A Chief Mate or Chief Officer, usually also synonymous with the First Mate or First Officer , 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 chief mate is responsible to the captain for the safety and security of the ship. Responsibilities include the crew's welfare and training in areas such as safety, firefighting, search and rescue. The Chief Mate is second in command on merchant ships that do not carry a Staff Captain.