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If your boat is taking on water, treat rapidly increasing or uncontrolled flooding as an emergency. Alert everyone, get people into properly fitted flotation, send a distress call early, and only then attempt pumping or a temporary repair when it is safe. A bilge pump can buy time, but it cannot guarantee that the boat will remain afloat.
The emergency-contact steps below are United States guidance from the U.S. Coast Guard. Elsewhere, use your local maritime rescue authority, radio channel and emergency number.
First actions: protect people and call for help
Do not wait to see whether the next pump cycle solves the problem. Flooding can accelerate as water reaches machinery, batteries, wiring, hatches and other openings. Coast Guard rescues have involved vessels whose inflow exceeded their pumps and later capsized or sank.
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- Alert everyone aboard. Tell passengers what is happening, keep them together and put on properly fitted personal flotation devices (PFDs). Do not send anyone into a dark, flooded, moving or otherwise unsafe compartment.
- Make the distress call as soon as the flooding is serious or worsening. Calling early gives rescuers more time to find you and lets you work while help is moving. Do not delay the call to troubleshoot, search for tools or complete a repair.
- Keep the boat in the safest practical attitude. Reduce speed or stop if movement is driving water through the opening, while maintaining enough control to avoid traffic, surf, rocks or other hazards.
- Assign simple jobs. One person handles the radio or phone, one monitors the water level and pump, and another keeps an accurate count of people and watches for hazards.
How to make a U.S. MAYDAY call
The U.S. Coast Guard says a marine VHF-FM radio is the preferred way to report an emergency from a vessel. Its instructions are published at Methods for Contacting the U.S. Coast Guard.
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- Set the radio to VHF Channel 16.
- Press the transmit button and say MAYDAY three times.
- Give the vessel name and/or a clear description.
- State your position or location. Use GPS coordinates, a known landmark, a buoy, a marina, a distance and bearing, or any combination that helps rescuers locate you.
- Describe the emergency: for example, uncontrolled flooding, a hull opening, collision damage or a broken window.
- State the number of people aboard, including anyone who is injured or has special needs.
- Listen for instructions and provide updates if your position, water level, propulsion, passenger count or plans change.
If you cannot use a radio, the Coast Guard lists dialing 911 or calling the nearest Coast Guard Rescue Coordination Center by telephone. Tell the operator that you are on a vessel, provide the same information and keep the phone available for return calls. This radio and phone procedure is U.S.-specific; boaters in other countries should use their local maritime rescue service and emergency number.
A practical call format
Use a short, calm message such as: “MAYDAY, MAYDAY, MAYDAY. This is [vessel name or description]. We are at [position]. We are taking on water through [known or suspected source]. There are [number] people aboard. We need immediate assistance.” Replace the bracketed words with real information; do not invent a position or give an uncertain estimate without labeling it as such.
Control the water only when it is safe
Run the installed bilge pump
Turn on the automatic or manual bilge pump and check that it is actually discharging water overboard. Verify that the switch has power, the discharge hose is connected and the outlet is not blocked. If the pump is cycling without lowering the level, treat that as evidence that the inflow may be greater than its capacity, not as reassurance that the system is working.
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Keep a second person watching the water while you check the pump. Battery-powered equipment can drain the battery that you need for communications, steering or navigation, so preserve electrical power for the distress call and essential control.
Use a portable dewatering pump if available
A portable pump can remove water from a compartment that the fixed bilge system cannot reach. Place its intake in the lowest safe point, keep the discharge clear and secure the hose so it does not come loose. Follow the pump maker’s electrical and fuel-safety instructions, especially around gasoline vapors, batteries and wet connectors.
Pumping is a damage-control measure, not a substitute for rescue. In a February 2024 Coast Guard case, the 31-foot sailing vessel Niamh reported flooding at a rate well beyond the bilge pumps’ capacity. Responders removed two people and used a pump to partially dewater the boat. The report is at Coast Guard rescues 2 from sinking boat offshore Sabine, Texas.
