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Masthead Wind Sensors for N2K

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I have been reading Panbo for a long time now but this is my first posting. Okay, now I am really confused! I have spoken to Raymarine and B&G techs and gotten different and conflicting answers.

I have a Catalina 34 with 25+ year electronics that I am replacing with NMEA 2000. I don't race, but I do like to sail efficiently. So far, I have an Evolution autopilot with a P70 that is awaiting installation. I've removed my old depth and speed transducers, patched one of the holes and installed an Airmar DST800.

For an MFD, I am looking towards either a B&G Zeus3 or a Raymarine Axiom. I have been told the B&G will control the Evolution (sail to apparent wind angle) and I have been told it will not. I understand I do need to use the P70 for calibration and I'm fine with that. My issue becomes getting wind data- both true and apparent.

I am told the Raymarine wind sensor will need to go through an ITC-5 and also an I70 (or similar) in order to generate N2K true data. I don't want added complexity and more gauges. Ah hah! Why not use a B&G 608 masthead sensor that will natively produce N2K data! I am told this will work, but it will only give apparent speed and angle. How do I get the true readings? Will the Evolution generate true wind? Will the Axiom? Will the Zeus? Answers are all over the place. Which piece of hardware will actually perform the calculations?

Then I thought maybe the way to go is with an Airmar 220 wind sensor which includes the GPS and can deliver native true and apparent data. I think this would eliminate any guess work. Until I came across this article
which argues that there can be only one source of GPS and that the GPS on the Airmar would essentially shut down. Is this true or would it still function to determine true readings, just not report GPS on the N2k network (since the GPS is coming from the Axiom or Zeus anyway)? In this kind of situation is an Airmar 220 no better than a 120 without GPS?

To complicate matters further, has anyone ever heard of the LJ Capteurs wind sensors referenced in the above forum thread? It is currently listed for sale at the Fugawi website. While I could get apparent data from this unit I am still back at square one as to what piece of hardware will generate the true speed and true direction data.

I am not married to either Raymarine or B&G (except to the autopilot at this point) so whichever MFD would be the better fit is how I am going to proceed. From a sailing perspective (dynamic lay lines, polar data, etc.) any thoughts here?

Your time, advice and guidance is very much appreciated. Thank you!

Tim Weber,
Wheaton, IL

6 Replies

  • Tim, Check out this entry for some info on how the LJ Capteurs C7 installs:

    It's not actually an N2K sensor but it acts like one with Windy Plug bridge, and that may mean an easier install. I've been seeing quite good performance and several MFDs and N2K instrument displays on my boat can compute True Wind from the LCJ apparent wind output and Heading received from another source.

    I may not have tried the LCJ with Simrad NSS but would be surprised if NSS (like Zeus2) did not compute True Wind (relative to water) and also Ground Wind (aka True Wind relative to ground).

    EVO1 should be able to use LCJ or any other AWA source to steer to wind, but suspect that only Axiom or other Ray display will give you full ap control. That's typical across brands.

    Axiom doesn't yet have much in the way of special sailing features, but they are promised.

  • Tim,

    B&G 508/608 + DST800 is the standard combo for sensors, and together they will produce true wind.

    Note that Ben says you need heading input to comput true wind, but that is a slip of his pen -- true wind (relative to water) requires boat speed through water (normally with a speed sensor, not COG, although some displays can be told to use COG) and ground wind (relative to ground) needs heading to translate the true wind angle which is still relative to where your boat is pointing to something relative to North.

  • Also, multiple sensors like multiple GPS sensors is fine with most brands. I've told my Zeus 3 to select the best GPS it sees (based on HDOP / # of sats).

    Raymarine used to have issues with multiple sensors, maybe they still do.

  • Thanks, Kees! You could have said "slip of old brain" instead ;-)

    Particularly embarrassing as I'm just finishing entry on new Airmar UDST800, which promises excellent STW accuracy. (And this time it's real ;-)

    Raymarine has gotten better at managing multiple sensors, but still not up to Navico.

  • Ben E and Kees-

    THANK YOU BOTH for taking the time to reply to me! I now have some confidence in how to proceed and that I should end up wit a functioning system. As much as I would like to go with the B&G, the Axiom might allow me to go with a 12" display for the price of a B&G 9" and hope the raymarine software gets some updates specific to sailors-- this would at least eliminate any AP interface issues.

    I'm also going to give the LCJ a shot especially after reading your review..... I had not seen this before but it gives me some additional reassurance.

    I also saw the link to the marinebeam tricolor...... give me another reason to drop the mast for both the wind sensor and tri-color upgrade.


  • So then to be sure, the Axiom in conjunction with the EVO autopilot, will calculate the true wind speed and direction, correct?

    Thanks again!