Chief officer

Captain and Chief officer are overlapping terms, formal or informal, for the commander of a military unit, the commander of a ship, airplane, spacecraft, or other vessel, or the commander of a port, fire department or police department, election precinct, etc. Captain is a military rank in armies, navies, coast guards, etc., typically at the level of an officer commanding a company of infantry, a ship, or a battery of artillery, or similar distinct unit. Chief officer may be used interchangeably with captain in some situations, as when a Captain-ranked Navy officer is serving as the commander of a ship. The terms also may be used as an informal or honorary title for persons in similar commanding roles.

A Chief Mate (C/M) or Chief Officer, usually also synonymous with the First Mate or First Officer (except on passenger liners, which often carry both), is a licensed member and head of the deck department of a merchant ship. The chief mate is customarily a watchstander and is in charge of the ship's cargo and deck crew. The actual title used will vary by ship's employment, by type of ship, by nationality, and by trade. Informally, the Chief Mate will often simply be called "The Mate." The term "Chief Mate" is not usually used in the Commonwealth, although Chief Officer and First Mate are.