Unveiling the Compass’s Core: The Foundation of Navigation
The Needle/Dial
The heart of the compass is the needle or dial. This magnetized component is free to rotate and will align itself with the Earth’s magnetic field. It’s usually marked with red or another contrasting color on the north-seeking end. This colored end of the needle is the critical element to pay attention to when navigating.
The Baseplate
The baseplate serves as the foundation, a stable platform on which all the other components are mounted. Often, a compass baseplate has ruler edges and a sighting line (also known as a direction-of-travel arrow) to help the user determine the bearing or direction to travel. This forms the structure of the entire device, and it’s from this that the user derives their directional readings.
The Rotating Bezel
The rotating bezel is a circular ring that can be turned around the compass housing. This is a critical component for measuring and setting bearings. It’s usually marked with degree markings (0 to 360) and often has cardinal points (N, S, E, W) clearly indicated. By manipulating the bezel, you can introduce the crucial declination adjustments, which allows the user to change compass direction to the correct bearing.
Sighting Lines
In certain compass designs, you may find sighting lines or a mirror, used to aid in the accurate measurement of bearings to distant objects. This helps the user aim at a distant object and read the bearing by aligning the compass with the object and reading the degrees on the bezel. This increases accuracy, especially when it’s necessary to obtain an exact reading.
Magnetic North vs. True North: Understanding the Difference
The compass, as we know, points towards magnetic north. However, magnetic north isn’t the same as true north (also referred to as geographic north), which is the direction to the North Pole. The difference between the two is crucial to understanding how to change compass direction and achieving accurate navigation.
True north is a fixed point, whereas magnetic north shifts slightly over time due to movements within the Earth’s core. This shift is known as magnetic declination. It’s important to understand and compensate for magnetic declination, especially when traveling longer distances. The disparity between these two points of north significantly impacts the bearing you follow, and failing to account for the difference can put you off course.
The implications are simple but far-reaching. Your compass may show a bearing that is off from the actual destination bearing. This discrepancy increases the greater the distance traveled. As you progress in your journey, the need to properly account for declination becomes essential.
Magnetic declination is measured in degrees, and the value varies depending on your location on the globe. The magnitude of the declination angle, and whether it is positive (east) or negative (west), will determine how you adjust your compass to align with true north. Correcting for this difference is a fundamental step in the process of learning how to change compass direction.
Bearing and Azimuth: Speaking the Language of Direction
Bearing and azimuth are critical terms in compass navigation, representing the angles used to define and measure directions. Mastering these concepts is essential for precise route planning and accurate navigation.
A bearing is the horizontal angle measured clockwise from a reference direction (usually north) to a specific point or destination. Bearings are usually given in degrees (0 to 360). To take a bearing, you would align your compass with the object and read the degree reading.
An azimuth is very similar to a bearing. It is also the horizontal angle measured clockwise from north, and is used to define a direction in relation to the compass.
The ability to measure, calculate, and use bearings is a core skill for all outdoor adventurers. A clear understanding is critical for mapping your journey and adhering to your planned route. Determining a bearing requires two pieces of information: your location and the direction of your objective. Once you know these two, you can determine the bearing with a map and compass.
Addressing the Influence of Magnetic Declination
As we’ve previously mentioned, magnetic declination is the angular difference between magnetic north and true north. To accurately navigate, it is essential to learn how to change compass direction by properly accounting for declination. This requires understanding how to determine your declination for a specific location and how to adjust your compass readings accordingly.
Finding Your Magnetic Declination: A Crucial Step
The initial step to correcting your compass reading is determining the declination for your current location. Fortunately, various resources are available to assist you in this process.
Topographic Maps
Topographic maps are an excellent resource, especially for outdoor adventurers. Most topographic maps display the magnetic declination for the area they cover, usually printed somewhere in the legend or margin. They provide the declination value and the annual change in declination, allowing you to know if the value has changed since the map was published.
Online Declination Finders
Online declination finders offer another efficient method. Many websites and apps allow you to enter your location (latitude and longitude, or a general address) and instantly retrieve the declination. These tools are continually updated with the most current data, providing a fast and reliable way to find the declination value for your location. Some examples include the NOAA (National Oceanic and Atmospheric Administration) website and various other online tools.
GPS Devices
GPS devices, while not solely dedicated to compass functions, sometimes display declination information. While this feature may vary across different models, the ability to access current declination data can streamline the navigation process.
Adjusting for Declination: Changing Your Compass Readings
Once you have determined the declination for your location, you must adjust your compass readings.
The principle of adding or subtracting declination is based on whether the magnetic declination is east or west of true north. A helpful mnemonic is, “East is least, West is best.” If the declination is east, subtract the declination from your compass bearing. If the declination is west, add the declination to your compass bearing. This process changes compass direction so that the reading is correct.
Let’s consider an example. If your compass bearing to a destination is 60 degrees, and your magnetic declination is 10 degrees east, you would subtract the declination from the bearing. Your corrected bearing would be 50 degrees. Conversely, if the magnetic declination is 10 degrees west, you would add it to the bearing, resulting in a corrected bearing of 70 degrees.
