MAYDAY Call — Exact Format
Transmit on VHF Channel 16 — monitored continuously by the USCG and all vessels required to carry a VHF radio. Your position is the single most important element. If you only transmit one thing, transmit your position.
MAYDAY Transmission Script
If no response within 2 minutes, repeat the full transmission. Switch to Channel 22A if directed by the USCG.
MAYDAY vs. Pan-Pan vs. Securite
MAYDAY
Grave and imminent danger to the vessel or persons aboard — fire, sinking, medical emergency requiring immediate rescue. Life at immediate risk.
Pan-Pan (Urgency)
Safety at risk but not immediately life-threatening — mechanical failure, person in water who is afloat, non-critical medical situation. Upgrade to MAYDAY if situation worsens.
Securite (Safety)
Navigational hazard warning — floating debris, hazardous weather, restricted channel traffic. Not an emergency call — used to warn other vessels.
DSC Digital Distress Alert
- ▸Channel 70 is digital only — no voice transmissions
- ▸DSC-equipped radios send MMSI number and GPS position automatically
- ▸Press and hold the distress button for 5 seconds to activate
- ▸After DSC alert, switch to Channel 16 for voice communication
- ▸USCG monitors Channel 70 continuously — response is typically within 2 minutes
Distress Signals — Visual, Audio & Electronic
Recreational vessels 16 feet and over on coastal and inland waters must carry USCG-approved visual distress signals (VDS). Night-only outings require night-only or combination signals. Day-only outings may use day-only signals.
Visual — Day
Visual — Night
Visual — Day & Night
Audio
Radio / Electronic
Exam Note: VDS Minimum Requirements
Recreational vessels 16 ft and over on coastal waters: minimum 3 approved signals that cover day, night, or both. Three combination signals (e.g., three red parachute flares) satisfy the requirement alone. Vessels under 16 ft on coastal waters are not required to carry VDS for day use but must carry night signals when operated after sunset.
Fire at Sea — Response & Fire Classes
Fire is the most feared emergency at sea. It grows exponentially — fight it immediately with the right agent or abandon the attempt and prepare to leave the vessel.
Fire Response — Priority Order
Alert crew — 'Fire!'
Assign stations immediately. One crew member mans the helm; others fight the fire and prepare abandon ship.
Stop vessel and turn upwind
Position the vessel so the fire is downwind. This prevents flames from blowing aft into crew areas and fuel tanks.
Shut off fuel and ventilation
Close all fuel seacocks. Shut engine compartment air vents to starve the fire of oxygen. Engine off.
Use fixed fire system if equipped
For engine room fires, activate the fixed CO₂ or Halon suppression system before opening the hatch — opening the hatch without suppression agent feeds oxygen to the fire.
Fight with the correct extinguisher
Match the extinguisher to the fire class (see chart below). Never use water on Class B or C fires. Aim at the base of the flame, not the top.
Prepare for abandon ship simultaneously
Don life jackets. Prepare EPIRB, flares, and grab bag. Do not wait until the fire wins — parallel preparation saves lives.
Transmit MAYDAY if not controlled quickly
If the fire is not controlled within 60 seconds, transmit MAYDAY. Position, nature of distress (fire), persons aboard. Other vessels may be minutes away.
Abandon ship if fire is winning
Do not sacrifice lives for the vessel. If the fire reaches fuel tanks, it is over. Board the life raft or enter the water upwind and upwave of the burning vessel.
Fire Classes — Agents and Restrictions
Ordinary combustibles
Wood, cloth, paper, rubber
Extinguish with
Flammable liquids & gases
Gasoline, diesel, oil, LPG
Extinguish with
Never use
Water — spreads fireEnergized electrical
Wiring, motors, electronics
Extinguish with
Never use
Water or foam — conductivity riskCombustible metals
Magnesium, titanium (rare)
Extinguish with
Never use
Water, CO₂, dry chemical — reaction riskAbandon Ship Procedures
The cardinal rule: do not abandon ship until the vessel is sinking beneath you. A vessel is always more visible to searchers than a life raft or persons in the water. Abandoning prematurely has cost lives when vessels were later found floating.
