Striking clocks use the traditional ship’s bells. The following is taken from Chapman’s standard reference book, Piloting, Seamanship and Small Boat Handling:
Ship’s bell time originated in sailing ship days, when the crew of a vessel was divided into Port and Starboard Watches, each on duty four hours, then off four hours. One stroke of the ship’s bell indicates the first half hour of the watch. Then an additional bell is struck for each succeeding half hour. Thus eight bells indicates the end of a four-hour watch. When the time calls for two or more strokes, they are sounded in groups of two.
The first five watches are as follows:
The next four hours are divided into two Dog Watches—the first Dog Watch, 4pm to 6pm (16:00 to 18:00 hours) and the Second Dog Watch, 6pm to 8pm (18:00 to 20:00 hours). By means of the Dog Watches, the watches can be changed every day, so that each watch gets a turn of eight hours rest at night. Otherwise each member of the crew would be on duty the same hours every day.
|Number of Bells||Bell Pattern||Hour (am and pm)|
|One bell||o||12:30, 4:30, 8:30|
|Two bells||oo||1:00, 5:00, 9:00|
|Three bells||oo o||1:30, 5:30, 9:30|
|Four bells||oo oo||2:00, 6:00, 10:00|
|Five bells||oo oo o||2:30, 6:30, 10:30|
|Six bells||oo oo oo||3:00, 7:00, 11:00|
|Seven bells||oo oo oo o||3:30, 7:30, 11:30|
|Eight bells||oo oo oo oo||4:00, 8:00, 12:00|