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International maritime signal flags

International maritime signal flags

Overview
The system of international maritime signal flags is one system of flag signals
Flag signals
Flag signals can mean any of various methods of using flags or pennants to send signals. Flags may have individual significance as signals, or two or more flags may be manipulated so that their relative positions convey symbols...

 representing individual letters of the alphabet in signal
International Code of Signals
The International Code of Signals is an international system of signals and codes for use by vessels to communicate important messages regarding safety of navigation and related matters. Signals can be sent by flaghoist, signal lamp , flag semaphore, radiotelegraphy, and radiotelephony...

s to or from ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

s. It is a component of the International Code of Signals
International Code of Signals
The International Code of Signals is an international system of signals and codes for use by vessels to communicate important messages regarding safety of navigation and related matters. Signals can be sent by flaghoist, signal lamp , flag semaphore, radiotelegraphy, and radiotelephony...

 (INTERCO).

There are various methods by which the flags can be used as signals:
  • each flag spells an alphabetic message, letter by letter.
  • individual flags have specific and standard meanings; for example, diving support vessel
    Diving support vessel
    A diving support vessel is a ship that is used as a floating base for professional diving projects.Commercial Diving Support Vessels emerged during the 1960s and 1970s when the need arose for diving operations to be performed below and around oil production platforms and associated installations in...

    s 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.
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Encyclopedia
The system of international maritime signal flags is one system of flag signals
Flag signals
Flag signals can mean any of various methods of using flags or pennants to send signals. Flags may have individual significance as signals, or two or more flags may be manipulated so that their relative positions convey symbols...

 representing individual letters of the alphabet in signal
International Code of Signals
The International Code of Signals is an international system of signals and codes for use by vessels to communicate important messages regarding safety of navigation and related matters. Signals can be sent by flaghoist, signal lamp , flag semaphore, radiotelegraphy, and radiotelephony...

s to or from ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

s. It is a component of the International Code of Signals
International Code of Signals
The International Code of Signals is an international system of signals and codes for use by vessels to communicate important messages regarding safety of navigation and related matters. Signals can be sent by flaghoist, signal lamp , flag semaphore, radiotelegraphy, and radiotelephony...

 (INTERCO).

Overview


There are various methods by which the flags can be used as signals:
  • each flag spells an alphabetic message, letter by letter.
  • individual flags have specific and standard meanings; for example, diving support vessel
    Diving support vessel
    A diving support vessel is a ship that is used as a floating base for professional diving projects.Commercial Diving Support Vessels emerged during the 1960s and 1970s when the need arose for diving operations to be performed below and around oil production platforms and associated installations in...

    s 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
    Battle of Trafalgar
    The Battle of Trafalgar was a sea battle fought between the British Royal Navy and the combined fleets of the French Navy and Spanish Navy, during the War of the Third Coalition of the Napoleonic Wars ....

    .
  • in yacht racing
    Yacht racing
    Yacht racing is the sport of competitive yachting.While sailing groups organize the most active and popular competitive yachting, other boating events are also held world-wide: speed motorboat racing; competitive canoeing, kayaking, and rowing; model yachting; and navigational contests Yacht racing...

     and dinghy racing
    Dinghy racing
    Dinghy racing is the competitive sport of sailing dinghies. Dinghy racing has affected aspects of the modern dinghy, including hull design, sail materials and sailplan, and techniques such as planing and trapezing.-Organisation of 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 Race Signals).


NATO uses the same flags, with a few unique to warships, alone or in short sets to communicate various unclassified messages. The NATO usage generally differs from the International meanings, and therefore warships will fly the Code/Answer flag above the signal to indicate it should be read using the International meaning.

During the allied occupations of Axis countries after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, use and display of those nations' national flags were banned. In order to comply with the international legal requirement that a ship identify its registry by displaying the appropriate national ensign, swallow-tailed versions of the C, D, and E signal flags were designated as, respectively, provisional German, Okinawan, and Japanese civil ensign
Civil ensign
The civil ensign is the national flag flown by civil ships to denote nationality...

s. Being swallowtails, they are commonly referred to as the "C-Pennant" (C-Doppelstander), "D-Pennant", and "E-Pennant".

