If you encounter an issue with AIS showing on your display (navigation software or chart Plotter) then you should follow this procedure.

1 – Issue with a Chart Plotter/VHF Radio

If you cannot display AIS targets on your Chart Plotter or VHF radio, then follow this:

• If you have connected your AIS to your Chart Plotter/VHF Radio via NMEA 0183 wires, then you must make sure that you have used the NMEA 0183 38400 baud wires (Orange + & Brown – for Digital Yacht AIS Transponders). The second step is to check your Chart Plotter / VHF Radio settings. The best solution here is to check your product manual but you must make sure that the NMEA 0183 port is set at 38400 baud and also that AIS targets are activated.

• If you have connected your AIS to your Chart Plotter/VHF Radio via NMEA 2000, then you must make sure that the NMEA 2000 network is working properly. This page might answer to your question. You should also make sure that AIS targets are activated in your chart plotter / VHF radio settings.

2 – Issue with a Navigation Software / App

If you cannot display AIS targets on your navigation software or app then follow this:

• For an Android/iOS app: The first step is to make sure that all apps are closed in the background, then you are connected to the product WiFi network. The second step is to configure your navigation app. This is explained in this page.

• For a PC Navigation Software: The first step is to make sure that the USB drivers are installed. You can download them here if needed. You must then find out the port COM allocated to your USB port. The last step is to configure your navigation software. This is explained in this page.

AIS Transmission/Reception depends on the AIS Class

• A Class B AIS transponder transmit at 2 watts whereas a Class A Transponder at 12.5 watts. The Class B+ SOTDMA transponder transmits at 5 watts. This difference in power has a huge impact on the transmission range of each transponder.

• For a Class B AIS transponder, the transmission range is usually 5 to 7 miles in perfect conditions. This means using a good VHF antenna, placed as high as possible and clear of other antennas. The cables and connectors must also be in good conditions. For a Class B+ 5W SOTDMA, it typically transmits at up to 15 miles.

• However, for the AIS reception, a Class B/Class B+ transponders can receive Class A AIS at up to 30 miles.

If you don’t have a good range

• If you are using a VHF antenna splitter for your transponder, make sure it is a ZeroLoss VHF Splitter like our SPL1500, SPL2000. You must also check the connectors and the cables between the VHF splitter and the AIS.

• If you are using a dedicated VHF antenna for your transponder, then make sure that it is at least 2 meters away from other VHF antennas. Also, you must check the VHF antenna, its cable and connectors.

If you don’t have a good range, we suggest you testing with another VHF aerial to check if you have a better range.

One of the most common questions we are asked by our AIS customers, is “what antenna should I use for my AIS ?”, so we thought we would post a short article to provide an answer on VHF Antenna Options for AIS.

Basically there are two VHF antenna options for AIS; fit a second dedicated VHF antenna a suitable distance from the vessels main VHF antenna. Or alternatively, use the main antenna for both VHF and AIS by fitting a special device called a “Splitter”.

Generally our recommendation for yacht owners who want to fit an AIS, is to use a “Zero Loss” splitter like our SPL2000. By utilising the main VHF antenna at the top of the mast, you will definitely get maximum transmit range. Plus the ease of installation often makes it a cheaper option than paying for a second antenna to be installed.

However, for power boaters who do not benefit from the height advantage of using the main antenna at the top of the mast. As well as for AIS receiver owners where the splitter can often cost more than the AIS receiver itself. It is often desirable to fit a second VHF antenna. This is particularly apparent if you intend to save money by doing the antenna installation yourself.

AIS operates on two dedicated channels within the marine VHF frequency range – 156.0 to 162.025 MHz. The two AIS channels are at the top end of this range namely; 161.975 and 162.025 MHz (channels 87B and 88B). Most VHF antennas are designed to give maximum gain across the whole VHF frequency range centred on Channel 16 (156.8 MHz).

Pretty much all of the antenna manufacturers now produce “AIS Tuned” antennas. These have their centre frequency shifted from Channel 16 to 162Mhz (exactly half way between the two AIS frequencies). If you choose to mount your AIS antenna on the stern rail of a yacht or radar arch of a power boat. Then using an “AIS tuned” antenna is a good idea. This will allow you to get an extra bit of gain. Thus compensating for the antenna being effectively at deck level.

The graph above shows how the tuning of the antenna to 162MHz gives it an extra boost in VSWR (gain) across the two AIS frequencies.

Which ever option you choose, having AIS on your boat will without doubt make your sailing experiences safer. As well as less stressful in poor visibility or when crossing busy shipping lanes. Even a simple receiver with a small whip antenna at deck level is effective. Allowing you to keep informed of what ships are around and which ones you need to keep an eye on.

The AIS system works on two channels in the VHF frequency range and in order to receive or transmit AIS information it is necessary for the AIS unit to be connected to a VHF antenna. One option is to fit a VHF splitter such as our SPL2000, which allows both the VHF radio and the AIS to use the boat’s main VHF antenna. The other option is to fit a second VHF antenna which is then just connected to the AIS.

Any VHF antenna can be used, although some antennas are “AIS tuned” to get maximum gain on the two AIS channels and also have a BNC type connector fitted (common on AIS units), rather than the traditional PL259 VHF connector.

If you decide to fit an additional VHF antenna for the AIS, you want to mount it as high as possible but you should be aware that it cannot be mounted right next to the existing VHF antenna and a certain amount of separation must be maintained to avoid the 25 watts of transmit power from your VHF radio going straight in to the AIS receiver circuitry, potentially damaging it. The diagram below shows the recommended minimum separation of the antennas.