A Boatswain's Call, Pipe Or Bosun's Whistle Is A Pipe Or A Non-Diaphragm Type Whistle Used On Naval Ships By A Boatswain. The Pipe Consists Of A Narrow Tube Which Directs Air Over A Metal Sphere With A Hole In The Top. The Player Opens And Closes The Hand Over The Hole To Change The Pitch. Now You Could Blow One And Be The Boatswain Yourself. Exclusive Nautical Home At Nagina International In A Vast First-Ever Collection. Keep Exploring For More Lovely Decors.