Signalling & Communication
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TermDefinition
- Flag Semaphore, Number Number 0 (Flag Semaphore)

Flag semaphore indicating the Number 0. This shape represents both the Number 0 (Flag Semaphore) and the Letter K (Flag Semaphore).
Before...
More Details - Morse Code, Signals & Communication Number 0 (Morse Code)
International Morse Code sequence representing the number 0.
- Flag / Pennant, Signals & Communication Numeral 0 (Flag Pennant)

The flag represents the numerical value of zero.
- Flag Semaphore, Number Number 1 (Flag Semaphore)

Flag semaphore indicating the number 1. This shape is the Number 1 (Flag Semaphore) and the Letter A (Flag Semaphore).
Before delivering...
More Details - Morse Code, Signals & Communication Number 1 (Morse Code)
International Morse Code sequence representing the number 1.
- Flag / Pennant, Signals & Communication Numeral 1 (Flag Pennant)

The flag represents the numerical value of one.
- Flag Semaphore, Number Number 2 (Flag Semaphore)

Flag semaphore indicating the number 2. This shape is the Number 2 (Flag Semaphore) and the Letter B (Flag Semaphore).
Before delivering...
More Details - Morse Code, Signals & Communication Number 2 (Morse Code)
International Morse Code sequence representing the number 2.
- Flag / Pennant, Signals & Communication Numeral 2 (Flag Pennant)

The flag represents the numerical value of two.
- Number 2 - Two (Too)
"Too" refers to the number two or the second in a series of items or actions. It can denote the quantity of something, such as two boats, two...
More Details - Flag Semaphore, Number Number 3 (Flag Semaphore)

Flag semaphore indicating the Number 3. This shape represents both the Number 3 (Flag Semaphore) and the Letter C (Flag Semaphore).
Before...
More Details - Morse Code, Signals & Communication Number 3 (Morse Code)
International Morse Code sequence representing the number 3.
- Flag / Pennant, Signals & Communication Numeral 3 (Flag Pennant)

The flag represents the numerical value of three.
- Number 3 - Three (Tree)
Tree is a signal that indicates the number 3 in communication between vessels or personnel. This signal can be conveyed visually using hand...
More Details - Number 4 - Four (For Er)
"Four" is the numerical value representing the quantity of 4. In marine terminology, "four" is also used to refer to the fourth officer on a...
More Details - Flag Semaphore, Number Number 4 (Flag Semaphore)

Flag semaphore indicating the Number 4. This shape represents both the Number 4 (Flag Semaphore) and the Letter D (Flag Semaphore).
Before...
More Details - Morse Code, Signals & Communication Number 4 (Morse Code)
International Morse Code sequence representing the number 4.
- Number 5 - Five (Fife)
"Five" is a numerical term representing the quantity of 5. In marine terminology, it may refer to a group of five individuals or objects, such as...
More Details - Flag Semaphore, Number Number 5 (Flag Semaphore)

Flag semaphore indicating the Number 5. This shape represents both the Number 5 (Flag Semaphore) and the Letter E (Flag Semaphore).
Before...
More Details - Morse Code, Signals & Communication Number 5 (Morse Code)
International Morse Code sequence representing the number 5.
- Flag Semaphore, Number Number 6 (Flag Semaphore)

Flag semaphore indicating the Number 6. This shape represents both the Number 6 (Flag Semaphore) and the Letter F (Flag Semaphore).
Before...
More Details - Morse Code, Signals & Communication Number 6 (Morse Code)
International Morse Code sequence representing the number 6
- Number 6 - Six
In marine terminology, "6" or "six" does not have a specific nautical meaning. It is simply the numerical value representing the quantity of...
More Details - Flag Semaphore, Number Number 7 (Flag Semaphore)

Flag semaphore indicating the Number 7. This shape represents both the Number 7 (Flag Semaphore) and the Letter G (Flag Semaphore).
Before...
More Details - Morse Code, Signals & Communication Number 7 (Morse Code)
International Morse Code sequence representing the number 7.
- Number 7 - Seven (Sev-En)
In maritime terminology, 7 or Seven (Sev-En) refers to the International Code of Signals flag representing the letter "7" in the phonetic...
More Details - Number 8 - Eight (Ait)
In marine terminology, an "ait" refers to a small island or islet located in a river or estuary. Aits are typically formed by sediment deposition...
More Details - Flag Semaphore, Number Number 8 (Flag Semaphore)

