1. Flag hoist

2. Flags
Although you may never see them displayed except at fleet parades, around naval installations, and areas with heavy international shipping traffic. International code flags are used to signal between two ships or between ship and shore, also called signalling flags, they are a set of flags of different colours, 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 pennants, one answering pennant, and three substituters or repeaters.

3. Flags
Only a few colours can be readily distinguished at sea. These are: red, blue, yellow, black, and white; and these cannot be mixed indiscriminately.
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.

4. Flags One-flag signals are urgent or very common signals
Two-flag signals are mostly distress and manoeuvring 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.

5. Single letter flag hoist
Alfa (alpha) – Diver down, keep clear
Bravo – I’m taking in, discharging or carrying dangerous goods
Charlie – Yes (affirmative)
Delta -- Keep clear of me, I’m manoevering with difficulty

6. Single letter flag hoist
Echo – I am altering my course to starboard
Foxtrot – I’m disabled, communicate with me
Golf – I require a pilot
Hotel – I have a pilot on board

7. Single letter flag hoist
India – I’m altering my course to port
Juliet – Keep clear, I’m on fire and have dangerous cargo
Kilo – I wish to communicate with you
Lima – You should stop your vessel instantly

8. Single letter flag hoist
Mike – My vessel is stopped and making no way
November – No (Negative)
Oscar -- Man overboard
Papa – I’m about to proceed to sea

9. Single letter flag hoist
Quebec -- My vessel is "healthy" and I request free practique
Romeo
Sierra – I am operating astern propulsion
Tango – Keep clear of me, I’m engaged in pair trawling

10. Single letter flag hoist
Uniform – You are running into danger
Victor – I Require assistance
Whiskey – I Require medical assistance
Xray -- Stop your intentions and wait for my signals

11. Single letter flag hoist
Yankee – I Am dragging my anchor
Zulu – I Require a tug

12. Letter flags 1 2 3 4 5  6 7 8 9 0 

13. Repeat First Flag
Repeat Second Flag
Repeat Third Flag
Decimal (point) and Answering pennant

14. Examples, two flag signals
AC - I am abandoning my vessel.
LO - I am not in my correct position: used by a light vessel.
RU - Keep clear of me; I am maneuvering with difficulty.
AN - I need a doctor.
NC - I am in distress and require immediate assistance.
SO - You should stop your vessel instantly.
BR - I require a helicopter.
PD - Your navigation lights are not visible.
UM - The Harbour is closed to traffic.
CD - I require immediate assistance.
PP - Keep well clear of me.
UP - Permission to enter Harbour is urgently requested. I have an emergency.

15. Answering pennant
At the dip – The code flag hoisted "at the dip“ indicates that the receiver has seen the signal from the transmitting ship
Close up – The code flag hoisted "close up" indicates that the receiver has understood the signal from the transmitting ship

16. Nation flag Meaning: This flag indicates the nationality of the vessel
Place:
On board of a vessel the nation flag may only be hoisted at the following places:
When the vessel is sailing, at the smallest mast or the one placed most aft.
In every other circumstance, in the mast on the stern of the vessel
It is strictly prohibited to place other flags than your nation flag on these places!

17. Courtesy flag Meaning:
The courtesy flag is a little nation flag of the country one is visiting
Place:
The courtesy flag is hoisted at the starboard yard of the front mast. If there is no yard, than the flag may be hoisted to the top of the front mast.
The courtesy flag will never be hoisted in the mast on the stern of the vessel.

18. Courtesy flag Remark Saoudi Arabia:
This country has two nation flags: one for its own and one for visitors.
The visitors must use the first flag. Here the sword is pointed at the mast. Symbolically, you point the sword to yourself and not to the country.
Saoudi Arabia uses the second flag. Her the sword is pointed away from the mast. Symbolically it is pointed to the visitors and protects the country.