What are the International Maritime Distress Signals?

International Maritime Distress Signals: How to Call for Help at Sea?

When emergencies strike on the water, your ability to call for help effectively is crucial. Understanding international distress signals at sea is not only essential for your safety but also a legal obligation under maritime law.

This guide explains the most recognised maritime distress signals, from visual cues to radio communication protocols, tailored for both small crafts and commercial vessels.

Visual Distress Signals at Sea:

Orange Smoke Signals (Daytime)

The international standard for daytime visual distress signalling is the orange smoke flare. When ignited, it emits a dense orange plume visible over long distances. Search and rescue (SAR) teams and nearby mariners universally recognise this as a call for immediate assistance.

When to Use: Daylight hours, clear weather
Best For: Small to medium-sized vessels; widely recognised by aerial and marine search units

Red Parachute Flares and Rockets (Nighttime)

Red pyrotechnic signals, including red rockets and parachute flares, are intended for night use. These high-visibility lights shoot into the sky and are ideal for attracting attention over large distances.

The International Maritime Distress Signals help at sea is the use of orange smoke. When a person on a vessel is in distress and requires assistance, they can ignite an orange smoke flare, which produces dense orange smoke that is highly visible during daylight hours. Mariners and search and rescue teams widely recognize this signal as indicating that someone requires help.

Note: These are less effective in daylight conditions and should be reserved for night emergencies.

But what are the Main Distress Signals at Sea? It's necessary to note that there are also other distress signals and equipment used at sea, visual, such as distress flags, signal mirrors, and pyrotechnic distress signals (such as red parachute flares and orange handheld smoke signals), which are used in different situations and conditions to signal distress and request assistance. Mariners should be familiar with the proper use of these signals and equipment and follow international regulations and guidelines for distress signalling. During the day, an orange smoke signal is used, but it is more appropriate to use it in some additionally dangerous situations.

The Regulations for the Safety of Navigation and the International Regulations for Preventing Collisions at Sea precisely prescribe the signals of danger and the need for assistance. Unless specifically indicated otherwise, all these regulations apply to all vessels, so everything mentioned is not universally applicable.

For example, firing firearms or other explosive signals at one-minute intervals and lighting fires in barrels do not apply to smaller vessels. Smaller vessels are not equipped for some standards of calling for help, such as signal reflectors or a square flag with a ball or a ball-like object above or below it. Smaller vessels are rarely equipped with an Inmarsat communication device or a radar transponder, for example, and these are not suitable for this type of call for help anyway.

Even if they are equipped with rockets, handheld flares, or sparklers that emit red stars one after another at short intervals, those are nighttime signals that are not very visible during the day.

Visual Distress Signals - FLAGS

Distress Flags (N Over C)

However, if the situation does not pose a significant danger, you can call for help less alarmingly. The International Code of Signals denotes distress by hoisting the N (November) flag above the C (Charlie) flag. This signal, which can be used in situations where electronic or pyrotechnic signals are unavailable, is a versatile and vital distress signal that all mariners should be familiar with.

Audio Distress Signals - Use a Sound Signal - Whistle

Whistles, Horns, and Sounding Devices

If you lack radio or visual distress equipment, sound signals are an effective fallback.

• Blow a whistle, sound a horn, or bang metal objects rhythmically.
• Use Morse Code SOS: ... --- ... (3 short, three long, three short).

These signals are straightforward yet widely understood, especially in coastal or busy boating areas.

Sound signals are one of the most basic ways to call for help. Blow a whistle, sound a horn, or bang on a metal object to create a rhythmic pattern of sounds. In Morse code, the international distress signal is three short blasts followed by three long blasts and then three short blasts (SOS). Repeating this pattern signals that you are in distress.

Hand and Arm Signals

Help is called for by raising and lowering outstretched arms.

Waving to another vessel when passing near each other at a safe distance is not uncommon, and it is often practiced. It's not just out of courtesy but also a sign that you looked out for each other while passing by and are now greeting each other.

But waving to call for help differs from waving to say hello.

So, if you have an even smaller boat not equipped with flares or distress flags, you can still use this method to call for help in an emergency at sea. You do so by repeatedly raising and lowering outstretched arms. On land, this is done with raised and slightly spread hands so that they, together with the body, resemble the letter Y. Both of these signs are clear enough if visible, so moving away from the cabin or climbing onto it is advisable. Never wave your hands above your head; it can be misinterpreted as a greeting. To attract additional attention, it is an excellent idea to sound a continuous horn, whistle, or any device for signalling in fog.

Waving your arms or other objects is indeed a simple but effective way to signal for help when you're in distress on the water. Waving can catch the attention of passing boats, ships, or aircraft and alert them to your situation. Here's how to effectively use waving as a distress signal:

• Use Contrasting Colours: Wear or wave objects that are brightly coloured and highly visible, such as an orange life jacket, a red shirt, or a brightly coloured flag. The contrast with the surrounding water will make you more noticeable. Use your arms or a reflective object to signal with large, sweeping motions.
• Try to position yourself in an area of your boat where you have the best visibility to potential rescuers. Standing on the highest point of your boat can help you be seen from a greater distance.
• Combine with Sound Signals: If you have a whistle or an air horn, blow it while waving to increase your chances of being visually and audibly noticed.

