A marine VHF radio is the single most important piece of communication equipment on any boat, and most new boaters either skip it entirely or treat it as a complicated piece of commercial gear they do not need. Both attitudes are wrong. A handheld VHF costs $120-200, requires no license for domestic recreational use, floats, and reaches the Coast Guard from anywhere in coastal waters. A phone in a waterproof case works on a calm reservoir within cell coverage and fails predictably in salt water, in cold, or out of signal. The VHF is the protocol that the entire commercial maritime world uses, which means that the cargo ship, the fishing boat, the marina, and the Coast Guard all monitor the same channels you do. Learning the basics takes about an hour and turns a piece of equipment most owners ignore into the most useful safety device on the boat.
What VHF is and why it works
Marine VHF (Very High Frequency) operates in the 156-174 MHz band with specific channels assigned for distress, hailing, working, and weather. The band uses line-of-sight propagation, which means range depends on antenna height rather than transmitter power. A 5-watt handheld with a 12-inch antenna gets 3-8 miles to another similar handheld and farther to a tall-antenna shore station. A 25-watt fixed mount unit with a 23-foot sailboat masthead antenna reaches 25-50 miles to similar fixed stations. Coast Guard towers with 200-foot antennas hear handhelds at 20+ miles on calm days.
The protocol is open. Every boat on the water listens to channel 16 (the international distress and hailing channel), which means a properly broadcast mayday is heard by everyone in range simultaneously, then relayed by larger vessels and shore stations until the Coast Guard responds.
Fixed mount vs handheld
Fixed mount VHF (Standard Horizon GX1850, Icom IC-M330, Garmin VHF 215) costs $180-400, runs on 12-volt boat power, transmits at 25 watts, and connects to a masthead or hardtop antenna. The combination gives the longest range and highest reliability. Most fixed units include DSC, GPS input, AIS receive, and a wired or wireless hailer.
Handheld VHF (Standard Horizon HX210, Icom IC-M37, Cobra MR HH350) costs $120-250, runs on internal batteries (8-12 hours typical), transmits at 5-6 watts, and uses a stubby integrated antenna. Floating waterproof models survive immersion to IPX7 or IPX8 and are the standard for kayak anglers, dinghy crews, and as a backup on larger boats.
For most recreational boats under 22 feet, a floating handheld is the right primary radio. For boats over 22 feet or any boat that ventures more than 5 miles offshore, the fixed mount is essential and a handheld backup is a strong supplement.
DSC and MMSI: the modern safety layer
DSC (Digital Selective Calling) is a feature on every VHF made since about 2010. Press and hold the red distress button under the cover and the radio sends a digital data burst on channel 70 containing your vessel identity (MMSI), GPS position, nature of distress (if you specify), and time. The data burst transmits in under a second and is received by the Coast Guard and every DSC-capable vessel in range. The radio then automatically switches to voice on channel 16.
The MMSI (Maritime Mobile Service Identity) is a nine-digit number that uniquely identifies your boat. For US recreational use you get one free from BoatUS (boatus.com/mmsi) or Sea Tow in about 10 minutes. Program it into the radio per the manual. Connect the radio to a GPS source or use the built-in GPS on newer models. Without an MMSI programmed, the red button does nothing useful.
Required and optional channels
Channel 16 is the international distress, safety, and hailing channel. You monitor it any time the radio is on. Coast Guard regulations require commercial vessels and recommend recreational vessels to monitor 16.
Channel 9 is an alternate hailing channel on US waters to reduce traffic on 16. Many marinas, harbormasters, and bridges monitor 9 in addition to 16.
Channel 13 is the bridge-to-bridge channel used by commercial captains for navigation safety on inland and coastal waters. If you encounter a large vessel in a tight channel, call them on 13 to coordinate passage.
Channels 22A, 21A, and 23A are Coast Guard working channels. After hailing on 16, the Coast Guard will switch you to 22A for the actual conversation.
Channels 68, 69, 71, 72, and 78A are non-commercial working channels for recreational boater chat once you have hailed someone on 16 or 9.
