Signaling

Marine systems of signals used to transmit information to and from ships. Marine signals can be sound signals, using bells, whistles, horns, sirens, and other devices, or visual signals. The latter include flag signals (both international and other codes), semaphores (flag semaphores and mechanical semaphores as well as signal panels used in aviation and other devices), signal figures (balls, cones, cylinders, and strips raised on halyards, stays, or acorns), and light signals (ship’s lights and searchlights).