 An example of this is when all new chief petty officers of the United States Navy are frocked on September 16 of each year, although their official date of rank will be at different times over the next year.The term "frocking" dates back to the Age of Sail, when communications between the Department of the Navy and ships at sea could take months.News of the promotion of an officer arrived, usually via letters brought by another ship, and often with orders for the newly promoted officer to report to a new ship or station.