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.

The flags are usually square, red and yellow, divided diagonaly 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.

Flag 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

For another flag communication system, see the international maritime signal flags.

The Semaphore Alphabet

B and 2 (LH down; RH out)

C and 3 (LH down; RH high)

D and 4 (LH down; RH up - or LH up; RH down)

E and 5 (LH high; RH down)

F and 6 (LH out; RH down)

G and 7 (LH low; RH down)

H and 8 (LH across low; RH out)

I and 9 (LH across low; RH up)

J and 'alphabetic' (LH out ; RH up)

K and 0 zero (LH up; RH low)

L (LH high; RH low)

M (LH out; RH low)

N (LH low; RH low)

O (LH across high; RH out)

P (LH up; RH out)

Q (LH high; RH out)

R (LH out; RH out)

S (LH low; RH out)

T (LH up; RH high)

U (LH high; RH high)

V (LH low; RH up)

W (LH out; RH across high)

X (LH low; RH across high)

Y (LH out; RH high)

Z (LH out; RH across low)

Numerical sign (LH high; RH up)

Annul sign (LH low; RH high)

Error (LH and RH raised and lowered together)