Abandon Ship Sequence
Transmit MAYDAY
Channel 16 — position, persons aboard, nature of emergency.
Activate EPIRB
Manual activation or verify float-free release is clear.
Don life jackets
All persons aboard — including immersion suits in cold water.
Collect grab bag
Flares, water, handheld VHF, mirror, knife, medications.
Deploy life raft
Inflate on the leeward side — board without entering the water if possible.
Board the raft
Most vulnerable persons first. Assist injured crew. Don't jump unless necessary.
Cut the painter when vessel sinks
Keep the line attached until the vessel actually goes under.
Deploy sea anchor
Reduces drift — keeps you closer to the last known position for search.
Signal rescuers
Flares, mirror, dye marker, handheld VHF, whistle. Activate on aircraft or vessel sighting.
Abandon Ship Gear Priority
If float-free, verify it activates on water entry. Otherwise activate manually.
All persons aboard — don before leaving the vessel.
Red parachute flares and handheld flares — carry all available.
Waterproof bag: water, food, mirror, knife, VHF handheld, cash, ID, medications.
Waterproof VHF — continue communications from the life raft.
Inflate and board upwind. Board without entering the water if possible.
Cold water — immersion suits extend survival time dramatically.
Mark position before abandoning. Rescuers will need your last known location.
Release in water to mark position for aerial search.
Deploy from raft to reduce drift and maintain position near last known location.
Life Raft — Key Points
- ▸Deploy on the leeward side — board from the vessel without entering the water
- ▸Painter line must be attached to the vessel before deploying
- ▸Tug the painter hard to trigger inflation — it does not inflate automatically
- ▸Keep clear of the vessel's propeller at all times
- ▸Cut the painter when the vessel sinks — not before
- ▸Deploy sea anchor immediately to reduce drift
- ▸Stay near last known position — that is where rescuers will search
- ▸Life rafts require annual or biannual service — check the service tag
Flooding & Taking On Water
Water ingress is a race against time. Know your vessel's through-hulls, carry wooden plugs next to every fitting, and know where your bilge pump switches are before you need them.
Locate and Plug the Source
- ▸Through-hull fittings — most common failure point; seacock may be corroded open
- ▸Stuffing box / shaft seal — should drip slowly, not stream water
- ▸Hose clamps and hoses — inspect all below-waterline hose connections
- ▸Hull breach or impact damage — collision, grounding, or submerged object
- ▸Softwood tapered plugs — mount one at every through-hull fitting
- ▸Damage control kit — underwater epoxy, hydraulic cement, expanding foam, rags
Dewatering Priority
- 1.Plug the source first — pumping without plugging is futile if inflow exceeds pump rate
- 2.Electric bilge pump — switch to automatic mode
- 3.Manual bilge pump — deploy crew to pump manually; typically higher output than electric
- 4.Bucket bailing — in extreme flooding, a large bucket removes more water than most built-in pumps
- 5.Move weight — shift crew and gear away from the flooded area to maintain trim and stability
- 6.Reduce speed — reduce dynamic water pressure on any breach
When to Initiate Mayday for Flooding
Transmit MAYDAY immediately if the flooding rate exceeds your pump capacity, if the source cannot be plugged, or if the vessel's stability is compromised. Do not wait until the vessel is at the point of sinking — early Mayday gives rescuers time to reach you before you must abandon ship.
Grounding — Response Procedure
Running aground ranges from a soft sand grounding (minor embarrassment) to a hard rock grounding (vessel loss). The first seconds dictate whether you compound the damage.
Shift to neutral immediately
Do not power off hard — prop wash can drive you further aground or pull sediment into intakes. Check for flooding first.
