distress signals

distress signals, a means of calling for help or assistance at sea. All ships over 300 tonnes are required to have equipment specified by Global Maritime Distress and Safety System (GMDSS) regulations. The following list of distress signals includes some of the required equipment, but is primarily intended as a guide for the crews of those vessels who cannot use such equipment because of malfunction, loss of power, etc. It must be understood that these signals must only be used if the vessel displaying or sending them is in imminent danger and that help is urgently required.1. a gun or other explosive signal fired at intervals of about a minute2. a continuous blast on any fog-signalling apparatus3. rockets or shells, throwing red stars fired singly at short intervals4. signalling SOS by sound or light (dot dot dot dash dash dash dot dot dot)5. the flags ‘N’ over ‘C’ of the International Code of Signals6. a signal comprising a square flag with a ball, or anything resembling a ball, above or below it7. the burning of a tar or oil barrel, or anything else which gives off flames8. a rocket parachute flare or a hand flare which shows a red light9. a smoke signal emanating orange-coloured smoke10. slowly and repeatedly raising and lowering outstretched arms11. signals transmitted by EPIRB12. digital selective calling distress signal13. a piece of canvas orange in colour with either a black square and circle or other appropriate symbol (for identification from the air)14. a dye marker15. SART (Search and Rescue Radar Transponders)The earliest distress signals were probably made by smoke or flames by burning pitch or tar on board, but when gunpowder came into general use during the 15th century the firing of cannon became the usual signal of distress. Although at that period there was no internationally agreed code, there are many instances of ships drifting ashore and summoning help by firing their guns.

In 1857 the International Code of Signals was established and a special flag was allocated for distress; other signals which came into use during the 19th century were a square flag with a ball above it, the distant signal of a cone pointed upwards with a ball above or below it, continuous sounding on foghorns, and, for night use, flames or shells or rockets throwing stars of any colour. It was not until 1954 that agreement was reached that distress rockets had to be red.

The most profound change in distress signalling was brought about by the invention of wireless telegraphy and the formation of the Marconi International Marine Communication Company in 1900. Several ocean liners were fitted with Marconi equipment the same year, as also was the Borkum lightship, whose crew were probably the first lives to be saved by a wireless call after their ship broke adrift in a gale. In January 1904 the Marconi Company issued a circular stating that the call ‘to be given by ships in distress or in any way requiring assistance shall be “CQD” ’. ‘CQ’ stood for all stations and ‘D’ stood for distress, although it became widely known as ‘Come Quickly, Danger’.

Because of the Titanic disaster, a 1919 Act of Parliament required British ships with 200 or more persons on board to have sufficient radio operators to keep a 24-hour watch. Experiments were also made with auto-alarms actuated by wireless distress calls, and in 1927 the British government approved such a device. It exempted any ship fitted with one from carrying the two additional wireless operators who were otherwise necessary to keep a continuous watch. In 1933 wirelesses became compulsory on all passenger ships, and on cargo ships of 1,600 tons upwards, and from 1954 it was internationally compulsory for all such ships to keep a continuous watch on the distress frequency, with either a radio officer or an auto-alarm. The distress call to actuate the auto-alarm was twelve dashes, each lasting four seconds, with one second between each. As from February 2005 ships and shore stations were no longer required to keep a listening watch for ‘mayday’ distress signals made manually. These now have to be transmitted automatically with GMDSS equipment.

See also signals at sea.