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Using the Cammenga

Cammenga Compass

Creme de la Creme

      Nowadays, how often can we purchase a product, knowing it's the best and not worry about the price? Originally designed to meet the exacting demands of military service, the Cammenga is the most accurate, durable, handheld compass on the market. It's not particularly expensive, comparative to men's general equipment. The aluminum body folds to form an integral case, protecting from impact and chemical spills. Deet will melt generic plastic compasses. The sapphire bearing is locked when closed, shielding it from impact shock.

The Cammenga is unique in that it is aimed like a rifle sight to provide extremely precise bearings using Mils. These bearings are used to triangulate our position. The key principle to using the Cammenga is to maintain good cheek weld, just like rifle sights. Align the notch and wire to the target, glance down and read the bearing through the magnifying lens. The Model 27 uses a compass card, rather than a needle and distinct graduated bezel. This makes taking a bearing quicker as the graduations turn with the needle.

The deep well design minimises needle drag, essentially offering global use. Most handheld compasses can only operate in one of five zones. Their needles stick if used outside their calibration. Cammenga's excellent dry copper induction dampening is resistant to extreme environments and snaps to North within three seconds. Most generic compasses use an alcohol solution to dampen needle oscillation; bubbles form when exposed to high altitude or low temperature, obstructing needle travel.

Orienting Map

Some compasses use a mechanism to offset for declination but these are vulnerable to bumps. A better approach is to offset the map to Magnetic North (MN) rather than to offset the compass to Grid North (GN). Extend the MN line in the map margin and draw multiple parallel lines using your protractor and pencil. Align a protractor to the map's MN lines to plot route headings and checkpoints in advance, without needing to orient the map or convert for declination. In the field, use a mini protractor and MN lines to find a new compass heading 'on the fly' without orienting the map. Alternatively, orient the map as described below, align the side of the Cammenga to the new route and rotate the bezel marker to the compass needle, as you would any baseplate compass. Some owners use luminous paint to convert the top luminescent sight line to an arrow. This assists baseplate and night navigation modes.

To orient the map, align the compass's graduated straight edge to the map's MN line. Rotate the map and compass as one unit, until the compass bearing reads 0 degrees at the black index line. The compass arrow and margin MN arrow will be parallel. Calibrate your compass before drawing additional MN lines on your map. This is useful for terrain association and plotting bearings. The Cammenga is sensitive to the presence of ferrous metal or magnets on our person. To calibrate, take a sighted bearing in Mils on a known line of direction, wearing all of your field gear. Compare the known magnetic azimuth to your compass bearing. If the variance is more than 10 Mils, then use your protractor to draw a new compensated MN line in the map margin and extend it onto the map as discussed above.

Cammenga 27 at night

Paper maps become less accurate over time as man made features come and go. The Earth's magnetic field can shift as much as 1 degree per year. Confirm your current declination on NOAA by selecting the country and city near the map location. Click the get location button. Click the compute button.

Cammenga's civilian variant, the Model 27, is outstanding value for money. It has identical mechanical performance to the military model, except phosphorescent illumination replaces tritium. This modification brings the price in line with generic plastic products. Tritium illumination is appropriate for tactical scenarios that require light discipline. The Model 27 requires a two-minute charge with white light, to provide two hours of visibility at night. Its weight of 7oz is acceptable considering the proven features, detailed above.
Cammenga Model 27 Compass (USA)
NOAA Declination Calculator

MN Lines

Cammenga Compass Learning Downloads.

Point navigation skills come into play when traversing featureless terrain or low visibility. Most people become lost during white out or fog conditions. Landnavigation.org has assembled an excellent introduction to point navigation, designed specifically for the Cammenga compass. Relevant low visibility techniques covered are trusting the compass, fixing position with resection or intersection, thumbing the map, dead reckoning, intermediate landmarks, human landmarks, back azimuths, negotiating obstacles, off aiming and emergency backstops.

Foggles are a convenient way to simulate low visibility for training purposes. Major terrain features are obscured; the compass and immediate surroundings remain visible. Land Navigation has some technical aspects. However, the color graphic presentation of these files, abstracts the detail to avoid overwhelming the reader. The sequencing could be more practical but there is a lot of useful information contained. These files are large, so save them to your hard drive for future reference. (Note: right click and select "save target as" to save each file directly to your hard drive)
Download Part 1: Compass, Map and Protractor
Download Part 2: Compass, Altimeter, Grid Refs and Ranging
Download Part 3: Planning, Baselines, Thumbing Map and Supplementary Skills
Download Part 4: Desert, Jungle, Artic, Low Vis and Low Light navigation
Download Part 5: Terrain Association Techniques

Protractor

3: Cammenga Compass Accessories.

