Quick Facts
| Mayday | Life-threatening emergency — vessel sinking, fire, medical emergency, life at immediate risk |
| Pan-Pan | Urgent situation, not yet life-threatening — serious injury, drifting toward hazard, man overboard located |
| Channel 16 | International distress and calling channel — always monitored by USCG, commercial vessels, and offshore-capable recreational boats |
| DSC Distress Button | Press and hold 5 seconds on a DSC-capable VHF — sends MMSI and GPS position automatically to USCG |
| EPIRB Activation | For abandoning ship or imminent life danger — triggers COSPAS-SARSAT satellite system and USCG MRCC response |
| False Activations | Can be billed by USCG — register EPIRB and cancel false activations immediately via USCG |
Most recreational sailors will never need to send a Mayday. But the crews who are most likely to survive a genuine emergency at sea are the ones who practiced the procedure before it mattered, who knew what button to press, what words to say, and in what order. Distress communications are not complicated — they are deliberately simple and repetitive so that a panicked person can execute them. The goal of this guide is to make the procedure automatic before you need it.
The Distress Signal Hierarchy
Distress signals exist in a hierarchy roughly organized from lower-technology to higher-technology, and from shorter to longer range. In any emergency, deploy multiple signals simultaneously rather than choosing one and waiting.
Visual signals include red parachute flares (visible at long range in daylight and night), handheld red flares (close range, useful when another vessel is in sight), orange smoke (daylight only, effective for aerial search), a signal mirror (very long range on a clear day — can be seen from aircraft at 10 miles), and waving arms or an orange flag. Flares have expiration dates; SOLAS-approved flares must be replaced when they expire.
Sound signals include the horn (three blasts repeated is a distress signal under COLREGS), a whistle, or shouting — useful only at short range. Sound carries surprisingly well across water at night, but it is a last resort, not a primary signal.
Radio is your most effective distress tool in most scenarios: a VHF Mayday call reaches the Coast Guard or other vessels within line-of-sight range, which is typically 20–30 miles from a masthead-mounted antenna on a sailboat, less from a hand-held. The DSC distress button on a properly registered VHF with GPS input sends a digital distress alert that is received simultaneously by all DSC-capable radios within range and, via the USCG's monitoring network, ashore.
Electronic beacons — EPIRB and PLB — are the longest-range signals, operating via satellite to reach COSPAS-SARSAT ground stations and then to the USCG Maritime Rescue Coordination Center regardless of where you are in the world. An activated 406 MHz EPIRB will generate a response from the nearest MRCC within minutes of satellite acquisition.
Mayday vs. Pan-Pan: Knowing the Difference
Mayday is the international radio distress signal for situations where life is in immediate danger. A vessel sinking, a fire aboard that is not under control, a crew member with a life-threatening medical emergency, a man overboard in cold water who cannot be recovered quickly — these are Mayday situations. The word comes from the French "m'aidez" (help me) and is recognized worldwide.
Pan-Pan (pronounced "pahn pahn") is the urgency signal — less than life-threatening but requiring priority attention. A crew member with a serious but not immediately life-threatening injury, a vessel taking on water slowly with the pump keeping up, a boat drifting toward a hazard with time still available, a man overboard who has been recovered and needs medical attention — these may be Pan-Pan calls. Pan-Pan gets priority handling on Channel 16 and brings a USCG response, but it signals that the situation is not yet critical.
When in doubt, call Mayday. The USCG would rather respond to a situation that turns out to be manageable than not respond to one that required immediate intervention. You can always downgrade a Mayday to Pan-Pan once you have contact with the Coast Guard and the situation is clarified.
The Mayday Call Format
The standardized Mayday call format exists so that anyone — USCG, a passing commercial vessel, another recreational boat — receives the critical information in a known sequence. Do not improvise; use the format.
