We have two of these bad boys and have no problem with them. I mount one in my Jeep even. I haven't noticed radical jumpiness in accuracy. Heck, I'm only trying to get within 20 feet or so anyway and I can figure it out from there. We love the Venture - low cost, lots of features, high battery life, etc, etc.
Here is how I mount it in my Jeep. This is with a softtop on so the only view of sky is from the windshield and the side window. I usually get 20 feet accuracy or better driving like this.
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Bill
Jeeps Only!
http://www.jeepsonly.com
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[This message was edited by JeepsOnly on July 28, 2002 at 11:18 AM.]