The boatswain was, back in Old English days, merely the lad, swainwith the duty of attending to the small open boats of that period.
His duty involved the care of the boat, of its oars and steering paddle, of its sails and rigging, if so equipped, and the summoning of its crew.
In very early days it is probable that the latter duty was performed by whistling through his own lips, but, by the fifteenth century or earlier, we may read that he “blewe his whystell full shryll.”
Corruption of the pronunciation to bosun was in colloquial use before the middle of the seventeenth century.
