Royal Navy Semaphore Procedure

Peculiar "arms" can sometimes be seen on photographs of Royal Navy warships. These were semaphores, yet another signalling device. The following description of their use in the RN has been taken from the 1913 edition of the Handbook of Signalling, printed by the Admiralty.

Note that a graphic of the actual code may be found at the bottom.


How Signals are to be read.

1. The Alphabetical Sign shows from which side the signs are to be read.

2. The Signs, as a general rule, are made by a Signalman facing the ships addressed; they are read from the right-hand side of the sending Signalman.

3. As it is often necessary to signal in opposite directions by the same semaphore, Signalmen must be careful to observe in which direction the Sender is facing, more especially when he is using hand flags, so that they can tell the side they must read the signs from their point of view. It should be noted that when the Alphabetical Sign is shown it is the left arm which is extended horizontally.

Rules for Semaphoring.

1. It must be remembered by the Sender that the semaphore arms should be presented to the observer with a strongly contrasting background; it is best to have the sky as a background, but where this is not possible, the background should be that which throws the semaphore arms into the greatest relief.

2. The semaphore arms must be placed at the exact position indicating the letters or signs, the arms being moved from sign to sign by the shortest route; a distinct pause being made at each sign, according to the rate of sending.

3. At the end of each word or group the arms are to be dropped to the closed position. When double letters occur, the arms are to be dropped to the closed position after the first letter is made and then moved out to the second letter without pausing.

4. As a general rule, with ships in Close Order, semaphore messages should be transmitted at the rate of 15 words per minute on the semaphore, or 20 words per minute with hand flags.

5. When using the mechanical semaphore it is important that the positions of the arms should exactly agree with the positions of the handles, and that there is a minimum of backlash in the chains.

6. When using hand flags the signs are formed in the same plane as the shoulders of the Sender, arms and staves at their full extent, forefingers along the staves. When at the closed position the arms should hang straight from the shoulder.

7. Code and Cypher Messages are not to be passed by semaphore but are to be made by Morse.

The Semaphore Flag.

1. Flag "E", hoisted either singly or inferior to Distinguishing Signals, denotes that a communication is about to be made by semaphore. The arms of the semaphore are, at the same time, to be set to the Alphabetical Sign.

Method of Answering

1. The Answering Pendant is to be hoisted at the dip immediately the ship or ships addressed see the signal and hoisted close up when they are ready to read and write down.

2. It is to be dipped when a word is lost, and the ship making the signal is then to repeat preceding words until the Answering Pendant is again hoisted close up.


1. When the ship or ships addressed have answered, the following procedure will be carried out:

Preamble: Hercules - Exmouth (full stop sign)

Message - time of origin

2. If there is no doubt as to the Ship of Origin or the ship addressed, the preamble to a signal is unnecessary and should be omitted, but it is always to be included in signals passed through a ship, or made to more than one ship, or if either the Sending or Receiving Ship is in such a position as to render her identity uncertain.

Special Signals

1. A Semaphore Signal is commenced with the Alphabetical Sign.

2. The Alphabetical Sign is also to precede each distinct message.

3. The Numeral Sign is always to precede signs on the Semaphore when they represent numbers.

4. The Annul Sign denotes that the word or group immediately preceding it is erased; the Alphabetical or Numeral Sign will then be made, followed by the last word or group sent correctly, and the message continued.

5. If, after a message has been concluded, it is required to alter any particular word, words, or group, the Annul Sign should be made, followed by the word, words, or group to be erased, and then the Alphabetical or Numeral Sign followed by the correct word, words, or group.

6. Should it be required to cancel the whole message, the Annul Sign followed by the word "All" is to be made.

7. In order to render the text of a message to be semaphored perfectly clear, the following signs are to be made use of:

Full Stop AAA
Tack-line or Break Sign II
Words to be in parenthesis KK
Words to be underlined UK
Words to be in inverted commas RR

8. Any of the other Signs employed in Post Office Morse may also be used if required.

When Figures should be Spelt

1. Unless there are special reasons to the contrary, figures and times which occur in the text of a message are to be spelt out by the Sender.

Time of Origin

1. All Signals made by semaphore are to conclude with a "Time of Origin", which is to be considered as part of the message and made by numerals.

2. The "Time of Origin" is to be the actual time at which the signal was ordered to be made.

3. It will be indicated by a group of four figures, representing hours and minutes; the first two being the hours, and the last two the minutes. The hours will be reckoned from Midnight 00 to Midnight 24.


Hints when Semaphoring

1. Small Affirmatives or Answering Pendants should not be left at the dip. If the sending ship does not stop in a reasonable time, the Affirmative or Answer should be hauled down, and a repetition called for.

2. "Dip and hoist" is also a useful check, though not infallible, as cases have occurred of two ships making it at the same time.

3. In large fleets it will be found convenient to arrange special flags for answering certain ships.

4. Whenever possible, each sender should have a copy of the signal, and a hand to dictate. Where semaphores are widely separated and one person attempts to dictate to two or more at the same time, mistakes are bound to occur.

5. In the case of a ship repeating, it is very important that the man reading another ship should be close alongside the man repeating.

6. An acknowledgement or a repeat back should be requested for all important signals when there is any possibility of an error.

Semaphore Code

[this seem to show the signs from the observer's point-of-view]

[semaphore code]

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Last Updated: 29 December, 2005.