Why VHF Beats Your Phone on the Water
Your smartphone works great at the marina. It works less well two miles offshore, in a cove where cell coverage drops, or when your battery dies and the boat is taking on water. VHF marine radio works when cell phones don't — it communicates directly between vessels and to the Coast Guard without relying on cellular towers. It's also the medium the Coast Guard actively monitors for distress calls, 24 hours a day, every day.
The good news: VHF radios are inexpensive (a quality handheld starts under $100), simple to operate, and much of what you need to know fits on a single page. If you're on the water without one, you're missing the most important piece of safety gear that isn't already required by law.
Channel 16: Always On, Always Monitor
Channel 16 is the international distress, safety, and calling frequency. The Coast Guard monitors Channel 16 continuously. All commercial vessels are legally required to maintain a watch on Channel 16 when underway. When you need help — or when another vessel needs to reach you — Channel 16 is where it happens.
Keep your radio on Channel 16 whenever you're underway. If you're listening to weather on Channel 1 (WX1) or chatting on a working channel, switch back to 16 as your primary monitor. Modern radios have a "dual watch" or "tri-watch" function that lets you scan between Channel 16 and one or two other channels simultaneously — use it.
Do not use Channel 16 for extended conversation. Hail a vessel on 16, agree to switch to a working channel, then move. The calling convention is: "Vessel [name], this is [your vessel name], switch to channel [68/69/71/72], over." Then move to that channel and respond.
Key Channels Every Boater Should Know
- Channel 16: Distress, safety, and calling. Always monitor this channel.
- Channel 9: Recreational boater calling channel. An alternative to 16 for initial hailing between recreational vessels in some areas.
- Channel 22A: U.S. Coast Guard communications after initial contact on 16. If the Coast Guard needs to speak with you at length, they'll ask you to switch to 22A.
- Channels 68, 69, 71, 72, 78A: Common recreational working channels for conversation between boats. Use these after hailing on 16.
- WX1, WX2, WX3: NOAA weather broadcasts. Check these before departure and periodically while underway.
- Channel 13: Bridge-to-bridge communications. Used by commercial vessels and mariners to communicate with bridges and other vessels in confined waterways. If you're transiting a waterway with commercial traffic, monitor 13 in addition to 16.
How to Make a MAYDAY Call
MAYDAY is declared when you or someone aboard faces grave and imminent danger — the vessel is sinking, there's a fire you can't control, someone is critically injured, a person is overboard and unrecovered. It's the highest level of distress and triggers an immediate Coast Guard response plus any vessel in range.
The format, which you should memorize:
- Switch to Channel 16.
- Press the transmit button and say: "MAYDAY MAYDAY MAYDAY"
- "This is [vessel name] [vessel name] [vessel name]" — repeat three times
- "MAYDAY [vessel name]"
- "Our position is [GPS coordinates or a description: '2 miles southeast of [landmark]']"
- "We are [nature of distress: sinking, on fire, man overboard, medical emergency]"
- "We have [number] people aboard"
- "[Any other relevant information: vessel description, EPIRB activated, abandoning ship]"
- "We request immediate assistance. Over."
Release the transmit button and listen for a response. If none, repeat. Keep the call short enough that the Coast Guard can get a word in when you release.
If your situation is less urgent — you need assistance but aren't in immediate danger — use a PAN-PAN call instead. "PAN-PAN PAN-PAN PAN-PAN, this is [vessel name]..." The rest of the format is the same. PAN-PAN means urgency without immediate threat to life; MAYDAY means you need help right now.
What Is DSC and Why Does It Matter?
Digital Selective Calling (DSC) is a digital technology built into most modern fixed-mount VHF radios. When connected to your GPS, a single button press — the red DISTRESS button — automatically transmits your vessel identity (MMSI number), your GPS position, the time, and the nature of your distress to the Coast Guard and all DSC-equipped vessels in range.
To use DSC, you need two things:
- A DSC-equipped radio connected to a GPS source (either internal GPS in the radio or an external GPS). Without a GPS connection, the distress signal still goes out but without your position — much less useful to rescuers.
- A registered MMSI number. MMSI (Maritime Mobile Service Identity) is a unique 9-digit identifier for your vessel. It's free to register through BoatUS, Sea Tow, or the FCC. Register it at BoatUS MMSI and program it into your radio before your first trip.
If you have an unregistered MMSI, the distress signal goes out but the Coast Guard has no record of who or what vessel sent it. Register it. It takes 5 minutes.
Fixed Mount vs. Handheld VHF
Fixed-mount radios transmit at up to 25 watts and have significantly greater range than handhelds (which typically transmit at 5-6 watts maximum). For a vessel with a permanent installation, a fixed-mount DSC VHF connected to GPS and a proper antenna is the right primary radio.
Handhelds are a critical backup and should be on board regardless. If the boat is sinking or flooding, you may not be able to reach the fixed radio. A waterproof handheld VHF in your lifejacket pocket works when everything else doesn't. Most modern handhelds float.
For small vessels, kayaks, paddleboats, or any situation where a fixed install isn't practical, a quality waterproof handheld is your primary and only radio. It's still vastly better than a cell phone on the water.
Radio License Requirements
Domestic recreational boaters operating on U.S. waters and not making international communications don't need a radio operator's license. However:
- If you travel to international waters (including Canada or Mexico), a Ship Station License for the vessel and a Restricted Radiotelephone Operator Permit for the operator are required.
- Commercial vessels have additional requirements.
For most recreational boaters in U.S. waters, no license is required. Don't let that be a reason not to carry a radio.
Test Your Knowledge
If you've never been tested on marine radio procedures, our free VHF Radio & DSC Quiz covers channels, MAYDAY format, DSC operation, and the scenarios you're most likely to encounter. It takes about 10 minutes and could be the most useful 10 minutes you spend before your next trip.