In centuries past sailors would be “on watch” for four hours, then “off watch” for four hours. This is easy to understand, but very hard work as you can never have more than a few hours continuous sleep.
Darwin’s voyage on the beagle operated an innovative for the time system of three watches with four hours on, eight hours off, which is much better for sleep.
Pelican also operates a three watch system with Forward, Main, and Mizzen watch crews, and I’m in the Middle Watch. Each watch crew is on duty every third watch. A simple system of six four hour watches would divide up the work equally, but leave some unhappy people with all the 3am slots.
Instead there are seven watches each day, which means you rotate through the watches each day.
First Watch – 8pm to midnight
Night watch – midnight to 4am
Morning Watch – 4am to 8am
Forenoon Watch – 8am to 12:30pm
Afternoon Watch – 12:30pm to 4pm
First Dog Watch – 4pm to 6pm
Last Dog Watch – 6pm to 8pm
These watches only operate when at Sea, and so far I’ve done a Last Dog, a morning, and a First Dog.