How to Find Your Declination
The essence of being able to navigate in the outdoors with only a map and compass is easy, but in practice it’s a bit more difficult. For example, you typically need to adjust for magnetic declination when setting a bearing. But fully understanding this concept can take some mental effort, and finding the most current setting for your location can be harder. If you don’t, then you greatly risk finding yourself well off course. So, let me share a tool with you that I am confident that you’ll find convenient and helpful.
I regularly use the application What’s My Declination? on my iPhone because, in effect, it helps me to find North, the touchstone of land navigation.
But you’re probably already asking yourself, “Huh? The needle of his compass should already be doing that.” And, you’d be correct. Sort of.
The reason is, in effect, there are four Norths. The north to which a compass needle points is Magnetic North. Meanwhile, a topographic map is aligned to Grid North as you try to make your way in the woods in relation to Polar North. So it’s paramount that you determine True North, by making a declination adjustment to compensate for the Earth’s magnetic pull on your compass needle. Only by doing so can you navigate effectively to your destination.
Unfortunately, not only does magnetic declination vary from location to location, but even in those locations it continues to change over time as the Earth’s molten core flows and shifts. As a result, the declination adjustment listed on your map could quite literally be decades out of date. Putting this into context, consider that even if your adjustment is off by only 5 degrees, how far off target you’d be over a 1 mile distance.
Luckily, the smart folks at the National Oceanographic and Atmospheric Administration (NOAA) are always working to keep us up to date. So, of course, I regularly use their resources, but I usually don’t have internet access when I’m in the woods. That’s where WMD? comes in handy!
This application will provide the most current setting of my present location or anyplace else I plan to visit. Better yet, it’ll do so with, or without, wifi or cell access.
Please check out our video below to learn more about WMD?.
And if you would like to learn the fundamentals of land navigation, or refresh your previous training, consider registering for one of our upcoming Basic Land Navigation classes.
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