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Look for the source without entering danger
From a stable position, inspect visible seacocks, hoses, fittings, transducers, hatches, windows, exhausts and collision damage. Shut a damaged seacock only if you can identify it and operate it without leaning overboard or entering a flooded space. Do not remove floorboards or open a compartment if doing so could expose someone to electrical shock, fuel vapors, shifting cargo or a sudden surge of water.
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If the opening is identifiable and conditions permit, a soft wooden plug, emergency patch or other purpose-made damage-control material may slow the inflow. Keep hands and tools clear of sharp edges and moving water, and do not send a passenger into a compartment that is becoming unstable.
Improvisation can work, but the method depends on the damage and the vessel. In a May 2024 rescue 35 miles off Clearwater, Coast Guard crews used a mattress and boat hooks to plug and shore a broken window while pumping water from a 47-foot vessel. That account, available in Coast Guard rescues 3 people, 1 dog 35 miles off Clearwater, describes trained responders improvising under specific conditions; it is not a universal repair recipe.
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Use buckets only as a last-resort supplement
A bucket can help remove a small amount of water when a pump is unavailable or its intake cannot reach the water. It is exhausting and slow, and it occupies a person who may be needed for communications or lookout duties. A 2023 Coast Guard report noted a sailor using bilge pumps and buckets while taking on water; the report also reminded boaters to leave a float plan with someone ashore. Bucketing does not replace a distress call, pumping or rescue.
Recognize when pumping is not keeping up
There is no universal water depth, leak rate or time-to-sink number that applies to every boat. Hull shape, compartmentation, sea state, damage location, load and pump capacity all change the outcome. Treat these observations as escalation signs:
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- The pump output is weak, intermittent or stops when the battery voltage falls.
- Water is reaching engines, batteries, fuel systems, electrical panels or steering gear.
- The boat develops a noticeable list, trim change, loss of freeboard or sluggish handling.
- Waves are entering through openings, or the source cannot be reached safely.
- People cannot move safely around the boat, or anyone is injured, exhausted or missing.
When any of these conditions appears, update the rescue authority and follow its instructions. Keep everyone in flotation, gather the radio, phone, signaling equipment, first-aid supplies and essential medication, and prepare for transfer or abandonment without scattering people.
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Prepare to leave the vessel if remaining aboard becomes unsafe
Rescue authorities determine the safest response for the circumstances; the Coast Guard reports do not establish a single abandonment threshold. Do not leave a vessel merely because the bilge is wet, but do not remain aboard solely to protect equipment when the boat is becoming unstable or rescue personnel direct you to transfer.
- Account for every person and report the count to rescuers. Include anyone who has entered a life raft, moved to another boat or gone overboard.
- Keep PFDs on and secure loose items that could injure people or interfere with evacuation.
- Bring the VHF radio or a waterproof handheld if doing so does not delay movement. Keep it on the rescue channel or the channel directed by authorities.
- Take signaling equipment, such as approved flares, only when it is accessible and safe to carry. Distress signals help rescuers locate people or a vessel, but they do not replace a MAYDAY.
- Use a life raft or other designated survival equipment according to its instructions. Stay together and follow the rescue crew’s directions during transfer.
- If someone enters the water, report the exact time, location and direction of movement immediately and keep visual contact if possible.
What each emergency tool can and cannot do
| Tool | Primary job | Important limitation |
|---|---|---|
| Installed bilge pump | Remove water automatically or by switch. | Capacity depends on pump, hose, power and battery condition; inflow can exceed it. |
| Portable dewatering pump | Move water from a hard-to-reach compartment or supplement the fixed pump. | Needs a safe power or fuel source and correct placement; it cannot stop a large breach. |
| Marine VHF radio | Send a MAYDAY and receive rescue instructions. | Range and reliability vary with antenna, terrain, weather and power; in U.S. guidance, Channel 16 is the emergency calling channel. |
| Distress signals | Help rescuers visually or electronically locate the vessel or people. | They have limited duration and visibility and require correct handling; they do not communicate the nature of the emergency. |
| Personal flotation device | Keep a person afloat if they must enter the water or transfer to survival equipment. | Fit, condition, wear and suitability for the person and conditions matter; no single model or universal legal requirement is established here. |
What recent Coast Guard cases demonstrate
Official incident reports illustrate why early communication and realistic expectations matter:
- Near Sabine, Texas, in February 2024, Niamh reported severe mechanical problems and flooding beyond bilge-pump capacity. Two people were rescued and the vessel was partially dewatered. The case supports calling before pumps fail, not waiting for a final loss of buoyancy.
