B&G Wind and Tack .... Help.

[Refueler]

OK .. on last trip :

Prior to departure .. I spent hours when wind was in various directions over days - checking the B&G wind displays. I managed to get offset apparently OK.

Departed Ventspils and Direction + Tack seemed ok ... as wind to boat angle changed - display followed etc. But no wind speed. Only direction. Tack display followed well and also in the small digital box gave the angle ... all seemed good.
Arrived Kuressaare and shut down systems.
Next morning fired up systems ... wind was about 30deg on port bow - Wind showed about 30 deg stbd bow .. but Tack showed correct. Switched on / off ... still same. ried offset and got both to show correct.
Departed Kuressaare .... Wind now showed wrong again .. Tack appeared OK .. Offset changed to bring Wind to correct - tack now wrong. Tried to compromise and found :

If I had wind direction correct - if wind to boat angle changed - the Wind display moved opposite way ... tack showed correct digital direction ..

Example :

Lets say wind is 270 (port beam) ... wind shows port beam. Tack shows similar.
Wind changes 30 deg ahead to 300 .. Wind display now shows 240 deg ... Tack shows digital similar.
Wind changes so that its 30 deg aft of beam ... Wind now shows it 30 deg ahead of beam

No matter what I tried - I could not get them to move correct direction. Wind speed not working at all.

 

[B27]

From memory, analogue B'n'G wind direction is a kind of three-phase signal, 3 wires each of which is carrying an angle signal, a DC voltage of sine (wind angle), sine (wind angle +120), sine (wind angle +240), each with an offset and gain so it's all positive voltages.

The instrument will attempt to calibrate out the different offsets and gains, but there comes a point where the signal coming from the masthead is beyond redemption and the readings stop making sense.

https://www.aandtinstruments.com/wp-content/uploads/2024/02/masthead-unit-tests.pdf

 

[Refueler]

From memory, analogue B'n'G wind direction is a kind of three-phase signal, 3 wires each of which is carrying an angle signal, a DC voltage of sine (wind angle), sine (wind angle +120), sine (wind angle +240), each with an offset and gain so it's all positive voltages.

The instrument will attempt to calibrate out the different offsets and gains, but there comes a point where the signal coming from the masthead is beyond redemption and the readings stop making sense.

https://www.aandtinstruments.com/wp-content/uploads/2024/02/masthead-unit-tests.pdf

Yep - I have that paper already - but requires two people to test as I cannot read display while at the wires.

 

[B27]

You could get 3 potentiometers and inject test voltages.
Otherwise you'll need an assistant.

 

[Alex_Blackwood]

OK .. on last trip :

Prior to departure .. I spent hours when wind was in various directions over days - checking the B&G wind displays. I managed to get offset apparently OK.

Departed Ventspils and Direction + Tack seemed ok ... as wind to boat angle changed - display followed etc. But no wind speed. Only direction. Tack display followed well and also in the small digital box gave the angle ... all seemed good.
Arrived Kuressaare and shut down systems.
Next morning fired up systems ... wind was about 30deg on port bow - Wind showed about 30 deg stbd bow .. but Tack showed correct. Switched on / off ... still same. ried offset and got both to show correct.
Departed Kuressaare .... Wind now showed wrong again .. Tack appeared OK .. Offset changed to bring Wind to correct - tack now wrong. Tried to compromise and found :

If I had wind direction correct - if wind to boat angle changed - the Wind display moved opposite way ... tack showed correct digital direction ..

Example :

Lets say wind is 270 (port beam) ... wind shows port beam. Tack shows similar.
Wind changes 30 deg ahead to 300 .. Wind display now shows 240 deg ... Tack shows digital similar.
Wind changes so that its 30 deg aft of beam ... Wind now shows it 30 deg ahead of beam

No matter what I tried - I could not get them to move correct direction. Wind speed not working at all.

Gut feeling is, you have one or more dodgy connections in the system. There is a degree(Pun not intended) of intermittent working in the system. Where to start considering your other descriptions of your system is anyone's guess. Fault could be anywhere, including your magic blue box.
Possibly start at one end and work methodically through the whole system to the other end, check every connection, joint, plug and socket
Sorry that the above is not a great deal of help. It is however what I would be inclined to do before throwing the book of theory at it.
Good luck!
Without being familiar with your system and set up I would suggest that concentrating on the speed and direction, first of all, may be a help. You may need the help of someone who is experienced and good at fault finding, you may be excellent yourself, I don't know. I do know many otherwise highly competent engineers and technicians who can't find a fault when it is staring them in the face. It's a thing!
Another little thought. Are you running with power on your "Magic Box"? I firmly believe in never saying "It can't be that" consider everything, no matter how obscure!

 

[Refueler]

UGH - The Blue Box !!

I'm fairly sure ... that Blue Box is a hang over from old gear ....

I am in discussion with BoatPark ... about possibly rewiring the boat ... not a thing to take on light heartedly ..

The B&G network I have from left to right :

DEPTH - STW - Unknown analogue gauge - TACK - WIND

All are interconnected correctly as per manual.

The B&G Depth doesn't like soft mud / silt bottom and will show ---- sometimes while the Airmar Sonar on the Garmin Plotter will still register depth .. The B&G depth appears to be taken from 'ducer that I assumed was redundant from the old Seafarer depth unit. But unless I am brave enough to pull it while afloat - I cannot be sure.