Compass types, Beginners Article
Plastic Verses Metal
This is intended to create a paper with simple directions concerning how you use a compass, and provide some insight as to how different compasses are the same.
Some pro's and cons. I will demonstrate that all compasses do exactly the same thing, though they look different. The first problem I had with seeing a more "normal" flat, or hiking compass is that the base is plastic. It seems that, over time, the possibility of scratching or breaking is there.
The military compass is contained in a metal case, and when you close it the rotating dial is lifted off its base. That means that "banging it around" will not cause so much damage to the mechanism. As well, the dial rides on a synthetic jewel, when in use. Good stuff.
Walker verses Engineer
To "shoot an azimuth," you determine the degree from North the direction is that you want to go. By holding the compass level, you let the needle "round" to North. Sighting, you spot a landmark, and figure its angle from where you are standing. That is, you figure the direction of travel you need to go, expressed as a degree, by looking.
Now, on the Hiking or the Trekker model, see pictures, you rotate the dial to the degree you want. That degree number is matched up with the line on the flat base. Then, if you turn the compass so that the N on the outer ring and the North Arrow are lined up, walk in the direction the front of the compass is pointing. Simple, and for this paper, probably enough about navigation.
On the Military Engineer compass, you sight your direction either through the compass, or flat like the hiking one, and turn the dial so that the short line and the North arrow are together. Again, as long as you get the rotating needle and the mark on the dial to line up, you are going the right direction, expressed as a degree. Same thing.
Sighting- holding the Compass flat
The Military Engineer Compass allows you two options. You can fold it flat, and it looks like the hiking one. The black line under the glass is fixed, and when you line your degree mark up with it, you have your direction of travel.
For most simple hiking, that is all you will ever need. You know, you went into the woods heading generally East. To get out, however lost you might be, head out generally West. Simple example, but again as far as this paper goes.
What most people do, when they have determined their direction of travel, expressed in a degree, is sight a distant landmark to head toward. That way, if they get turned around or otherwise off course, while hiking, they can find some rise to climb up in order to sight their landmark. That is how Pilot Mountain, in North Carolina, (the Mount Pilot of Andy Griffith,) got its name.
Sighting- Mirrored or Engineer Compass
The Silva Trekker compass I have has a mirror on it. The idea here is that when you have your degree mark set you can sight when North is lined up, in the mirror. By folding the mirror at an angle, the notch at the top of the case serves as a sighting mark for your distant landmark. The fact that the image is reversed in the mirror does not matter, as again, all you want to do is be sure the red N on the ring and the Red, and the Red, North pointing arrow of the compass are matched up.
The Engineer compass uses a magnifying glass, at an angle to the base, to let you see the dial face of the compass. Again, you need to have the North mark on the dial and the North pointing arrow lined up. Now, with everything lined up on the dial, you can look across the notch on the magnifying glass holder and line it up with the thread in the middle of the slot on the case.
Whatever is in that line matches up with your direction of travel. (You would probably pick your landmark first, that is kind of where you want to go. This is not a surveying party.)
Sighting, Using the Cheaper compass
The black so called Engineer Compass I got at WalMart for about six dollars is still another story. The dial on it is so loose, you can remove it. There are two lines, which move together. I think that they wanted it to look like the Military model, but missed. The Military model has one line fixed, that gives you the center line of the whole compass body, and a second one you can rotate when you get everything lined up. Having both lines move make no sense. Still, you can use this cheaper compass. It works well as a general hiking compass.
Spare parts for six dollars
When I first got my Military Engineer Compass, for about ninety dollars, there were some bits of metal still attached to the ring that holds the magnifying glass. Sure enough, in trying to clean it, I scratched, and ruined it. Turns out I could take the same kind of plastic lens from my simple, black, engineer compass from WalMart, and epoxy it in place. (Don't try this at home, it is not easy.) As the original lens and the replacement were both plastic, it all worked out well. What is left of the WalMart compass still works for general use hiking.
websites for compass purchases
Silva - Gps Compass Compasses Binoculars Headlamps
I have the Silva Trekker, not shown on this site.
Cammenga, who makes the Military Lensatic Compass
The model with Tritium, which glows in the dark on its own, for about ten years after you buy it, is forty dollars more then the one that works with phosphorus, that you must shine a light on. Otherwise, the compasses seem to be the same.
I have the 3hcs, which is ninety dollars, with the tritium.
The 27CS is without Tritium and is fifty dollars.