A.M.S.

Weird B&G pilot behavior

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My pilot is acting strangely.....it is a Triton, and when I set a bearing, it flickers up and down by 5 degrees.  Boat steers the course properly, but the compass rose on the display jumps back and forth and the actual set bearing does as well.   Is this a known failure mode, or some adjustment?  I have used it for few years without difficulty.  Just go back from a haul out and engine work, but nothing electrical...any ideas?

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Sounds as though both your AP Course Computer and inputs it recieves from your Control Head (Triton) and other transducers including compass are fine but either your Triton display function is on the way out or the compass data it is receiving either from the network or AP Course computer direct is corrupt or the Triton is not processing it.

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Interesting.  I have dual displays, both seem to be doing the same thing.....is there a common point that could be failing?

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If two displays acting the same that removes them from the cause list . Does your compass data go to the network then to AP Course Computer or to AP Course Computer then to the network? Either way check your TWD v AWA/Course to quickly check integrity of Compass output. It should replicate behaviour of your Triton.

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45 minutes ago, A.M.S. said:

Just go back from a haul out and engine work,

Maybe not good ideas, but you didn't specify. FWIW, I'd look in the area around the compass for stray tools or moved gear. Calibration circles might help. Could be a bad connection. Maybe something got nudged while the work was done.

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I'd guess that perhaps you're using true headings and getting variation from a GPS that's not sending variation sufficiently frequently. Are you in a place on the planet where variation is five degrees?

Are you set up for magnetic or true? What's your heading source? Does the heading display jump about without the pilot?

 

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When using WIND steering everything seems good.  I is only when set for HEADING that the fluctuation occurs.   I’ll climb back and check inputs and look for loose tools this morning!  Seems odd that it always fluctuates by 5 degrees and when the heading fluctuates, so does the course and it is almost rhythmic 

thanks

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The plot thickens:  recalibrate both compasses 42 and 100.  No improvement.  Switched heading info from 100 to 42.....improved until I turned on the autopilot, then back to jumping 5 degrees.  Increased damping to see if that would even it out....nope....jumps at the same rate sometimes 60 Htz or so.  Not sure how to tell whether or not compass goes to computer or  network first though.

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2 hours ago, A.M.S. said:

60 Htz or so

About the speed you'd get NMEA updates? Maybe two heading sentences from different sources? Since the pilot isn't changing course with the jumps is it just an MFD display issue? Do you usually turn the power off to your instruments at the breaker? Maybe something was disconnected from the battery during the refit and lost it's setup?

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60Hz? I'd be surprised if you could see 2Hz on your instruments.

Are you setup for true or magnetic heading?

 

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https://ww2.bandg.com/downloads/triton-owners-manual/

Maybe look at: setup -> advanced settings -> sources -> compass

It'd also be interesting to see what devices are on the list.

My WAG is that you have displays from multiple sources (eg. gps (AIS?) and rate compass). Perhaps you need to select your compass source again for some reason. It would be odd. I'm sure the setup is intended to survive a power loss but maybe it didn't for some reason. At any rate, it should be an easy theory to test.

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15 hours ago, A.M.S. said:

When using WIND steering everything seems good.  I is only when set for HEADING that the fluctuation occurs.  

 

9 hours ago, A.M.S. said:

The plot thickens:  recalibrate both compasses 42 and 100.  No improvement.  Switched heading info from 100 to 42.....improved until I turned on the autopilot, then back to jumping 5 degrees.  

 

On 11/18/2018 at 12:53 PM, A.M.S. said:

when I set a bearing, it flickers up and down by 5 degrees.  Boat steers the course properly, but the compass rose on the display jumps back and forth and the actual set bearing does as well.  

You have the identical problem on two MFD's and two compasses and both compasses output in NMEA requiring no analogue to NMEA conversion. So that seems to isolate them as the cause. However only one is a "rate compass" suitable for AP use, being the 42. Therefore the 100 compass should be disabled as a source.

