Friday, August 27, 2010

Can my GPS replace my map?

Ever thought that with the purchase of your upmarket colour screen GPS that you don't need to take a map with you any longer? Wrong, wrong, wrong .....

Many years experience with using GPS on bushwalks has convinced me otherwise.


Ever had your batteries go flat at a critical time? Ever had your GPS freeze and then reset itself to factory settings wiping all your waypoints and routes when you have rebooted it? Ever dropped your "waterproof" GPS onto rocks and had it bounce into a nearby waterhole and then slowly sink as it fills with water? Ever struggled with the buttons on your GPS  in the dark while wearing gloves?

Well I have and that's why I always take a map as my primary navigation tool.

I use my GPS to check my location at each stop, to find a difficult campsite or waterhole, or the precise turn off from a ridge line down a spur. I haven't yet, but I might one day use TRACKBACK to return to a previous known point when I am geographically embarrassed. I sometimes use it to estimate walking speed so I can estimate how long it will take to reach a campsite. With some GPS you can determine sunset, sunrise and tides, which can be very useful information on some bushwalks. I have used it to find altitude and therefore help me determine my location on a known track or to work out how much further it is up to a saddle. Of course some of these can be done with a map alone, but often it involves calculations and looking for labelled contour lines.


Normally I don't have my GPS turned on continuously during a walk but there are times when its fun to get back home and be able to trace a difficult or off-track route on a map or Google Earth or to determine your walk profile using elevations. If you take lots of photos, there is software that will link you photos with the GPS location using your time log, assuming you have the clock on your camera set correctly to the same time -zone.

I use my map to give me the big picture, orientate myself, show local topography and allow me to follow my route continuously by reading "map-to-ground" and by "thumbing" the map. It takes lots of practice but is very rewarding. I actually enjoy map reading, anticipating what I will see around the bend and looking at my surroundings as I walk. As my map reading skills improve, I find myself using a GPS less and less.

The danger with a GPS is that you are so engrossed looking at the screen that you don't actually see your surroundings. If you become "lost" then you have no mental image of the route you have taken to get you back to a known point.

Murphy's Law can be guaranteed to ensure that at the point when you need it most that your GPS will fail!
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This article by Bush Walker is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

1 comment:

  1. Does anyone know some good mapping software that will link to a GPS for a Mac?

    ReplyDelete