The practice of using bells stems from the days of the sailing ships. Sailors couldn't afford to have their own time pieces and relied on the ship's bells to tell time. The ship's boy kept time by using a half-hour glass. Each time the sand ran out, he would turn the glass over and ring the appropriate number of bells. Each ship “watch” is four hours, or eight bells, in length.
The tradition of Eight Bells pays respect to deceased mariners and signifies that a sailor's “watch” is over.