On Royal Navy ships of the sailing era the ships bell was used to tell everyone on board what the time was. Usually a half hour sand glass was used and as the Midshipman of the Watch turned it over the bell was rung a number of times to let the crew know how long they had been on watch and when the relief was due to take over. To allow for any discrepancies in turning the glass the naval day started at noon when the noon sight (the Captain and senior officers establishing when the Sun reached it’s daily zenith) could be used to start the daily cycle.

Depending on the number of crew available and the number of trained watch keeping officers, the crew could be divided into two or three watches. Usually it was two, the starboard and larboard watches. The three watch system was more popular with crews as they got a full eight hours off but not as widely used.

The 24 hours were divided into 5 four hour watches and 2 two hour watches. The Latter had the effect of swapping the crew over so that the same people were not always on duty at the same time. The watches were named :

• the Afternoon Watch was from noon to 16:00 (4 p.m.)
• the First Dog Watch (2 hours) was from 16:00 (4 p.m. to 18:00 (6 p.m.)
• The Last Dog Watch (2 hours) was from 18:00 (6 p.m.) to 20:00 (8 p.m.)
• The First Watch was from 20:00 (8 p.m.) to midnight
• The Middle Watch was from midnight to 04:00 (4 a.m.)
• The Morning Watch was from 04:00 (4 a.m.) to 08:00 (8 a.m.)
• The Forenoon Watch was from 08:00 (8 a.m.) to noon

During these watches the bell was rung each half hour with the number of rings being increased by one each time. So half hour into the watch was one bell, one hour in was two bells 1.5 hours 3 bells etc. with the watch ending at eight bells (except the First Dog watch which ended at four bells).

You can therefore use the above to calculate the time used in the books. If a cutting out expedition is to set out at four bells in the morning watch it will be leaving at 6 o’clock in the morning.