On VHF Channel 16, at maximum power (typically 25 watts), transmit:
"Mayday, Mayday, Mayday. This is [vessel name], [vessel name], [vessel name]. Mayday [vessel name]. My position is [GPS coordinates in degrees and decimal minutes, or bearing and distance from a named landmark]. [Nature of distress — sinking, fire, medical emergency]. I have [number] persons aboard. [Any other critical information — vessel description, taking on water, requesting immediate assistance]. Over."
Then release the transmit button and listen. If you receive no response within 15 minutes, repeat the entire call. Keep repeating every 15 minutes, or more often if the situation is deteriorating rapidly.
Your position is the most critical piece of information. If you have GPS, read the coordinates directly from the display. If not, give the best position you can — a bearing and distance from a named buoy, lighthouse, or headland is better than nothing. Practice reading your GPS coordinates before you need to under stress.
The DSC Distress Button
Modern VHF radios — any sold in the US market in recent years — are equipped with Digital Selective Calling (DSC). There is a red distress button, typically covered by a flip-up guard, prominently positioned on the radio face. In a distress situation, press and hold it for five seconds. The radio will automatically transmit a formatted digital distress alert on Channel 70 containing your MMSI number and, if the radio is connected to a GPS source (either built-in or via NMEA interface), your precise position with timestamp.
The USCG monitors Channel 70 continuously and receives DSC alerts almost instantly. Other DSC-equipped vessels within range receive the alert and will see your position on their chart plotters if they are connected. The DSC alert is faster than a voice Mayday for getting your position to the Coast Guard — it requires no verbal message and works even if you are too incapacitated to speak clearly.
Your MMSI must be registered with the FCC and the BoatUS Foundation (or the USCG directly for documented vessels). Registration links your MMSI to your vessel description and emergency contacts, which the USCG uses when they receive the alert. An unregistered MMSI generates a response but requires more investigation time. Registration is free and takes ten minutes.
EPIRB Activation
An EPIRB (Emergency Position Indicating Radio Beacon) is activated when you are preparing to abandon ship, when life is in immediate and serious danger, and when you need global SAR coordination rather than just local VHF response. It is not an alternative to a Mayday call — it is a supplement for situations where you may not be able to maintain radio communications, or where you are abandoning the vessel into a life raft.
The 406 MHz EPIRB transmits to COSPAS-SARSAT satellites, which relay the alert to the nearest ground station, which passes it to the USCG MRCC. The MRCC identifies the beacon by registration, knows your vessel details and emergency contacts, and dispatches SAR assets. Modern Category I EPIRBs (float-free bracket mounted) activate automatically if the vessel sinks. Category II EPIRBs require manual activation.
Register your EPIRB with the FCC. The registration database is what connects your beacon ID to your vessel description. An unregistered EPIRB generates an alert that the MRCC must investigate — wasting time that matters. Registration is free at beaconregistration.noaa.gov.
False activations are a significant problem. The USCG deploys assets to every EPIRB alert. A false activation from a mishandled unit or accidental triggering in a dinghy while working on the boat can cost tens of thousands of dollars in SAR costs and can result in the vessel owner being billed for those costs. If your EPIRB activates accidentally, cancel the alert by switching the unit off, and immediately call the USCG on Channel 16 or by phone (1-800-323-7233) to report the false activation.
What to Do While Waiting for the USCG
After you have sent the distress signal and made contact with the USCG, stay with the boat as long as safely possible. A vessel — even a disabled one, even one taking on water — is vastly easier for SAR assets to find than a person or a life raft in open water. The radar cross-section of a sailboat is orders of magnitude larger than a life raft; the visual profile is far more distinctive. Abandon only when staying aboard becomes clearly more dangerous than going into the raft.
Keep all visual signals active. If you have flares, deploy them when you see or hear approaching aircraft or vessels. Keep the VHF on and answer any transmissions — the USCG coxswain will want to speak with you as they approach to get an updated position and condition report. Keep a crew member assigned to watch for approaching vessels while another manages the radio.
