Also called a boatswain’s/bosun’s call or pipe, with its traditional shape, unchanged for centuries, his whistle was the bosun’s badge of rank. Its shrill sound could be heard over the din of the howling wind, flapping sails, and crashing waves. That’s when the crew had to act as one, to save the cargo as well as body and soul. Dozens of signals, from “All hands on deck” to “Men aloft” were routine… and instantly obeyed.
The notes made by the whistle are produced by blowing with even or varying pressure (to give a warbling sound) or by vibrating the tongue for a trilling sound. This note is further modified by opening or partially closing the hand round the buoy, for a variable “throttling” effect.