Installing a Digital Yacht AIS transponder
Ben fits a Class B transponder designed for small boats
After upgrading my boat’s instruments, I wanted to add AIS. We’d previously had an AIS receiver which had been useful when crossing the Channel, but as we planned a lot of offshore sailing this season, we wanted to add an AIS transponder. There are lots of options available, and our NMEA 2000 network should make installation easy. But which to choose?
One of the issues on a small boat is space. We already had two GPS antennas on the pushpit, so we wanted to minimise both the wiring and the forest of aerials. That’s when we discovered the Digital Yacht AIT1500. This is a transponder designed for small boats, with its own internal GPS antenna and a small footprint. It’s also keenly priced. The small footprint meant it would fit behind the chart table’s dashboard, and from there I could easily run an AIS antenna wire to the pushpit. A masthead antenna would give greater range, and using a VHF/AIS splitter would mean we could use one aerial for VHF and AIS – but that added expense. Having an AIS aerial on the pushpit would give reasonable range (one officer we spoke to said they tend to see yachts wtih a pushpit antenna at around the 8-mile range.) It would also add a useful emergency VHF antenna should we lose the mast – with a patch cable we can use the new AIS antenna for the VHF.
We chose a Glomex stubby AIS antenna, which is tuned correctly for AIS and should be resistant to damage on the pushpit.
Installation
The first step was to program the AIT1500. It comes with a USB lead attached, and a CD with ProAIS2 software on. This allows you to program the transponder with the boat’s MMSI number, boat name, length and other relevant data, via the attached USB lead. This done, it could be installed on the boat. This entailed adding an extra T-piece to the network backbone (which we located in the forepeak, next to the transducers) and a drop cable to the AIS transponder.
The transponder will work as soon as it has power – which is provided by the NMEA drop cable. When connected to a working network, it also transfers the data to any compatible instruments on the network – in our case a B&G Vulcan 5 plotter.
We have been very impressed with the system. Mid-channel we could see ships altering course (by monitoring the COG and rate of turn data) a few miles away to pass behind us in the shipping lanes, and have used it more than once to find out a vessel’s call sign to make contact.
A further advantage is that family and friends are able to see how you’re getting on by tracking you via a website such as www.marinetraffic.com – although whether you see that as a good thing depends entirely on your sailing (and your conscience). We have found it to be a great tool, feel safer with it there, and have found it enhances our passagemaking by giving us more information about the vessels around us. We’re glad we fitted it!