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 effectively 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 allow the entire crew to be fed in short order.