assistance, marine VHF is the intended radio system.

Work with your local marine electronics specialist to help plan a new or upgraded DSC VHF radio system. Get that GPS tie-in and double check that your MMSI information is current. Then brief everyone onboard how to place a distress call, and go cruising with confidence that anyone, anytime knows how to lift the red protective cover and press the button for immediate assistance.

About the Author

Gordon West joined the NMEA in 1969 while working as a licensed Certified Marine Electronics Technician. A frequent contributor to the Journal, West also writes several monthly columns about marine electronics and is the author of the General Radio Operator License Study Book in Preparation for the FCC Element 1, 3 and Radar Element 8 License.

Author: Gordon West