Boat Computer and Electronics

[Peter Milne]

Amos,I have a Dell notebook, 133Mz, 32 MB, 10 GB hard drive, CD-Rom and an active matrix screen that I would like to retire to the boat.On the boat I have a Garmin 128 GPS mounted at the helm station and connected to my Autopilot (Autohelm 6000Plus), which works like a charm.How would I connect my notebook to this system and what software do I need to i) load waypoints into the GPS unit(I find entering waypoints into the GPS unit a pain with a high probability of error); and ii) use my notebook as a chartplotter? Will my computer survive the marine environment as long as I keep it dry?Thanks,Peter Milne

 

[Scott May]

Interfacing

You'll need a chart plotting program w/cd's for your area. Run a 2 pair cable (shielded) from the garmin Nema 0183 output to the location of your laptop. You'll need to connect a 9 pin connector to the cable with nema TX going to pin 2, nema RX going to pin 3 and use pin 5 as your GND. You may have to flip-flop the pins 2 and 3 if your not able to get data to the laptop(a null modem adapter will do this).If your still not getting data you can check to see if you have data present with a common digital multimeter. Put the probes on TX and Rx, you should see bursts of 5 volts DC every few seconds. You will also be able to drive the auto pilot with your computer plotting program.If you keep the PC dry you should have no problems with it. Just make sure you have it in a stable location.one other not make sure you have the correct Nema sentences turned on at your GPS. you can verify this with the Garmin manual.

 

[Amos Cordova]

Interface your system......

Peter,Peter,Most of the navigation softwares will allow upload of route waypoints from the computer nav station to the Garmin 128. Some will allow download as well. With the use of digital charts and a nav software such as The Capn. Voyager you will have the ability to use the computer nav station as a full real time plotting system.The interface from GPS to computer is relatively simple as an interface cable will come with the software. This cable has a serial port connection on one end, which connects to the computer, and three bare wires for connecting to the GPS and/or autopilot.There are electronic components available to ease the install between the Computer, GPS, Autopilot and other NMEA devices such as depth sounder, as well as add a level of protection from voltage spikes. This protection is called opto-isolation and is well worth the money. See the tips for info on this. To interface to the autopilot, a switch is neccessary to control which set of NMEA data the autopilot is receiving. The switch set in the computer position allows output data from the computer to relay to the autopilot. This allows the route information to download from the computer nav software to the autopilot.The switch placed in GPS position allows the route information to download from the GPS and not from the computer.Most autopilots will accept only one set of NMEA data for use at a time. The switch allows the control of which set of data to send to the autopilot.Your computer will corrode do to salt air. Use a Computer Stowage kit to reduce the chances of circuit board damage. Also it will probably be neccessary to upgrade the RAM on your laptop to at least 64MB. My motto is "RAM is like money, You can never have enough".I run a P133 and it is slow using some of the newer, resource intensive nav software. Amos