Putting all our data on the map case makes for a busy and disorganized layout. A waterproof pocket notebook can store route leg headings, route leg distances, check point bearings, landmark check offs, grid references, emergency backstop headings, pace count tables and timed travel tables. Pair it with a pencil or space pen. Use permanent markers to highlight the route, MN line, handrails, checkpoints and backstops on the map case. Color code for clarity. Use a correction pen for removal.

The military style protractor looks like a daunting piece of equipment but it's pretty easy to grasp. It has triangular cut outs for plotting GPS coordinates on 1:25K, 1:50K and 1:100k maps. The compass rose is graduated in degrees and Mils. It's designed for advance planning, when it may not be possible to align the map, place the compass on the route and record the heading. We may be in a room with magnetic interference or an area with different declination.

Plotting grid references is covered in download part 2. To calculate a magnetic heading, place the crosshair on the start point of the route leg and align protractor edges with MN lines drawn on the map. The heading is indicated where the end point of the route leg intersects the rose. The crosshair has a hole for a piece of red thread secured by a knot on each side. Use it to extend the line between route start and end points, to assure intersection with the rose. Drawing multiple MN lines on the map alleviates the need for declination conversion, as described earlier.
Foggles
Notebook
Map Case
Map Protractor
Permanent Markers
Correction Pen

Ranger Bead Use

Pace count is accurate to 500 meters when dead reckoning to a point target and several miles to an area target. Pacecounter beads help keep track of distance traveled. Timed travel is less accurate than pace count but useful for terrain association as it's easier to sustain. A simple stopwatch is worthwhile, the timer is interrupted at each halt, alleviating the need to record each start/stop time with a standard wristwatch. At a typical speed of 5 kph, 1.2 minutes equates to 100 meters distance. Download Part 2 has more information on pace count and timed travel tables.

Button failure is a common complaint with stopwatches. The Pro Survivor has been tested to withstand one million button cycles. It is silent, water resistant, has a large display and is operable with gloved hands. The buttons have a tactile click rather than an audible beep. The G-Shock 5600 military wristwatch also functions as a simple stopwatch.

The precision of the Cammenga isn't always necessary. The Suunto M-9 wrist compass compliments the primary compass in this respect. Worn on the wrist, it's convenient for quick bearing checks during terrain association. It functions as a miniature Cammenga with sights, compass card, readout window, phosphorescent display and rotating capsule to lock in headings. Sights are a front notch and rear inverted post. The M9 has liquid damping and northern hemisphere balance. It's a complimentary compass rather than a stand-alone unit.

Night adaptation goggles are used by astronomers and night hunters that exit lighted homes in the middle of the night to pursue their interest. The red filter prevents white light from bleaching out photosensitive chemicals produced in the retina. Wear them for twenty minutes to develop full dark adaptation.
Pacecounter Beads
Pro Survivor Stopwatch
G-Shock 5600 Wristwatch
M9 Wrist Compass
Adapter Goggles

Flashlight Filter

The Surefire FM70 is a professional grade flashlight filter kit developed for map reading and body fluid discrimination under low light. Blue light protects our eyes night adaption and suffers minimal feature washout on standard topographic maps. Map water features are color coded blue and wash out under blue light. Any relevant water features should be marked with a yellow highlighter to appear black under blue light.

The FM70 is a fourth generation product that mechanically locks onto the flashlight bezel to prevent loss or accidental white light discharge. A mechanical catch locks the filter over the flashlight lens. Lifting the catch releases the spring loaded filter lens that retracts flush to the flashlight body. Preceding friction locked designs slipped off, popped open or snagged in white light mode. The FM70 design eliminates these malfunctions.

The FM70 is compatible with any 1.00" or 1.25" Surefire flashlight bezel. However the dual output 6PX Pro is the most suitable model. Low output is 15 lumens. High output is 320 lumens. Low output blue light supports low light map reading and medical care. High output blue light assists tracking blood trails. Blood deposits on foliage will appear pitch black under blue light. Other body fluids such as sweat, saliva and urine will fluoresces under blue light. This is because the blue light filter transmits a certain amount of UV too. Blood also appears black under pure UV light. Blood only fluoresces under UV if pre-treated with Luminol.
Surfire 6PX Pro (USA)
Surfire FM70 Filter Kit

Questions & Feedback.

Well, that's about it guys. I hope you found this guide useful. If you have any questions or feedback, feel free to contact me through the welcome page.

Personal Photo

Ian ST John.

 
  
  
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