WX1 through WX10 are receive-only NOAA continuous weather broadcasts. Set a button to scroll through the WX channels and find the one strongest in your area.
Range expectations and antennas
Range is dominated by antenna height. A handheld held at chest level transmits effectively to about the visible horizon (3-5 miles) for surface targets, farther to elevated targets like ships and shore stations. A masthead antenna at 30 feet reaches 6-8 miles to a similar masthead and 30-50 miles to a Coast Guard tower.
The antenna matters more than the radio. A $200 fixed mount with a cheap 3-foot stainless antenna will be outperformed by a $150 fixed mount with a quality 8-foot Shakespeare or Digital antenna mounted high. For sailboats, the masthead position is the single largest range improvement.
How to talk on VHF
VHF etiquette. Listen before you transmit. Press the transmit button, pause half a second, then speak. Say the name of the vessel you are calling three times, then your own vessel name once, then “over” or “go ahead”. On hearing your name, the other party responds and suggests a working channel. Both stations switch to the working channel for the conversation, then return to 16 when done.
For emergencies, use Mayday for life-threatening situations, Pan-Pan for urgent but not life-threatening situations (mechanical breakdown, lost overboard but recovered), and Securité for safety broadcasts (debris in channel, navigation hazards). Coast Guard rescuers are trained on these distinctions and will respond accordingly.
Test it before you need it
Once a season, do a radio check on channel 9 (not 16 in non-emergency) or use the automatic radio check service in many US harbors (Sea Tow operates one on channel 27 or 28 in many regions). Verify your DSC distress works by checking the GPS position in the menu, not by pressing the red button (which alerts the Coast Guard). Replace batteries on handhelds annually. Inspect coax connections on fixed mounts each spring.
Frequently asked questions
Do I need a license to use a marine VHF radio in the US?+
For recreational use on US waters in a vessel that does not travel internationally, you do not need an FCC license. You can buy a VHF, install it, and use channel 16 today. If you travel internationally (Bahamas, Mexico, Canada beyond casual crossings) or carry a satellite EPIRB tied to your vessel, you need a Ship Station License and a Restricted Radiotelephone Operator Permit, both filed with the FCC.
What is an MMSI number and do I need one?+
An MMSI is a nine-digit number that identifies your specific vessel on DSC-capable radios. You need one if your VHF has DSC (most do since 2010). Recreational boaters get a free MMSI from BoatUS or Sea Tow in about ten minutes online. Commercial and internationally traveling vessels get MMSIs from the FCC. Programming the MMSI into the radio enables the red distress button to send your identity, position, and emergency type to the Coast Guard and nearby vessels.
Handheld VHF or fixed mount, which one do I need?+
Both, if budget allows. A fixed mount unit at 25 watts with a masthead antenna gives 20-50 mile range and is your primary radio. A floating handheld at 5-6 watts and 3-8 mile range is your backup, your dinghy radio, and your survival radio if you abandon ship. For boats under 22 feet, a handheld alone is often acceptable because there is no convenient place to mount a fixed unit and the antenna height limits range anyway.
What channels do I actually need to know?+
Channel 16 is the international hailing and distress channel. Channel 9 is an alternate hailing channel on US waters. Channel 13 is bridge to bridge for commercial traffic and large vessel coordination. Channels 68, 69, 71, 72, and 78A are non-commercial working channels for recreational chat. Channels 22A and 21A are Coast Guard working channels. Weather channels (WX1-WX10) carry continuous NOAA forecasts. Memorize 16, 9, 13, and one working channel.
How do I make a mayday call?+
Tune to channel 16, set output to 25 watts (high power), and press the transmit button. Say Mayday three times. Identify your vessel name three times. State your position by latitude and longitude or by reference to a known landmark. State the nature of the emergency (sinking, fire, medical, abandoning ship). State the number of people aboard. State assistance required. Release the transmit button and wait for a response. If you have DSC, press and hold the red distress button instead and your radio will send all of this electronically in addition to your voice call.
