In the Royal Navy the day is divided into six watches of 4 hours… except the Dog Watch (4pm to 8pm) which was sub-divided (or dogged) into 2 x 2 hour watches to allow sailors to eat their evening meal at the normal time, (5pm or 6pm.)

00:00  to  04:00 - Middle Watch

04:00  to  08:00 - Morning Watch

08:00  to  12:00 - Forenoon Watch

12:00  to  16:00 - Afternoon Watch

{16:00  to  18:00 - First Dog Watch}

{18:00  to  20:00 - Last Dog Watch}

20:00  to  00:00 - First Watch

As a child, I remember hearing that one should not drink an alcoholic beverage “before six bells have sounded.” 

Nobody explained to me that this meant six bells in the Forenoon Watch… Therefore, I thought it was perfectly acceptable to have a little tipple with my breakfast, after six bells during the Morning Watch!