Magnetic declination is an essential principle to understand when navigating your way through the wilds with map and compass.
Yet it's a tricky thing to remember, at least the way it has traditionally been taught, using an addition / subtraction method. Just when you think you've grasped it, the concept floats away, like fog in the morning light.
Well there is a simple, practical approach to adjusting for magnetic declination when finding your bearings. The whole explanation begins with a definition of 'north."
There are 2 Norths
A lot of people know that there are 2 norths in terms of maps and compasses. A map shows true north, or the Geographic North Pole where all lines of longitude meet. The earth rotates around an imaginary axis that runs through the North and South Poles.
A compass needle points to magnetic north, which is determined by the earth's magnetic field. The location of magnetic north moves over time, at about 5 miles per hour. Right now it is slowly creeping around somewhere NW of Hudson's Bay in Canada, about 450 miles away from true north.
Magnetic Declination
The angular difference between true north and magnetic north is known as "declination," or "variation" in the aviation world. Declination is different for different parts of the globe. In Washington State, the angle of declination is 20?east. This means that magnetic north is 20? east of true north. In Tennessee the angle of declination is 0?, and in Maine, it's 20? west.
Declination values can be found in the margins or legend on topographic maps. Because the point of magnetic north is constantly moving, it is important to have a recent topo map for finding your way in the woods.
A similar point to remember is that compasses are calibrated for different parts of the world. So when you purchase a compass, be sure that it is intended to be used in the area of your big hiking vacations.
How to Find Your Bearing
Follow these steps to find your bearing:
1. Place the compass on the map with the arrow on the base plate pointing in the direction you want to go.
2. Turn the dial face of the compass so that north on the compass is parallel with north on the map.
3. Place your compass level in the palm of your hand and turn yourself until the needle in the compass aligns with the North marking on the face dial.
4. The big arrow on the base plate is now aligned with your bearing.
Declination Value and Bearings - A Trick to Make it Stick
If you walked 10 miles through the woods in Washington State, without factoring declination value in your bearings, you would finish over 3 miles off target. That's too much!
To avoid confusion in finding bearings, keep the central principle in mind:
Make map bearing = magnetic bearing.
You will achieve this in the field by adjusting your bearings to compensate for magnetic declination. There are 2 ways to account for magnetic declination in finding your bearings: an adjustable compass and marking your non-adjustable compass.
The easiest way is with an adjustable compass. Simply turn the declination adjustment screw on the compass to the correct value and all readings are automatically converted to true north. If it's available, it's always best to have an adjustable compass on your walk.
The next best way to account for declination is to mark the declination value on your non-adjustable compass at the beginning of your journey.
That's simple to do. For example, when the map indicates a declination value of 20? west, you will mark your compass dial at 340?. If the map indicates a declination value of 10? east, you will mark your compass at 10?. Make the mark with a permanent marker and erase later with rubbing alcohol.
Now when you take your bearings in the field, place your compass level in the palm of your hand and turn yourself until the needle in the compass aligns with the declination marking on the face dial. Then the big arrow on the base plate will point toward your bearing and automatically compensate for magnetic declination.
Outdoors Adventurer, Writer and Webmaster Will Robertson lives with his family in Little Rock, Arkansas.
Explore the best hiking vacations and gear on the planet at: http://www.hiking-vacations-and-gear.com
Rolling Meadows Cadillac Escalade rental .. Lockport Chicago limo O’HareYou aren't lightweight backpacking if you are carrying twenty-five pounds... Read More
Up to now the preponderant view held by many historians... Read More
Mt. Washington Valley Trails & Mt Washington - NHThe highest... Read More
On Lake Michigan, at the end of the Stonington Peninsula,... Read More
We love spending time outdoors and if you are expecting... Read More
Have you ever thought you might like to try a... Read More
Barnegat Light, NJ is the home to "Old Barney" a... Read More
Whale watching is a spellbinding, entertaining, and thought-provoking adventure trip.... Read More
The thing with enjoying the great outdoors is seeing aspects... Read More
An inflatable boat trailer is needed if the user has... Read More
One afternoon during a trip across the country in our... Read More
How to get the most out of your trekking poles... Read More
Ultralight backpackers want to give up weight, not comfort. Sleeping... Read More
White-water rafting can be one of the most exhilarating experiences... Read More
Going on a gorilla safari must rank as one of... Read More
Boondocking is fun! Boondockers go anywhere they want, at any... Read More
Base camp sits at 12,000 feet - stark, windy, unshaded... Read More
For the 92nd time, the Tour de France has started.... Read More
There are two types of used inflatable boats for sale... Read More
Six different islands in Hawaii are open to tourism. Most... Read More
The kind of things you pack when you go on... Read More
Costa Rica is a small country - just 75 mi/120... Read More
Western Australia ? South-West Coast driving holiday. Great Australian Road... Read More
The Kuan Yin Shrine in Bangkok is in an old... Read More
Sun, Sand and Surf ? an apt description for Goa?... Read More
Des Moines rental limo ..If you love the thrill and adventure of kayak travel,... Read More
If you're looking to spot a whale, the first few... Read More
As the weather cools in late summer and the days... Read More
Isn't it time you stepped out of the concrete jungle... Read More
Mt. Washington Valley Trails & Mt Washington - NHThe highest... Read More
Perhaps you have wondered about taking an RV vacation. It... Read More
The Kuan Yin Shrine in Bangkok is in an old... Read More
Why ultralight backpacks? Devotees of ultralight backpacking know you reduce... Read More
Mystic Seaport celebrates the seafaring past of New England. Known... Read More
Normally when you think Safari you think Big 5. The... Read More
Ultralight backpackers want to give up weight, not comfort. Sleeping... Read More
A Hawaii volcano tour can be a most memorable experience,... Read More
The kind of things you pack when you go on... Read More
Of course you know about Southern California's premier attraction, Disneyland... Read More
If you've been dreaming of traveling the highways in your... Read More
Recently I attended a Boy Scout Leader Roundtable meeting where... Read More
The Udzungwa Mountains National park was created primarily for the... Read More
The Usamabara Mountains are very special mountains, often that tired... Read More
Six different islands in Hawaii are open to tourism. Most... Read More
Lake Winnipesaukee is the largest and one of the deepest... Read More
White Water on the Comal river in Central Texas is... Read More
So unknown is this treasure of Lake Jipe not many... Read More
Have you taken up hiking as a new form of... Read More
Mount Sunflower, Kansas. Ebright Azimuth, Delaware. Hawkeye Point, Iowa. Hoosier... Read More
Organized river rafting trips are a good idea for novices... Read More
Outdoors |