BASE PLATE

Clear Base Plate

A clear base plate is a nice feature to have. For those who fully utilize the power of a compass and use the compass with maps a clear base plate allows you to read maps, determine a bearing, mark the bearing on your map and / or measure distances. We recommend steering clear of solid base plates.

Baseplate Magnifying Lens

A magnifying lens built into the base plate is a great feature and will likely be utilized many times over the lifetime of your compass. Maps can be a challenge to read. Many maps are reduced in size to accommodate a larger landmass. Now take that map and read it at night with no ambient light and look for a font likely < 2 pts in size... GOOD LUCK!! If you are over 40... cash in the map and use it for fire tinder!!  As a bonus a good magnifying lens can be utilized as an improvised fire starter when partnered with the sun.

Straight Edge Scale Markings for Accurate Map Reading

A clear base plate with scale markings based on standard map scales is a great feature to have. Having to use a torn up piece of paper to figure out distance on a wet log in dusk conditions is not particularly pleasant nor accurate. Having build in scales will come in handing many times over the life of your compass.

Orienting Lines

With in the main bezel frame of the compass look for orienting lines. These lines are invaluable when using the compass on a map. These lines help you to determine a bearing or square up your compass with the map to determine accurate readings.

Rubber Non-slip Feet

Rubber feet on your base plate is helpful as you plot readings on your map and determine bearings. These rubber feet prevent your compass from slipping on the map. Particularly if your map is encased in a map case.

BEZEL

Large Easy to Read Bezel

The readability of your bezel is important. Make sure the number and hash marks can be easily read. Once you make the purchase and find yourself in the woods the bezel will become more of a challenge to focus on and sight up.  Less expensive compasses often are very difficult to read and on occasion the paint used for each hash mark has bled outside the hash mark crease making the readability poor. Look for larger numbers, cardinals, inter-cardinals and hash marks.

Easy-grip Bezel in 2-Degree Increments

A good quality bezel will make your job as a navigator much easier. Many compasses have ridges in one degree increments. These help to prevent cold and / or wet hands from slipping on the bezel. A small number of compasses come in one degree increment readings and a smaller number come with 5 degree increment readings. We have found the one degree increments are just to small and are difficult to read. Even if you can read them you wind up needing to count in order to ensure you haven't miscalculated. The 5 degree version is simply inaccurate and leaves the door open for error. Make sure you select a compass with 2 degree increments.

Luminous Outer Ring for Low-Light Reading

Make sure you get a compass with luminous cardinal points. Nothing is worse than navigating at night solely by the light of a head lamp or flashlight. Pay particular attention to wording on the descriptions. Some will claim to have high visibility markings or easy read marking carefully avoiding the operative word "luminous". Don't compromise or be tricked into some other gimmick.

Clinometer

A clinometer function is not critical but is very nice to have. This allows you  to assess slopes and determine avalanche danger or high risk rock slide areas. If you decide to do with a clinometer function on our compass MAKE SURE you know how it works and how to use it. Also make sure you practice with it. Trying to figure this out while in the field under pressure will likely produce sub-optimal results.

SIGHTS

Sighting notch & Mirror

There are two schools of thought with concerning the question is compass lid is a good thing or bad thing. After over 10,000 hours in the woods and navigating in extreme conditions with limited visibility and through highly dense vegetation. Our experience tells us that having a lid on your compass with a sighting notch & mirror is by far the better tool to have. Reasons for our recommendation are as follows: (1) After you have determined your bearing and set your compass the door can be closed ensuring the bearing is not accidentally knocked off it's setting. (2) The sight at the top of the door enables you to take far more accurate readings and stay exactly on course. Without the sights your conducting SWAGS. (3) The mirror inside the door serves two purposes. (3.a) It allows you to shoot your bearing and keep the compass level. Without using a mirror to shoot bearings the compass is more than likely NOT level which can influence the needle float giving you inaccurate readings. Sighting the compass and viewing the needle a the same time without a mirror is counter productive and inaccurate... go with the mirror. (3.b) The mirror and the sight can be turned around and used for signaling. The sight is great for targeting an air craft and the mirror use with the sun then sends the signal to the air craft. (4) The mirror in conjunction with the magnifier on the base place (you did get the magnifier on the base plate didn't you?) can be used to start a fire by directing and focusing the sun into the magnification point.

Split-sighting mirror

Silva Ranger 515 CL comes with a split sighting mirror. This is a vertical slit right down the middle of the mirror. What a great feature and boots navigation efficiency for superior accuracy when navigating on distant landmarks. This is not a standard feature on compasses but highly valuable. As a secondary function the split sighting mirror offers benefit when attempting to signal an air craft and directing the sun right into the center of the mirror. 

FUNCTIONS

Adjustable Declination Scale

To account for the difference between magnetic & true north make sure you have an adjustable declination scale. About 20% of compasses do not have a declination adjustment. If you shop by price and don't look for this you are likely to end up with a compass without this type of adjustment. MAKE SURE you get an adjustable compass unless you like math and are willing to bank on your ability to always adjust for the declinations each and every time you shoot a bearing.

Adjustment Key

The fundamental foundation of how a compass works is based off magnetic declination. So what is declination? Magnetic declination is the angle between magnetic north (the direction the north end of a compass needle points) and true north. The declination is positive when the magnetic north is east of true north. The term magnetic variation is a synonym, and is more often used in navigation. Isogonic lines are where the declination has the same value, and the lines where the declination is zero are called agonic lines. If you can't adjust your declination and ensure it is accurate your ability to navigate by the compass has just become more difficult. Most compasses use an adjustment key to set your declination. Some respected brands that used these are brand such as Suunto or Silva. Brunton has introduced a newer concept where the center mechanism within the bezel can be pinched and adjusted by holding the bezel and twisting the center component to the left or right. The plus of this feature is that you eliminate the key and it is easier to adjust the delination. The down size is it's easier to adjust the declination which opens the door for the declination to be accidentally knocked off it's setting. Your delination is adjusted very few times relative to used. Likely, adjustment will occur 

Lanyard

Most if not all compasses come with a lanyard. But just in case make sure you have a good lanyard and if you use the lanyard that comes with the compass it's a good one. I've noticed recently many compass compasses have tried to cut cost by providing a poor lanyard that is very thin and slight to short. Better yet get a 24 to 30 inch piece of 550 para cord and make a lanyard. This is a great addition and in an emergency you now have additional cordage. Make sure you give yourself room to hold the compass away from you and sight your compass.

Global needle works anywhere on earth