Compass vs. GPS
I bought my GPS as a safety measure for hiking. I would mark the trail head and shove it in my pack. I figured if I got lost, the GPS would point me back to my car.
Since it was waterproof, I figured it would help kayaking. The actual scenario I envisioned was being out on the water when pea-soup fog rolled into the area. I could use the GPS to find the launch or latest waypoint I marked.
And I would use it to tell me how far I paddled. It even gave me a speed reading.
That's more useful than you think. No, I'm not worried about speeding. But using it taught me I can paddle comfortably at 3.5 mph. Which helps me judge travel time and navigation.
The GPS also has a compass - which I never really used it for that. Good thing. Last week I tried out a deck compass on my kayak. Just for the heck of it, I compared it to the compass reading from the GPS.
They gave me different readings. I'm talking 20 to 30 degrees difference. How did I know which was right? I compared what I saw with features on the map I bought. The map wasn't super detailed or accurate. But it was enough to lead me to have faith in my deck compass.
I'm keeping the GPS. I've tested the waypoint marking and am confident that it work.
But even in this day of great tecnology, compass and map skills are not wasted.
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I assume you checked true versus magnetic north as the cause of the GPS discrepancy? Unless otherwise configured the GPS will display true north while your deck compass will display magnetic north. In Maine, that difference should be about 20° depending on the area.
Also, most GPS devices don't have an electronic compass in them. They look back at the most recent few seconds of travel and figure the heading information from that. So assuming your GPS didn't have an electronic compass (most but a few of the high end models don't) the heading information displayed reflects your most recent previous movements rather than your current direction.
But I completely agree with the moral of the story, a GPS does not replace a map and compass, but it is another good safety tool to have.
Posted by
TimJuly 13, 2007 02:32 PM
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