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).
Dog watch there are only two, to eat an evening meal at about the traditional time. The "Oxford English Dictionary" states that the word 'dogwatch' is a direct translation from either German or Dutch of a similar term. It originally referred to the night-watch on ships — that is, the time when (on land) all but the dog were asleep. The name is also said to be derived from Sirius, the "Dog Star", on the claim that Sirius was the first star that can be seen at night. An alternative folk etymology is that the name arose because someone tasked with one