VHF Radio Basics and Channel Etiquette: What Every Boater Should Know

Your cell phone is not a safety device. It works fine until you're four miles offshore with one bar, and even when it does connect, it reaches exactly one person at a time. A VHF radio reaches every boat within range, the Coast Guard, and the towboat captain who happens to be two miles away — all with a single transmission. That's the difference, and it's why a properly installed VHF is still the most important piece of communication gear on your boat.  I hope you enjoy this informative article on the basics of using a VHF radio while out on your boat.   If you have any questions, reach out to us here at Deep Blue Yacht Supply and we will be glad to help answer any VHF/Radio questions. 

Here's what you need to know to use one correctly, plus the etiquette that separates the boaters who sound like they know what they're doing from the ones who clog up Channel 16 on a Saturday afternoon.

How VHF Actually Works (And Why Range Disappoints People)

VHF marine radio is line-of-sight. The signal travels in a straight line and does not follow the curve of the earth, which means your effective range is determined almost entirely by antenna height — not by how much you paid for the radio.

A typical setup looks like this:

• Boat to boat, both with low antennas: roughly 5 to 10 miles
• Boat to a tall shore station or Coast Guard tower: 20 to 30+ miles
• Handheld to handheld: often under 5 miles

Two boats with 8-foot antennas talking to each other will get far less range than either one talking to a tower 200 feet up on shore. This is also why sailboaters put the antenna at the masthead — height beats wattage every time.

Fixed-mount vs. handheld. A fixed-mount radio transmits at 25 watts and connects to a real antenna. A handheld transmits at 5 or 6 watts through a stubby rubber antenna a few feet above the water. Handhelds are excellent backups — get a floating, waterproof one and keep it in your ditch bag — but they are not a substitute for a properly installed fixed unit.

Antenna selection matters more than most people realize. Higher-gain antennas focus the signal into a flatter pattern, which extends range but punishes any vessel that rolls or heels. General guidance:

• 3 dB (3–4 ft): sailboats, small boats, anything that heels or pitches hard
• 6 dB (8 ft): the standard choice for most powerboats
• 9 dB (17–23 ft): large, stable vessels only

And before you blame the radio for poor range, check the coax and connections. Corroded fittings and water-intruded cable are the number one cause of a VHF that "stopped working."

DSC and Your MMSI: The Feature Half of Boaters Never Turn On

Nearly every VHF sold in the last two decades has Digital Selective Calling. Press the protected red distress button and the radio transmits a digital alert on Channel 70 containing your vessel identity and — if it's wired correctly — your exact position. The Coast Guard and every DSC-equipped vessel in range gets it instantly.

Two things have to happen first:

1. Program your MMSI. The Maritime Mobile Service Identity is your radio's nine-digit phone number. Recreational boaters staying in U.S. waters can get one free through BoatUS or Sea Tow (both excellent run operations in our opinion). If you're heading to the Bahamas or anywhere international, you need one issued by the FCC along with a ship station license.

2. Connect the radio to GPS. A DSC distress call without position data is dramatically less useful. Most modern radios have an internal GPS or accept an NMEA feed from your chartplotter. If yours shows "No Position" or a blinking GPS indicator, fix it before your next trip.

Note that most radios only let you enter the MMSI a limited number of times before requiring a factory reset. Enter it carefully.

Do U.S. boaters need an FCC license? For recreational vessels under 65 feet operating in domestic waters, generally no. You need a ship station license for international voyages, for vessels over 65 feet, and for commercial operation.

The Channels You Actually Need

Channel assignments differ between the U.S., Canada, and international bands. Make sure your radio is set to the correct region — it's a menu setting, and it's a common source of confusion for boaters crossing to the Bahamas.

Basic Operating Technique

• Listen before you transmit. Stepping on another transmission helps nobody.
• Press, pause, then speak. Key the mic, wait half a beat, then talk. Otherwise the first word gets clipped.
• Hold the mic an inch or two from your mouth and speak across it, not into it, at a normal conversational volume. Shouting distorts.
• Use low power (1W) for anything close range. It keeps the airwaves clear and saves battery. Switch to 25W for distance.
• Say "over" when you're done talking and "out" when the conversation is finished. "Over and out" is a contradiction — it's a movie thing, not a radio thing.

Channel Etiquette: The Unwritten Rules

Channel 16 is a hailing and distress channel, not a chat room. Call the other vessel, get an answer, agree on a working channel, and switch. Standard form:

"Sea Breeze, Sea Breeze, this is Meridian, Meridian. Over."

"Meridian, this is Sea Breeze. Over."

"Sea Breeze, switch and answer six-eight. Over."

Then move to 68 and have your conversation there.

Keep it short. Non-emergency exchanges on working channels should stay under three minutes, and you should wait a few minutes before calling the same vessel again if there's no answer.

No profanity, no music, no false calls. These are FCC violations, not just bad manners. Making a false distress call is a federal crime that carries heavy fines and potential prison time, along with liability for the cost of the response.

Don't do radio checks on Channel 16. Use Channel 9, or better, use the automated radio check service available on dedicated channels in many coastal areas — it plays your transmission back so you can hear exactly how you sound.

Monitor 16 whenever you're underway. Most radios have a dual-watch or scan function so you can sit on a working channel while still catching traffic on 16. Somebody's distress call is only useful if people are listening.

Distress Calls: Know These Three Words

MAYDAY — grave and imminent danger to a vessel or person. Fire, sinking, medical emergency, man overboard.

PAN-PAN (pronounced pahn-pahn) — urgency, but not immediate danger to life. Engine failure in a shipping channel, a serious but stable injury.

SÉCURITÉ (pronounced say-cure-i-tay) — safety and navigational information. A hazard in the channel, a large vessel maneuvering, an approaching squall line.

The Mayday Script

Hit the DSC distress button first, then get on Channel 16 at high power:

1. "Mayday, Mayday, Mayday."
2. "This is [vessel name, three times, then call sign or MMSI]."
3. "Mayday, [vessel name]."
4. Position — latitude/longitude if you have it, or bearing and distance from a known landmark.
5. Nature of distress — "taking on water," "fire in the engine room."
6. Assistance needed.
7. Number of people aboard.
8. Vessel description — length, type, hull color.
9. "Over."

Then release the mic and listen. Tape a copy of this near the helm. In the moment when you actually need it, nobody remembers the order.

Before Your Next Trip

Take five minutes at the dock and run through this:

• Radio powers up, squelch adjusted so background hiss just disappears
• MMSI programmed and GPS position showing
• Antenna connections clean, coax undamaged
• Successful radio check on Channel 9
• Handheld backup charged and stowed where you can reach it
• Mayday script posted at the helm

Great gear and good habits are what keep boat ownership enjoyable instead of stressful. At Deep Blue Yacht Supply, we've spent nearly two decades helping boat owners get the right parts and the right answers; from propellers and running gear to the hardware that keeps everything turning. If you have a question about your setup, call us. We'll take the time to help, whether you buy something or not.  Smooth seas and tight lines from your friends at Deep Blue Yacht Supply.