Thursday, July 11, 2013

BLOG 49. Compass or GPS?


BLOG 49. COMPASS OR GPS?
by Cliff Jacobson

Compass or GPS?

At the outset I should make it clear that I love my GPS.  I bring it on every canoe trip. This said, I ALWAYS carry a compass—two of them, in fact.  Both are Orienteering models; one (a Suunto MC-2) has a declination device and a balanced needle that remains level anywhere in the world; the other is a basic Boy Scout style model. The Suunto is on a lanyard in my pocket; the backup compass is in a pack.

People are buying GPS’s like mad these days, but precious few know how to use them. Some are so hooked on GPS technology that they leave paper maps at home and rely entirely on the little chip-map in the GPS—a dangerous mistake. After all, batteries can die, electronics can go bad; screens can break etc. And contrary to the claims of manufacturers, a “waterproof” GPS will take on water if it’s submerged for very long.  Equally important is that a GPS screen is too small to permit wide-ranging detail.  Of course, you can pan around to see more area, but you won’t see the “big picture”, which is useful for planning the days ahead.  Enlarging the map scale reduces the viewing area; making it smaller limits detail.  That’s why you need a topographic map that shows the entire route!

A knowledge of map and compass navigation is a must before you commit to GPS.  Why? Because it’s easy to make an error when programming GPS waypoints, especially in UTM (Universal Trans Mercator) mode. Unless your GPS has a detailed built-in topo map (the free North American base map provided with the instrument isn’t good enough), with detail equal to a topographic map, you’ll need to hand plot waypoint coordinates, and it’s much easier and more accurate to do this in UTM mode than in latitude/longitude.  (I’ll detail the UTM system in a future blog, or see my books, “Basic Illustrated Map & Compass” or “Expedition Canoeing”).  Without a working knowledge of map and compass, you’re almost certain to get lost if you make a waypoint plotting error.

Most people who own field model GPS’s have only a rudimentary knowledge of navigation. They know the eight principal compass directions, and that “north” is at the top of a map, but little else.  Declination is a mystery, as are the “three north’s” (true, grid, magnetic). Some think that topographic map gridlines point true north and south, which they seldom do. 
Cliff checks his position with a GPS--along the Snake River, Yukon
My friend, Larry Rice, an author and frequent contributor to canoeing magazines, told me he once went on a wilderness canoe trip in northern Canada which was “guided” by a man who supposedly was very experienced.  The man sent the crew an email stating that to reduce weight and bulk everyone should leave their topo maps and GPS at home.  He said that his GPS contained a detailed map of their entire route, and that’s all they would need.

My friend rolled his eyes at this announcement and of course, brought his own map, compass and GPS.  He said that each day the crew would rally around his topo map to discuss the big picture. The leader’s GPS chip-map was simply too small to show an over-view. Ironically, the “leader” could not always accurately pin-point the crew’s location on Larry’s paper map. I hazard to think what might have happened if Larry had taken the email to heart and the leader had lost or damaged his GPS.

Much as I love my GPS, I find that it’s not all that useful on the small lakes that characterize much of the BWCA.  For this, a map and compass gets me around just fine.

I would encourage all to become proficient with map and compass before they commit to a GPS. That way, programming errors will quickly be identified. I might add that detailed GPS maps are not available for many remote areas.  But paper topo maps cover them all.  Overhanging vegetation, canyon walls or heavy cloud cover can prevent an accurate GPS fix.  And on rare occasions (as in 911!) the system is shut down. Unless you drop your compass off a cliff or run over it with a truck, it will always work! And the information on a topo map can never be corrupted.

Technology is wonderful but it cannot replace skills or common sense. Bad stuff happens when one least expects it.  That’s why I always bring two orienteering style compasses, two sets of maps and a GPS on all my northern canoe adventures.

Cliff Jacobson
www.cliff-jacobson.com

XXX

2 comments:

spouse said...

Good article. Did the Snake with 5 others in '89. Great trip. This pic looks like it's right before the little canyon section. Lot's of grizzlies, Dall sheep and ptarmigan. Put in at Duo Lakes. Wolves howling that night. The Dempster was gorgeous. Heading for the BWCA in another week. Love your books. Oh yeah, did the Mara/Burnside,NWT in '87. Fantastic. You should do it if not already.

Cliff Jacobson said...

You hit the location head on! I've done the Burnside but not the Mara. Great river, only one portage, if I recall.
Cheers,
Cliff

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