Garmin GPS-12 marks taken at both ends of the Bayview Bridge after downloading to ChartView Tracker using a Maptech edition 2.2 chart.
The Garmin GPS 12 position was about 128 feet to north of where it is on the chart and 147 feet to the east of where it is on the chart.
What is going wrong here?
How can we compensate for it?
Both the chart and the GPS were set to WGS 84 reference.
Below is the leading light on the Michigan Avenue Bridge. I walked on the sidewalk to the point right under the light and did averaging that showed the error to be under +/-12 feet. The result showed that the GPS was about 118 feet to the north and 98 feet to the the east of the charted location. So the errors are similar and consistent. There must be some way to correct for this kind of consistent discrepency? I have been searching the manual for how to insert user datum as a correction, but can't find the information. Changing User Datum DX to 160 ft and DY to 137 ft got the lat and long display on the Garmin GPS-12 to agree with the chart, but when I downloaded the marks to my Chartview I still got the same old uncorrected lat and longs into Chartview.
Thanks Markus Ritter
