How to Use a Lensatic Compass
A compass is an instrument used for navigation by utilizing the earth’s magnetic field. It consists of a magnetized needle set in a face much like a clock. In place of numbers, the face is marked with the directions north, south, east, and west.
A lensatic compass is a type of compass that uses a magnetized dial instead of a plain needle. The dial is marked with directions, while the face is marked with numbers used to detect more accurate direction. Hence, its primary function is taking accurate bearings for land navigation. For this reason, lensatic compasses are highly coveted equipment used by the military.
Components of a Lensatic Compass
A lensatic compass consists of three components:
- Cover
The cover shields the compass rose dial. It houses sighting wires and dots used in night navigation. - Base
This component contains all the compass’ moving parts. It also contains a floating dial that rotates to indicate direction every time the compass maintains a level position. At its center rests the directional arrow, which always points to the North. East falls at 90 degrees and West at 270 degrees.The base also contains two scales — the outer and inner scales. The former denotes miles, while the latter denotes degrees.
The bezel ring at the base is a ratchet device that turns 120 clicks on full rotation. Laid on the glass face of the bezel ring is a short incandescent line that works with the North-directional arrow in navigation.
The base’s final component is the thumb loop. It simply attaches to the base as a means for handling.
- Lens
The lens reads the floating dial. The cover contains a slot for rear-sight navigation that functions with the front sight wires to pinpoint objects. The slot also shields the compass when closed through a lock and clamp system.
Taking a Bearing
- Unlock the cover midway, setting the compass card at a 90 degree angle.
- Lift the lens arms to a 45 degree angle.
- Stabilize the compass by placing your thumb inside the thumb hook. Make sure that the hook is all the way towards the bottom before inserting your thumb.
- Find the target object.
- Make adjustments so that the sighting wire lies in the middle of the target object.
- Take the fine degree marking on the compass card by shifting the lens up and down until the degree mark reads. Do not shift your gaze from the target object.
- Read the bearings in degrees.
Setting a Bearing
- Follow the above directions.
- Align the marking on the bezel with the north direction arrow. The orientation is set once these two are aligned.
- Proceed on the course pointed by the sighting wire.
Following a Bearing
- Follow the above directions.
- Select a landmark in the distance to serve as a reference point.
- If the reference point is blocked by a tree or disappears because of the weather, use the compass to stay on course.
- Set new bearings for your reference point occasionally.
