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 Watch system A watch system, watch schedule, or watch bill is a method of assigning regular periods of work duty aboard ships and some other areas of employment. A watch system allows the ship's crew to operate the ship 24 hours a day for the duration of long voyages or operations. Many watch systems incorporate the concept of dogging, whereby one watch is split into two shorter watches so that there is an odd number each day. Doing so allows crew members to have a different watch schedule each day. Often, the dog watches are set at dinner time to