ComNav Class A AIS transponder, with NMEA 2000!

... written for Panbo by Ben Ellison and posted on Dec 14, 2009
ComNav Compact Class A AIS.jpg

Very cool!  It looks like the compact and relatively inexpensive Class A AIS Transponder that SRT teased last summer is not only getting close to real, but that it will also -- nice surprise -- have NMEA 2000 output (in addition to regular NMEA 0183 HS and RS232 PC outputs).  The ComNav data sheet is available here (thanks, Dave!), but there are some caveats...

For one, the Voyager X3, as ComNav is calling it, is not yet FCC approved and therefore it's not yet for sale in the U.S.  And the price is not listed (I've asked), so we don't yet know if ComNav met SRT's hoped for "less than $2,000 retail."  Plus, the N2K output won't come until a software upgrade is issued in "late 2010."
   But given all those caveats, this sure looks like an interesting new option in AIS.  At 8"W x 4.2" H x 5.4" D, the Voyager X3 is sort of similar to the neat Simrad AI-50, only with the ability to transmit at 12 watts instead of 2.  A yacht carrying a compact Class A transponder like this will get seen a lot further away, and will also be able to input its navigation state and destination, just like the big boys.  And whereas we know that SRT actually builds these for OEM clients, we can probably expect to see it under other brand names soon.
   And what about SRT's promise for a small, inexpensive AIS receiver printed circuit board?  Well, I have no idea if Standard Horizon is using one in its new GX radio combos, but I'm pretty sure there's one inside Digital Yacht's new ANT200 seen below.  Yup, that's a complete true dual channel receiver just 4 inches in diameter, and it only costs $300 with it's own stubby VHF antenna.  Digital Yacht's got another interesting AIS receiver product I'll detail soon, and it sure looks like SRT is making good on its promises.



I've learned from ComNav that the expected MSRP for the Voyager X3 will be $2,999. So maybe I spoke too soon about SRT's promises coming true. In fact, you can already buy an ACR Nauticast2 Class A transponder for $2,999:

Then again, the price of SRT's original, and perfectly good, OEM Class B transponder has fallen nicely over time:

Posted by: Ben at December 14, 2009 3:06 PM | Reply

Ben: If we see retail discounts of ~20% on Comnav like we do on Furuno than $3,000 is still a pretty good starting price, about one third lower than the Furuno FA150.

But the Comnav is actually an inch *wider* than the Furuno and the "late 2010" date for N2K is ridiculous. Why bother, since anyone who wants one now will have to use 0183 directly (as there are no 0183-2000 bridges that support AIS at the moment)? I doubt that many who run 0183 wires now will pull them when the N2K firmware revision is released. (Though I guess maybe I would!)

But I do think the idea of putting N2K on a piece of "professional" gear is interesting, in that it acknowledges that recreational boaters are growing unhappy with the prospects (real or imagined) of second-class-citizen treatment of Class B AIS users.


Posted by: Adam at December 14, 2009 6:23 PM | Reply

Adam, The Furuno FA150 is actually a two piece system, with the black box FA1501 AIS transponder much larger than the FA1502 Monitor. That's not really clear on the web page, but it's illustrated in the install manual:

And an interesting link regarding SRT and expanding Class A mandates:

Posted by: Ben at December 14, 2009 7:06 PM | Reply

I think "transponder" is a misnomer for AIS equipment. The term was coined in Aviation for a radio that transmits a response when interrogated by radio from a ground based radar site. AIS does not wait for someone to ask it where it is, it just transmits and receives continuously. For that reason, I hold that "Transciever" is the proper term, and notice that most manufacturers seem to agree. Vendors are more sensitive to the language that customers might search for, and tend to use both terms in their literature.

Posted by: Sandy Daugherty at April 6, 2010 4:44 PM | Reply

We've been around this tree before, Sandy. I think you're right that AIS doesn't quite meet the definition of transponder because it's automatic. On the other hand, the time organizing scheme is interactive. Plus transceiver, while completely true, is too general.

At any rate, the USCG and other authorities use transponder, and that's good enough for me...

Posted by: Ben at April 6, 2010 4:52 PM | Reply

I called ComNaV today to verify that this update has happened. Not yet...

Is there such a thing as a Class A AIS that is NMEA 2000 capable?

Posted by: Howard at September 23, 2014 6:21 PM | Reply

Howard -

Take a look at the McMurdo Smartfind M5, a Class A AIS that uses NMEA 2000. See:

Unfortunately, it's not inexpensive (it retails for approximately $2,200 in Europe) and I don't know if it is for sale in the United States.

Posted by: Dan in reply to Howard at September 24, 2014 12:26 PM | Reply

Thanks Dan for the Link! It doesn't appear to be FCC approved..

Posted by: Howard at September 29, 2014 6:09 PM | Reply

I do see the McMurdo Class A AIS displayed at U.S. boat shows, so I think it's approved. The approval may be under AMEC, which actually manufacturers it.

Howard, ComNav told you that their Class A doesn't yet support NMEA 2000? That would be darn surprising as it's actually made by SRT which has numerous N2K AIS devices.

Posted by: Ben at September 30, 2014 9:38 AM | Reply

Yes Ben, I called ComNav directly and was told that it does NOT support NMEA2000.

I will search for the Amec, it is not under Mcmurdo or their parent company.

Posted by: Howard at September 30, 2014 9:15 PM | Reply

Milltech also sells the AMEC Class A in the U.S., and lists it with NMEA 2000 output:

But I also found further confirmation that the SRT-made Class A sold under ComNav, Em-Trak and other brands never got working N2K output:

Posted by: Ben in reply to Howard at September 30, 2014 9:35 PM | Reply

I have sent an email inquiry to Milltech. They are local to me. I am hoping they have put one in place or are willing to let me test it on a NMEA 2000 network. I have the rest of the week off to spend on boat projects.

