The boatswain (etymologically 'the servant, or attendant, of a boat') is the petty officer, or in the Royal Navy a warrant (~ non-commissioned) officer, who is responsible for ropes, rigging, anchors and cables, etc, and the regular, routine maintenance of the vessel's decks and other surfaces.
The word is always now pronounced 'BO-sun' (IPA: /'bəʊ sən/), which explains the familiar (and not incorrect) spellings bosun and earlier bo'sun and bo's'un. This pronunciation has been observable in various written forms from the fifteenth century.
- The ship's boatswain in the days of sail was one of the important warrant officers in the ship, one whose skills were central to the safe and efficient running of the vessel, like those of the sailmaker and carpenter. In the age of steam, his importance diminished, and the rank of boatswain no longer exists in the Royal Navy. It is first recorded in a similar context in 1040, and the last boatswain retired in 1990.
- A boatswain's chair is a device where a plank is so fastened to rope that it may be raised and lowered with a man sitting on the plank, for purposes of, for example, working on a mast or rigging, or painting the outsides of a ship's hull.
- A boatswain's pipe or boatswain's whistle is the characteristic instrument traditionally used in navies to give orders, and for certain ceremonial purposes such as piping the side, to form a guard of honour to receive important visitors aboard.
- Sin bosun is a slang term in the Royal Navy for a ship's chaplain.
Don't confuse the homophones bosun and boson - see boson - bosun