It would appear you actual COG and so GPS data is OK, reinforced by you saying the set bearing fluctuating. I'm assuming your GPS source is the 100 (GPS with Compass).

If everything is OK with AP off and with AP sourced to TWA or AWA is OK, it seems then your problem lies with either your;

a) AP Course Computer recieiving and or transmitting compass course data from/to MFD and from a functioning 42 compass, or 

b) The 42 compass either outputting scrambled data or if that OK its physical connection point to the network.

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Thanks....compass jumps even with AP OFF, but was ok until I activated it the first time.  Interesting that the default setting was to use the 100 compass as well.  However the display jumps when using either the 100 compass OR the 42....

i guess it’s time to track down a b&g tech......

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What is the compass?

How many GPS are connected (AIS includes GPS data)

Is the boat setup for True or Magnetic?

What heading unit is selected?

 

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Bandg RC 42.  And ZR 100

2   ?   Connected to radio, but AIS SHOULD be coming in through dedicated AIS.  Could a setting on the radio sending data to AP incorrectly be causing this?

magnetic

problem exist with both E compass and GPS unit

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It would be interesting to know if your compass agrees with one of the MFD heading outputs and what your local magnetic variation is.

Perhaps you could take pics of the screens you are seeing and post them?

Your MFDs can display headings from many sources sequentially. They probably just show the last data that was posted to the network eg. AIS, GPS, II, compass etc. Ideally, your AP will only steer using the data source you selected for it. I think you'd want to use the rate compass.

Some questions that it'd be nice to know the answers to are:

1) is the AP set to steer from the proper source?

2) can you confirm that it is only using that source?

3) what heading information is cycling through your display?

4) why is there a discrepancy?

If you can see the raw network traffic you might be able to figure out what's going on. If not you could start isolating sources from the network. You might have options to turn them off or to unplug them. Be aware that some devices that pass data (eg. and AIS radio) might have an "off" mode where they continue to pass data.

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I would start by removing all but one compass from the system - try just the RC42 rate compass and see if it jumps, then try just the ZG100.  Without seeing a network diagram hard to tell but is there any way that you might have a data feedback loop causing the problem?

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Agree with WHK. This is undoubtedly a problem associated with multiple heading sources - you have four. Switch of the GPS and AIS and remove the ZG100's NMEA2000 connection so that just your RC42 is active. If the problem goes away then you need to focus on your heading source selection settings.

 

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Unless you are the unluckiest person on earth my guess is it will come back to this dual GPS/Compass thing and other competing data courses that somehow you have altered the mix from everything being OK.

On 11/19/2018 at 4:52 PM, jack_sparrow said:

  However only one is a "rate compass" suitable for AP use, being the 42. Therefore the 100 compass should be disabled as a source.

 

1 hour ago, Moonduster said:

Switch of the GPS and AIS and remove the ZG100's NMEA2000 connection so that just your RC42 is active. 

 

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6 hours ago, Moonduster said:

Agree with WHK. This is undoubtedly a problem associated with multiple heading sources - you have four. Switch of the GPS and AIS and remove the ZG100's NMEA2000 connection so that just your RC42 is active. If the problem goes away then you need to focus on your heading source selection settings.

 

This.

I wasn't able to view the movie. Maybe just my browser or internet connection.

It would be really odd, though not inconceivable, that a single source would toggle between two headings. Either way, isolating the sources will simplify the problem. I'd want to make sure the correct sensor was connected to the AP and I'd only want sensors that are sending correct data connected to the network.

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Thanks for all the input....boat is a few hundred miles from me, so will need to get out there to test some of this....and some of this is over my head too.  I think I can unplug a compass though, so at least maybe that will help to narrow down the culprit.

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Problem solved!  The Tritons were set to “auto” for magnetic declination.  Correct declination for my longitude is about 12 degrees, but auto was setting at 17 degrees.  Took it off “auto” and input 12 degrees manually, and everything is smooth......!

Of course now I am left with the problem of why it wasn’t accurate when set to “auto”.......!

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