The ships bell is struck every half hour. A single stroke is struck a half hour after the beginning of each watch, at 12:30, 4:30, and 8:30 (both am and pm). An additional stroke is added at each tolling, every half hour, so that 8 bells is struck at the end of the watch. The interval between strikes is either one or two seconds, alternating. In the table below, the hyphen represents a 1-second interval and the long dash a 2-second interval.
Strikes When How struck
1 12:30am 4:30am 8:30am 12:30pm 4:30pm 8:30pm B
2 1:00 am 5:00am 9:00am 1:00pm 5:00pm 9:00pm B-B
3 1:30am 5:30am 9:30am 1:30pm 5:30pm 9:30pm B-BB
4 2:00am 6:00am 10:00am 2:00pm 6:00pm 10:00pm B-BB-B
5 2:30am 6:30am 10:30am 2:30pm 6:30pm 10:30pm B-BB-BB
6 3:00am 7:00am 11:00am 3:00pm 7:00pm 11:00pm B-BB-BB-B
7 3:30am 7:30am 11:30am 3:30pm 7:30pm 11:30pm B-BB-BB-BB
8 4:00am 8:00am noon 4:00pm 8:00pm midnight B-BB-BB-BB-B
Ships bells are no longer rung on merchant ships, but the custom is maintained on passenger, training, and naval vessels.