International maritime signal flags
Appearance
The system of international maritime signal flags is a way of representing individual letters of the alphabet in signals to or from ships. It is a component of the International Code of Signals. [1]
There are various methods that the flags can be used as signals:
- each flag spells out a letter of an alphabetic message.
- individual flags have specific and standard meanings; for example, diving support vessels raise the "A flag" indicating their inability to move from their current location because they have a diver underwater.
- one or more flags form a code word whose meaning can be looked up in a code book held by both parties. An example is the Popham numeric code used at the Battle of Trafalgar.
- in yacht racing and dinghy racing, flags have other meanings; for example, the P flag is used as the "preparatory" flag to indicate an imminent start, and the S flag means "shortened course" (for more details see Racing Rules of Sailing#Race Signal).
NATO uses an extra set of flags to communicate specific types of messages.
Letters
-
AI have a diver down; keep well clear at slow speed. With three numerals, azimuth or bearing.
-
BI am taking in, or discharging, or carrying dangerous goods. (Originally used by the Royal Navy specifically for military explosives.)
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CAffirmative. With three numerals, course.
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DKeep clear of me; I am maneuvering with difficulty. With two, four, or six numerals, date.
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EI am altering my course to starboard.
-
FI am disabled; communicate with me.
-
GI require a pilot. When made by fishing vessels operating in close proximity on the fishing grounds it means: "I am hauling nets". With four or five numerals, longitude. (The last two numerals denote minutes and the rest degrees.)
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HI have a pilot on board.
-
II am altering my course to port.
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JI am on fire and have dangerous cargo on board: keep well clear of me, or I am leaking dangerous cargo.
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KI wish to communicate with you. With one numeral, I wish to communicate with you by; 1) Morse signalling by hand-flags or arms; 2) Loud hailer (megaphone); 3) Morse signalling lamp; 4) Sound signals.
-
LIn harbor: The ship is under Quarantine.
At sea: You should stop your vessel instantly. With four numerals, latitude. (The first two denote degrees and the rest minutes.) -
MMy vessel is stopped and making no way through the water.
-
NNegative.
-
OMan overboard. (often attached to the man overboard pole on boats). With a sinister hoist, the semaphore flag.
-
PThe Blue Peter.
In harbor: All persons should report on board as the vessel is about to proceed to sea.
At sea: It may be used by fishing vessels to mean: "My nets have come fast upon an obstruction". -
QMy vessel is "healthy" and I request free pratique.
-
RThe way is off my ship. With one or more numerals, distance in nautical miles.
-
SI am operating astern propulsion. With one or more numerals, speed in knots.
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TKeep clear of me; I am engaged in pair trawling. With four numerals, local time. (The first two denote hours and the rest minutes.)
-
UYou are running into danger.
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VI require assistance. With one or more numerals, speed in kilometres per hour.
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WI require medical assistance.
-
XStop carrying out your intentions and watch for my signals.
-
YI am dragging my anchor.
* ^ N and C together (No and Yes) is used as a distress signal.
Numbers
Type of flag | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
Allied flags | ||||||||||
Pennants |
Other flags
Prompt | First substitute | Second substitute | Third substitute | Fourth substitute |
Allied signals | ||||
Code/answer (ANS) | Preparative (PREP) | Question (INT) | Negation (NEGAT) | Designation (DESIG) |
Course Pennant (CORPEN) | Turn (TURN) | Screen (SCREEN) | Speed (SPEED) | Station (STATION) |
Port (PORT) | Starboard (STBD) | Formation (FORM) | Division (DIV) | Squadron (SQUAD) |
Group (FLOT) | Subdivision (SUBDIV) | Emergency (EMERG) |
See also
- England expects that every man will do his duty
- Flag signals
- NATO phonetic alphabet
- Character encoding
References
International Code of Signals. International Maritime Organisation. 1995.
External links
Wikimedia Commons has media related to International Code of Signals.
- The flags and their meanings NOTE: Outdated meanings.
- Freeware to aid memorizing the flags from The Navy Patuxent Sailing Club
- Flags Fantastic - Nautical flags (A - Z & Pennant)
- La flag-alfabeto - signal flags used for the Esperanto language. Description: the flags for the esperanto letters with diacritical marks have the lighter color in the normal flag replaced with light green, which is not used in any normal flag.
- Signalman manual
- Nautical Flags Alphabet
- brief history of naval signals