Flag semaphore indicating the Number 8. This shape represents both the Number 8 (Flag Semaphore) and the Letter H (Flag Semaphore).
Before...
More Details - Morse Code, Signals & Communication Number 8 (Morse Code)
International Morse Code sequence representing the number 8.
- Number 9 - Nine (Nin Er)
In marine terminology, "9" or "nine" is a code used to indicate the number nine in radio communications or when spelling out numbers. This code...
More Details - Flag Semaphore, Number Number 9 (Flag Semaphore)

Flag semaphore indicating the Number 9. This shape represents both the Number 9 (Flag Semaphore) and the Letter I (Flag Semaphore).
Before...
More Details - Morse Code, Signals & Communication Number 9 (Morse Code)
International Morse Code sequence representing the number 9.
- Flag / Pennant, Signals & Communication Code Flag Alpha (A)

The International Maritime Signal Flag Alpha.
Meaning
I have a diver down; keep well clear at slow speed.
More Details
If appended with a Numeral... - Flag Semaphore, Signals & Communication Letter A (Flag Semaphore)

This shape represents the Letter A (Flag Semaphore) and the Number 1 (Flag Semaphore).
The presumed signals are letters. The signaller...
More Details - Morse Code, Signals & Communication Letter A (Morse Code)
International Morse Code sequence representing the letter A.
- Phonetic Alphabet, Signals & Communication Alpha
Pronounced: AL-far
Letter "A" in the phonetic alphabet system.
- General Nautical Terminology, Signals & Communication Ampitude Modulation (AM)
A method of transmitting information by varying the strength (amplitude) of a carrier wave in proportion to the signal being sent.
Amplitude...
More Details - Flag Semaphore Attention (Flag Semaphore)

This shape is used to gain the receiver's attention and is used at the beginning of a transmission. The message recipient responds with the...
More Details - Flag / Pennant, Signals & Communication Code Flag Bravo (B)

The International Maritime Signal Flag Bravo.
Meaning
I am taking in or discharging or carrying dangerous goods.
- Flag Semaphore, Signals & Communication Letter B (Flag Semaphore)

This shape represents the Letter B (Flag Semaphore) and the Number 2 (Flag Semaphore).
- Morse Code, Signals & Communication Letter B (Morse Code)
International Morse Code sequence representing the letter B.
- Phonetic Alphabet, Signals & Communication Bravo
Pronounced: BRAH-voh
The term for the letter B in the NATO Phonetic Alphabet.
- General Nautical Terminology, Signals & Communication Call Sign
A unique identifier assigned to a vessel or maritime station for communication purposes, typically used in radio transmissions.
A call sign is...
More Details - Flag Semaphore, Signals & Communication Cancel--Disregard (Flag Semaphore)

Cancel (or Disregard) informs the receiver to disregard the previous message or cancel the signalling. There is no specific attachment to...
More Details - Flag / Pennant, Signals & Communication Code Flag Charlie (C)

The International Maritime Signal Flag Charlie.
Meaning
Affirmative.
If appended with a Numeral Pennant, a Magnetic Bearing. - Phonetic Alphabet, Signals & Communication Charlie
Pronounced: CHAR-lee
The term for the letter C in the NATO Phonetic Alphabet.
- Flag Semaphore, Signals & Communication Letter C (Flag Semaphore)

This shape represents the Letter C (Flag Semaphore) and the Number 3 (Flag Semaphore).
- Morse Code, Signals & Communication Letter C (Morse Code)
International Morse Code sequence representing the letter C.
- Flag / Pennant, Signals & Communication Code Flag Delta (D)

