Of the different types of compass, the most common are lensatic compasses (also known as military or marching compasses) and cartographic compasses. Both have common characteristics and some important differences that make them more suitable for certain uses. This time we are going to explain how to use a lensatic compass.
This compass is specially designed to mark bearings to distant points and follow the direction minimizing error. If we want to know the course to reach a visible point on the ground (a peak, for example), we just have to point the compass towards our destination and read the degrees marked by the direction line. These compasses are more suitable for navigation on the ground and not for use in conjunction with cartographic maps.
How to use a lensatic compass?
It can be easier than using a map if you know where you are and where you are going, or it can be more complex because you have no idea where you are standing.
Assuming you know where you are, the steps to set a course are as follows:
- You are going to shoot the visual. That is, you will fix your gaze using the compass sight pointing towards the object or place you want to reach.
- Once you aim correctly, you will allow the needle to stabilize.
- Using the lens or magnifying glass, you will read the degrees that the direct line marks you towards where you are pointing.
Now you may be wondering how to orient yourself with a lensatic compass. Well, we are going to explain two ways to shoot the visual, one with greater precision and another with a little less precision.
Using the ventral technique:
- You will open the compass cover until it is in its final horizontal position aligned with the face or the rest of the compass base.
- Now you will hold it with both hands firmly and take it towards your belly, resting your elbows on the sides of your abdomen.
- You will turn your whole body, keeping the compass close to your belly, until the compass direction line points to the place you want to go.
Shoot the visual with ventral technique
It is a simple technique, quick to learn and you can use it without the need to use a map or binoculars. You can also use it on any type of terrain. On the other hand, it has the disadvantage of requiring very good visibility, without the haze and of being up to a little more than three times less precise than the facial technique that we will explain below:
Using the facial technique:
This time you will open the lid until it is in its vertical position, at 90 ° to the base of the compass. Now you will lift the lens holder that will help you see through the scope and towards the needle. Make sure you can fully read the degrees indicated by the direction line. In this assembly, there is a variant and that is that you can take the lens and the cover to meet and rest on each other.
You will hold the compass with one hand very much like holding a firearm, inserting the thumb of that hand into the ring and bringing that hand with the other hand towards your chin. You will place both hands until the main hand with which you are holding the compass rests on your cheekbone.
Now you will shoot the sight through the slot or look that has the azimuth thread or hair that will help you have greater precision in the marked direction. You will match the center of the place or object you want to go to with the azimuth wire and the sight (notch) at the top of the lid.
Once the three points are aligned, you will read with the lens’s help, the degrees indicated by the compass. You will let the needle stabilize, always ensuring that the compass is horizontal so that there is no error in the measurement.
Learn the degrees that the direct line marks you and that will be the course to which you should go. You will be able to reach your destination even if you no longer have the vision, always pointing and turning your whole body until the direction line marks the degrees you initially set.
Suppose you have no idea where you are. In that case, it is advisable to use the map and triangulate your position from a high area that allows you to see or cover a large area, as we explained earlier in explaining the use of the cartographic compass. Leave the link of triangulation and use of the map.
This second technique is more than 3 times more accurate than belly and you better respond to oriented in the mountains, how to orient in nature or any other type of terrain.
It is broken down into two main parts:
- Support or casing that, when deployed, indicates the direction we should take.
- A graduated watertight capsule containing the magnetic needle.
In the first place, we have to “throw the visual,” that is, point the compass towards our destination. For this, we unfold the compass until the cover reaches 90º concerning its base. We hold it by inserting the thumb on the ring (the same ring that is used to close the compass when it is folded), we lift it to the face and, resting our hand on the cheekbone, we point towards the place we want to go or know its direction.
How to catch the compass to pull the line
To facilitate this work, the compass’s cover comes with an opening that is traversed longitudinally by a fine wire, known as azimuth hair (see the first image of the article). Also, the lens holder comes with a vertical notch. And to obtain the greatest precision when it comes to knowing our course, it is enough to match these three elements: the place where we are going or from which we want to know its course, the azimuth hair, and the notch of the lens cover. At this time, we must be very careful to keep the compass horizontally and wait for the magnetic needle to stabilize properly. Any movement or inclination would result in an erroneous heading measurement.
Finally, we can only read the circumference’s degrees under the direction line painted on the glass that covers the magnetic needle. These compasses come with a small lens(which incorporates the notch we talked about previously). When pulling the visual, it allows us to comfortably read the degrees under the direction line.
After this process, we will already know the course we have to follow to reach our destination. It will be very useful when we temporarily lose sight of it, either because some type of geographical accident hides it, forest, … or by loss of visibility due to fog, among other factors. If this happens, just take out the compass, hold it horizontally in your hand, and turn your entire body with it until the graduated circumference marks the memorized bearing under the direction line.