Complex sentence: Some sailing ships use traditional ship's bells to tell the time and regulate the watch system, with the bell being rung once for every half hour into the watch and rung eight times at watch end (a four-hour watch).
Split into simpler sentences: Some sailing ships use traditional ship's bells to tell the time and regulate the watch system. The bell being rung once for every half hour into the watch and rung eight times at watch end (a four hour watch).