Sighting Compasses

Sighting compasses are used to determine the azimuth of far away targets.  These are great for finding unknown locations via Resection and Intersection methods.  Targets can be pinpointed on a map via Intersection where azimuths are taken from multiple known locations and these azimuths are used to make directional lines on a map.  Similarly, your unknown location can be pinpointed by taking a back-azimuth from multiple known targets (such as mountain tops) with a technique known as Resection.  These techniques are used for search and rescue, determining where you are at, surveying, calling in helicopter landing zones or airstrikes.  

For navigation, sighting compasses allow you to travel in straighter lines by enabling you to pick out long distance navigation points (such as tree tops) you can head towards.  For those accustomed to this type of navigating, a sighting compass is a must.

Recommendation

• Most Scouts will do well with a basic Baseplate Compass

• If a Sighting Compass is needed:

  • Suunto MC-2 NH Mirror Compass

  • Cammenga Lensatic Compass

    • Can be found surplus - sometimes new for $40

    • Don't buy a $10 Chinese Copy - it doesn't work the same

Map Protractor

A map protractor is an indispensable tool when plotting long distance azimuths and angles.  This is infrequently carried by backpackers and is often substituted with a clear baseplate compass, which works fine for shorter distance measurements.  If your adventure requires accurate long distance plotting, then you should have a quality sighting compass, a good map AND a map protractor. 

Many Mirrored Sighting Compasses such as the Suunto MC-2 have a transparent baseplate and can be used as a protractor like other baseplate compasses.  Compasses with a opaque case, such as the Cammenga and Brunton Transits don't work well as a precision protractors.  These need a separate protractor for optimal use. 

Mirror Compasses

Mirror Compasses are the most common sighting compasses on the market.  The use a mirror on a hinge that allows you to aim your compass forward while viewing a mirror image of your compass dial.  This allows you to align everything for precision and to take a reading without taking your eye off your target.  The are also very compact and light weight.

The mirror can also be used for signaling and to check out part of your body you can't see for tick and wound checks. 

Suunto MC-2 G Mirror Compass

The MC-2 also comes in a Global model.  The Global version has a 20 degrees tilt, special bearing that allows it to be used in both the Northern and Southern Hemispheres.  It also makes it easier and quicker to get bearing when your compass isn't perfectly level and when on the move. 

These sometimes go on sale for less than a non-global compass.  

Lensatic and Prismatic Compasses

These compasses use a lens or prism to view your dail while you aim your compass at a target.  This allows for very accurate data collection.  They are often overbuilt for heavy duty surveying, geology or milityary use. 

Cammenga Tritium Compass 3H Lensatic Compass

The Lensatic compass has a lens on the rear side of the compass used for reading azimuth readings.  These compasses allow for very accurate azimuth readings (Accuracy +/- 40 mils).  These are the standard compasses used by the military to navigate in foreign lands.  It can also be used as a surveying compass as well as to call in artillery and airstrikes by the military.  

The Tritium 3H version of this compass comes with 7 vials of radioactive tritium.  The tritium glows in the dark, allowing the user to take accurate readings in complete darkness.  Non radioactive versions are also available and are more affordable. 

Instead of using a liquid to dampen the needle, the H3 uses a copper induction-damping ring to slow and steady the needle.  This non-liquid filled needle housing allows for use in temperatures between -50 to +150° F.  Suunto lists their operating range of liquid filled compasses at -22 to +140° F.  Note that quality-liquid filled compasses are NOT filled with water.  The don't freeze at subfreezing temperatures, but bubbles may form when they get cold.

The metal shockproof, damage-resistant design with copper induction-damping ring may allow it to take accurate and reliable readings in a post apocalypse environment, but it is anything but lightweight.  The metal case also prevents you from using the compass as a protractor, a popular feature of baseplate compasses. 

Scoutmasters who served in the military may prefer these over baseplate compasses due to familiarity or nostalgia.  Those used the to precision of these compasses may also feel at a loss with a baseplate compass. 

Geological and Surveying Compasses

These compasses are designed for taking very precise reads.  They are used by geologists, surveyors and the military. 

These compass types are generally designed for static use and NOT for orienteering.  They can be very bulky and heavy and not great for general navigation purposes.  

These are NOT recommended for outings and a simple baseplate compass will better serve a Scout for 95% of they will be expected to do. 

Brunton Pocket Transit Compasses

Transit Compasses such as the Brunton Pocket Transit utilizes magnetic induction damping rather than fluid to dampen needle oscillation.  These are precision tools used primarily geologists, archaeologists, environmental engineers, mining engineers, surveyors and for crew-served artillery.  It is Accuracy +/- 10 mils.

Military and Civilian Transits provides slope, angle of site, and azimuth readings.  The dial can be calibrated for grid or magnetic azimuths, which is a big bonus over the standards military Lensatic Compass. That said, Transits lack a rotation bearing ring, which is very useful for navigating on the move.

These are incredible tools, but too much for Scouts and most outdoors use.  A quality Transit will set you back several hundred dollars - which is excessive unless you are using it for geology, surveying or calling in precision strikes. 

Optical Sighting Compasses

These us a optical viewer to view readings while aiming the compass at a target.  Pros for this are speed and ease of use when taking an azimuth for a far away target.  

These are expensive and a mirrored sighting compass will likely serve a Scouts much better as sighting compasses are NOT designed for orienteering. 

Other Sighting Compasses

There are many other sighting compasses that work well for navigations.  Some are readily available in the US and some are a bit less common.