Raymarine AIS500, unique Class B transponder

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now pleased to have Ben Stein as a very able publisher, webmaster, and editing colleague. Please don't regard him as an "expert"; he's getting quite old and thinks that "fadiddling fumble-putz" is a more accurate description.

39 Responses

  1. Olsonist says:

    There is still nothing on the Raymarine website. The AIS 250 can be found for $800. Hmmm… I think this is the first AIS Class B transponder I could buy.
    Logically the splitter should be two parts:
    a) on AIS transmit, give it priority and just disconnect VHF from the antenna. Having the splitter integrated with the AIS simplifies this considerably since the AIS logic knows when a frame is going to start. The splitter doesn’t need to sense AIS transmit.
    b) on receive, it is just an AIS receiver splitter.
    Having the splitter integrated with AIS helps somewhat but having it integrated with VHF probably wouldn’t help any further.

  2. Larry Brandt says:

    My guess is that the splitter senses VHF-in-use and sends an inhibit signal to the AIS transceiver, thus delaying the AIS burst until the first open moment following VHF transmit. I imagine that a 25 watt VHF transmission would have (ought to have) priority over an AIS transmission.
    $800 is really pricey for a single channel receiver, but integration is worth a bit more money.
    Kudos to Raymarine for properly naming their box a “transceiver”.

  3. Drew Clark says:

    Slightly different topic,but has anyone had a close look at the new AIS-1000 Class B transponder that West Marine has started selling? Looks a lot like the Shine Micro AIS-BX unit but is advertised at $100 less…Ben, any insights on this new device?

  4. Ben Ellison Ben Ellison says:

    Yes, Drew, that certainly does look like Shine’s AIS-BX as well as the Class B transponders sold by True Heading and Digital Yacht. I’ve tried the latter two and they work fine. The only real difference I saw was the data break-out cable; Digital Yacht’s is easier to use if you’re installing to a plotter as well as a PC.
    It’s great to see that West Marine is selling Class B and I think their online static data form is well done. Also good to see some price competition, but note that the AIS-1000 comes without needed antennas.

  5. marinate says:

    Ben – I think the West Marine Class B does include a GPS antenna according to the website, but no VHF.

  6. Richard says:

    There is no way that there could be a “VHF Inhibit” signal to delay the AIS transmission.
    Instead, if the user is transmitting on his VHF Radio during the transponder’s “Network Time Slot”, the transmission will not go out.
    I feel that this could potentially be very dangerous in a closing situation where someone is trying to communicate by voice while others are carefully watching for a 30 second update from the transponder that will not be transmitted.
    Can you check what happens when a connected VHF Radio is keyed for transmission for over 30 seconds???? If my theory is correct, the AIS message will not be sent. Furthermore, if there happens to be a conversation and the VHF is keyed again at the wrong moment, it is possible that well over a minute of time could pass before the local network is updated. Ironically, it could potentially be several minutes if other boats in the network are using Multiplexed AIS Receivers to monitor the network…
    Some may argue that this is an unlikely scenario but when in emergency manuevering situations, VHF radio usage increases dramatically and it is precisely at this time that timely updates from AIS will be most important.

  7. Ken says:

    Has anyone tested the output power on the ais 250? I did on my unit. When transmitting through the ais250 on my vhf radio (Icom 504) there was a big drop in forward power. It dropped it down to around 15 watts. Will the ais 500 do the same thing?

  8. Dan (b393capt) says:

    Richard, I agree:
    1) VHF inhibit signal makes no sense … AIS has to keep to it’s timeslot. Use it or lose it. I haven’t taken the time to look, but I would imagine if the AIS time slot is missed multiple times … it would even need to be negotiated again.
    2) Agree as well … “In an emergency manuevering situation, VHF radio usage increases dramatically and it is precisely at this time updates from AIS will be most important” … that has driven my decision to have a seperate AIS antenna, and do so even though it’s only practical to have it mounted on my stern rail rather than my 50 foot mast where it would have had greater range. (I can’t easily get a 2nd vhf antenna wire thru my mast conduits). Even if the range is cut in half, I would rather that then having my AIS transmit signal dropped when I am using my VHF.
    … you didn’t mention it, but far more concerning then not having my AIS transmit signal dropped, is that while I am speaking on VHF I am not receiving AIS info from nearby boats that I am trying to negotiate a passing situation with. After all, I would really like that confirmation that they did alter course as expected as opposed to the reverse.

