Semaphore Flag Signalling System Explained

by OldSailor on October 4, 2007

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The aim of this post is to make you aware about Semaphore Flag Signalling System. When the electronic communication equipments fail onboard, this is the only means of ship to ship visual communication available.

The Semaphore flag signaling system is an alphabet signalling system based on the waving of a pair of hand-held flags in a particular pattern.

clip_image001

The flags are usually square, red and yellow, divided diagonally with the red portion in the upper hoist.

The flags are held, arms extended, in various positions representing each of the letters of the alphabet. The pattern resembles a clock face divided into eight positions: up, down, out, high, low, for each of the left and right hands (LH and RH) six letters require the hand to be brought across the body so that both flags are on the same side.

clip_image002Flag positions in Semaphore

One way to visualize the semaphore alphabet is in terms of circles:

  • first circle: A, B, C, D, E, F, G;
  • second circle: H, I, K, L, M, N (omitting J);
  • third circle: O, P, Q, R, S;
  • fourth circle: T, U, Y and ‘annul’;
  • fifth circle: ‘numeric’, J (or ‘alphabetic’), V;
  • sixth circle: W, X;
  • seventh circle: Z

In the first circle, the letters A to C are made with the right arm, and E to G with the left, and D with either as convenient. In the second circle, the right arm is kept still at the letter A position and the left arm makes the movements; similarly in the remaining circles, the right arm remains fixed while the left arm moves. The arms are kept straight when changing from one position to another.

The Semaphore Alphabet

clip_image003A and 1 (LH down RH low)

clip_image004B and 2 (LH down; RH out)

clip_image005C and 3 (LH down; RH high)

clip_image006D and 4 (LH down; RH up – or LH up; RH down)

clip_image007E and 5 (LH high; RH down)

clip_image008F and 6 (LH out; RH down)

clip_image009G and 7 (LH low; RH down)

clip_image010H and 8 (LH across low; RH out)

clip_image011I and 9 (LH across low; RH up)

clip_image012J and ‘alphabetic’ (LH out ; RH up)

clip_image013K and 0 zero (LH up; RH low)

clip_image014L (LH high; RH low)

clip_image015M (LH out; RH low)

clip_image016N (LH low; RH low)

clip_image017O (LH across high; RH out)

clip_image018P (LH up; RH out)

clip_image019Q (LH high; RH out)

clip_image020R (LH out; RH out)

clip_image021S (LH low; RH out)

clip_image022T (LH up; RH high)

clip_image023U (LH high; RH high)

clip_image024V (LH low; RH up)

clip_image025W (LH out; RH across high)

clip_image026X (LH low; RH across high)

clip_image027Y (LH out; RH high)

clip_image028Z (LH out; RH across low)

clip_image029Numerical sign (LH high; RH up)

clip_image030Annul sign (LH low; RH high)

clip_image031Error (LH and RH raised and lowered together)

Image Source: http://www.anbg.gov.au/flags/semaphore.html

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