If you’re thinking of adding Class B AIS to your boat, you may want to pay attention here. Don’t worry, there’s nothing especially complicated about it, but you might save yourself some time by learning from my experience.

I’ve just installed a Shine Micro AIS-BX Class B transceiver. Here’s the finished installation aboard Two Lucky Fish, my C-Dory 22:

The AIS-BX is the unit in the upper left. As you can see, I’ve got the cables tidied up, at least compared to my initial hook-up. A few are still peaking out here and there. I probably need to deploy a few more wire ties!

See, four separate cables emerge from the back of the AIS-BX. From left to right, they are:

• VHF Antenna (white)
• GPS Antenna (black, thin)
• 9-conductor RS-232 cable (grey, thick)
• 2-conductor 12V power (grey, thin)

The simplest connection is the GPS antenna, which is connected to a tiny GPS “puck” antenna with a magnetic base. Just find a spot with a clear view of the sky for the puck, route the cable, and screw the antenna cable to the fitting on the AIS-BX. Done!

The other simple connection is the power. The AIS-BX requires 12V. The red wire goes to a positive terminal, and the black one to ground. If that last sentence was news to you, please hire somebody to complete your installation.

The antenna connection SHOULD be even simpler. Here’s why it’s not: You need to install a VHF antenna (or, better still, a VHF antenna optimized for the AIS frequencies) and route the cable to your AIS unit. This may require drilling holes in the cabin and sealing them with polysulfide.

Once you’ve got the antenna installed, the cable routed, and any holes filled, it should be simple. Unless, like me, you’re using a standard VHF antenna with a PL-259 connecter on the end of the cable. All AIS equipment with which I am familiar uses BNC connectors. So you need an adapter.

That’s not really a problem, except that the PL-259 plug, plus the PL-259/BNC adapter, plus the BNC mount on the chassis can be about three inches long. Too long, in the case of the Shine Micro AIS-BX, to fit within the enclosure.

Even without the cover on, the AIS-BX is an exceedingly sturdy, well-proptected bit of electronics. Here’s how I had things hooked up on Friday, and it all worked fine.

But I really wanted to hook it up “correctly”, so I had to figure out a way to eliminate the PL-259/BNC adapter. Here’s what I can up with: I already had a Shakespeare 4357-S AM/FM-VHF Marine Band Separator. It’s a unit that allows you to use your VHF antenna for conventional AM/FM radio, but protects the AM/FM unit from being destroyed when you transmit over your VHF.

You plug your antenna into the little black box, and you plug the cable coming out of the little black box into your VHF transceiver. The AM/FM antenna plugs into the back of the box; you can’t see the socket in this image.

The loose bits in the picture above are pieces of a BNC crimp-on coax cable terminator. Once I was finished, here’s what I had.

Which worked just fine, thanks!

With the VHF antenna cable connected, you’ve only got one other connection to make: data communication between the AIS-BX and your chartplotter.

I saved the worst for last. The data connection can be a challenge, or it can be easy, and will vary depending on what you’re trying to connect to.

In my case, I had already figured out how to manage the data connections when I installed my Milltech SR161 AIS receive-only unit. I count myself extremely lucky that I was able to simply plug the AIS-BX’s 9-pin RS-232 cable into the RS-232-to-Raymarine-NMEA cable I spliced together with magic 3M wire connectors.

Only one issue remains unresolved: Shine Micro tells me that the AIS-BX won’t consolidate incoming low-speed NMEA data into the outgoing high-speed NMEA datastream heading for the chartplotter. This matters to me because I want DSC positions received via VHF to display on my old Raymarine C-80 chartplotter, which only has a single NMEA connection. Will I need to develop a new workaround? Or is it finally time to buy an NMEA multiplexer?