The virtues of VHF


Step on a boat, move far enough from shore or another boat to make your spoken or even the shouted words inaudible and you will have to rely on some assisted means of communication. Guglielmo Marconi’s first successful radio transmission from a vessel presents us with a plethora of communication options, including some specialized for marine use: VHF/DSC-FM, MF and HF single sideband in addition to cell phones, satellite telephones and ham band transceivers. The challenge is to select the communication system that will be most effective in the environment in which we normally voyage.

We will concentrate on voice communication for those who voyage primarily in in-shore waters (within about 20 nautical miles of shore) but who will, when the opportunity arises, gladly make extended coastwise passages out to a few hundred miles offshore. Our goal is to ensure that we will have two-way communication, a level beyond the one-way signaling provided by a 406-MHz EPIRB. (When venturing more than a few miles from shore, voyagers should carry either an EPIRB or a PLB).

Whatever system we elect to use must satisfy both routine, good weather, “all is wonderful out here” communication needs and maximize our ability to obtain outside assistance if we need it. We must be able to reach anyone near us, including those within radio range but out of sight beyond the visible horizon. Relayed messages have played a critical role both in rescue situations and by providing information that keeps an inconvenience from becoming an emergency. It is therefore essential that our primary means for communication be a broadcast device, one that will be heard by a multitude of listeners.

Not a reliable marine distress device
Unfortunately, too many recreational mariners are relying on their amazingly capable cellular telephones as their primary communications device. A check of the received distress call logs for many Coast Guard sectors and stations shows that all too often the call for assistance was made using a cell phone and that very often the call was interrupted before the information needed to conduct an efficient search and rescue effort was received. Search missions based on minimal information are costly, can delay response to other emergency calls and can expose the SAR personnel to unnecessary risk.

The technical risks in relying on a cell phone as the sole means for communication begin with the fact that the cell phone is a narrowcast device. By design it “talks” to only one listener at a time. Only the called party knows that you are “on the air.” The privacy this characteristic provides in normal conversations is a complete negative when people on nearby boats don’t know of your need for assistance. In contrast, VHF radio broadcasts your message to every radio in range of your vessel. Additional limitations inherent in relying on a cell phone include the fact that cell tower antenna patterns are carefully aligned with areas where high concentrations of cell phone users are likely to be found, not necessarily offshore.

A further complication occurs when cruising to areas where the available cell system is incompatible with the cell phone on board the boat. There is no question that a cell phone can be almost indispensable on a boat, for example, an iPhone (a computer with an integral cell phone) can serve as a back-up chart plotter and can even be used to obtain usable information for practicing celestial navigation.

However, a VHF marine band radio is the essential communication device for all vessels, regardless of size or where they may operate. A VHF radio’s greatest virtue is that it is required equipment on all ships and commercial vessels, most large yachts and is used by all of the world’s Coast Guards and Naval vessels. It is without a doubt the most effective way to contact another vessel.

Covering more area
The most basic VHF radio, even a minimum power (1-watt) handheld, will enable you to contact other VHF equipped vessels within a range of at least five miles from your location, an area of about 80 square miles! If you are in the coastal waters served by the Coast Guard’s new Rescue 21 communication system the signal from your 1-watt, handheld radio will very likely be received even when you are 20 nautical miles from one of the shore-side R-21 antennas. Equip your sailboat with a masthead antenna and a fixed mount, 25-watt radio and your effective communication range to other similarly equipped boats will likely encompass an area of about 800 square miles.

The safety value of the VHF marine radio was attested to on Oct. 26, 1996, when the Federal Communications Commission, acting in conformance to a new law passed by Congress, eliminated the requirement for a radio station license (and the then substantial fee) for VHF radios, radar and any type of EPIRB voluntarily installed on recreational vessels that operate in U.S. waters or cruise in international waters. (A license is still required for U.S. vessels that may operate in foreign waters or communicate with foreign stations.) The immense value of the VHF radio is further recognized by the requirement that a VHF radio must be installed as a prerequisite for issuing the radio station license required for equipment such as a MF/HF transceiver.

The overall value of the VHF radio system was significantly enhanced with the introduction of digital selective calling (DSC), a capability that has been required in all fixed mount radios approved since early 1999. Prior to the availability of DSC hailing, success in attempting to contact another vessel depended on whether the channel 16 voice hailing call was heard on the other vessel. And that was often determined by the setting of the receiving radio’s volume control and the presence of an alert watchstander. Today, reception of a DSC-initiated “all ships” or “mayday” call will cause any DSC-equipped radio in range to emit a loud and distinctive sound, regardless of the setting of the volume control. The Global Maritime Distress and Safety System (GMDSS) equipment carried on board all Safety of Life at Sea (SOLAS) convention vessels includes VHF/DSC radios, making it very likely that such ships will be alerted to a VHF/DSC call.

The MF/HF marine band SSB radio transceiver can be a valuable part of the communication system on a boat, especially for voyages offshore and beyond the range of VHF coast stations. However, for most coastal sailors a satellite telephone, such as those available from Iridium or Globalstar, will provide capabilities that surpass the MF/HF radio, especially in an emergency situation where it can be used as an adjunct to an EPIRB. There are numerous instances where a satellite phone was used to inform the Coast Guard of the details of the emergency that prompted the activation of the vessel’s EPIRB. A handheld satellite phone is independent of the vessel’s power and antenna systems. Like a VHF radio, a satellite phone can be used by relatively untrained crew and along with the VHF radio should be a number one priority for the boat’s ditch bag.

An ideal communication equipment suite will include a fixed mount VHF/DSC radio, connected to a GPS or loran receiver; a handheld VHF radio (preferably one with DSC capability and integral GPS receiver); a satellite telephone, a strobe light and an EPIRB or PLB. The recommendation for a strobe light stems from conversations with Coast Guard pilots who commented on the value of the strobe light when they were trying to see a vessel or life raft.

VHF/DSC radio tutorial

The BoatU.S. Web site ( provides access to a seven-part tutorial about the selection, installation and use of VHF/DSC radio. Select the “Boating Safety” tab on the top row and then the “VHF/DSC Radio Tutorial” tab. The tutorial, developed with the cooperation of the U.S. Coast Guard, provides a wealth of useful information and includes a VHF/DSC radio simulator you can use to familiarize yourself with the DSC MAYDAY and routine DSC hailing functions. An adjacent tab under the Boating Safety tab provides access to the free Maritime Mobile Service Identity (MMSI) registration process.

Chuck Husick

By Ocean Navigator