Skip to content
Watch MuseumHorology Atlas

Tools · ship's time

Ship's bells: what time is it at sea?

On board ship the time is told in bells: one more every half-hour through each four-hour watch, up to eight bells at its end. This live ship's bell clock shows — and strikes — the bells for the time now or any time you choose, with the names of the watches and both ways of counting the dog watches.

Right now, by this device's clock

—

Reading this device's clock…

Strokes are sounded in pairs, with any odd stroke last: 2 · 2 · 2 · 2.

Counting the dog watches

How ship's time works

A ship's crew is divided into groups that take turns on duty, each turn being a "watch". The day is divided into seven watches: five of four hours and two short "dog watches" of two hours between 16:00 and 20:00. Unlike a church or house clock, the bell does not tell the hour. It counts the half-hours since the watch began: one bell after the first half-hour, two after the first hour, and so on to eight bells, when the watch changes and the count starts again.

The custom comes from the age of sail, when the watch was timed with a half-hour sandglass and the bell was struck each time the glass was turned. The strokes were sounded in pairs so that they were easy to count.

Bells struck through the day. Where the two usages differ (the last dog watch) both are given.
WatchTimesBells at each half-hour
Middle watch00:00–04:0000:30 101:00 201:30 302:00 402:30 503:00 603:30 704:00 8
Morning watch04:00–08:0004:30 105:00 205:30 306:00 406:30 507:00 607:30 708:00 8
Forenoon watch08:00–12:0008:30 109:00 209:30 310:00 410:30 511:00 611:30 712:00 8
Afternoon watch12:00–16:0012:30 113:00 213:30 314:00 414:30 515:00 615:30 716:00 8
First dog watch16:00–18:0016:30 117:00 217:30 318:00 4
Last dog watch18:00–20:0018:30 5 (RN 1)19:00 6 (RN 2)19:30 7 (RN 3)20:00 8
First watch20:00–00:0020:30 121:00 221:30 322:00 422:30 523:00 623:30 700:00 8

Ship's bell clocks

From the late 19th century clockmakers made clocks that strike ship's time automatically. The Chelsea Clock Company of Massachusetts patented a ship's bell clock with a fully enclosed striking mechanism in 1900, and the US Navy became one of its main customers; other makers produced them too. Many such clocks count straight through from one to eight bells every four hours, so they do not follow the Royal Navy's dog-watch usage — listen to yours at 18:30 to find out which it does.

Reading a ship's bell clock

A ship's bell clock has an ordinary twelve-hour dial; only the strike is different. Five bells can therefore mean 02:30, 06:30, 10:30, 14:30, 18:30 or 22:30 — the dial tells you which. Most have a lever or knob to silence the strike at night, and a separate winding square for the striking train.

Questions people ask

What time is eight bells?

Eight bells is struck at the end of each four-hour watch: at 04:00, 08:00, 12:00, 16:00, 20:00 and midnight. Between them the bell is struck once more every half-hour, so 00:30 is one bell and 02:00 is four bells.

Why are ship's bells struck in pairs?

The strokes are grouped in twos, with any odd stroke at the end, so that they are easy to count: five bells sounds as ding-ding, ding-ding, ding.

What is a dog watch?

The watch from 16:00 to 20:00 is split into two two-hour 'dog watches', the first and the last (or second). That gives an odd number of watches in the day, so the crew's turns rotate from day to day, and lets everyone eat an evening meal.

Why does the Royal Navy strike the last dog watch differently?

In British usage the last dog watch is struck one, two and three bells (18:30, 19:00, 19:30) and then eight bells at 20:00, instead of five, six and seven. The usage dates from after the Nore mutiny of 1797; naval tradition explains it with the story that five bells in the last dog watch was to have been the mutineers' signal.

Do ship's bell clocks strike the dog watches?

Many ship's bell clocks simply count from one to eight bells through every four hours, so in the last dog watch they strike five, six and seven bells, as in the classical American table. A clock that strikes one bell at 18:30 follows the British count; choose 'Royal Navy' above to see it.

How was the time kept before clocks?

In the age of sail the watch was timed with a half-hour sandglass, and the bell was struck each time the glass was turned. Before time zones, noon was not taken from the glass but struck when the officer of the watch confirmed local noon by the sun.

What does 'eight bells' mean outside ship's time?

Because eight bells ends a watch, the phrase is also used of a sailor's death ('end of the watch'). At midnight on New Year's Eve some ships strike sixteen bells, eight for the old year and eight for the new.

Go further