Posted by: Howard at October 1, 2014 12:27 AM | Reply

I am interested in using a class A on a "pleasureboat" since I have seen how much reduced the range of class B transceivers is compared to class A even giving fault-free masttop antenna installations. Class B does not in my experience give more than 12nm while there seems to be almost no limit with class A. I have myself seen nearly 100nm on rare occasions.
I don't like the added power draw, though, and my main questions are:
- do I violate a law and can expect negative consequences if I fail to update the voyage-related data when I am supposed to or if I set this information to blank (if that is possible)?
- does a unit such as the AMEC take heading data from NMEA2000 or do I need to provide this via the separate sensor ports shown in the wiring diagram using NMEA0183? An will the unit work correctly when no heading data is available? (I think so because I have seen class A targets displayed perpendicular to a pier)

Posted by: Henning at October 1, 2014 12:43 PM | Reply

I cannot find anything that would preclude a recreational boat to utilize a class A.

The power is a little more, but 12nm is pretty darn far. Even at 25knot cruise, that is is still a 1/2 hour of avoidance time.

The main reason I am interested in the Class A is for the rapid position update. We cruise at 24-28knots. Class B only updates every 30 seconds. I have seen some conflicting info on that though.

I received an email back about the AMECO 701. I asked your exact question and then some. The response was less than convincing. It basically said "sure does, says it right there in the manual". I was hoping for first hand experience. I don't want to be a trial user. This model is not sold by nearly as many OEMs as the SRT Class A. The ComNav is the least expensive of that version and with the NMEA 2000 AIS adapter from acti sense, it still adds up to less money. Especially since the AMECO distributor is local and I would end up paying 9.5% sales tax on top of the $2500 purchase price.

Posted by: Howard at October 1, 2014 6:26 PM | Reply

This is the response I received from the importer. They communicated with the manufacturer in Taiwan.

"Camino-701 can only receive inputs from NMEA0183 and any NMEA0183 message supported by Camino-701 can be output through NMEA2000. So Howard should not have issue connecting through NMEA2000."
Hope this gives you what you need.

Not a very clear response, but it looks like the NMEA2000 is only output.

I have a variety of ways of addressing this.. I am just looking to do a clean install of NMEA 2000 install. At this point it has just been a pursuit to find something for the sake of the pursuit.

My interest in Class A is solely because of the rapid position update. I cruise at 25 - 30 Knots.

I have an Airmar GH2183 for my GPS/Heading sensor. I can either purchase the special Airmar cable that has both 0183 and 2000 pigtails or purchase the Actisense NMEA 0183 AIS converter.

Nothing has been simple with the Furuno TZ touch system.. but I really like it. Not understanding the bits/pieces needed to get things done. (Separate power supply for the radar, heading sensor needed for radar overlay, etc)

Posted by: Howard at October 3, 2014 3:58 PM | Reply

Howard: thank you for taking the trouble of asking AMEC.
Yes, I also don't like the slow update rate of Class B.
I agree, most of the time 12nm is more than enough. But most of the time leaves some of the time when it isn't enough. For me this is on passage in the open ocean with big ships crossing my course when I have wished they could see me sooner. With a container ship steaming at 18 knots and us moving at 6 we are closing in at up to 24 knots, meaning 12nm is no more than a half hour. I cannot expect them to change course the instant they see me. If I give them 10 minutes to take action, then we are down to 20 minutes to CPA which I will spend with my eyes glued to the screen.
If they could see me reliably at 48nm = 2 hours and I could have seen them change course 1 hour or 45 minutes to CPA, that would have made a passing just that much more comfortable for me a few times.
About heading input: I have an Airmar H2183, which like yours can additionally provide NMEA0183 heading but this would mean to run another cable through the boat and one more channel to develop a problem (which would be hard to detect and to troubleshoot). And if you use a NGW-1 for heading input than you might as well use the other channel of the NGW-1 for AIS output. So the ComNav may be the better choice after all.
About the requirement to update voyage-related data on a pleasureboat (and also the requirement to run it all the time): After googling and browsing through legalese for a while I have understood that I am not likely to find a law explicitly allowing this but rather that there does not seem to a be a law explicitly disallowing it - which in effect could be the same thing. If I am not required to operate class A AIS then (this is my understanding) I am also not required to run it all the time or update voyage data whenever I go out for an afternoon of sailing if I chose to install class A. Nowhere did I find a sentence saying "if you chose to have it even though there is no requirement to have it then you have to operate it to the same requirements in effect for those that have to have it."
So I will seriously consider it and the ComNav seems like a good solution.

Posted by: Henning at October 4, 2014 5:40 PM | Reply

Ok, I know I am beating a dead horse, but I am going to explore a bit more.

I found a Furuno Class A AIS FA-150 with antennas AND a Furuno GP-32 GPS receiver for a total of $250.00 A reputable yacht outfitter is selling them. I was able to get the password for the AIS so that I can change the ships static data (MMSI most important!)

I am hoping that there is an optional board installed in the AIS called a NET 100 board by Furuno. It is a LAN connection for the NAVNET network. If not I will have to purchase that board at a retail of $425.00 There are no manuals/specifications online for the LAN board, but I am hoping that it shares all of the AIS data over the network. We will see!

I haven't received a response to this question on either the THT or Furuno's own support forum. This appears to be one the black arts/Furuno keeping the info close to the dealer's technicians chests.

Posted by: Howard at October 20, 2014 4:43 PM | Reply

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