TrueNorth User Guide

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TrueNorth Military Compass User Guide

This guide will help you understand your compass and use it effectively for navigation and measurement. Follow these instructions to make the most of your compass.


Compass Overview

  1. Thumb Ring: Provides a stable grip.

  2. North Line with North Arrow: Indicates magnetic north.

  3. Bubble Level: Ensures the compass is level.

  4. Compass Rose: 360° scale for precise bearings.

  5. Rotary Dial: 360° scale for angular adjustments.

  6. Inch Scale: For basic measurements.

  7. Base Table: Supports the compass.

  8. Housing: Protects internal components.

  9. Lens Prism: Vertically adjustable for clear readings.

  10. Sapphire Bearing: Ensures smooth rotation.

  11. Centimeter Scale: Additional measurement tool.

  12. Stand Thread: For tripod mounting.

  13. Sighting Window: Includes sighting line for alignment.

  14. Lid: Protects the compass and components.

(Include diagram of compass parts labeled with numbers 1-14 for visual reference)


Using the Compass

1. Taking a Bearing

  • Open the compass until the lid is perpendicular to the housing.

  • Fold the prism holder forward and adjust its height until the dial is sharply focused.

  • Turn your body while holding the compass so that the sighting line aligns with your target.

  • Read the bearing where the sighting line intersects the compass dial.

(Include a diagram illustrating how to take a bearing with the compass)

2. Walking a Bearing

  • Once the bearing is set, look through the prism and align your body until the bearing is visible on the dial.

  • The sighting line will guide you directly toward your target.

3. Orienting a Map

  • Place the compass on the map with one edge along a meridian.

  • Turn the map and compass until the north arrow on the dial aligns with the map’s north.

  • The map is now oriented to match the terrain.

(Include a diagram showing map orientation using the compass)

4. Determining Direction on a Map

  • Align the compass edge with your position and the target on the map.

  • Turn the dial until the arrow points north.

  • Read the bearing where the sighting line intersects the dial.

5. Determining Direction in the Field

  • Select a prominent landmark along your intended direction.

  • Align the sighting line with the landmark and take the bearing.

  • Walk toward the landmark, repeating the process as needed.

6. Determining Your Position

  • Choose a visible landmark approximately 90° from your direction of travel.

  • Take a bearing to the landmark and mark it on your map.

  • Repeat with a second landmark to pinpoint your location.

(Include a diagram illustrating position triangulation using two landmarks)


Advanced Functions

1. Measuring Angles

  • Align the compass sighting line with one edge of the object.

  • Note the degree on the dial.

  • Turn the compass to the opposite edge and subtract the two readings to find the angle.

2. Measuring Distances

  • Use the provided tables to calculate distances based on angles and gradients.

  • For example, a 10% gradient indicates the object’s width is 1/10th of the distance.

(Include sample calculations and a diagram showing distance measurement using gradients)

3. Using the Clinometer (Optional Accessory)

  • Align the compass with the object’s base.

  • Slightly tilt the compass and note the angle of inclination on the scale.

  • Use the provided table to compute the object’s height or slope.

(Include a diagram demonstrating clinometer use to measure slope and height)


Maintenance and Tips

  • Ensure the compass is level using the bubble level for accurate readings.

  • The liquid-filled capsule ensures stability. Temporary bubbles may appear but will settle after 24-48 hours of use.

  • The integrated spirit level and tripod mount allow for advanced surveying tasks.

  • Replace the capsule if necessary by removing the screws on the base and ensuring the foam pad is properly reinserted.

(Include a diagram showing how to replace the liquid-filled capsule)


Understanding Magnetic Declination

Magnetic declination is the difference between true north and magnetic north. Adjust for declination by adding or subtracting the local value:

  • Western Declination: Add the value to your compass reading.

  • Eastern Declination: Subtract the value from your compass reading.

Refer to local maps or topographic resources for the correct declination in your area.

(Include a sample table of declination adjustments based on location)


Key Tables for Reference

  • Table 1: Angles, gradients, and height-to-distance ratios.

  • Table 2: Expanded measurements for advanced calculations.

(Include these tables visually in the guide)


Troubleshooting

  • Rattling Sound: Check for loose parts inside the compass. Disassemble carefully to identify and fix the issue.

  • Blurred Readings: Adjust the prism height or clean the sighting window.

  • Temporary Air Bubbles: Allow the compass to stabilize for 24-48 hours under normal conditions.


For additional support, contact Off-Grid Gear customer service. Thank you for choosing the TrueNorth Military Compass for your navigation needs!