BT2 user manual - H-5911-9004-02-B Page | 14
• A good-quality, hand-held compass. This is the least accurate option. Stand behind the alignment jig and
take a compass bearing looking along the jig in the direction that the probe is, or will be, pointing. If using a
magnetic compass, ensure that the immediate area is free from external magnetic influences, such as drill
rigs or mobile phones.
Note that if a compass is used, the measured bearing will be relative to magnetic north. The relationship
between the magnetic bearing from the compass and any local grid north that is used for other survey data
will need to be established if data from the Boretrak2 is to be used in conjunction with data from other
systems such as GPS or the Quarryman Pro.
Note that the heading of the alignment jig is independent from the direction of the hole being surveyed. The
measured heading provides a starting reference for the survey. Once the gyro is aligned in this heading, the gyro
tracks any subsequent changes of orientation.
Establishing the reference heading of the jig can take place at any time before or after the deployment. As long as
the alignment jig is not moved between aligning the gyro and surveying the heading, you can establish the reference
heading when the Boretrak2 survey is not in progress.
Figure 2 Surveyed heading of the alignment jig
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