  9. del says:

    I think it should be the other way around – the AIS transmission is very short (26ms) so if the VHF is in use when the AIS needs to TX, the AIS should override the VHF and send its msg. This will cause a short outage on the VHF, but with good design can be made almost un-noticable.
    An alternative would be to combine the VHF and AIS transmissions (like we do in LMR base stations) and so both would get transmitted at the same time, however, all designs I have seen for this mode inevitably result in a significant loss in RF Tx power – which would not be good….
    Personally, I use a separate antenna for AIS mounted on the stern rail – both to avoid these problems and to provide a back-up if I happen to lose the main VHF antenna – which is on top of a 10m mast. Power boats wouldn’t have this problem, of course….

  10. Dan (b393capt) says:

    del, I suspect the range you get with a stern mounted antenna is more than enough.
    What range do you experience? Which antenna did you choose to use ? Any regrets ?

  11. Larry Brandt says:

    “has to keep to it’s timeslot. Use it or lose it.”
    I must have been (and still could be) on the wrong track in my understanding of how AIS works. I have always thought that AIS transmissions were not time sensitive…timed to a second’s, or microsecond’s detail, anyway.
    My interpretation is that AIS burps out its autonomous message entirely independent of any other vessel; and if so, then there is no time slot to use or lose.
    What is the practical impact on the reception by other vessels if your AIS transmission happens to be delayed by a few seconds, or even a minute in case someone wishes to read James Joyce’s Ulysses over the VHF? I think zip.
    My understanding is that AIS transmits its data burst every 2 to 10 seconds underway, but there can be little adverse effect if that burst is once-in-a-great-while delayed for 30 seconds, or even a minute or more.

  12. Ben Ellison Ben Ellison says:

    Larry, AIS is extremely time sensitive, and thus dependent on the GPS system clocks. Class A uses a very sophisticated slot organizing technique called SOTDMA. Class B uses a different technique called CS which integrates with Class A transmissions but never steps on them.

  13. del says:

    I must endorse Bens comments, AIS is very critical on timing. However, I can see where you may get your ideas from, if you miss a burst, does it matter when there will be another one in 10 seconds time? Probably not in most situations, but a delay of a minute while the crew finishes chatting on the VHF could well be critical!
    I’m running a home-brew Rx-only box at the moment with a standard antenna from the cupboard in the office where we store stuff that “might come in useful one day”! It’s mounted on top of the davits at the stern, so its base is about 2m above the water line. I’ve pulled in contacts from over 20 miles regularly while sitting on the mooring and 30 miles when running through Poole harbour, though as I didn’t get out much last season, it remains to be seen how repeatable this is.

  14. Larry Brandt says:

    I just returned from the Seattle Boat Show where I had the opportunity to talk to a Raymarine sales guy about the new AIS. He claimed to not be completely up on AIS, but I liked a couple things he said.
    “AIS A is polite. It waits and listens for about 5 seconds before it transmits, just to make sure it doesn’t step on someone. AIS B is even more polite, because it waits and listens for an even longer period.” I liked that description.
    He also said, about the splitter question, that if the AIS transmits during a VHF transmission, “the AIS burst would just get lost in the VHF power out”. Get swamped, in other words. Then the AIS would have to wait another period before transmitting again.

  15. del says:

    Both AIS A and B are polite, but not in the way described by your Raymarine chap!
    This is from memory, so I may get the odd detail wrong but:
    Class A switches on, waits for 1 minute while it records all the slots that are already in use, and those already allocated by any local base station. It randomly chooses a slot from one of the ones that is not in use and transmits into it, at the same time reserving its next slot that it wants to tx into, so everyone else knows about it and doesn’t tx over the top of it next time around.
    Class B randomly selects a slot within a few seconds of every 30 second time interval and listens for a few ms to see if it is occupied. If it is, it chooses another random slot from the same time period. If all opportunities are exhausted (I think its 10seconds either side of the 30second nominal period), it gives up and tries again 30 seconds later.
    I still think its bad news for the AIS burst to get trashed by the VHF….

  16. Larry Brandt says:

    Thanks for the insights. Yes, I agree that a splitter isn’t an optimum solution for Class B, and not only because of the loss of the AIS transmit burst when VHF is in use…also for the attenuation in VHF power, per posting by Ken above.

  17. Mark says:

    Has anyone played with one of these yet?

  18. Dirk van de Stege says:

    I do have a VHF antenna and Glomex V9112 fm/tv antenna both at 15 mtrs on top of the mast. The Glomex antenna has an controllable antenna amplifier near the chart table, but it also has an output impedance of 75 Ohm, which is different from the 50 Ohm of the marine equipment.
    I wonder if I could use this antenne with an impedance transformer 50/75 Ohm for an AIS receiver. What do you think?
    Regards from The Netherlands

  19. Rochambeau says:

    Is there any idea of the cost of the AIS500 Class B tranceiver?

  20. Olsonist says:

    The Raymarine website says:
    Raymarine is pleased to announce the introduction of our ST70 Plus multifunction instrument system and AIS500 transceiver module. ST70 Plus and the AIS500 will be making their North American debut at the 2009 Miami International Boat Show, February 12th-16th.

