Aiming off (intentional error)
Aiming off is a technique used to find an objective on a definite, continuous line, such as a river, mountain ridge, coastline, road, etc. The navigator deliberately sets a course which is calculated to strike the line some distance to the right or left of the objective. Thus when the line is reached, there is no doubt as to which way to turn to reach the objective. For example, if aiming off to the right, you know you must turn left.
The amount of aiming off will depend on a number of factors, but as a guide for average conditions and distances, 10° could be added to or subtracted from the bearing. The longer the distance over which aiming off will be carried out, the smaller the aiming difference can be.