If your radio has DSC, press the red distress button first. Then on VHF channel 16, at high power: say MAYDAY three times and your boat’s name three times, then your position, what’s wrong, how many people are aboard and the help you need. Say “OVER” and listen. No radio? Call 911, say “boat emergency, I’m on the water,” and give the same details in the same order.
Then release the transmit button and listen. If nobody answers within about a minute, repeat. This is the standard structure taught in boating and VHF courses, and the order matters: whoever takes your call writes it down in that order.
The two calls exist so that Channel 16 carries distress traffic only when it’s real. Picking the right one isn’t about manners: it decides how every station that hears you reacts.
Grave and imminent danger to a boat or a life: sinking, fire, person overboard, serious injury.
Everyone who hears it must stop transmitting and help if they can. Never make a false Mayday.
Urgent, but no immediate danger to life: engine failure in a channel, a boat drifting toward a hazard, a medical problem that isn’t critical yet.
Same structure, with “PAN-PAN” three times instead. If nobody’s life is at risk and you just need a tow, see boat broke down: who to call.
Most small boats (jon boats, jet skis, kayaks, paddle boards) carry no VHF at all. Then the call is 911: say you’re on the water, name the lake, river or bay, and give the same items in the same order: who you are, where you are, what’s wrong, how many people. The hardest part under stress is the position, so read latitude and longitude straight off a GPS app instead of describing the shoreline. On inland lakes and rivers, 911 is how you reach the sheriff’s marine unit, conservation officers or fire rescue.
On the coast and the Great Lakes, the radio comes first if you have one: Channel 16 is the primary VHF distress channel, and a call there reaches the Coast Guard and every boat nearby at once. The Coast Guard doesn’t advocate cell phones as a substitute for VHF radio, but says they “can have a place on board as an added measure of safety” (A Boater’s Guide to the Federal Requirements for Recreational Boats, USCG, rev. Nov 2023). More in how to call the Coast Guard and our list of Coast Guard phone numbers.
By phone, the app dials 911 in US waters and shows a six-step script of what to say, with your position read out in words. In radio mode it shows this Mayday form filled in with your boat’s name, call sign in the NATO alphabet, MMSI and live position, plus DSC and Pan-Pan guidance. It doesn’t transmit anything itself and isn’t connected to the Coast Guard: you read the words on your own radio or phone. It doesn’t replace the radio or the training; it replaces the remembering. See how it works →