Remember that the effectiveness of waving as a distress signal depends on the visibility of your location, the presence of nearby vessels or aircraft, and the time of day to increase your chances of getting help in an emergency at sea.

In low-tech emergencies, repeatedly raising and lowering outstretched arms is a recognised distress gesture, distinct from a friendly wave.

Tips:

• Stand on the highest visible part of the boat
• Use bright or contrasting colours (e.g., orange life jackets, flags)
• Combine with audible signals (whistles or horns) for greater visibility

Calling for HELP via VHF

Radio Communication Protocols

If you have a marine VHF radio on board, use it to call for help. Tune the radio to channel 16, the international hailing and distress frequency. Speak clearly and calmly, giving your vessel's name, location, emergency nature, and number of people on board. Wait for a response and provide any additional information requested.
If you assess that you are potentially in danger and need urgent assistance, send a distress call via VHF radio on channel 16, following the prescribed protocol, with "PAN-PAN."

Using VHF Radio – Channel 16

If equipped, a marine VHF radio is one of the most reliable ways to request help.

Steps:

1. Tune to Channel 16 (International Distress & Hailing Frequency).
2. Speak clearly: "MAYDAY, MAYDAY, MAYDAY. This is [vessel name], located at [coordinates]. We are experiencing [type of emergency]. [Number] of people onboard. Requesting immediate assistance."
3. Please wait for a response and follow any further instructions.

If the situation is urgent but not immediately life-threatening, use the "PAN-PAN" call instead of "MAYDAY."

Important: Small personal boats are not always legally required to carry a VHF radio unless navigating in specific coastal zones. Nonetheless, it is strongly recommended for all seagoing vessels.

The surrounding vessels may not hear you because, according to the existing Regulations on Boats, Dinghies, and Yachts, boats for personal use do not need to have a VHF radio if they are not registered for navigation regions I and II.

However, the coastal radio station will surely hear you and organize assistance based on the situation assessment.

Distress Signalling for Small vs. Large Vessels

• Small vessels often lack advanced equipment, such as radar transponders, Inmarsat devices, or SOLAS-grade pyrotechnics. Must rely on visual, auditory, and basic electronic means.
• Larger Vessels: May have access to EPIRBs, SARTs, Inmarsat, and integrated distress signalling systems that automate emergency notifications to global monitoring stations.

Regardless of vessel size, all seafarers must be familiar with the Regulations for the Safety of Navigation and International Regulations for Preventing Collisions at Sea (COLREGs).

Legal Duty to Render Aid

Under Maritime Law, specifically Article 764 of the Maritime Code, every mariner is not just legally but also ethically obligated to help others in distress, even in wartime conditions or if the person refuses help. This reinforces the global principle of solidarity and safety at sea, underscoring the importance of rendering aid in distress situations.

Best Practices for Visibility and Signaling

Conclusion: What are the 6 internationally recognised distress signals at sea?

Here are 6 internationally recognised distress signals at sea, as defined by the International Maritime Organisation (IMO) and SOLAS Convention. These signals are simple, universally understood, and can be used by anyone in distress, providing a sense of reassurance and confidence in your ability to call for help.

1. Orange Smoke Signal

• When Used: Daylight
• Purpose: Produces dense orange smoke for high daytime visibility
• Used By: Life rafts, small vessels, individuals

2. Red Parachute Flare or Rocket

• When Used: Nighttime
• Purpose: Launches high and burns brightly in red to attract distant vessels or aircraft
• Key Benefit: Visible over long distances

3. Signal Flags – N Over C (November over Charlie)

• When Used: Daytime
• Purpose: Visual distress signal using nautical flags
• Interpretation: "I am in distress and require immediate assistance"

4. Radio Distress Call – VHF Channel 16

• Call Types:
  • MAYDAY (immediate danger to life/vessel)
  • PAN-PAN (urgent, not life-threatening)
• When Used: Anytime, if a VHF radio is available

5. Sound Signal

Sound signals are one of the most basic and effective ways to call for help. Whether you blow a whistle, sound a horn, or bang on a metal object, the rhythmic pattern of sounds you create can be a powerful distress signal. In Morse code, the international distress signal is three short blasts followed by three long blasts and then three short blasts (SOS). Repeating this pattern signals that you are in distress, empowering you with a simple yet effective tool in emergencies.

6. Waving Arms Repeatedly

• When Used: Day or night
• Purpose: Manual signal for help when equipment is unavailable
• Correct Motion: Repeatedly raising and lowering both arms outstretched

✅ Pro Tip: Combine multiple methods (e.g., visual + audio + radio) to increase chances of detection and rescue.

Whether you're navigating a coastal waterway or venturing into open sea, knowing how to recognize and send international distress signals at sea is critical. Equip your vessel properly, familiarize yourself with signaling protocols, and always be prepared to help or request help. It's not just good seamanship, it's maritime law.

Sources & References:

• International Maritime Organization (IMO) – www.imo.org
• U.S. Coast Guard Boating Safety – www.uscgboating.org
• SOLAS Convention – Safety of Life at Sea Regulations

Last updated: October 3, 2025

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