International Signal Code Flags are used to signal between two ships or between ship and shore. Also called signaling flags, they are a set of flags of different colors, shapes and markings which used singly or in combination have different meanings. The flags include 26 square flags which depict the letters of the alphabet, ten numeral pendants, one answering pendant, and three repeaters.

Only a few colors can be readily distinguished at sea. These are: red, blue, yellow, black, and white. You will notice, for clarity, the flags shown are either red and white, yellow and blue, blue and white, or black and white; besides plain red, white, and blue.

One-flag signals are urgent signals. Two-flag signals are mostly distress and maneuvering signals. Three-flag signals are for points of the compass, relative bearings, standard times, verbs, punctuation, also general code and decode signals. Four-flags are used for geographical signals, names of ships, bearings, etc. Five-flag signals are those relating to time and position. Six-flag signals are used when necessary to indicate north or south or east or west in latitude and longitude signals. Seven-flags are for longitude signals containing more than one hundred degrees.

A – Alpha – I have a diver down

C – Charlie – Affirmative or yes.

D – Delta – Keep clear of me; I am maneuvering with difficulty.

E – Echo – I am altering my course to starboard.

F – Foxtrot – I am disabled.

G – Golf – I require a pilot.

H – Hotel -I have a pilot on board.

I – India – I am altering my course to port.

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

K – Kilo – I wish to communicate with you.

L - Lima – At sea: You should stop your vessel instantly.

M – Mike – My vessel is stopped and making no way through the water.

N – November – Negative or No.

O – Oscar - Man Overboard.

P – Papa – The Blue Peter. At sea: It may be used by fishing vessels to mean: “My nets have come fast upon an obstruction”.

Q – Quebec - My vessel is “healthy” and I request free pratique.

R – Romeo -The way is off my ship. With one or more numerals, distance in nautical miles.

S – Sierra – I am operating astern propulsion.

T – Tango – Keep clear of me.

U – Uniform – You are running into danger.

V – Victor – I require assistance.

W – Whiskey – I require medical assistance.

X – Xray – Stop carrying out your intentions.

Y – Yankee -I am dragging my anchor.

Z – Zulu – I require a tug.

* N and C together (No and Yes) is used as a distress signal.