[pct-l] altimeter

[Ken Powers]

I have used a Suunto watch altimeter since 2000. As someone said, the altimeter is only as good as its barometric calibration. In recent years I have started carrying a Garmin 60cs gps which also includes a barometric altimeter. Same problem. Sometimes I recalibrate it several times a day. This brings up another problem.

Many trails have the altitude at milepoints. I have found the reported altitudes to be incorrect many times (Usually after I have recalibrated my altimeter). So I started using the topo lines on maps as suggested by Jerry. But I find the maps are also inaccurate at times. One example on the Tahoe Rim Trail - My gps location plotted on the map showed me on the south side of a small ravine. The map showed the trail north of the small ravine. I have also found that the base USGS maps that underlie most maps are not consistent between different scales. The inconsistency may be related to the ages of the maps. On older maps the topo lines as well as the trails were hand drawn. The USGS only updates these base maps based on demand. We found base maps that haven't been updated since the 1920's.

In the end you have to use your good judgment about where you are on a map and what your elevation is. Good judgment seems to grow with experience 

Ken
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