that it provides for but does not require closed loop control of the direction of drilling as described above the direction of drilling may be directly controlled by comparing measured and predetermined dogleg severity and tool face values on fig6 dogleg severity and tool face values are determined at 380 and 345 respectively and compared to predetermined values at 310 and 350 respectively such comparisons may be utilized to determine new blade positions 325 for the steering tool and thus to control the direction of drilling with continued reference to fig6 one exemplary embodiment of control method 300 is now described in more detail at 310 a controller compares a measured dogleg severity determined at 380 as described in more detail below with a required dogleg severity 305 e g preprogrammed into the controller or communicated to the controller from the surface as also described above with respect to fig3 the comparison may for example include subtracting the measured dogleg severity from the required dogleg severity the difference between the measured 380 and required 305 dogleg severity values may be utilized to determine a new offset value for the steering tool at 320 in one exemplary embodiment an offset value in 320 is determined such that the average dogleg severity calculated in 315 e g along a predetermined section of the borehole equals the required dogleg severity 305 in one embodiment the offset determined in 320 is the radial distance between the longitudinal axis of the steering tool and the longitudinal axis of the borehole such an offset is related e g proportionally to the dogleg severity and may be utilized to calculate new blade positions as.