Marine VHF Radios:
Why You Need One?

Revised by BoatUS editors in April 2012

There is no shortage today of ways to get your message across. But when you're out on the water, what's the best device to maintain your lifeline to shore?

Today's boaters are faced with many choices for ship-to-ship and ship-to-shore communications. VHFs, cell phones, Single Sidebands, and satellite communications, to mention a few.

VHF Radios

VHF (Very High Frequency) radios are the two-way radios most commonly used by pleasure boaters and commercial ships in coastal and inland waters. They are essential for emergency situations, and are monitored 24 hours a day by the Coast Guard. All boats should be equipped with at least one and should stand by on Channel 16 (for emergencies, distress calls, safety alerts and USCG Notices to Mariners) and 13 (for vessel bridge to bridge communications which often give crucial information). Most VHF radios have the ability to scan multiple channels. However this feature will often cut off part of a communication, which communication may be crucial to your safety. Therefore, it’s best practice to have two sets on (like a fixed and hand-held) and have one stand by on 16 and another, usually the portable, on 13.

Fixed-Mount VHF Radios

VHF radios are available in both fixed-mount and hand-held models. All fixed-mount VHFs have a maximum output of 25 watts, the maximum allowed by the FCC. VHF is a line-of-sight system, which means the radio waves won't bend to follow the curvature of the earth. The VHF antenna must "see" the antenna of a distant station. Therefore, antenna height is important in determining range. The effective useful range of a VHF radio is around 20-25 miles although sometimes much longer transmission ranges occur. This, however, should not be relied upon.  The Coast Guard can communicate a much longer range because of their high towers and stronger output power and other specialized technology.

Hand-Held VHF Radios

VHF handhelds also offer many of the same features found on fixed-mount units. They offer portability in the same way a cordless phone allows more mobility at home. A handheld radio may be just what you need for use in a dinghy, small boat without electrical systems, or as an emergency backup for your boat's radio. Handhelds have a maximum output of six watts. Due to their short antennas and lower power, they have a limited range of five miles.

A significant increase in range can be achieved by connecting an external antenna or using a telescoping antenna mounted to the hand-held radio. Battery life varies with the size of the battery pack. Many models have optional battery packs with longer operating times, or greater transmitting power, or both. Some have battery saver circuits that turn off the receiver to save power. The battery life of a handheld can be increased by switching from full transmit power to one watt of transmit power.

Necessary VHF Channels

The most important channel on a VHF radio is Channel 16, the international distress and calling frequency. Channel 9 is used for hailing, radio checks, plus some other functions. In some states, for example, 9 is the bridge tender's channel. Channel 6 is for ship-to-ship safety calls after contact is made on another frequency. Channel 13 is for boat-to-boat navigation and also used by bridge tenders in some states. It is normally set by default to low power but newer sets usually have a temporary override power boost button that allows the radio to transmit at its maximum power if you’re on a frequency, such as 13, that is set by default for low power.

Channel 22 is for emergency transmissions once directed by the Coast Guard to switch from another channel. WX-1-3 and above are the NOAA weather channels.  When you buy your VHF radio you should receive a list of channels and uses.

DSC Capability

Digital Selective Calling, or DSC, is the equivalent of a "mayday button" on a VHF or SSB. When activated, it automatically broadcasts an encoded distress call that will be picked up by all nearby vessels equipped with DSC. If the radio is interfaced with a Loran or GPS, it will also automatically broadcast the distressed vessel's position. A few high-end radios now include it as a feature, so when it becomes fully operational, your VHF will be able to take advantage of this latest feature. To use DSC, you must obtain a MMSI (Maritime Mobile Service Identity) number. You may do so free of charge at this web address: Keep in mind that the U.S. Coast Guard is not yet responding to DSC transmissions. Currently, monitoring is scheduled to begin in 2007.

Cellular Telephones

Having a cell phone on board allows you to keep in touch with land-based people and businesses easily. They are very convenient and should be used in tandem with a VHF. Cell phones, although very convenient on land, are less reliable on the water. Most are not water resistant, and their range is relatively short. The maximum range to and from a cell antenna/station varies. Range is further complicated by the fact that the majority of cell antenna/stations are placed with land-based use in mind, so the distance offshore that a vessel can remain in contact is frequently short. You can increase range with external cell phone antennas placed as high as possible on the boat and further with signal amplifiers. Cell phones can also be expensive to operate, although there are many different packages available. Your communication power with a cell phone is limited on the water because the other ship you are trying to contact must also have a cell phone. In some areas, you can place a call to the local Coast Guard station by dialing *CG.”  Sometimes the Coast Guard will ask you on VHF to continue the communication with them using your cell phone, in order to clear the frequency.

Family Radio Service Radios

Family Radio Service radios are intended for personal, non-commercial use like CB radios. They are very handy because they can be used on land for communication without a license. They are perfect for outdoor trips with friends and family where you need to stay in contact. And they also help with communications while still on the boat. You can talk to each other from bow to stern, from below to above deck, and more! The range is typically 1-2 miles and is line-of-sight like VHFs and cell phones. They have limited battery power and no emergency channel. They operate in the 460mHz UHF band between VHF radios and cell phones and transmit at 0.5 watts. Because these units have become so popular, you may want to pre-arrange what channel you will be using and test it out-very often one or more channels will be overloaded, especially in crowded areas.


Single sidebands operate in the medium frequency (MF) and/or high-frequency (HF) bands for direct-voice communications over distances exceeding 25 miles (depending on antenna heights and atmospheric conditions). SSBs are commonly available with an output power from 50-150 watts. An SSB's range is affected by the strength of the radiated signal, among other things. The maximum reliable range in the 2-3mHz (MF) band during the day is typically 50-150 miles. Transmission in HF band can reach thousands of miles.

Unlike VHF radios, SSBs require a large ground plane in order to radiate its signal.  Unless the boat’s hull is metal, the ground plane is typically installed in the form of a large copper mesh panel (sometimes built onto the fiberglass hull). With SSBs, antenna selection and installation is also more complicated. SSBs generally require a much longer antenna than VHFs, and different antenna tuning for different bands. This last issue requires a tuner, in line with the antenna, for the SSB radio to operate properly.

Satellite Communications

Satellite phones in theory will operate anywhere, because their signal bounces off satellites, but there are in fact dead zones where they don’t work well. The hardware and service charge is relatively quite expensive, and while these can be used also for text such as email, again the cost is relatively expensive. Compression programs are available for emails, but again, emails generally need to be kept brief to avoid high costs.

Our Recommendation

For reliable on-the-water communications by most boaters, either hand-held or fixed-mount VHF radios are usually most appropriate, depending on your circumstances. And two is better than one because of the potential importance of communications. When you're stuck in a jam-whether from engine failure or a fierce storm approaching, a VHF radio can be your lifeline to the world. In Coast Guard jurisdictions, VHFs are monitored 24 hours a day, seven days a week. For extra assurance, the USCG and most TowBoatU.S. towers can locate your boat by tracking your VHF signal. VHFs are handy in an emergency, but they have other uses such as boat operations like drawbridge openings and communicating with commercial and other recreational vessels. The Federal Communications Commission (FCC) regulates marine radio traffic and dictates that all other uses are secondary to safety, so chatting is frowned upon by the FCC and forbidden on Channel 16 and 9, 22A and many other channels.  Specific channels are assigned by the FCC for specific types of communications.

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