The International Maritime Signal Flag Delta.
Meaning
I am manoeuvring with difficulty.
If appended with a Numeral Pennant, a Date. - Phonetic Alphabet, Signals & Communication Delta
Pronounced: DEL-ta
The term for the letter D in the NATO Phonetic Alphabet.
- General Nautical Terminology, Safety, Signals & Communication Digital Selective Calling (DSC)
An automated VHF and MF/HF radio communication system used in maritime environments to send distress alerts, establish contact, and exchange...
More Details - Flag Semaphore, Signals & Communication Letter D (Flag Semaphore)

This shape represents the Letter D (Flag Semaphore) and the Number 4 (Flag Semaphore).
- Morse Code, Signals & Communication Letter D (Morse Code)
International Morse Code sequence representing the letter D.
- Phonetic Alphabet, Signals & Communication Echo
Pronounced: ECK-oh
The term for the letter E in the NATO Phonetic Alphabet.
- Flag / Pennant, Signals & Communication Code Flag Echo (E)

The International Maritime Signal Flag Echo.
Meaning
- Flag Semaphore, Signals & Communication Letter E (Flag Semaphore)

This shape represents the Letter E (Flag Semaphore) and the Number 5 (Flag Semaphore).
- Morse Code, Signals & Communication Letter E (Morse Code)
International Morse Code sequence representing the letter E.
- Flag Semaphore, Signals & Communication Error (Flag Semaphore)

Waving both flags up and down indicates an error in the communication.
- Flag Semaphore, Signals & Communication Error (Flag Semaphore)


Repeated eight times, Letter E (Flag Signal) indicates an error.
- Flag / Pennant, Signals & Communication Code Flag Foxtrot (F)

The International Maritime Signal Flag Foxtrot.
Meaning
I am disabled; communicate with me.
- Flag / Pennant, Signals & Communication First Substitute (ICS Flag)

Substitute or repeater flags allow messages with duplicate characters to be signalled without requiring multiple sets of flags.
- Did you know?, Flag Semaphore, Signals & Communication Flag Semaphore Signals
A system for conveying information at a distance through visual signals using hand-held flags.
The position of the flags encodes the...
More Details - Flag Semaphore, Signals & Communication Letter F (Flag Semaphore)

This shape represents the Letter F (Flag Semaphore) and the Number 6 (Flag Semaphore).
- Morse Code, Signals & Communication Letter F (Morse Code)
International Morse Code sequence representing the letter F.
- Phonetic Alphabet, Signals & Communication Foxtrot
Pronounced: FOKS-trot
The term for the letter F in the NATO Phonetic Alphabet.
- General Nautical Terminology, Signals & Communication Frequency Modulation (FM)
A method of encoding information in a carrier wave by varying its frequency, commonly used in marine radio communications.
Frequency...
More Details - Flag / Pennant, Signals & Communication Code Flag Golf (G)

The International Maritime Signal Flag Golf.
Meaning
I require a pilot.
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By fishing vessels: I am hauling nets.
If appended by a Numeral... - Flag Semaphore, Signals & Communication Letter G (Flag Semaphore)

This shape represents the Letter G (Flag Semaphore) and the Number 7 (Flag Semaphore).
- Morse Code, Signals & Communication Letter G (Morse Code)
International Morse Code sequence representing the letter G.
- Signals & Communication Global Maritime Distress and Safety System Sea Areas
A map of the UK indicating the 3 sea areas around the coast and the coast of nearby European countries. White pointers indicate Medium Frequency...
More Details - Phonetic Alphabet, Signals & Communication Golf
Pronounced: GOLF
The term for the letter G in the NATO Phonetic Alphabet.
- Flag / Pennant, Signals & Communication Code Flag Hotel (H)

The International Maritime Signal Flag Hotel.
Meaning
I have a pilot on board.
- General Nautical Terminology, Signals & Communication High Frequency (HF)
The radio frequency range between 3 and 30 megahertz (MHz), commonly used for long-range marine communications via skywave propagation.
High...
More Details - Flag Semaphore, Signals & Communication Letter H (Flag Semaphore)

