The United States military needs to know how to navigate on land when all digital systems fail.
For this, they use a lensatic compass, among other navigation equipment and techniques.
But what is a lensatic compass?
Most people have never heard of them, but soon enough, you’re going to be a master at using them. They could be your saving grace during an SHTF situation.
It’s a bit tricky, but once you get the hang of it, you’re solid. You want to know how to use a lensatic compass?
This is the guide for you.
What is a Lensatic Compass?
It’s one of the most versatile navigation tools we have available today. A lensatic compass features a small pop-out area for your thumb, and a lid on top of the main compass body.
You can look through a small window of the top (that’s the lens), and navigate smoothly from there. Let’s break down the individual parts of a lensatic compass so you can understand every element behind how it works.
- Thumb Loop: This keeps the face of the compass closed, but it’s also used – as you might have guessed – to loop your thumb through during operation. Since you’ll be holding your lensatic compass upright and straight in front of you, you need the thumb loop to help hold her steady.
- Sighting Slot: The sighting slot houses the lens in many lensatic compass models.
- Lens: This is what you see the compass through. The lens appears just above the thumb loop and aligns with the sighting wire. The lens will magnify your bezel point on the compass itself, allowing you to right your aim.
- Magnetic Arrow: Also referred to as the magnetic needle, this piece is the most important part of any compass. This gives you direction.
- Sighting Wire: This comes in handy right out of the box. Your sighting wire helps you calibrate your lensatic compass, but it’s also used to sight in on an object or landmark when you’re trying to navigate your way through the land. More on this later.
- Bezel Ring: We know what bezels are from monitors, TVs, and our smartphones, but in this instance a bezel ring does something a little different. It physically holds the upper glass crystal into place, and contains a clicking function to help change the degrees of the compass. In most lensatic compasses, every single click is equal to 3°, meaning there are typically 120 different dial clicks on the bezel ring (120 x 3 = 360 degrees).
- Floating Dial: This automatically aligns north. You can imagine how this would be useful.
- Graduated Straightedge: Just like the rulers you used in school, these help you measure degrees on the face of your compass and they will be used on maps.
- Cover: The chassis or physical housing that the components of the lensatic compass rests in. This can also be referred to simply as a case.
Sounds like a lot more than a regular compass, doesn’t it?
Once you master using a lensatic compass, it becomes the only way you’ll ever navigate around the wilderness moving forward. There is nothing better than being at the heart of your navigation as a prepper, and truly knowing where you’re headed without the need for technological input.
How to Use it With a Map
This is a hard and fast guide on how to use your lensatic compass with a map, which is what it was designed for.
- Lay the compass down on your map. You’ll notice the north/south symbol on a corner of your map with a straight 90° line going up. Line it up with that.
- Check to see if the north directional arrow is inline with the arrow/line of the compass. If not, recalibrate before continuing.
- Designate your starting and ending points on the map. You need to know where you’re going before toying with the compass.
- Lay the compass on the map, using the straight edge to create a line from your starting point to your destination.
- Using the rotating bezel, turn it until the direction of travel arrow lines up with the north arrow.
- Once you are physically at your starting location, it’s time to put your compass to good use. Stand so that you can see where the north arrow is pointing, and where your direction of travel arrow is pointing. You want to line up your view so the direction of travel arrow is straight ahead.
- Now it’s time to use the lens. Your lens piece will appear just above your thumb loop. Tilt it forwards until you can see your sighting arrow. Gently pull the lid down until the sighting line is visible through the lens.
- Look through the lens and sighting line. As long as you’re lined up with your direction of travel arrow (keeping that north arrow visible for reference), you need to look through the sighting line and pick a landmark ahead of you. Travel to that landmark.
- Once you reach your landmark, align yourself again to make sure you’re on the right path. Use the lens to look through the sighting line to find another landmark, and repeat until you reach your destination.
If you don’t start out using your lensatic compass with a map, then it’s just a regular compass. If your destination is further than what the side edging allows for, you can use an actual ruler to align with the side of your compass edge to help you get to your destination.
What Can Disrupt a Compass?
Any kinds of magnets whatsoever. A compass needle aligns with the magnetic fields in the Earth, which is what it uses to help you find true north.
But it isn’t just magnets – there are other culprits at play, here. These other objects can interfere with compasses, and no matter how miniscule the differences may seem, it can leave an impact.
- Wristwatches: Your watch is using a battery of some sort, even if it’s quartz. The magnetic property in your watch could be disrupting a lensatic compass, especially if you’re using your watch-claden hand to hold the lensatic compass by the thumb loop. This is generally subtle, but if you keep the compass still and move your watch hand away, you’ll notice it responds with slight movements.
- Keys: I don’t know why you would have your keys next to your compass, but if you do, it could interfere with your lensatic compass. The only real reason I see this being a problem is if you store your keys next to your compass overnight, or something like that.
- Tables With Metal Legs: Metal tables, metal legs – they could both cause issues for your lensatic compass. While it’s unlikely that you’re going to leave your compass on these tables for very long, you may actually have to recalibrate them anyway.
Without getting over-complicated, a standard compass is different from a lensatic compass. They both use magnetization to help you find where you are and where you’re going, but there’s a catch.
Standard compasses use floating dials, but lensatic compasses use a damping mechanism powered by electromagnetic induction. It’s a subtle difference, but it’s a roundabout way of saying lensatic compasses are less prone to interference than others.
How to Store Your Compass?
The number one destroyer of compasses and any enclosed items like these is moisture. When moisture seeps into the lens case of your lensatic compass, it causes major problems.
Most lensatic compasses are designed to withstand moisture to a certain extent, but nobody makes them perfect. Because most of the components are housed in a casing, moisture can wreak havoc once it’s in there.
When you return from using your lensatic compass, take it apart as much as possible to detect any moisture. At that point, leave it out in a spot where it can really dry overnight until you know the internal components are no longer moist.
Now it’s time to store your compass. While this doesn’t technically register as an electronic, we’re going to treat it like one.
You’ll want to stick to areas that are cool and dry, and don’t offer any immediate threats to technological devices. A good temperature of 65°F to 78° should keep the humidity down and help preserve the structural integrity of the compass.
Last but not lease, lensatic compasses are prone to scratching. When the actual lens gets damaged, it unnecessarily impairs simple operation. Keep it in a case, or wrapped up in a thick cloth to prevent those damages.
Becoming the Master of Navigation
Lensatic compasses are seasoned or experienced navigator tools. They’re not traditionally used for camping trips or simple navigation, but if you’re serious about prepping, this is a must-have in your EDC bag and bug out bag.