|
| |
How to use Lensatic Compass
INTRODUCTION
The Lensatic compass differs from the type most hikers are familiar with, the
traditional "orienteering" compasses. The Lensatic, a design preferred by
military forces for its precision and durability, is designed to take
hyper-accurate bearings for land navigation and directing artillery fire!
It is composed of four basic parts, the compass card (rose) itself, with
housing, degree scale and rotating bezel; the sighting-wire unit/top cover; the
thumb hook; and the lens for which it is named.
TO TAKE A BEARING/AZIMUTH
Open the top cover half-way, such that it forms a 90* angle with the compass
card. Lift the lens arm up to roughly a 45* angle, and make sure the thumb hook
is all the way to the bottom. Place your thumb into the hook for stability.
Looking at the target Object, position the Sighting Wire in the middle of the
Object. Move the lens up and down such that you can read the fine degree
markings from the card without taking your eyes off the Object. Read the bearing
in degrees, or if preferred, MILS.
TO SET A BEARING
Sight on your destination as above and note the bearing in degrees. Rotate the
marking on the moving bezel into alignment with Magnetic North as indicated by
the compass card. This allows you to orient yourself after traveling because you
will rotate yourself so that the compass's Magnetic North aligns with the
bezel's marking. Then, the bearing indicated through the sighting wire is the
direction
you must travel to remain on course.
TO FOLLOW A BEARING
After orienting yourself as above, select a landmark in the distance and use
that as a reference point while hiking. When the landmark is not visible, due to
trees, clouds, etc., simply follow the bearing indicated on your Lensatic
Compass. From time to time, you will want to confirm your direction by taking a
new bearing to the landmark.
ORIENTEERING WITH THE LENSATIC
Orienteering with the Lensatic is not as simple as with purpose-build
orienteering compasses, such as the Silva line, but it is not difficult, either.
Most modern Lensatics feature a square case, one side ruled, so that you may use
it to triangulate known Landmarks to your position. The built-in ruler is
designed for military grid maps, but will work with USGS topo maps too, with a
bit of arithmetic. As the Lensatic lacks a protractor, you must either bring one
along--the military supplies a protractor for this purpose--or improvise using
the compass card itself, which is nicely divided into degrees! O happy day!
Quick tip:
Ever wonder how far you could see from the top of that mountain?
Here's the rule of thumb: multiply your elevation above the surroundings (in
thousands of feet) by 1.25.
Is it always accurate? hard to say on land with things like mountains and trees
in the way, but this is how NASA calculates it for astronauts, so it's good
enough for us. It's also a good way to impress your hiking buddies!
|
