Inspect derricks, or order their inspection, prior to being raised or lowered.
Inspect derricks for flaws, and clean and oil derricks to maintain proper working conditions.
Control the viscosity and weight of the drilling fluid.
Repair pumps, mud tanks, and related equipment.
Set and bolt crown blocks to posts at tops of derricks.
Listen to mud pumps and check regularly for vibration and other problems to ensure that rig pumps and drilling mud systems are working properly.
Start pumps that circulate mud through drill pipes and boreholes to cool drill bits and flush out drill cuttings.
Position and align derrick elements, using harnesses and platform climbing devices.
Supervise crew members, and provide assistance in training them.
Guide lengths of pipe into and out of elevators.