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 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.

In the traditional Royal Navy watch system (a system used by most other Commonwealth navies), 'watch' refers to a period of time and to a grouping of personnel. Those members of the crew whose work must be done at all times of the day - known as 'watch-keepers' - are assigned to one of two watches: the Starboard or the Port watch. These can be further divided into two parts, e.g. First Port, Second Starboard. These two watches - or more usually the four parts of watches - alternate in working the following watches:

The Royal Navy traditional submarine three watch system is 2 on 4 off during the day (8 a.m. to 8 p.m.) and 3 on 6 off during the night (8 p.m. to 8 a.m.).

The same arrangement of watch times can also be used with a crew divided into three sections. This gives each sailor more time off-duty, sometimes allowing sleeping periods of over seven hours. Names for the three watches—instead of Port and Starboard—vary from ship to ship. Naming schemes such as "Foremast", "Mainmast" and "Mizzen" and "Red", "White" and "Blue" are common.

The so-called "five-and-dime" arrangement splits the day into five-hour watches, with the exception of a four-hour watch from 22:00 to 02:00.

Aboard United States submarines, where the working day is 18 hours instead of 24, the crew is normally divided into three sections, with each section standing 6 hours of watch followed by 12 hours off-watch. The 12 hours off-watch are further divided into the first 6 hours being used for maintenance, cleaning, and entertainment; while the second 6 hours are usually for sleeping.

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