On military vessels, it is mandatory that critical areas be constantly manned. These areas are typically The Bridge, CIC, and Engineering. Other areas may require a 24 hour watch at the discretion of the Command or on as an "as needed" basis. Such areas could include and Occupied Brig, flight line, or Med bay.
On a fully crewed ship, a typical 4 section rotation is used. This rotation has crew members standing watch for 4 hours, and off watch for 12 hours. Typically, crew members will also have a 4 hour "work day" either before or after their watch. In most cases, however, ships are under manned and do not have the personnel for a 4 section watch. so a 3 or even 2 section watch rotation is used instead. on a typical 3 section watch, crew members stand a 4 hour watch and have 8 hours of rest but often need to spend 4 hours of day time as "work day".
In the case of the Raziel, Rolf has chosen to go with a slightly different watch rotation. He has decided on a 3 section 8/16 rotation. what this means is that there are 3 sections that stand a 8 hour watch with 16 hours off every day. First watch is from 0400 to 1200, second watch is 1200 to 2000, and third watch is 2000 to 0400. watch standers will also have a 4 hour "work day" either before or after their watch depending on the Division Head's requirements to perform general maintenance and other tasks.
Many of you will note that Captain Malra was not included on the section list. This is because as Captain, he has other duties that are more important than sitting on the bridge for several hours. Captains will often sit in on a watch, but in actuality spend very little time on the bridge if a ship underway. Normally this applies to the XO as well, but due to Raziel's under staffing, this is not an option (although i believe Rolf would assign himself a watch in any case)