Different Types of Non-Pyrotechnic Marine Distress Signals Used On Ships

At the time emergencies at sea, maritime distress signals are used by ships. These distress signals help to identify and pinpoint the location of the emergency scenario, whereby faster rescue operational measures can be ushered in.



Marine distress signals can be of two types – the pyrotechnic signals and the non-pyrotechnic signals. A brief detailing about the two can be explained as follows:

Pyrotechnic Signals: These signals incorporate the usage of fireworks or materials that involve flame and smoke. Usage of flares is the most commonly used method of pyrotechnic signalling.

Non-Pyrotechnic Signalling: The very opposite of pyrotechnic signals, the non-pyrotechnic signalling methodology involves the usage of flags and radio transmissions as marine distress signalling.


The various variants of non-pyrotechnic signals can be listed down as follows:

Orange Signal Flag: The Orange distress signalling flag, as the name suggests, is an orange flag with a black-coloured square with a black-coloured circle placed below it. Generally, the orange distress signal flag is waved or hung in order to indicate an emergency. The non-pyrotechnic signal however can be used only during daylight as nightlight renders it inconspicuous.


As an alternative to the orange flag marine distress signal, colour coded flags are also used as non-pyrotechnic maritime distress signals.


Marker Dyes: Marker dyes indicating the area where the emergency has occurred are also used as non-pyrotechnic methods of distress signalling. A marker dye is put in the sea and it generally covers around 50 metres of the area where it is dropped in the water.


SOS: The SOS signal is another method of non-pyrotechnic signalling. Incorporating the usage of the Morse code, the SOS signalling consists of dots and dashes interspersed at regular intervals. The SOS code is flashed by electric lights during the night hour.


Radio Signals: Using marine radio frequency, Mayday distress messages can be sent to avail help during marine emergency situations. Alternatively, using the Digital Service Calling (DSC) facility through radio channels also acts an effective maritime distress signalling.


Mirrors: With the help of mirrors that are dropped in the water, distress signals can be sent. These mirrors not only reflect the light to pinpoint the location of the emergency but are also non-corrosive at the same time. This helps to prolong their usage for a longer period of time.

Other known maritime distress signals that do not involve the usage of pyrotechnic signalling are arm-waving, usage of SOLAS-sanctioned whistle-blowers and blowing through fog-horns to avail rescue and aid.


All non-pyrotechnic methods of signalling need to comply with the USCG standards in order to be utilised. Users therefore need to be very careful in the usage of these signalling devices so that they do not encounter any problems even after using them appropriately.

Pyrotechnic signals have been regarded as the best maritime distress signalling methods. However, unprecedented accidents on account of their usage have led to the rise of non-pyrotechnic signalling methodologies. And in spite of their deficiencies, these methods are very important marine distress signalling options available at ships’ disposal.


You may also like to read-SOLAS requirement for GMDSS





Image Credits: 


smithsonianmag, ellettbrothers


Get Free News Updates Daily

Join 40000+ maritime professionals who receive daily newsletters, offers and more..

Digital Maritime Resources For The Smart Mariner

Take me to the eBook Store


  1. Russ Garbutt says

    Any reference to distress signals used by ships must comply with ANNEX IV. Distress signals of the International regulations for preventing collisions at sea to be complete.

    For instance pyrotechnics may include:- Section 1
    a) Gun or other explosive signal fired at intervals of about one minute.
    c) Rockets or shells, throwing red stars fired one at a time at sort intervals.
    h) Flames on the vessel (as from a burning tar barrel, oil barrel etc.)
    i) Rocket parachute flare or hand flare showing a red light.
    j) Smoke sinal giving off orange-coloured smoke.

    Non pyrotechnics include:- Section 1
    b) Continuous sounding with any fog-signalling apparatus.
    d) A signal made by rdiotelegraphy or by any other signalling method consisting of te group ***_ _ _ *** (SOS) in the Morse Code.
    e) A signal sent by radiotelephony conssiting of the spoken word ‘Mayday’.
    f) The International Code Signal of distress indicated by NC
    g) A signal consisting of a square flag having above or below it a ball or anything resembling a ball.
    k) Slowly and repeatedly raising and lowering arms outstretched to each side.
    l) The radiotelegraph alarm signal.
    m) The radiotelephone alarm signal.
    n) Signals transmitted by emergency position-indicating radio beacons.
    o) Approved signals transmitted byradiocommunication systems, including survival craft radar transponders.

    3. attention is drawn to the trelevant sections of the International Code of Signals, the Merchant Ship Search and Rescue Manual and the following signals:-
    a) A piece of orange-coloured canvas with either a black square and circle or other appropriate symbol (for identification by air)
    b) A dye marker.

    Kind regards
    Captain Russ Garbutt

Leave a Reply

Your email address will not be published. Required fields are marked *

Marine Insight Forums | Join the Community

Ask your queries and get answered by experts. Share your knowledge and experience with other maritime professionals. Grow your network!!