Letter flags (with ICS meaning)


* N and C together (No and Yes) is used as a distress signal
Distress signal
A distress signal is an internationally recognized means for obtaining help. Distress signals take the form of or are commonly made by using radio signals, displaying a visually detected item or illumination, or making an audible sound, from a distance....

.

** Also signallable on a ship's whistle using Morse code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...

. See International Code of Signals
International Code of Signals
The International Code of Signals is an international system of signals and codes for use by vessels to communicate important messages regarding safety of navigation and related matters. Signals can be sent by flaghoist, signal lamp , flag semaphore, radiotelegraphy, and radiotelephony...

.

*** The Z flag was also famously hoisted by Adm. Heihachiro Togo at the 1905 Battle of Tsushima
Battle of Tsushima
The Battle of Tsushima , commonly known as the “Sea of Japan Naval Battle” in Japan and the “Battle of Tsushima Strait”, was the major naval battle fought between Russia and Japan during the Russo-Japanese War...

 as the Japanese fleet prepared to engage the Russian fleet. In Japanese coding at the time, the flag meant, "The Empire's fate depends on the result of this battle, let every man do his utmost duty."

Substitute


Substitute or repeater flags allow messages with duplicate characters to be signaled without the need for multiple sets of flags.

The four NATO substitute flags are as follows:
First substitute Second substitute Third substitute Fourth substitute


To illustrate their use, here are some messages and the way they would be encoded:
"N"
"O"
"NO"
"NON"
"NOO"
"NOON"
"NONO"
"NONON"
"NONNN"

See also

  • Character encoding
    Character encoding
    A character encoding system consists of a code that pairs each character from a given repertoire with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the transmission of data through telecommunication networks or storage of text in...

  • Day shapes
    Day shapes
    Day Shapes are mast head signals indicating the navgation status of a vessel at sea to other vessels.The meanings of the shapes are defined by the International Regulations for Preventing Collisions at Sea.The most common signals are as follows:-...

  • Diver down flag
    Diver down flag
    A diver down flag, or scuba flag, is a flag used on the water to indicate that there is a diver below. It is red with a white stripe from the upper left corner to the lower right corner, and was designed and introduced in 1956 by Ted Nixon of U.S. Divers, from an idea of Navy veteran Denzel James...

  • England expects that every man will do his duty
    England expects that every man will do his duty
    "England expects that every man will do his duty" was a signal sent by Admiral Horatio Nelson, 1st Viscount Nelson from his flagship HMS Victory as the Battle of Trafalgar was about to commence on 21 October 1805. Trafalgar was the decisive naval engagement of the Napoleonic Wars...

  • Flag of Germany after World War II (C-Pennant)
  • Flag semaphore
    Flag semaphore
    Semaphore Flags is the system for conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags; it is read when the flag is in a fixed position...

  • Heliograph
    Heliograph
    A heliograph is a wireless solar telegraph that signals by flashes of sunlight reflected by a mirror. The flashes are produced by momentarily pivoting the mirror, or by interrupting the beam with a shutter...

  • International Code of Signals
    International Code of Signals
    The International Code of Signals is an international system of signals and codes for use by vessels to communicate important messages regarding safety of navigation and related matters. Signals can be sent by flaghoist, signal lamp , flag semaphore, radiotelegraphy, and radiotelephony...

  • List of international common standards
  • NATO phonetic alphabet
    NATO phonetic alphabet
    The NATO phonetic alphabet, more accurately known as the NATO spelling alphabet and also called the ICAO phonetic or spelling alphabet, the ITU phonetic alphabet, and the international radiotelephony spelling alphabet, is the most widely used spelling alphabet...

  • Signal lamp
    Signal lamp
    A signal lamp is a visual signaling device for optical communication . Modern signal lamps are a focused lamp which can produce a pulse of light...


External links