2022: Recommendations for AIS transceiver?

[Krumelur]

An AIS transceiver is high up on my "nerd stuff" list. Has anybody (recently) installed one and can speak about experience, brand used etc?

[Yngmar]

I've recently installed an em-trak on another boat and it was fine. They got it sponsored on account of being Youtubers with a bunch of followers.

Our Matsutec is also still fine after several years of cruising and cost a lot less for people who aren't being sponored

Simrad/Garmin/Raymarine ones are generic circuit board designs with a branded plastic case and best avoided (in case you ever wondered why they all use the exact same ProAIS software, that's why). They work but you pointlessly pay for the brand without getting any benefits out of that. Em-trak uses the same board, but had competetive pricing last I checked.

You'll want it to have the right outputs for the rest of your system, which means choosing between NMEA0183 and N2k (some have both). Then you can pick if you want a USB output, Wifi output or even Ethernet (or combinations thereof). If you choose Wifi, make sure it can either act as AP or join an existing network, else if you expand later you'll be stuck. Some have SD card slots for recording your tracks but I don't really see the point of that.

Ignore any marketing waffle about Class B, B+ or A, it makes no practical difference. A good, well matched antenna makes a big difference though. You can buy a AIS specific antenna, or you can take VHF antenna and clip a (carefully calculated) bit off the top to match it to the AIS frequency, which helped a surprising amount. Also the antenna should be installed as high as possible and clear of obstructions, yet well away from the marine VHF antenna. Ours lives on the stern arch, which seems to do well.

Active antenna splitters for running VHF and AIS off one antenna are absolute garbage and must be avoided. They break all of the time. I've seen so many dead ones and the Simrad ones failed in a silly way where the AIS path got locked in and therefore the marine VHF stopped working completely. Just don't even think about a splitter. Simrad boat gave up and fitted another antenna after the third warranty replacement.

[Krumelur]

Good input.

I have already a Raymarine A75 plotter installed - I don't know whether it's using NMEA0183 or N2000.
I would want to see AIS information on that existing plotter and on my iPad (Navionics). The plotter provides a WiFi access point and Navionics can connect to it but then I'm losing access to the internet (tethering to iPhone). Not sure what the best option would be.

As far as the splitters are concerned: I really don't want another antenna. I'll remember your words if/when the splitter breaks ;-)

[Salty]

I went down the splitter route, and can confirm it was a pain, the use of the VHF radio became compromised and I had no space on my boat for stuff that did not work 100% for 100% of the time. The splitter was removed and, by that time I had a stern arch, so a new AIS transmitting aerial was placed high up on the arch. The VHF radio was connected back in directly to its original mast head antenna, and now I had full ability to transmit on the radio as well as full use of the AIS all of the time.
The AIS unit I purchased was the Icom model with its own display and which was located within the cabin on my B36. Because it was not in front of me when helming the boat, I needed to extend the output to the helm and convert its NMEA0183 signal to NMEA2000 which the Raymarine chart plotter would then accept. Getting the right piece of converting hardware programmed with the right software was also a pain, and I had to rely on the seller to do that as the instructions given were just mumbojumbo to me. Anyway, the system was then connected up and so far* as I know has worked faultlessly since.

* Sold the boat a couple of years back, but the new owner and I have kept in touch.

[reystos]

I am using an EM-TRAK B923, we organized a group buy with our sailing club. The device is connected between the VHF antenna and the radio. There is a small extension cord in the package, so if you put the AIS near your radio, you need no modifications to the wiring. VHF works just like before.

The B923 is from the cheaper devices emtrak provides, so it has no wifi. But it does have an NMEA0183 output, which I have routed to a Wifi bridge. It feeds AIS targets and information to my mobile phone, my tablet and any other crew devices connected to the wifi bridge. We run Navionics and it is very convenient. There is no space for a chart plotter in the cockpit so everything is done wirelessly.

[Krumelur]

That sounds close to what I would like to achieve.
I would want to have AIS information on my Raymarine A75 but also on the iPad, which is my main navigation device.
So everything the A75 has should also be on the iPad.

What would the setup be like if I still want internet access on the iPad (no SIM card, needs to tether to a WiFi AP)?
The A75 provides an AP but how do I get that into the internet then?

[reystos]

Things to check before you decide:

0. Check your VHF antenna's internal resistance with a multimeter. It should be infinite. Any less than that, or suspicion of a closed circuit could indicate a shorted antenna line (which was the case on my boat). If you accidentally connect your AIS to a shorted antenna line, it will go kaboom and no warranty for you.
In my case, the VHF seemed to be working somehow, but the antenna was long gone. Replaced everything and they work very very well now - both AIS and the VHF behind it.

1. What protocols does your chart plotter understand / support? You can find that in its manual. NMEA0183 and NMEA2000 are the most common, but they are not compatible. Seatalk is another protocol for Raymarine instruments and there are a few others manufacturers that use their own.
The B923 provides both NMEA2000 and NMEA0183 data outputs. You have to find the wiring in the little harness they give you and pick which lines to use. There is a configuration utility in case you need to change baud rates, output ports etc, but I did not touch it - there was no need. All these devices need to have a common ground terminal, to talk to one another. Most likely you will not need to care since all is fed from the same on-board battery system.

2. Is everything going to be done wirelessly? While the WIFI-NMEA bridge links via wifi your mobile phone/tablet/ipad to the AIS (or whatever other NMEA0183 speaking devices you have feeding it), it takes up one output line from the AIS.
The potential problem that can rise here is that if your chart plotter and your wifi speaks NMEA0183, you will need to feed both from the AIS device.
If your plotter speaks NMEA2000 and the AIS does not, you need a converter. Even after having all available documentation, it takes a bit of time to figure out which goes where.

3. To the best of my knowledge you cannot have internet via the wifi-nmea bridge. Given I use it on my phone, I just turn on 3G/4G/5G or whatever is available, while I am connected to the wifi, so never is a problem. Navionics and similar apps allow you to download and keep the maps on your device. So you do not need to be online while using them. AIS targets are updated in real time once the system is up and running and if the antenna is in good shape.

[Yngmar]

That sounds close to what I would like to achieve.
I would want to have AIS information on my Raymarine A75 but also on the iPad, which is my main navigation device.
So everything the A75 has should also be on the iPad.

What would the setup be like if I still want internet access on the iPad (no SIM card, needs to tether to a WiFi AP)?
The A75 provides an AP but how do I get that into the internet then?

The A75 has both SeaTalkNG (N2k with proprietary connectors) and NMEA0183 inputs. To get AIS onto the A75, you need to hook it up to either N2k or NMEA0183 (do verify in the manual that it can take high-speed NMEA0183 input, not the usual 4800 bps, otherwise it will not work).

To get everything onto Wifi and have internet access, you need all Wifi devices joining the access point that provides the internet access. That would be your iPad, the plotter and the AIS receiver (which must support Wifi). You can then connect the iPad to the right TCP/UDP port on the AIS (see documentation) to get AIS data. Takes a bit of setting up and like I said, you must be careful that all the devices involved support joining an existing network rather than hosting their own.