On Thu, 14 Dec 2006 20:53:15 GMT, Rich Hampel
wrote:

ou can do so with graphical magnification .... but the answer is
nearly ALWAYS wrong.

Wrong is relative, and it depends on the chart. Most of my vector
charts for US waters with stable shorelines are accurate to within 50
or 60 feet. If you are 50 feet away from your charted position, is
that wrong? It depends. 99% of the time 50 feet is good enough to
bring you into line with a Mark I eyeball fix, and that's good enough
for me. For those areas with unstable inlets, shorelines and/or 1800s
survey data, the type of chart makes very little difference. They are
no better than a general guideline to get you started.