Another method involves adjusting the compass bezel. Many compasses are designed with a declination adjustment feature. To use this, rotate the bezel so that the index line (often marked with a small triangle) is offset by the declination amount. For example, if the declination is 10 degrees east, rotate the bezel 10 degrees east (counterclockwise on most compasses) so that the index line aligns with the 10-degree mark on the bezel. Once the bezel is properly set, any bearing taken with the compass will already be declination-adjusted. This will change compass direction to match the true north bearing of your destination.
Declination-adjusted compasses are also available, incorporating built-in mechanisms to compensate for magnetic declination. These compasses are designed to provide instant, accurate readings without the need for manual calculations. This can simplify the navigation process, particularly for beginners.
Declination: More Than Just a Static Value
Declination is not a static value. It changes over time, and the rate of change varies depending on your location. This change, called secular variation, is caused by shifting within the Earth’s core. Therefore, it’s crucial to stay updated on the current declination for your area. Checking for updates can be done using the same resources you used to find your declination in the first place, as the values on topographic maps and online declination finders are regularly updated.
Taking and Following a Bearing: Charting Your Course
Once you understand magnetic declination and have adjusted your compass, the next step is to learn how to actually take and follow a bearing.
Determining a Bearing to a Destination: A Detailed Look
Before you set off, you need to plan your route. This involves determining the bearing you need to follow to reach your destination.
First, orient your map. Place the compass on the map and align the edge of the compass’s baseplate with the line connecting your current position to your destination. Make sure that the direction-of-travel arrow of the baseplate points towards your destination.
Then, rotate the compass housing (bezel) until the orienting lines on the compass dial align with the north lines on your map (typically marked with a series of parallel lines that point towards true north). Ensure that the red (or north-seeking) end of the needle is aligned with the orienting lines.
Finally, read the bearing. The bearing is the degree mark on the bezel that is aligned with the direction-of-travel arrow.
Following a Bearing in the Field: Staying on Track
With your bearing determined, you can now follow that direction in the field.
Hold the compass in front of you, ensuring the direction-of-travel arrow is pointing directly away from you. Rotate your body until the north-seeking needle aligns with the orienting lines inside the compass housing. Once the needle and orienting lines are lined up, the direction-of-travel arrow points towards your desired bearing.
Walk in the direction indicated by the direction-of-travel arrow. Select a distant landmark (a tree, rock, or distinct feature) along that bearing to help you maintain your direction. Periodically, re-check your bearing and choose another landmark ahead of you, to make sure you do not drift off course.
Back bearings provide a crucial safety net, allowing you to verify your current position. If you take a back bearing (the opposite of the bearing you are travelling on) and compare it to your original position on the map, you can ensure you’re on the right track.
Navigation, especially in the outdoors, can be challenging. The ability to consistently understand and utilize the methods to change compass direction is an important component of becoming a proficient navigator.
Troubleshooting and Practical Adjustments: Refining Your Skills
Navigating with a compass in the field can present challenges, ranging from magnetic interference to observer error. Addressing these challenges is key to improving accuracy and making on-the-spot adjustments.
Sources of Error: Avoiding Common Pitfalls
Magnetic interference is a primary source of error. Metal objects such as car keys, belt buckles, or nearby power lines can disrupt the compass needle’s alignment, leading to inaccurate readings. The best approach is to move away from potential sources of interference before taking a bearing.
Compass inaccuracies are also possible. Check your compass frequently against a known bearing or reliable reference, such as a GPS device or a map. Any noticeable deviation may require adjustments.
Observer error also plays a role. Ensure that you hold the compass level and avoid tilting it during bearing measurements.
Making Practical Adjustments: Adaptability in Action
Knowing how to make practical adjustments helps to optimize your navigation skills.
Drift, a gradual deviation from your intended course caused by wind, currents, or uneven terrain, demands constant vigilance. Be aware of the factors and compensate by making frequent bearing adjustments, using landmarks, or employing back bearings to refine your course and stay on track. This frequent adjustment allows you to continuously change compass direction as needed.
When available, sighting lines or the mirror on the compass enhance accuracy by allowing you to sight a distant object more precisely. By aligning the compass with the feature and the needle, it is easier to read and maintain your bearing.
Regularly check your compass for accuracy. If your compass is consistently off, it may require maintenance.
Conclusion: Mastering the Art of Compass Navigation
This guide has illuminated the fundamental principles and practical techniques for successfully changing your compass direction. From understanding the compass basics to mastering declination adjustments and on-the-ground navigation, the ability to correctly manage compass direction is crucial for all outdoor adventurers.
By consistently practicing and refining these techniques, you’ll build confidence and develop a deeper appreciation for the art of navigation. As you step outside, remember to always check your position and practice safe navigation habits. With your knowledge of how to change compass direction combined with consistent application, you’ll be well-equipped to explore the world with confidence and precision. This article is the foundation of successful navigation.
