Switch installed for AIS- Standard Horizon Gx 2150\ Garmin chart plotter 740

Middle of December 2016 - Tied up in Marina Mazatlán, Mexico

The problem:
 We have a
Standard Horizon VHF radio “Matrix AIS+” GX 2150 and if it does not get position data, it sounds an alarm. It sounds after 10 min then every 20 min. No way to turn it off. You can reset it but that is it. We had it wired to the Garmin 740 Chart plotter but if we turned off electronics while at the dock or anchor then the alarm would sound.

The solution 1:

 So we decided to go without the AIS info on the chart plotter and just the Standard Horizon radio for the AIS info.  This is not as convenient but it works OK.
We installed a Standard Horizon GPS antenna (already covered in a blog post here) and wired it to the Standard Horizon VHF radio “Matrix AIS+” GX2150. This is all documented already on this blog. This worked fine but we were missing the AIS info on the chart plotter doing overnighters. Also we can set up alarms easy on the Garmin740 chart plotter for AIS.
We installed the switch first here to see if tis would even work (proof of concept).
So we installed a switch in order to switch between the Standard Horizon GX2150 VHF radio and the Garmin 740 chart plotter.
 Later we moved the switch to the nav station and put wires from the terminal blocks to the switch.
The wires to the switch are:
 Brown wire from GPS antenna to one end.
 Blue wire from the Standard Horizon VHF radio (AIS out)  to middle connection on switch goes to Garmin 740 chart plotter..
 Blue wire from Garmin to other end of switch (position data) in to radio from Garmin chart plotter 740.
These wires may vary in color for your setup. This just shows that it can be done and is not that difficult.
This is not quite straight forward but takes less than a minute to switch. That is because the GPS antenna sends position data at 4800 baud rate and the Garmin AIS position data needs to be sent at 38400 baud rate.

So we flip the switch to say the Garmin chart plotter and then the Standard Horizon VHF radio GX2150 we go to:
Position data displayed on screen. 23 16.217N - 106 27.313W
We press and hold the call menu till we see the “General Setup” menu.
Then select General Setup and then chose “NMEA Data In\Out” menu.

  There we can switch to say 38400 for the Garmin chart plotter or the 4800 for the GPS antenna. In this case the 38400 and off we go, no alarm!

 By having position data, the radio can send out a distress call and sends our exact location.

We also have position data from the Garmin chart plotter 740 being sent to on our IC-M802 HF Marine Transceiver (radio) which has a much long range than the 30 mi or so VHF range so is even better for a distress signal. but that is a different blog entry :).

Switched to antenna now for the radio only.

When we have the switch to the Garmin chart plotter 740 we get AIS!

Final solution:
 Our final solution is to purchase a AIS transponder to receive AND send AIS and install it on our Garmin network. Then the Garmin chart plotter would have its own source for position data and the radio would also for the GPS antenna. No more switching and we would broadcast our position in AIS.

We are currently looking at the “Vesper Marine” XB-8000 AIS transponder. We get top gear for the boat and this one looks good so far but we are still looking. We will have the boat for another decade at least so an AIS transponder seems like a good choice. We would also like to get AIS transponders for our life vests.

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