Well, I am no expert, BUT,
NEMA is a protocol for outputting differences between course, turning info,
etc, nothing o do with mapping at all. The Maps actually take a
proportionally lat-lon coordinate, and place this in the place where they
belong on a particular mapping system, BBS, and a bunch of new ones. They
are apples and oranges.

NEMA is just a communication language that identifies certain things such as
errors in course and sends that error out to be plotted in radar, or
autopilot, etc it does not care at all about any maps that were provided to
you for visual ease of use.

Allot of the newer mapping systems are in fact usable among the different
manufacturers, but there are different methods for creating layers which
allow a position to be indicated on a map that translate to a DMS position.

But, maps ARE not all interchangeable, period, I have had 3 GPS receivers
and have had to have 3 different formats of software in order to be able to
properly correlate a position to a map.

You can get a position off of just about any mapping system on a PC, but you
may have to manually upload that info to a GPS.

Now as far as just the GPS receiver attached to a PC, there is probably much
more flexibility as to software compatibility as the PC can handle
translations, but to say all of them are interchangeable is probably a
incorrect and un-safe statement.

Mike
"Gualtier Malde (Chuck)" wrote in message
...
I came across a Garmin 18 WAAS-enhanced GPS for a laptop. That led me to
search for other types and brands, but I didn't get many answers.

These units are sold with road use in mind. What if I wanted to use one
with nautical charts? Does anyone know if the BSB and roadmap formats are
the same?

I'd like to hear from anyone who might be using this equipment.