1. n. [Drilling]

The work shift of a drilling crew that starts in the morning. Drilling operations usually occur around the clock because of the cost to rent a rig. As a result, there are usually two separate crews working 12-hour tours to keep the operation going. Some companies prefer three 8-hour tours: the daylight tour starts at daylight or 8 a.m., and the graveyard tour is the overnight shift or the shift that begins at midnight. (Pronounced "tower" in many areas.)

See related terms: drilling crew,  evening tour,  graveyard tour,  tour