  21. Ben Ellison Ben Ellison says:

    I’m in Miami now. Will see Navico Broadband Radar on the water today, and the new Raymarine stuff on the water tomorrow. Will report as time permits!

  22. Olsonist says:

    The Raymarine website finally has some information.
    MSRP: $1,399.00
    “Easy-to-integrate with built in GPS, VHF splitter and NMEA multiplexer
    Activate silent mode directly from a Raymarine MFD interface
    16 channel dedicated GPS with external antenna included
    Simple interfacing with Raymarine gear using SeaTalkng or NMEA 0183”
    I’m not sure what they mean by NMEA multiplexor. Can I take NMEA 0183 from my speedo and broadcast it onto the N2K bus? Can the GPS antenna be mounted inside Garmin GPS 17x style?

  23. Stephen Santoro says:

    I have installed the new AIS 500 on my sail boat and although the install was not difficult and it does receive vessel data is appears to continually cycle on and off loosing the GPS fix and giving me a Transmit time out. Waiting for Raymarine response.

  24. Peter says:

    I am new to this thread and it might be slightly off topic, but does anybody know how to get to the serial port on the Raymarine AIS500? I received mine “fully programmed” but it only has my MMSI number and no other information. I have been told by the retailer that I can confirm/update the non-MMSI information (I know MMSI fiddling is prohibited by the FCC), but can’t figure out how to get to the serial connection that lets me use proAIS and a laptop to do the programing.
    Any help appreciated. Thanks

  25. Peter says:

    Please ignore my preceding post — it is rediculously easy to do. It turns out that the serial port is not on the unit itself (as I had been advised) but rather comes out of the main pigtail from the unit, about 18 inches or so from the connection into the unit. The serial port (9 pin) is at the end of the pigtail (which in my case had been tucked away and covered up — at the risk of sounding defensive). Once plugged in, I powered up the laptop and then the AIS unit and started the proAis software and it was exactly as outlined by RM. Note that the AIS instal manual has a highlighted warning not to have any MFD’s powered on, which is not in the proAIS documentation. Sorry for the waste of elecrons.

  26. jnkendal says:

    I am intending to buy the AIS500. Currently I have a C70 plotter (aft cockpit) and a C120 plotter (navigation station).
    I spoke to Raymarine USA and asked them about being able to display AIS data on both displays. One technician stated that it was possible by connecting the AIS500 NMEA output to one of the plotters (I prefer the C120 simply because of its accessibility) and then the SeaTalk will transfer the data to the C70.
    Another technician called me and stated that it was not possible.
    So, I am puzzled – is it or is it not possible to display AIS data on both C70 and C120 plotters simultaneously? And if it is possible, how is this achieved?
    Any information will be appreciated.

  27. Ben Ellison Ben Ellison says:

    Well, the installation manual is online:
    but it is pretty vague about possible set ups. I would think that if you connected the AIS500 to one of the C-Series via NMEA0183, it would get to the other one via SeaTalkHS, as other 0183 data does. But maybe not?
    It also seems possible to route the AIS500’s 0183 output to each C-Series. Most 0183 outputs have enough moxie to talk with two listeners simultaneously. But maybe not?
    Of you could use the unit’s RS232 (PC) output to drive one of the C-Series. It and 0183 are very similar.
    Finally, you could maybe use the SeaTalk2 (aka NMEA 2000) ports on your C-Series, though you’ll have to use adaptor cables to get from the SeaTalkNG (also NMEA 2000) cable on the AIS500. But Raymarine has to update the C-Series software to understand N2K AIS messages. I know that’s planned for the E-Series but not sure for the C. I do know that the AIS500 is outputting those messages (except for the new Class B static data message).
    In short, there are lots of ways to install an AIS500, but Raymarine really should be clear about what works where.

  28. Anonymous says:

    Finally, a third response from RM.
    I am now advised to connect the AIS500 NMEA 36.4K baud output to both the C70 and C120 NMEA input, and connect the NMEA 36.4K baud input from the AIS500 to one plotter only (C120).
    They (RM) state that the AIS500 output should have sufficient output power to provide data to both units.
    By doing this there should be no corruption of data/display in both plotters.
    As an aside, the AIS500 has its own GPS rxr and therefore can be used as either primary or backup NMEA0183 4.8K baud data to other systems, eg. DCS systems.