This shape represents the Letter H (Flag Semaphore) and the Number 8 (Flag Semaphore).
- Morse Code, Signals & Communication Letter H (Morse Code)
International Morse Code sequence representing the letter H.
- Phonetic Alphabet, Signals & Communication Hotel
Pronounced: hoh-TELL
The term for the letter H in the NATO Phonetic Alphabet.
- Flag / Pennant, Signals & Communication Code Flag India (I)

The International Maritime Signal Flag India.
Meaning
I am altering course to port.
- Flag Semaphore, Signals & Communication Letter I (Flag Semaphore)

This shape represents the Letter I (Flag Semaphore) and the Number 9 (Flag Semaphore).
- Morse Code, Signals & Communication Letter I (Morse Code)
International Morse Code sequence representing the letter I.
- Phonetic Alphabet, Signals & Communication India
Pronounced: IN-dee-ah
The term for the letter I in the NATO Phonetic Alphabet.
- Flag / Pennant, General Nautical Terminology, Signals & Communication International Code of Signals (ICS)
A system of flags, codes, and symbols used by ships to communicate essential messages and ensure safety at sea, regardless of language...
More Details - Flag / Pennant, Signals & Communication International Maritime Signal Flags
A system of flags ships use to communicate messages, signals, or important information visually. Flags often represent letters, numbers, or...
More Details - Morse Code, Signals & Communication International Morse Code
A standardised system of encoding text characters as sequences of dots (short signals) and dashes (long signals) used for communication,...
More Details - Organisation, Signals & Communication International Telecommunication Union (ITU)
A specialised agency of the United Nations responsible for coordinating global telecommunication operations and services, including radio...
More Details - Flag / Pennant, Signals & Communication Code Flag Juliett (J)

The International Maritime Signal Flag Juliett.
Meaning
I am on fire and have dangerous cargo on board: keep well clear of me.
More Details
OR
I am... - Flag Semaphore, Signals & Communication Letter J (Flag Semaphore)

This signal is also used to transition from letters to numbers when communicating a message.
- Morse Code, Signals & Communication Letter J (Morse Code)
International Morse Code sequence representing the letter J.
- Did you know?, Phonetic Alphabet, Signals & Communication Juliett
Pronounced: JOO-lee-ETT
The term for the letter J in the NATO Phonetic Alphabet.
More Details - Flag / Pennant, Signals & Communication Code Flag Kilo (K)

The International Maritime Signal Flag Kilo.
Meaning
I wish to communicate with you.
More Details
If appended by a Numeral Pennant:
I wish to... - Phonetic Alphabet, Signals & Communication Kilo
Pronounced: key-loh
The term for the letter K in the NATO Phonetic Alphabet.
- Flag Semaphore, Signals & Communication Letter K (Flag Semaphore)

This shape represents the Letter K (Flag Semaphore) and the Number 0 (Flag Semaphore).
- Morse Code, Signals & Communication Letter K (Morse Code)
International Morse Code sequence representing the letter K.
- Flag / Pennant, Signals & Communication Code Flag Lima (L)

The International Maritime Signal Flag Lima.
Meaning
Stop immediately.
More Details
If appended by a Numeral Pennant, Latitude (the first 2 digits... - Flag Semaphore, Signals & Communication Letters to Follow (Flag Semaphore)

This flag semaphore signal indicates a change from numbers to letters (Letters to follow). This switches back from numbers to the default...
More Details - Phonetic Alphabet, Signals & Communication Lima
Pronounced: LEE-mah
The term for the letter L in the NATO Phonetic Alphabet.
- Flag Semaphore, Signals & Communication Letter L (Flag Semaphore)

Flag semaphore indicating the letter L.
- Morse Code, Signals & Communication Letter L (Morse Code)
International Morse Code sequence representing the letter L.
- General Nautical Terminology, Safety, Signals & Communication MayDay
An internationally recognised distress signal used in voice communication to indicate a grave or imminent, life-threatening emergency at...
More Details - Flag / Pennant, Signals & Communication Code Flag Mike (M)

The International Maritime Signal Flag Mike.
Meaning
- General Nautical Terminology, Signals & Communication Medium Frequency (MF)
The range of radio frequencies between 300 kHz and 3 MHz, commonly used in marine communication and navigation systems.
Medium Frequency (MF)...
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