The captain or master commanded the ship from the quarterdeck. The quarterdeck was traditionally the place where the captain walked when on deck, usually on the windward side. The navigator also used it when taking his sights when fixing the vessel's position. On most ships, it was customary that only officers could use the quarterdeck, others being allowed there only when assigned for specific duties. By extension, on flush-decked ships the after part of the main deck, where the officers took their station, was also known as the quarterdeck.