Signal Flags

International maritime signal flags is an Internation Code of Signals (ICS) system that uses flags to represent individual letters of the alphabet to aid in signalling to or from sailing vessels.

Below is a list of letters and their representing flag and meaning.

A

I have a diver down; keep well clear at slow speed. With three numerals, azimuth or bearing.
B

I am taking in, or discharging, or carrying dangerous goods. (Originally used by the Royal Navy specifically for military explosives.)
C

Affirmative. With three numerals, course in degrees magnetic.
D

Keep clear of me; I am maneuvering with difficulty. With two, four, or six numerals, date.
E

I am altering my course to starboard.
F

I am disabled; communicate with me.
G

I 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.)
H

I have a pilot on board.
I

I am altering my course to port.
J

I am on fire and have dangerous cargo on board: keep well clear of me, or I am leaking dangerous cargo.
K

I 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.
L

In 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.)
M

My vessel is stopped and making no way through the water.
N

Negative.
O

Man overboard. (often attached to the man overboard pole on boats). With a sinister hoist, the semaphore flag.
P

The 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'.
Q

My vessel is 'healthy' and I request free pratique.
R

The way is off my ship. With one or more numerals, distance in nautical miles.
S

I am operating astern propulsion. With one or more numerals, speed in knots.
T

Keep clear of me; I am engaged in pair trawling. With four numerals, local time. (The first two denote hours and the rest minutes.)
U

You are running into danger.
V

I require assistance. With one or more numerals, speed in kilometres per hour.
W

I require medical assistance.
X

Stop carrying out your intentions and watch for my signals.
Y

I am dragging my anchor.
Z

I require a tug. When made by fishing vessels operating in close proximity on the fishing grounds it means: 'I am shooting nets'. With one or more numerals, time (UTC). (The first two denote hours and the rest minutes.)