  29. Peter says:

    My installation of the RM AIS500 is with three networked RM E System multi-function displays. I have just heard that RM, which is updating the E System software to v.5.52 (this week, I am told), will NOT support the E System MFDs using a SeaTalk interface with the AIS500 — so it will only connect through 0183. This is really aggravating since the sales material for the AIS500 shows features that are only available if using SeaTalk, or RM’s version of 2k.
    Has anybody heard anything about this? Are there any work-arounds? Thanks

  30. Ben Ellison Ben Ellison says:

    I have not heard about this, Peter. But I can tell you that the AIS500 is putting out AIS data over SeaTalkNG/NMEA 2000 and it is understood by the Garmin and Lowrance MFDs on my test bridge with the exception of Class B static data, a message that only got added to standard N2K recently. There are a couple of glitches like that in N2K AIS, but I think they’ll be ironed out eventually.
    What AIS500 features are only supported via SeaTalkNG? Also, if you do the install to one MFD via NMEA 0183, won’t the data get to the other MFDs via SeaTalkHS?

  31. Peter says:

    Thanks Ben. I have just gotten the E System update (v. 5.52) and so am still fiddingly with it. Under the old version at least, 0183 didn’t permit the promised ability to turn off transmission (the so-called stealth mode) and, more significantly, it didn’t broadcast vessel name or other information (only the MMSI). I will see if I can figure out whether the new update addresses these and come back. On the install, I would think that if the initial MFD is connected through 0183, even though the daisy-chained other MFDs are connected through ST HS, the downstream MFDs won’t have any more data or functionality than the intitial MFD. Right?
    On Jeffrey’s note, we have a Simrad AP tied into the system that stopped talking to the RMs when I changed the baud rate to accommodate the AIS. We ended up putting the AIS on a different MFD, and setting only that MFD to the 36.4 rate, and then changing back the MFD tied into the Simrad to a 4.8 rate — so far this seems to be working and the Simrad is talking to RM again.

  32. Ben Ellison Ben Ellison says:

    Peter, except for the Silent Mode button, I don’t think your MFD has anything to do with what your AIS500 is transmitting. If someone is seeing your target but not your boat name (after a few minutes), the chances are very high that the problem is in that person’s AIS viewer, not your transponder.

  33. just a few tidbits from working with Raymarine to get a working AIS500. there appears to be a timing issue that prevents the unit from working within the Puget Sound area. it cannot gain a slot assignment, times out, and reboots randomly. Raymarine acknowledges this issue, and is working this week on a solution.
    additionally, sad to say, the odds are very low that Raymarine is going to support Silent Mode and Buddy Lists on the C-series (classic). indeed, they are attempting to phase it out as soon as possible. it seems odd to market a new device, give every indication that the features it advertises will work with existing chartplotters and interfaces .. only to find that isn’t the case. my ST290 (NMEA2000 compliant) system will not support these new products via the Seatalk2 bus.
    for more details, check my website for the ongoing saga of AIS500 woes and scheduled updates.
    daniel taylor

  34. daniel taylor says:

    I wanted to report that Raymarine engineering has identified the AIS500 software bug and will be distributing a software update. indeed, the problem was caused by a particular station in the Puget Sound area transmitting a multi-slot message #8, that wasn’t handled correctly and caused a processor crash and subsequent rebooting. for more details, including a description of the problem from Raymarine engineering, check my website.
    daniel taylor

  35. marc provost says:

    anybody any idea??? When i go power off with mij raymarine plotter C90 my AIS500 goes automaticley in silent mode… ??? what can i do about it??

  36. Oliver says:

    You will learn that die AIS500 works very different from what the manuals say. I have a discussion with Raymarine rigt now because it is NOT possible to switch to silent mode with the software proais, branded by Raymarine.
    Well, it is possible to switch to silent mode, but only with the unbranded proais soft. Raymarine tells me dont do, dont even think about it, becaue you brick you unit. Well I did it and for the time being it works. But Raymarine is “proud” of features and quotes that everywhere which are not implemented, thats a fact.
    Oliver Langen

  37. JenIWard says:

    How does one go about changing the name/registration details? We purchased a boat from the US it is now registered in Canada with a new name and we would like to update the AIS details.
    Can anyone point us in the right direction?

    • Ben Ellison Ben Ellison says:

      Hi Jeni, There’s a useful thread about how to do this on the Raymarine Forum:


      As you’ll see, it’s gotten a bit tricky to run the AISPro configuration software because the AIS500 only has a serial port so your likely-more-modern laptop probably needs an adaptor to connect via its USB port. That hassle, plus the improvements in newer AIS transponders, may indicate that replacing the unit is the way to go.

    • Ben Ellison Ben Ellison says:

      Jen, it also occurs to me that you should have access to the MMSI being used by your AIS as the associated contact info is sometimes used by search and rescue authorities. In the U.S., Class B transceivers can not have their MMSI changed by the user, and the free MMSI’s given out by BoatUS and similar are not supposed to be used outside U.S. waters. It’s all a bit messy I’m afraid.

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