Check for flooding and hull damage
Inspect bilges. Listen for unusual sounds. Check through-hull fittings and the keel area. Grounding on rock vs. sand has very different damage profiles.
Mark position and assess tide
Note GPS position, time, and tide state. If tide is rising, you may float free without assistance. If falling, act quickly.
Sound for deepest water
Use a boathook, lead line, or handheld depth sounder to identify the direction of deepest water — that is your exit route.
Attempt to back off
Back down on the reciprocal of your approach course — the way you came in. Move crew weight aft to raise the bow. Heel the vessel to reduce draft.
Kedge off with an anchor
Set an anchor in deep water by dinghy or by swimming it. Use the windlass or winch to pull the vessel toward the anchor and off the shoal.
Request assistance if aground hard
Transmit Pan-Pan or MAYDAY as appropriate. Notify the USCG. If the vessel is damaged, begin Mayday procedures. BoatUS or Sea Tow can provide commercial assistance.
Soft Grounding (Sand / Mud)
Vessel likely undamaged. Back off on reciprocal course. Move crew weight aft. Heel the vessel by moving crew to one side. Kedge with anchor if needed. Rising tide helps.
Hard Grounding (Rock / Reef)
Inspect for hull damage before attempting to move. Moving over rock can open a breach. If hull is intact, kedge off carefully. If damaged, plug the breach before refloating.
Grounding with Flooding
Do not refloat until you have assessed the damage. Refloating a badly holed vessel can cause rapid sinking in deep water. Transmit Mayday, begin dewatering, assess stability.
EPIRB & Emergency Equipment
EPIRB — Category I vs. Category II
Category I (Float-Free)
Automatically releases and activates when submerged in 3–10 feet of water. Mounted in a float-free bracket on deck. Ideal for offshore voyaging where crew may not be able to activate manually.
Category II (Manual)
Must be manually activated. Can also be submerged to activate. Less expensive — suitable for nearshore boating. Must be grabbed and activated during abandon ship procedure.
Both categories:
- • Transmit on 406 MHz to COSPAS-SARSAT satellites
- • GPS-integrated units include your precise position
- • Register your EPIRB at beaconregistration.noaa.gov
- • Battery and hydrostatic release must be replaced by stamped date
- • Test monthly using the built-in self-test only
PLB vs. EPIRB
| Feature | EPIRB | PLB |
|---|---|---|
| Registered to | Vessel | Individual |
| Float-free option | Yes (Cat I) | No |
| Battery life | 48 hours | 24 hours |
| Buoyant | Yes | No (carry on body) |
| Satellite network | COSPAS-SARSAT | COSPAS-SARSAT |
Never Activate Falsely
Activating an EPIRB or transmitting a MAYDAY when there is no emergency is a federal offense under 47 USC 325. False alerts divert Coast Guard resources from real emergencies and can result in significant fines. Use only the built-in self-test function for routine checks.
Exam Tips — What the USCG Tests
MAYDAY format is heavily tested
The exam tests both the order of MAYDAY elements and the number of repetitions. Vessel name is said three times, MAYDAY is said three times at the start. Position is the most critical element — tested separately.
Fire class B — never use water
This is a high-frequency exam question. Class B fires (fuel, oil, gasoline) must never be fought with water — water spreads burning liquid. CO₂ and dry chemical are the correct agents.
EPIRB registration is required
The exam tests that EPIRBs must be registered with NOAA. An unregistered EPIRB still transmits a signal, but responders will not have vessel and owner information to confirm the alert.
Category I EPIRB activates automatically
Category I automatically releases and activates when submerged. Category II requires manual activation. This distinction appears frequently in exam questions about offshore emergency equipment.
Do not abandon ship prematurely
Exam scenarios often include distractor choices that suggest abandoning ship too early. The correct answer is almost always to stay with the vessel until it is actually sinking — a vessel is more visible to searchers.
