A plumb bob is used to centre a tripod upon which a theodolite, Total Station or GPS may be mounted - and can do so to an accuracy of 1-2mm. The accuracy of a plumb bob may be affected in windy conditions. Plumb bobs are generally used to give an approximate setting before refining the setting using the optical plummet found on the instrument itself.

Examples Of Usage:

• Centering of a survey instrument or target over a ground mark to an accuracy of a few millimetres.
• Plumb bobs are generally used to give an approximate centering before refining the setting using the optical plummet found on the instrument itself.
• Alignment of a tape or chain along a particular line of site.
• Marking the end of a tape or chain when measuring distances on sloping ground or across obstacles.

Factors Influencing the use of Plumb Bobs

• The accuracy of a plumb bob may be affected by windy conditions.
• The plumb bob may require a settling time to lose the effects of oscillations from handling.