- Near Clearwater in May 2024, a broken window let water into a 47-foot vessel. Responders pumped the boat and used a mattress and boat hooks to plug and support the window. The repair was an incident-specific improvisation.
- Near Kauai in August 2024, a Coast Guard report recorded approximately 100 gallons aboard and active flooding of approximately one gallon per minute. Those are observations from that one assistance case, not a general danger threshold or prediction for another vessel. See Coast Guard assists 1 aboard vessel taking on water near Kauai.
- In December 2023, a Coast Guard aircrew rescued a U.S. citizen from a sailing vessel taking on water 170 nautical miles northwest of Puerto Rico. The account is at Coast Guard aircrews rescue U.S. citizen from sailing vessel taking on water 170 nautical miles northwest of Puerto Rico.
As Petty Officer 1st Class Jesse Guitierrez, operations officer at Coast Guard Station Sand Key, explained in the Clearwater report: “Coast Guard crews constantly train for shipboard emergencies to mitigate flooding, and part of that training includes improvising in emergency situations.” Training helps responders adapt, but passengers should not attempt hazardous repairs to imitate a rescue crew.
Information to keep ready while waiting
Rescuers can act faster when one person maintains a clear information log. Record the time the flooding was first noticed, the suspected source, pump status, battery condition, position, heading, weather or sea-state changes and any transfer of people. Mark the latest position on the chart or navigation display and send an update if you drift significantly.
Keep an accurate passenger count. Tell the rescue authority about children, pets, injuries, mobility limitations, medical needs, immersion or anyone who cannot swim. If the radio call drops out, continue monitoring Channel 16 in the United States and try again from a clear location with the antenna vertical.
Preparation that reduces the consequences
- Test the fixed bilge pump, float switch, discharge hose, battery and alarm before departure.
- Carry a portable dewatering pump, spare hose, plugs or damage-control materials appropriate to the vessel, buckets and waterproof lighting.
- Keep a charged marine VHF radio accessible, and know how to select Channel 16 and transmit a MAYDAY.
- Inspect seacocks, hoses, clamps, through-hulls, windows, hatches, drain plugs and transducers for damage or looseness.
- Store PFDs where every passenger can reach them immediately; check fit before leaving the dock.
- Carry approved distress signals and learn their operating limits and local carriage rules.
- File a float plan with a trusted person ashore. Include the vessel description, route, people aboard, communications equipment, departure and return times, and instructions for contacting the rescue authority if you do not report in.
- Take a boating-safety course or arrange a vessel safety check so equipment and procedures are familiar before an emergency.
Common mistakes to avoid
- Waiting for certainty: You do not need to identify the exact leak before making a MAYDAY call.
- Assuming a pump proves the boat is safe: Pump output can be lower than the incoming flow, especially after battery or hose problems.
- Sending one person below alone: Flooded compartments can contain electrical, fuel, structural and entrapment hazards.
- Leaving flotation behind: Put PFDs on before conditions deteriorate, not after someone falls overboard.
- Giving an incomplete position: A vessel name without location, or a location without the number of people aboard, slows the rescue picture.
- Separating during evacuation: Keep people together and report every movement to responders.
The priority order is consistent: protect people, communicate early, slow the inflow only when it is safe, and follow rescue instructions. Equipment can preserve time; it cannot make an uncontrolled flood predictable.
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