In one of my previous projects I built a masthead wind sensor using an Arduino to process the signals and output a NMEA string. Next I wanted to make an instrument on the boat to display the information. I found a cheap non-working B&G Network Wind display on eBay which fit the bill and set about taking it apart. The display is analogue with a motor and hall sensor to move the wind angle arm. I found that the arm was on too tight and was rubbing on the backing, making it hard for the motor to drive it. After fixing this, I also changed the coin cell battery in the unit which was dead flat. Next I investigated how to simulate the inputs!
Before I bought the unit, I did some research and found that B&G have freely available documents on their website describing the signals that their masthead anemometers generate. The speed input is a simple pulse of varying frequency, and the direction input consists of three analogue inputs that follow an offset sine wave pattern through 360 degrees.
So to drive these three analogue inputs from an Arduino, I used the analogueWrite function combined with a low pass filter for smoothing. This Low-pass Filter Calculator is a great tool for finding suitable values to experiment with. I ended up with a 2K resistor and 22uF capacitor for each of the three signals. I also ignored the fact that the proper signals peak at 6.3V and just used the 5V peak from the Arduino, which seems to work fine.
With a bit of testing I was able to plot the speed vs pulse frequency relationship in order to display the apparent speed correctly. Although my current algorithm (code here) is quite rough and needs to be more accurate, I will also rewrite it so it uses proper timer interrupts. Otherwise I have successfully given new life to an old wind display by simulating a masthead sensor, and can now work on merging it with my other projects for a complete DIY wind system! Stay tuned!
Mechinations 
I have thought it would be interesting to send pulses like this to an inexpensive bicycle computer, to display speed over ground, or wind speed, or depth.
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Hi
Did you figure out what the internal battery does. I have that unit and it has suddenly gone dead so wondering of it is just this battery
Thanks for any advice
It’s hard to say exactly, but I think the battery would just keep the settings in memory when the unit is switched off. I don’t expect it would be critical to the unit working or not.
how did you take the unit apart? I’m wanting to rewaterproof mine. There are no obvious screws holding the cover to the back that I can see!
To take it apart you basically have to cut the black silicone off, that seems to hold the front on to the back.
tx Tom
Hi
Really great job, impression!
When you were in the b&g wind display, did you find any way to connect nmea 0183 wind sensor to it. I broke mine b&g 496 masthead unit can and compatible ones are very expensive. I do have another mhu with nmea output but I don,t know how to connect to b&g network.
Best regards
Ingemar
Hi, when I took my B&G display apart I did not see any way to use a NMEA input. The B&G display manual did not mention NMEA input either, hence why I had to ‘re-create’ the masthead signals.
Can I ask how you get the direction needle off?
Sorry, I can’t remember!
By the way, the 496 mhu, I have figured out how to repair the “broken thread” issue,also how to change the bearings
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How did you change the battery? I have the same unit, which appears to have the battery terminals glued or soldered to the battery preventing its removal. I’m a bit concerned applying heat (solder iron) to the battery considering the nature of Lithium batteries.
hi if the batt does not work do you have an error display ind like E17????
Sorry, I can’t remember
Hi my name is luciano.
My 496 B & G wind driver is broked due to a tree hit.
Today it was impossible for me to find the item since it is out of production.
I would like to buy a new wind driver and use the “B&G network wind” which still works very well.
The old 496, as explained in your blog, works with 6 cables 2 for power 4 for the analog signal to be transferred to the “B&G network wind”. Surely this is not a NMEA 0183 signal.
Today there are drivers on the market that communicate with NMEA 0183 or NMEA 2000.
I would like to connect a new wind driver that speaks in NMEA0183, at the “B&G network wind”.
I read your code for arduino and it seems more like a demo to communicate with “B&G network wind”.
Have you already implemented the part of the algorithm that translates the sentence $ – MWV or $ – VWR of NMEA 0183 and then sends the analog signals to the “B&G network wind”? Do you know if something like this already exists?
Is there an easier way to accomplish what I have in mind?
I’m a civil engineer and if you want i can collaborate with you, for play and to emproove my knowledge. :).
Thank you for your guide.
Regards
Luciano
Hi, nice work with your 496 and network wind!
Please would you be so kind as to help us with ours?
We bought a 2003 Lagoon 380 with a B&G network. The wind direction indicator on the ‘Network Wind’ worked fine, but the bearing on the cups for wind speed had failed. Having now bought a replacement sender / bearing unit and installed the MHU the display shows both the speed and direction, but only for about 5-10 seconds after the unit is turned on and then doesn’t register.
Any advice you may be able to give would be appreciated.
Kind regards
Craig
Hi all, I am looking for someone with a Northstar Explorer W315 (also called Navman) Analog wind gauge that has a working sensor to get the voltage tables, I am having a hard time reverse engineering only from the gauge. The discontinuities make the needle jump is you do not send slowly changing and close voltages to the meter. The Northstar Explorer W315 gauge has only two wind direction input lines that work similarly to the B&G. Cheers!
Hi, I am trying to do the opposite of what you did. I have a B&G 213 masthead unit that I am trying to tie into an arduino, thence to a NMEA 2000 network.. The hardware hookup is simple. It’s converting the 3 voltage inputs into an accurate directional indication that is giving me a problem. Would you know a math formula, or formulas that can be used in an arduino sketch to decipher this? My math education stopped at basic algebra, so any help would be GREATLY appreciated.
Great work!
I’ve got an old Network Wind, Quad and Pilot system with two 3FD displays, and would like to extract NMEA from this: I understand the Network instruments transmit NMEA bidirectionally, but I can’t find the pin out for the Network cable. It looks like Fastnet, but I’m not sure it’s the same. Do you have any suggestions/people to contact? Cheers