How to Use the Telescopic Alidade
The optical system simultaneously projects the image of the compass
card, together with a view of the spirit level, onto the optical view of the
telescope. By this means, both the object and its bearing can be viewed
at the same time through the alidade eyepiece.
Figure 2-20 illustrates taking a visual bearing with a telescopic alidade.
In this example, the bearing to the lighthouse is 022°.
Follow these steps to properly take a bearing with a telescopic alidade.
Place the ring on top of the gyro repeater and twist locks into
Point the front lens of the alidade towards the object to be
Tip: Sight along the handle to quickly find an object.
Look into the eyepiece and rotate the alidade right or left until
the object is aligned with the crosshair.
Keep the alidade level by observing the spirit level in the top
part of the view.
With the object lined up and level, read the bearing from the
reflected compass card. Read the inside compass card for true
Figure 2-20. View through an alidade.