On Sun, 15 Aug 2004 16:22:07 -0400, "peter"
wrote:

I have a dual helm trawler, 40', and plan to add electronic charting with a
good GPS with an external arial. I want to view this on a lap top
independent of input wiring so I can go to either helm whenever so ....... I
want to install a Local Area Network (all new to me but sounds reasonable).

Has anyone tried to do this? Sounds so practical. I have yet to buy
anything yet so any advice would be a help! Guess I need a GPS, laptop
with plotting software and LAN module, and the where-with-all to get the
data out to the LAN from the GPS.

Thanks all!



I have some experience in this area. I personally doubt that you'll
be happy schlepping a laptop between helm stations. It will always be
in the wrong place when you need it. I will start raining just as you
decide to switch. A big wave will arrive as you are moving and you
will toss the laptop to the fishes. Further, laptops with daylight
visible displays are pretty expensive.

On the technical side, you could do it, but it's trickier than you
seem to think. If the GPS supplies NMEA 0183 data, you're looking at
a RS232 (standard PC serial port, more or less) or RS-422 (similar to
RS232 in concept, but different in implementation) connection. You
need to get the data onto the network. You could use a serial to
ethernet convertor that supports RS232 or RS422. They're available,
but not at typical computer stores. Since no charting software that I
am aware of accepts network data,you have to convert back to RS232 for
the PC. You may have the option to convert the network data to a
virtual serial port via software. Don't forget that you need to set
up an ethernet hub to connect all the pieces of the network. Also, as
long as you're doing it, might as well go wireless. It's much the
same problem, technically.

It would be easier and probably more useful to use one PC to acquire
the GPS data and display charts at the lower station, another to
display on the flybridge. You'd still need to set up the network and
the hub, but that's gotten pretty easy.

__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at worldwidewiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
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