John Buoy Marine Communications (Part 3)

The finished Lower Con

Now that everything is tested, I actually have to install it into the boat. But I still have one problem to solve. The AIS radio is just working off a small test antenna, and that won’t be very useful out on the water. After a bit of searching it made sense to use a VHF splitter on the lower VHF radio to power the AIS antenna. This also meant getting cable adapters to fit the MCX connection on the radio.

Those were pretty much all the parts I need. This should give me an end-to end system once I get it installed. As a bonus, this splitter also gives me an FM antenna, which I need since the original FM antenna on the boat quit working long ago, and my repair job with a stubby antenna has almost zero reception. So I headed down to the marina with some extra wire and both tablets to try this out. I have a panel under the lower con with space for the computer board, and it also gives me access to the power and cabling that I need to run.

This looked better when I was done.

The big problem is that I wanted to hide the adapter inside the cabinet, but the way it is built I can’t figure out how to get access to where I want it. I don’t really feel like tearing the whole thing apart, so I’ll mount it up top and just do my best. Problem 2 is that I don’t have a way to run the USB connector for the GPS down into the space. I messed about with this, until I realized that the main Chartplotter sent position on the NMEA 0183 signal. The USB GPS was actually redundant. So I put it into the drawer as a backup.

I routed a fresh power connection from an unused circuit to the power terminals, and dropped NMEA and Antenna wires from on top of the con into the main board. I wrapped the cable bundle with cable wrap, and had the computer end set to go. I also routed the FM antenna extender down through the console and into the lower compartment, so I could pull it over to the radio later.

On top, I put a small switch in a little project box so I could turn the Splitter on and off, and connected and wrapped power to the splitter and VHF. I reattached all the NMEA wires with a clean connector, and wrapped them all up. I mounted the Splitter, connected all the antenna cables, then wrapped and secured the whole bundle. It took a while, but it didn’t look too bad. I’d still like to hide it later.

With all this in place, I powered up the Chartplotter/Sonar unit, both VHF radios, and the computer setup. Once the GPS had my location, I started checking.

  • The Upper VHF had GPS data – Good!
  • The Lower VHF had GPS data – Good!

Then I started a tablet, and ran OpenCPN. It connected, and within a few seconds, I could see everything working:

  • It was pulling my position and the current depth  (in Meters) from the NMEA signal.
  • It had local ships showing up from the AIS antenna.
  • It also had Temp and Barometer data in the feed, but I didn’t have a display setup yet.
Yup. That’s AIS in yellow.

With that successful test, I walked around the boat with the tablet in my hand. The WiFi signal was strong. I’ll need to test when underway to see if we get any electrical interference, but I’m really pleased so far. I cleaned up, and pulled the antenna through the access panels over to the FM radio, and plugged in. Reception was perfect. Nice!

Antenna in the back, and Aux in front. And CDs!

I still don’t have my radar hooked into this system, but that will have to wait. So far, this is what I need, plus more.