The division of the ship's company into two parties, one called the starboard, and the other the larboard or port watch, alluding to the situation of their hammocks when hung up; these two watches are, however, separated into two others, a first and second part of each, making four in all. The crew can also be divided into three watches. The officers are divided into three watches, in order to lighten their duty; but it is to be borne in mind that the watch may sleep when their services are not demanded, whereas it is a crime, liable to death, for an officer to sleep on his watch. In a ship of war the watch is generally commanded by a lieutenant, and in merchant ships by one of the mates. The word is also applied to the time during which the watch remains on deck, usually four hours, with the exception of the dog-watches.