USCG response time varies enormously. Near a busy Coast Guard station in coastal water, helicopter response may be under 30 minutes. A hundred miles offshore, the response may come from a Coast Guard cutter at 18 knots — four to six hours away. Beyond SAR helicopter range (approximately 200 nautical miles from the nearest station, variable by weather and available assets), the USCG will coordinate commercial vessel diversions — instructing a nearby cargo ship to divert to your position. This process is slower and less predictable. Offshore, an EPIRB and good seamanship — staying with the boat, keeping visual signals active, maintaining VHF communication — are your survival tools while the system works.
Related Guides
For UK and European waters: The RNLI and European Sea Rescue Services →
For commercial towing when the situation is not life-threatening: Sea Tow vs. BoatUS: Towing Memberships →
← Towing & Sea Rescue | Safety Guides →
Frequently Asked Questions
What is the difference between a Mayday and a Pan-Pan call and when should each be used? Mayday is the international radio distress signal for situations where life is in immediate danger — a vessel sinking, a fire aboard not under control, a life-threatening medical emergency, or a man overboard in cold water who cannot be recovered quickly. Pan-Pan (pronounced 'pahn pahn') is the urgency signal for situations less than life-threatening but requiring priority attention: a serious but not immediately life-threatening injury, a vessel taking on water slowly with the pump keeping up, or a boat drifting toward a hazard with time still available. When in doubt, call Mayday — the USCG would rather respond to a situation that turns out to be manageable than not respond to one that required immediate intervention.
What is the exact format of a VHF Mayday call? On VHF Channel 16 at maximum power (typically 25 watts), transmit: 'Mayday, Mayday, Mayday. This is [vessel name], [vessel name], [vessel name]. Mayday [vessel name]. My position is [GPS coordinates or bearing and distance from named landmark]. [Nature of distress]. I have [number] persons aboard. [Any other critical information]. Over.' Then release the transmit button and listen; if no response is received within 15 minutes, repeat the entire call. Your position is the most critical piece of information — practice reading GPS coordinates before you need to under stress.
How does the DSC distress button work and why is MMSI registration important? The red distress button on a DSC-capable VHF, pressed and held for five seconds, automatically transmits a formatted digital distress alert on Channel 70 containing your MMSI number and, if the radio is connected to a GPS source, your precise position with timestamp — the USCG monitors Channel 70 continuously and receives the alert almost instantly. Other DSC-equipped vessels within range receive the alert and see your position on their chart plotters if connected. Your MMSI must be registered with the FCC, linking it to your vessel description and emergency contacts — an unregistered MMSI generates a response but requires more investigation time, and registration is free.
When should an EPIRB be activated and what happens after it transmits? An EPIRB should be activated when preparing to abandon ship, when life is in immediate and serious danger, and when global SAR coordination is needed rather than just local VHF response — it is a supplement for situations where radio communications may be lost, not an alternative to a Mayday call. The 406 MHz EPIRB transmits to COSPAS-SARSAT satellites, which relay the alert to the nearest ground station and then to the USCG MRCC, which identifies the beacon by registration, knows the vessel details and emergency contacts, and dispatches SAR assets. Register your EPIRB at beaconregistration.noaa.gov — an unregistered EPIRB generates an alert that requires investigation, wasting time that matters.
What should you do aboard while waiting for the Coast Guard after sending a distress signal? Stay with the boat as long as safely possible — a vessel, even a disabled one taking on water, is vastly easier for SAR assets to find than a person or life raft in open water, with a radar cross-section orders of magnitude larger than a life raft. Keep all visual signals active and deploy flares when you see or hear approaching aircraft or vessels; keep the VHF on and answer any transmissions, as the USCG coxswain will want to speak with you as they approach for an updated position and condition report. USCG response time varies enormously: near a busy station in coastal water, helicopter response may be under 30 minutes, while a hundred miles offshore the response may come from a cutter at 18 knots — four to six hours away.