Channel 70 is DSC only — no voice
A frequent exam error is confusing Channel 70 with Channel 16. Channel 70 is digital selective calling only — no voice communications. Channel 16 is the voice distress channel.
Grounding — neutral first
The first action when aground is to shift to neutral — not reverse, not full ahead. Powering hard can worsen hull damage or drive the vessel further onto the shoal.
VDS requirements for recreational boats
Vessels 16 ft and over on coastal waters must carry at least 3 approved VDS. Three combination flares satisfy both day and night requirements. Boats under 16 ft operated after dark still require night signals.
Frequently Asked Questions
What is the correct format for a MAYDAY call on VHF Channel 16?
The correct MAYDAY format is: 'MAYDAY MAYDAY MAYDAY, THIS IS [vessel name × 3], MAYDAY [vessel name], [position — lat/lon or bearing and distance from a known landmark], NATURE OF DISTRESS [fire, flooding, medical emergency, etc.], [number of persons aboard], [vessel description — type, length, color], [any other useful information], OVER.' Say MAYDAY three times at the beginning, and repeat the vessel name three times after 'THIS IS.' Transmit on Channel 16, which is monitored by the USCG and other vessels at all times.
What are the three categories of visual distress signals (VDS) required by the USCG?
Visual distress signals are categorized as: (1) Day signals — orange smoke signals (handheld or floating), orange flag with black square and circle; (2) Night signals — electric distress lights, red parachute flares, red handheld flares; (3) Day/Night combination — red parachute rocket flares, red handheld flares (visible day and night). Federally, recreational vessels 16 feet and over on coastal waters must carry approved VDS. Vessels must carry at least three signals — minimum three day, three night, or three combination signals.
What is the distress signal using a flashlight or signal mirror?
In Morse code, the international distress signal SOS is three short flashes (S), three long flashes (O), three short flashes (S) — · · · — — — · · ·. A signal mirror can direct sunlight toward aircraft or vessels and is visible up to 10 miles in good conditions. Waving both arms slowly up and down above the head is also an internationally recognized distress signal for vessels in distress. These non-pyrotechnic signals supplement but do not replace USCG-approved VDS equipment.
What are the steps in a proper abandon ship procedure?
Abandon ship in this sequence: (1) Issue MAYDAY on Channel 16 with position, number aboard, and nature of emergency; (2) Activate the EPIRB — if it is float-free, verify it releases and activates; (3) Don life jackets on all persons aboard; (4) Prepare survival gear — flares, water, first aid kit, grab bag; (5) Deploy life raft if carried — inflate and board from upwind side; (6) Board the life raft — do not jump into the water unless the vessel is sinking under you; (7) Secure the painter line between the raft and the vessel until the vessel actually sinks, then cut it; (8) Deploy the sea anchor to reduce drift; (9) Signal rescuers using flares, mirror, dye marker. The cardinal rule: do not abandon ship until the vessel is sinking — a vessel is always more visible to rescuers than a life raft.
How should a captain respond to flooding or taking on water?
Respond to flooding in order of priority: (1) Locate the source — seacock failure, hull breach, through-hull fitting, or damaged shaft log; (2) Plug the leak using softwood plugs, rags, or a damage control kit; (3) Start bilge pumps — switch electric bilge pump to automatic and deploy manual backup; (4) If flooding cannot be controlled, begin Mayday procedures and move crew to prepared abandon ship stations; (5) Reduce vessel speed and adjust heading to minimize water pressure on the breach; (6) Move weight away from the flooded compartment to maintain stability. Softwood plugs should be mounted near every through-hull fitting so they are immediately available. A bucket bailing can exceed an electric bilge pump in high-rate flooding — use everything available.
What is the USCG procedure for a vessel that has run aground?
