A mariner’s whistle is a thin metal tube extending from a hollow ball: it was used to command sailors’ attention at sea. It’s a period charge, used as a badge by de Vere, Earl of Oxford, who had been Lord of the Admiralty, d.1513 [Coat of Arms IV(27), July 56, p.96; also Siddons II.2 303]. Post-period heraldic authors misinterpreted the badge as a wine bottle, but more recent research has corrected this. The mariner’s whistle is fesswise by default. See also musical instruments.
William Fletcher of Carbery bears: Per bend azure and gules, a bend Or between three arrows in pale fesswise reversed and a mariner’s whistle palewise argent.