This is another article in the series “how to justify splurging money on toys”.
We all know that exercise is necessary for your health. I like to walk. My family and I go on hikes every week-end. For variety’s sake, we try to go to a different place each time. I peruse the fine 1:50,000 maps (“topo” maps) from Natural Resources Canada (http://maps.NRCan.gc.ca), looking for cart tracks and other obscure trails. Then off we go, trying not to get lost in the woods.
We’ve had some great times. There’s nothing like being alone, walking down a logging road, framed by a cathedral of spruce, listening to the wind rustling in the leaves, seeing the look of delight on your little daugther’s face as she discovers frogs, mushrooms and spiders.
The only problem is that there are often new roads and forks. If you go strictly by the map, you can easily take a premature turn. The maps are even wrong at times. So you need a GPS if you don’t want to spend the night in the woods.
As you probaly know, Global Positioning Systems are little units that receive signals broadcast from 24 satellites that orbit the earth. By measuring the time and angle of the signals, a GPS unit can compute your position with an accuracy of 10 meters (less than 3 meters if you’re military).
I visited our local Mountain Equipment Coop store. The staff were friendly, but hadn’t been trained on the GPS. There were many models, and I hadn’t done my homework. A few months ago I had borrowed a friend’s older GPS, a first-generation Magellan, and had had disappointing results, so I was a little skeptical.
I asked the staff to photocopy a topo map of downtown Halifax, corresponding to where the store was located. I calculated the coordinates of the store, then me & a hapless sales clerk walked six floors to the top of a neighbouring parking garage, lined up three units in the hot summer sun, and waited for the GPS units to capture satellites. In a few minutes, all units were reading pretty much the same, which proved they worked. So I bought a Garmin Geko 201. It was the lightest of the three, and my wife liked the cute lizard logo and the shade of green.
A GPS takes some effort to learn. There are many features, most of which you’ll never use. Once you master the basics, however, it’s pretty straightforward to operate.
A GPS can display coordinates in degrees/minutes/seconds. Any spot on the earth can be described by its latitude or distance from the Equator (the Equator is 0°, the poles are 90° N and S respectively), and its longitude or distance from Greenwich, England. Greenwich is 0°; the International Date Line at the antipode is 180°.
If you use the 1:50,000 topographical maps, however, you won’t use degrees. Instead, you will use meters as based on the Universal Transverse Mercator (UTM) projection. A ‘projection’ is the geographer’s solution to flattening a spherical surface onto a plane.
The topo maps are covered with gridlines, 2 cm or 1 km apart. You can estimate your position on the grid by interpolating within the squares. For example, if I take a reading on my doorstep, the GPS reads 0388200 and 4991950. The first four digits ‘0388’ and ‘4991’ give me the vertical and horizontal grid lines on the Wolfville map (map #21 H/1 in the NRC numbering system), and the last three digits give the millimeters into the square.
For an detailed explanation of UTM, check out:
http://www.nps.gov/prwi/readutm.htm
http://www.maptools.com/UsingUTM/
A GPS is terrific for finding out where you are. For example, as we drive along the back roads of Kings county, my wife reads off the changing UTM coordinates. Knowing in advance the coordinates I’m looking for, I can stop exactly where I need to turn onto an obscure dirt road, or hidden path. Without the GPS, I’d whiz right past the turn and never notice it.
There’s an incredible rush of power at being able to pinpoint exactly where you are on a map, even if you’re far from civilization. You feel almost invincible.
You can also get yourself into trouble. I had a scary experience this summer at Nova Scotia’s picturesque Cape Split.
Cape Split is a long hike: 10 km or 4 hours return, on hilly terrain along deadly precipices. My family and I had gone in on the north trail. Once you reach the tip, the view is awesome: the tide roars past the rock pinnacles, to and from the Bay of Fundy. It is said that the volume of water is greater than all the rivers in the world.
While we were there, a hiker from another party broke her leg, and was retrieved by a Search & Rescue helicopter.
Anyway, I decided we’d return through the less-used south trail. Things went well at first. I was following what seemed to be the beaten path. After an hour, the GPS readings indicated we were straying from the path. It appears we had been following the footsteps of previous hikers who were as lost as we were.
That is when I discovered that the GPS can tell you were you’ve been, but you still need a trusty compass to point you in the right direction.
I also discovered that the south trail had not been well maintained. Trees had fallen over the regular path, obscuring the tracks of generations of hikers. We were lost, and it was less than two hours to sunset. With me were my twelve-year-old daughter, my wife who had sprained her knee earlier, and two strangers who thought I knew what I was doing. I got a sinking feeling in the pit of my stomach. I was scared and embarassed.
According to the map, if we crossed the peninsula and went due north we could rejoin the north trail. It was about 1 km uphill. I figured we could do it. I didn’t find out until later that one woman had had shoulder surgery two weeks before.
I hadn’t counted on the obstacles we soon encountered: a large grove of fallen spruce trees, chest-high, with prickly branches all the way to the ground were blocking our path. There was no way to climb over or under them.
After much weaving about, I found a way around the fallen trees. I was very relieved when we heard the voices of other hikers, and rejoined the north trail. After, I couldn’t walk for a week.
Hey, what doesn’t kill you makes you stronger.
In conclusion, GPS technology is changing rapidly. Review the available information thoroughly before buying. You really need to see & feel the models, so forget eBay and head for the store to buy from a local dealer. You’ll appreciate it when you realize you made a mistake and want to exchange it for another model.
The Garmin site has some great GPS stories:
http://www.garmin.com/whatsNew/adventures.html
Next time you’re on a plane, stick the GPS in the window and see it read your speed: 700 km/hr!