On Thu, 26 Nov 2009 11:32:40 -0500, "Armond Perretta"
wrote:

Has anyone tried this in a similar situation (i.e., specifically where the
GPS does not correspond to the latest charts)? Is this a good idea in the
first place?

I have tried it but I'm not sure that I'll do it again. The
corrections typically apply only to a limited area since they are the
result of charting error, not GPS lat/lon error. In my experience it
is all too easy to forget that you have applied an offset. That leads
to trouble when you go to some new area where the charting error is
either different or non-existent.