Dog watch of Ship's Bell clocks) website explanation it says that ..."the Evening Watch is periodically divided into two watches. These are called Dog Watches because they "dog" the watch schedule for all divisions ahead by one watch period". It can be surmised that this may mean an action similar to the "feed dogs" on a sewing machine, although obviously the use of the term predates the use in the sewing machine. Dog watch Dog watch, in marine or naval terminology, is a watch, a period of work duty or a work shift, between 16:00 and 20:00 (4 pm and 8 pm).
Watch system 1700; sometimes a light midnight meal is provided for the 0000 turnover. Various alternative watch schedules have been devised, which are typically referred to as Swedish watches. Although there is no standard for what constitutes a Swedish watch, the variations all feature some element of extended watches to accommodate longer time off. Like the traditional watch system, they begin at 2000 hours. Some popular variations have durations of 6, 6, 4, 4, 4 and 5, 5, 5, 5, 4. On merchant ships, watchstanders typically stand watch for three periods of four consecutive hours. This system has a couple of advantages: