Offset or Calibrate Wind Direction

[goodwinds]

Yes, I calibrate via head unit, it’s a old ST50, and doesn’t have factory reset. I can calibrate a full 360degrees, and seems to be accurate. Will search Douwe posts, however not sure it’s the P70 Pilot issue, it’s just reading the data, and no calibration like the ST70 pilots

[rgleason]

I believe douwe installed an autopilot like yours, and has worked out some of these issues. He has a thread about it. .

[rgleason]

See Douwe's thread here


autopilot route plugin - Page 3 - Cruisers & Sailing Forums

[goodwinds]

Thanks for the link. I think we have drifted off topic. I’m not trying to get Autopilot route management happening. Just trying to understand if the NMEA PLUGIN has the ability to do a addition calculation on the AWA data from the STNG-NMEA0183 data string, that offsets the current data. Even if I take the EVO1 out of the system, I’m just trying to get the same wind direction angle that is displayed on the old ST50 wind, and on Opencpn AWA dashboard. I can live without the P70 displaying the right AWA( though would be nice).
So, imagine my ST50 is displaying 60 degrees to Port, OpenCPN dashboard is displaying 90-100 degrees to Port. So that is what I was wondering if the NMEA plugin could offset, so take STNG converted data, plus or minus xx degrees and display the new data in AWA in OpenCPN dashboard.

Appreciate your help, however nothing really to do with Autopilot routes.

Thanks Goodwinds

[rgleason]

I suggest you isolate the systems completely and test. Is this the physical arrangement of the equipment?

Arrangement 1
ST50 Wind --> ST1 network <--> ST-STNG converter <--> Actisense STNG -NMEA0183(NGW-1 USB) <---> Nmea0183 <---> OpenCPN

Arrangement 2
ST50 Wind --> ST1 network <--> ST-STNG converter <--> Evo1 Autopilot

Use only Arrangement 2 (no Evo1)
See what you get. Explain in detail. Take screenshots. Provide a recorded VDR file uploaded and attached here, also upload opencpn.ini file or equal and opencpn.log files please. Advise regarding your WMM settings. Please see How to request support and report problems if I cannot find the answer in resources listed above?

Also suggest you read your p70 manual and your ST50 manual.
If this is not the arrangement, provide better details. Thanks.

[wingssail]

Originally Posted by odonnellryan

My wind sensor wants a vertical mounting surface, but my solar arch is not vertical. However I was able to mount it onto the arch, but of course not in the correct orientation!

Is there a way to add an offset in degrees to the wind display? I wasn't able to find anything through research. I can fabricate a way to mount it correctly I'm sure but would like to see if this could work first

Maybe I'm missing something Odonnellry but your manual states:

"To obtain accurate readings, the vane must be correctly oriented when mounting the anemometer outside. By default, the wind vane reports the correct wind direction if the anemometer arm points true north. To ensure correct orientation of the wind vane, mount the anemometer so that the arm points true north. If your anemometer arm cannot be mounted aiming true north, you will need to calibrate the wind direction, either on your console for Vantage Pro2 or on your WeatherLink.com page for EnviroMonitor. See your Vantage Pro2 Console Manual or Envoy Manual."

To me this implies two things:

1. Your Vantage is going to provide wind direction relative to true north, not relative to the bow of your boat (and assuming it is vertical and aligned towards true north)

2, It is designed to be displayed on a proprietary monitor, which has calibration settings.

[rgleason]

Is there a way to add an offset in degrees to the wind display? I wasn't able to find anything through research.

Not yet, but someone could make a PR for that.
Also Tactics_pi could use a way to input the angle of tacking masts, so that would be a separate PR.

[goodwinds]

Hey All,

Was playing with the original issue the other day(ST50 Wind Display and Open CPN Wind Display are always 60 degrees out), and still thinking the either the NMEA Convertor or the Add/Ignore sentences in connection in Opencpn I might be able to make this work.

I used the Debug script, turned off all other connection inputs (GPS and AIS) aside from ST50 set, through the ST-STNG Converter - Actisense NGW-1 and noticed that there are 2 strings off information that refer to Wind Direction being:
MWV & VWR, and I noticed the that difference between them is the exact difference in my wind reading offsets in Opencpn and ST50, or the wind data is actually the same,MWV being Bow as 0 degree and counting to 360 degrees clockwise around the boat, and VWR being Bow as 0 degrees, and 180 degrees left or right of bow? .

See String below, MWV has Wind Angle Relative at 300 degrees, and VWR has Wind Direction magnitude in degrees at 60 degrees Left of Bow, which is roughly where Opencpn wind direction is pointing.

Note, the ST50 Wind was reading close to 0 degrees, as I was on a mooring.

(Serial:COM6) $WIMWV,300.12,R,13.1,N,A*20<0x0D><0x0A>
(Serial:COM6) $WIVWR,59.9,L,13.1,N,6.7,M,24.3,K*7B<0x0D><0x0A>

Actual capture of data
(Serial:COM6) $IIRSA,-2.4,A,,V*52<0x0D><0x0A>
(Serial:COM6) $IIMDA,,I,,B,,C,25,C,,,,C,,T,,M,,N,,M*1D<0x0D><0x0 A>
(Serial:COM6) $WIMWV,304.12,R,13.92,N,A*1E<0x0D><0x0A>
(Serial:COM6) $WIVWR,55.9,L,13.9,N,7.2,M,25.8,K*71<0x0D><0x0A>
(Serial:COM6) $SDDPT,4.18,-0,*75<0x0D><0x0A>
(Serial:COM6) $TIROT,136.78,A*00<0x0D><0x0A>
(Serial:COM6) $IIRSA,-2.4,A,,V*52<0x0D><0x0A>
(Serial:COM6) $IIVHW,,T,166.4,M,0,N,0,K*7E<0x0D><0x0A>
(Serial:COM6) $SDDBT,13.71,f,4.18,M,2.29,F*06<0x0D><0x0A>
(Serial:COM6) $IIMDA,,I,,B,,C,24,C,,,,C,,T,,M,,N,,M*1C<0x0D><0x0 A>
(Serial:COM6) $IIMTW,24,C*0B<0x0D><0x0A>
(Serial:COM6) $WIMWV,300.12,R,13.1,N,A*20<0x0D><0x0A>
(Serial:COM6) $WIVWR,59.9,L,13.1,N,6.7,M,24.3,K*7B<0x0D><0x0A>
(Serial:COM6) $HCHDG,166.4,,,,*47<0x0D><0x0A>
(Serial:COM6) $IIVLW,7442.5,N,0,N,,N,,N*63<0x0D><0x0A>
(Serial:COM6) $SDDPT,4.18,-0,*75<0x0D><0x0A>
(Serial:COM6) $TIROT,147.38,A*02<0x0D><0x0A>
(Serial:COM6) $IIRSA,-2.4,A,,V*52<0x0D><0x0A>
(Serial:COM6) $IIMDA,,I,,B,,C,24,C,,,,C,,T,,M,,N,,M*1C<0x0D><0x0 A>
(Serial:COM6) $WIMWV,299.12,R,13.1,N,A*21<0x0D><0x0A>
(Serial:COM6) $WIVWR,60.9,L,13.1,N,6.7,M,24.3,K*71<0x0D><0x0A>
(Serial:COM6) $SDDPT,4.15,-0,*78<0x0D><0x0A>
(Serial:COM6) $TIROT,149.52,A*00<0x0D><0x0A>
(Serial:COM6) $IIRSA,-2.4,A,,V*52<0x0D><0x0A>
(Serial:COM6) $IIVHW,,T,171.4,M,0,N,0,K*78<0x0D><0x0A>
(Serial:COM6) $SDDBT,13.62,f,4.15,M,2.27,F*07<0x0D><0x0A>
(Serial:COM6) $IIMDA,,I,,B,,C,24,C,,,,C,,T,,M,,N,,M*1C<0x0D><0x0 A>
(Serial:COM6) $IIMTW,24,C*0B<0x0D><0x0A>
(Serial:COM6) $WIMWV,294.12,R,13.1,N,A*2C<0x0D><0x0A>
(Serial:COM6) $WIVWR,65.9,L,13.1,N,6.7,M,24.3,K*74<0x0D><0x0A>
(Serial:COM6) $HCHDG,171.4,,,,*41<0x0D><0x0A>
(Serial:COM6) $IIVLW,7442.5,N,0,N,,N,,N*63<0x0D><0x0A>
(Serial:COM6) $SDDPT,4.15,-0,*78<0x0D><0x0A>
(Serial:COM6) $TIROT,157.21,A*0B<0x0D><0x0A>
(Serial:COM6) $IIRSA,-2.5,A,,V*53<0x0D><0x0A>


Attached is screen shot of Dashboards on Opencpn, the ST50 wind would of been point directly into wind.

I tried disabling the MWV sentence, and all Wind Diection/Speed etc stopped, then I tried enabling the MWV, and disabled VWR sentence, and it worked as before, so the data Opencpn uses for the wind direction is coming from the MWV string I guess....I also actually disabled/blocked every sentence aside from MWV (Yes I had to add MWV sentence) and it continued working as before, still 60 degrees off the ST50 Display.
I presume that MWV relative/ true field is for apparent or true? and the angle is from the 0 degree point used in ST50 calibration?

However what does the VWR do with any of the calculations?

MWV - Wind Speed and Angle
1 2 3 4 5
| | | | |
$--MWV,x.x,a,x.x,a*hh<CR><LF>
Field Number:
1. Wind Angle, 0 to 359 degrees
2. Reference, R = Relative, T = True
3. Wind Speed
4. Wind Speed Units, K/M/
5. Status, A = Data Valid, V = Invalid
6. Checksum
VWR - Relative Wind Speed and Angle
1 2 3 4 5 6 7 8 9
| | | | | | | | |
$--VWR,x.x,a,x.x,N,x.x,M,x.x,K*hh<CR><LF>
Field Number:
1. Wind direction magnitude in degrees
2. Wind direction Left/Right of bow
3. Speed
4. N = Knots
5. Speed
6. M = Meters Per Second
7. Speed
8. K = Kilometers Per Hour
9. Checksum

So, the question is, I presume the data from the ST50 is output incorrect for wind direction unless the data is getting corrupted through the converters, but only this 1 field of a full set of ST50's data, so is there anyway to use the NMEA Convertor Plugin to block this field and take the 2nd field of data from the MWV sentence and manipulate it to a new value, or basically add 60 degrees???
I noticed some threads on Opencpn Plugin page where others are changing temp C to F by calculations, and lots of other funky calculations, so I'm hoping someone knows how to do this, or has other suggestions now seeing the data sentences.
And if so, can suggest something to try.

I'm pretty sure I've tried, but next time at the boat I was going to calibrate the ST50 by just holding the move right button down and let it go right around the clock 6 odd times to see if that helps, however it hasn't helped in the past, but then I wasn't reading the sentence data to compare while doing it.

Thanks in advance

Goodwinds

[Hakan]

goodwinds..
All your assumptions seems correct and if you can't adjust the wind meter to show correct angle you may use the NMEAconverter plugin to adjust the value by about -60°. Kind of tricky though since you have to assure the MWV value is between 0° and 360° and VWR is not more than 180°. And if your corrections for VWR makes it to go below 0 you have to change it positive and switch the Left/Right sign.
These calculations may be difficult to handle in the NMEAconverter plugin but it would be possible. See https://opencpn.org/wiki/dokuwiki/do...nmea_converter

OCPN dashboard actually does use both MWV and VWR but not both at the same time. If MWV is received it gets higher priority so VWR is then omitted. Unfortunately is this prioritization stable within a OCPN session so when you filtered out MWV from your incoming data VWR will not be used until OCPN is restarted. This may be corrected in next version of OCPN.

So---
OCPN has (so far) no functions to calibrate the wind angle from a wind instrument. We expect the instruments own logic to handle this.
NMEAconverter plugin may be used to correct a false value like this but can be demanding and you may use only one of MWV or VWR.

My advice is to try again to make the physical installation of the wind vane to point in your bow direction.


Good luck

[goodwinds]

Originally Posted by Hakan

goodwinds..
All your assumptions seems correct and if you can't adjust the wind meter to show correct angle you may use the NMEAconverter plugin to adjust the value by about -60°. Kind of tricky though since you have to assure the MWV value is between 0° and 360° and VWR is not more than 180°. And if your corrections for VWR makes it to go below 0 you have to change it positive and switch the Left/Right sign.
These calculations may be difficult to handle in the NMEAconverter plugin but it would be possible. See https://opencpn.org/wiki/dokuwiki/do...nmea_converter

OCPN dashboard actually does use both MWV and VWR but not both at the same time. If MWV is received it gets higher priority so VWR is then omitted. Unfortunately is this prioritization stable within a OCPN session so when you filtered out MWV from your incoming data VWR will not be used until OCPN is restarted. This may be corrected in next version of OCPN.

So---
OCPN has (so far) no functions to calibrate the wind angle from a wind instrument. We expect the instruments own logic to handle this.
NMEAconverter plugin may be used to correct a false value like this but can be demanding and you may use only one of MWV or VWR.

My advice is to try again to make the physical installation of the wind vane to point in your bow direction.