When aground: (1) Immediately shift the engine to neutral — do not attempt to power off immediately as prop wash may drive you further aground or stir sediment into cooling water intakes; (2) Check for hull damage and flooding — inspect bilges, listen for unusual sounds, check through-hulls; (3) Mark your position on the chart/GPS and note tide state — if the tide is rising, you may float free; (4) Determine which way is deepest water using a pole or lead line; (5) If soft grounding, try backing off on the reciprocal of your approach course, heel the vessel by moving crew weight, or use an anchor set in deep water to kedge off; (6) If hard aground with damage, transmit Securite or Pan-Pan and request assistance; (7) Never rock the vessel violently — this can worsen hull damage on a hard bottom.
What are the four classes of fire and the correct extinguishing agent for each?
The four fire classes are: Class A — ordinary combustibles (wood, paper, cloth) — extinguish with water or dry chemical; Class B — flammable liquids and gases (fuel, oil, grease) — extinguish with CO2, dry chemical, or foam — never use water as it spreads the fire; Class C — energized electrical equipment — extinguish with CO2 or dry chemical — never use water or foam; Class D — combustible metals (rare on recreational vessels) — use dry powder only. Marine fires are most commonly Class B (fuel/oil) or Class C (electrical). CO2 extinguishers are effective for Class B and C fires in enclosed engine compartments without the residue of dry chemical.
What is the EPIRB and when should it be activated?
An EPIRB (Emergency Position Indicating Radio Beacon) transmits a distress signal on 406 MHz to COSPAS-SARSAT satellites, which relay position data to USCG rescue coordination centers. Float-free EPIRBs (Category I) automatically activate when submerged; manual EPIRBs (Category II) must be manually activated. Activate the EPIRB when the vessel is in distress and you have transmitted a MAYDAY — or when imminent sinking makes transmission impossible. A registered EPIRB provides the USCG with your vessel information, owner contact, and GPS position (if GPS-integrated). Never activate an EPIRB for a test or non-emergency — it is a federal offense. EPIRB batteries must be replaced by the date stamped on the unit.
What is the Pan-Pan signal and when is it used instead of MAYDAY?
Pan-Pan (pronounced 'pahn-pahn') is the international urgency signal — used when the safety of the vessel or person is at risk but the situation is not immediately life-threatening. Examples: a medical emergency on board that requires assistance but is not immediately fatal, a person in the water who is conscious and afloat, mechanical failure that leaves the vessel adrift but not sinking. The format is: 'PAN PAN PAN PAN PAN PAN, ALL STATIONS, THIS IS [vessel name × 3], [position], [nature of problem], [assistance needed], OVER.' Transmit on Channel 16. If the situation escalates, upgrade to MAYDAY at any time. MAYDAY is reserved for 'grave and imminent danger' requiring immediate assistance.
What steps should a captain take when fire breaks out on board?
Fire response at sea: (1) Alert crew — call 'Fire!' and assign stations; (2) Stop the vessel and position it upwind of the fire if underway — this prevents fanning flames aft; (3) If an engine room fire, shut the engine and close all air vents to starve the fire of oxygen — use the fixed CO2 system if equipped before opening the hatch; (4) Fight the fire with the appropriate extinguisher — never use water on Class B or C fires; (5) Simultaneously prepare for abandon ship — don life jackets, prepare the EPIRB, prepare flares; (6) Transmit MAYDAY if the fire cannot be controlled quickly; (7) If the fire is not controlled within 60 seconds, do not risk lives fighting it — prepare to abandon ship. Fire grows exponentially — every second counts. Ensure fire extinguishers are mounted, inspected, and accessible.
Related Study Guides
Man Overboard Procedures
Williamson Turn, Anderson Turn, Pan-Pan call, hypothermia survival times, and MOB recovery.
VHF Marine Radio Guide
Channel assignments, MAYDAY procedure, DSC, GMDSS, and FCC licensing for the OUPV exam.
Deck General Safety
Fire classes, PFDs, EPIRB, stability, MARPOL, and all distress equipment for the captain exam.
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