[Paddlewise] GPS & Electronic Charts

Dan Hagen <dan_at_hagen.net> wrote:
<snip>
>>>>>Note that you do not have to buy electronic charts to do this (although
that is an option). If you already have paper charts, you can scan them
into your computer, and use a program such as OziExplorer (the best!) to
convert the scanned images into charts. <<<<<

Why do you consider OziExplorer the best?  (Just curious). I started out using
Ozi, but found GPSTool to be a little more intuitive, plus it's available in a
freeware (rather than shareware) version with relatively few features disabled
(at least that I would be very concerned about).  Also, even the freeware
version allows you to use 3 points for calibrating scanned charts, while Ozi (I
believe) only allows 2 in the shareware version.  (Granted, probably not a key
difference for non-tightwads).

<another snip>
>>>>>(4) The standard eTrex does not have differential (DGPS) capability
built in. Newer Garmin receivers (including the 76) can provide
differentially corrected (DGPS) fixes without the use of a separate DGPS
receiver/antenna. This improves the accuracy of the fix, and more
importantly the accuracy of the compass function and speed readout. Even
when zoomed into the "20-foot" setting on my newest receiver (where each
pixel is less than one foot), I see no significant drift when standing
still. DGPS really works! I do not see why anyone would buy a handheld
receiver without built in differential capability.<<<<<

With the discontinuation of selective availability, do you still find this to be
a significant advantage?  I've found that on open water, I can often get
position fixes that my GPS "thinks" are good to within 15 to 20 feet.  I'll
agree that I've been disappointed with the accuracy of the GPS compass readings,
though speed readings seem very accurate (at least compared to the speedometer
in my car!).

>>>>>(5) The eTrex lacks a wide range of other useful features, including
tide tables. My newest handheld displays tide tables (and graphs) for a
wide range of primary and secondary tide stations in the U.S. and Canada.<<<<<

That sounds really cool.  What GPS's have this feature?

By the way, thanks for the very informative post (especially interesting for us
Etrex users!)

Evan
Woodinville, Washington



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