Good luck

Thanks Hakan

Yes your points make sense, I hadn’t thought of adding 60 to 359 degrees, would be interesting to see where the needle pointed 🤣

Question about physical installation, if I moved the vane so OCPN and additionally my P70 reading the same, wouldn’t the original ST50 then be 60 out, and when I calibrate back to 0 (wind on bow) then OCPN would again follow the difference.

Example, as calibrating the ST50, I can watch the wind on OCPN Angle change as the ST50 moves, so I’m not sure physical installation would change the difference in wind angle.

Cheers
Goodwind

[Hakan]

Goodwind..
I wasn't quit aware of you have more viewers connected. I may have read bad. So if you can manage the calculations in NMEAconverter that may be most efficient. That's up to you.
And BTW what's discussed about VWR is also valid for VWT if you receive that.

[wingssail]

Originally Posted by goodwinds

MWV & VWR, and I noticed the that difference between them is the exact difference in my wind reading offsets in Opencpn and ST50, or the wind data is actually the same,MWV being Bow as 0 degree and counting to 360 degrees clockwise around the boat, and VWR being Bow as 0 degrees, and 180 degrees left or right of bow? .
*
See String below, MWV has Wind Angle Relative at 300 degrees, and VWR has Wind Direction magnitude in degrees at 60 degrees Left of Bow, which is roughly where Opencpn wind direction is pointing.
*
Note, the ST50 Wind was reading close to 0 degrees, as I was on a mooring.
*
(Serial:COM6) $WI_*MWV,300.12,R*_,13.1,N,A*20<0x0D><0x0A>
(Serial:COM6) $WI*_VWR,59.9,L_*,13.1,N,6.7,M,24.3,K*7B<0x0D><0x0 A>

Goodwinds

Pardon me guys, I don't mean to insert myself into your discussion but it looks to me that the MWV and VWR sentences are completely consistent with each other and OpenCPN displays the data as it should. I'd say the problem is in the ST50.

The facts seem to be:

• The wind is on the bow, (by observation)
• The ST50 display show the wind on the bow (so far so good)
• The NMEA sentences show the wind at relative 300 (60L)
• You asked Raymarine and they just said maybe output is faulty

I think you have to conclude the ST50 is sending the wrong data about wind direction. It is possible a component along the way is subtracting 60 degrees but that seems like a stretch.

rgleason's suggestion to isolate the components and observe the sentences at each step would prove it, if it is possible to do so.

Recalibrating the ST50 may change the display but I'd reckon a guess that it will also change the NMEA output, and they will still be off. A system reset, if possible, might do it.

Modifying the sentences with NMEAconverter plugin might be an interesting programming exercise.

Otherwise, replace the ST50.

[Bill O]

Originally Posted by wingssail

Maybe I'm missing something Odonnellry but your manual states:

"To obtain accurate readings, the vane must be correctly oriented when mounting the anemometer outside. By default, the wind vane reports the correct wind direction if the anemometer arm points true north. To ensure correct orientation of the wind vane, mount the anemometer so that the arm points true north. If your anemometer arm cannot be mounted aiming true north, you will need to calibrate the wind direction, either on your console for Vantage Pro2 or on your WeatherLink.com page for EnviroMonitor. See your Vantage Pro2 Console Manual or Envoy Manual."

To me this implies two things:

1. Your Vantage is going to provide wind direction relative to true north, not relative to the bow of your boat (and assuming it is vertical and aligned towards true north)

2, It is designed to be displayed on a proprietary monitor, which has calibration settings.

We have a Vantage View on our boat we use as a weather station and back up anemometer and it works well. Yes, you do need to have the proprietary display, but it does have some nice features like custom barometer alarm settings to sense rates of fall/rise. The barometer alarm has alerted us many times to storms that we didn't see coming. It worth it for just that function.
Unfortunately the previous post from the manual gave directions to mount the Vantage as a land based weather station. Highly illogical why anyone would ever set up a wind instrument facing N on a boat, when it should be towards the bow.
Since we wanted an independent unit, will say I've never looked at the data coming out of the Vantage to see if it was NMEA. I know the Vantage Pro2 replacement anemometer can be used w/ the pypilot weather sensor so it must be sending out usable data.


Bill O.

[Hakan]

I think we're in several threads now: http://www.cruisersforum.com/forums/...ml#post3051112

[goodwinds]

Originally Posted by Hakan

I think we're in several threads now: http://www.cruisersforum.com/forums/...ml#post3051112

Indeed we are, and your patch worked a treat!! Still incorrect on AP, however explained in other thread.
Cheers again Hakan

Goodwinds