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Minor signal flag system proposals

Last modified: 2011-12-23 by rob raeside
Keywords: signal flag |
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Bigot de Morogues Signal Flags

Joe McMillan in discussing Signaling at Sea notes:

While Bigot de Morogues' signal code for the most part followed in the older tradition of assigning meanings to particular flags hoisted at specified locations, he also included a provision in his code for ten numerary flags, hoisted in 336 combinations of up to three flags each, and added both a preparatory flag to signal that a coded message would be transmitted and a requirement that the receiving ship acknowledge the signal.

Siegel [sig12] notes: …

(Number signals could be made as well … . For this purpose serve, after a preparation signal, the first nine flags, which hoisted in the mizzen represent ones, in the main tens, and in the fore hundreds.)

Is Siegel mistaken here (not a common occurrence), or are these combinations of up to three flags each indeed hoisted one flag per mast? And now that I see them side by side: was there a flag for zero, or was that just an empty position? (Nine flags versus ten flags.)
Peter Hans van den Muijzenberg, 16 October 2005

I looked at "Le Manoeuvrier" of Bourdé de Villehuet in Toulon at the Military Library. I consulted the 5th edition of 1832. Bourdé speaks about the system put of use and invented by Mr. de la Bourdonnaye. The base was pennon, like those of all the streamers easiest to attach in any place of a vessel.

The red pennon was worth 1
white 2
blue 3
yellow 4
red with white tail 5
red with blue tail 6
white with blue tail 7
white with red tail 8
blue with yellow tail 9
yellow with red tail 0

One makes the signals indifferently with all the masts or yards. The pennon of the top will be number 1, the second number 2, the third number 3, the fourth number 4. If one wants to make several signals at the same time with the same rope, one will separate each signal by a small red banderole without point, which will be useful like comma between the signals. It will be observed that these pennons are quite sharp colors like large blue (gros bleu in the text), scarlet red, arsenic yellow and white. The pennons, pennants, cornets or houses of the nation which are used to make known and to mark divisions will never be taken as signal.
Dominique Cureau, 28 October 2005

The fact that you consulted the 5th edition of 1832, implies that the De la Bourdannais system of signaling at sea had been employed throughout by the Royal, Republican and Imperial French navies until at least 1832. Is this a correct deduction?
Andries Burgers, 29 October 2005

In fact no. The official system of signaling at sea used by French Marine is the system of du Pavillon. The book of Bourdé de Villehuet was a bestseller in France and England (see the notice at

But it was only one of the proposals at the time
Dominique Cureau, 30 October 2005

Knowles Signal flags

Knowles was a contemporary of Kempenfeldt and Howe. Kempenfeldt apparently tried the extreme of a two-flag grid with a large number of different flags (though not as large as the 50 that was necessary for the official instructions at the time). Knowles was at the other extreme with a 3-flag grid to just signal numbers 1-9. With two sets of three flags, red white, and blue, he followed Mahé de la Bourdonnai in signaling numbers that represent messages. That was the combination of borrowing from the French and Red, White, and Blue.
Peter Hans van den Muijzenberg, 16 October 2005

For Great Britain Knowles' rejected proposal introduced the separation of signal and message in modern times. I've just found a reference, though, that a similar system was used by the Romans.

Knowles method, which was not put into practice, was to have single digits represented by two flags, which were red, and/or white and/or blue, selected from a nine square grid:

Knowles Signal Flag System numeric color is represented by the color in the top row over the color in the first column
  red white blue
red 1 4 7
white 2 5 8
blue 3 6 9

Thus for example, blue over white was 8.
David Prothero, 17 October 2005

Mahé de la Bourdonnais Signal Flags

According to William Perrin in 'British Flags':

His (Mahé de la Bourdonnais) signals seem never to have been adopted, [foot-note] but the system is described by Bourdé de Villehuet in 'Le Manoeuvrier', published in 1769, one of the classic works on tactics of the 18th century.

[Footnote. In his memoirs it is stated that in 1746 he had written a book on Signals and Naval Evolutions.]
David Prothero, 14 October 2005

In general the assumption is he had ten flags of different colours, and three sets of those. "Three sets of" "10 flags of different colours".

The French national library does list the 1765 version. (The 1769 version is somewhat of a dubious reprint of 1765 with small changes in orthography. They do contain the same information, though.) Also, the Amsterdams Scheepvaart Museum has several editions, as well as De bestierder, a Dutch translation.

Regarding the thirty flags:

Suppose you were to signal hoists of three flags, which you had assigned meaning to, and for this you would have at hand ten flags for each position in the hoist, though flags with corresponding value would be exactly the same.

How long would it take you to notice that you could do this with one set of flags except for the cases where the same digit occurred twice or trice?

For some of us from the year 2000 the answer would be something like "About three hoists." I can come up with three possible scenarios explaining why Mahé de la Bourdonnais did not have the same realization:

  1. He didn't actually work this out in practice.
  2. He didn't string them in hoists, but had each set at a different mast.
  3. His flags were really all different?

Either suggestion is somewhat plausible, as this signaling system would improve upon the system described by Hoste, which did use more than thirty flags and did hoist them distributed over all three masts. Though Mahé de la Bourdonnais looked far enough outside the box to base his improvement on a principle not in use at the time, he may still have copied some of the characteristics from his predecessor.
Peter Hans van den Muijzenberg, 15 October 2005