Single-shot inclination-only survey tools (TOTCO)
Single-shot inclination-only survey tools are mechanical inclination indicators, often called by the trade name 'TOTCO' although they are also made by other manufacturers. They are normally owned and run by the drilling contractors. The instruments should be properly maintained and calibrated, at least every 25 shots.
The TOTCO Drift Indicator is a simple surveying instrument consisting of a mechanical timer and an angle unit.
The timer is set assuming a descent rate of 300ft/min in mud. Angle units are available . . .