Simrad MFD - course and heading do not align.

[mvweebles]

I'm on a 10-hour run from Baja (MX) to San Diego. First longish run of systems. My Simrad MFD has developed a 25-degree difference between steering heading and course to waypoint. Screenshot attached tells the story (course to waypoint is correct compass reading, steering heading is incorrect). First couple hours system worked fine. I have checked the compass and nothing changed, and power-cycled the system. At some point I'll try heading in different directions to see if that makes a difference.

Any sage advice or suggestions where I can find a solution?

Peter

 

[FWT]

I'm on a 10-hour run from Baja (MX) to San Diego. First longish run of systems. My Simrad MFD has developed a 25-degree difference between steering heading and course to waypoint. Screenshot attached tells the story (course to waypoint is correct compass reading, steering heading is incorrect). First couple hours system worked fine. I have checked the compass and nothing changed, and power-cycled the system. At some point I'll try heading in different directions to see if that makes a difference.

Any sage advice or suggestions where I can find a solution?

Peter View attachment 142007

There are two different calibration routines.

The manual explains the drill. To set the compass you do a gentle circle, slowly. The manual has parameters of how slow and what degree of turn are within the limits. So you go into that path, and hit the right button.

There is something similar to set the autopilot.

Apart from that, its the usual advice to be sure you do not have something metallic close to the compass.

 

[mvweebles]

Thanks very much FWT. I'm pretty sure I calibrated the system 2 years ago when I first sea trialed but I'm not positive. Right now I'm in 4 foot swells with a bit of wind chop on top so calibration will have to wait. But that sounds like an excellent next step.

Peter

 

[FWT]

Happy to help. I have a new package, so I have been tinkering with it to get it set up the way I want.

Another thing to check on the compass / GPS. Buried deep is a selection to use the GPS antenna within the MFD, or an external. Though the external one was selected, a few weeks later I found it had reverted to the internal one.

The point being, you are beginning to use it after a long layup. Its probably a good idea to go through it all to insure its still set up the way you want.

 

[High Wire]

I can’t read the screen that well but make sure both are set for magnetic with the same variation setting.

 

[oguidry]

What compass is the Simrad MFD using?

 

[diver dave]

….



Apart from that, its the usual advice to be sure you do not have something metallic close to the compass.

Including tool box and high current DC conductors.

 

[kchace]

I have a very similar Simrad setup. I would check carefully to see what SOURCE each is using for heading information. They may be different.

Ken

 

[twistedtree]

I agree with others suggesting a calibration issue with your compass, which I presume is a magnetic compass of some sort. Probably an RC42 for a Simrad system.


COG comes from your GPS, calculated continuously as your position moved. Heading comes from your compass and when working correctly tells you where the bow is pointing, which isn't necessarily the direction the boat is actually moving.


I'm guessing that of the two, the COG is correct?

 

[tiltrider1]

Here in the PNW we rarely see heading and COG agreeing due to wind and current. Twenty five degree difference does seem excessive. One way to check this is with your radar. If your COG and your radar are in agreement then you know the heading needs help.

 

[SteveK]

Here in the PNW we rarely see heading and COG agreeing due to wind and current. Twenty five degree difference does seem excessive. One way to check this is with your radar. If your COG and your radar are in agreement then you know the heading needs help.

wind and current is my thought as well. crabbing.
The boat icon looks like 25* off course line 305. High tech chartplotter and autopilot to show that.

 

[Bacchus]

Peter
I've experienced similar discrepancies with my Simrad auto pilot. My MFD is a Raymarine but all mfgs systems are somewhat similar.
As others mentioned, you are seeing inputs from different sources...
The COG comes from the GPS and should be accurate for your actual course (movement)
The Heading is the direction your boat is pointed and gets its info from a fluxgate compass usually mounted on the boat centerline somewhere in the bilge around mid ship.
Your magnetic compass at the helm is not connected to navigational electronics but is your navigational aid

I recalibrate my fluxgate but saw no change is discrepancy until I found and moved a tool box that I stored under my steps to the galley where it was out of the way yet easy to grap if/when needed. Bingo!... I was back in generally good agreement of heading & COG in calm conditions.
In addition to calibrating the fluxgate one should also "zero" and determine a deviation table for your magnetic / helm compass if you are looking for good agreement. My helm compass is difficult to be very precise and I have not bothered with deviation tables so I expect some minor discrepancy.

My guess is something magnetic is affecting your fluxgate and is likely the source of your discrrpancy... especially if the difference is a new phenomenon.

 

[oguidry]

I reiterate my previous question which is - what electronic compass is providing heading data to the autopilot?

My previous boat had Simrad electronics that included a Precision 9 Rate Compass. That is the compass normally sold with the Simrad autopilot.

I had the exact problem that the original poster has. It was calibrated multiple times, replaced with a new Precision 9 and the magnetic field in the mounting area carefully checked. All this was done by a skilled Simrad approved tech.

Nothing worked and the solution was a Simrad HS60 GPS Compass that solved the problem. Simrad no longer sells the HS60. Your best replacement for the Precision 9 is probably the Si-Tex V200-2 GNSS Compass.

The Hull Truth is a good source of informatin on this subject.

 

[Greg QS]

I have a garmin system I have seen this before. With all the multiple screens/overlays we have to work with it is easy to have a screen/overlay setting off from one screen to the next. . When the screens overlay and are not set to the same display settings you get this problem. You probally have the chart ( in garmin language) heading up, and the autopilot set to course up. Or some other overlay conflict like that.

I have it on occasion when the radar overlays are on. My targets seem to shift to the starboard. Visually they look the off also; But only on the overlay screen . On the side by side screen everything looked oriented fine. Once overlayed the problem showed up. It took a while to figure out but One was set to heading up and one to course up. A simple setting between the screens fixed the problem for me.

Make sure the autopilot display settings and the chart are both set to course up. Check the display settings for the chart to the vessel also.

You could even have one thing set to North up and one set to true north . I think mag difference alone is 14deg. Your screen shot shows you heading north up the coast.
Check the display settings also is you compass reading and auto piolet both set the same . Is one set to true north an the other Mag north? Any setting conflict like this will cause these types of display issues .

I would try to diagnose by going to the most basic simple screen. The start adding you display overlays or side bars one at a time. At some point you will suddenly find the error showing up. Then check the setting between the added item and the on screen items.



Its the same idea as when you run the boat in heading up on auto piolet the screen constantly shifts around. If you run in course up the screen is stable and the boat may rotate on the screen. and my vessel indicator line will swing side to side over the course line.

 

[diver dave]

I reiterate my previous question which is - what electronic compass is providing heading data to the autopilot?


Nothing worked and the solution was a Simrad HS60 GPS Compass that solved the problem. .. .

Thats an impressive piece. It does NOT contain a fluxgate sensor, but rather dual separated gps antennas, and a gyro to mitigate short term gps dropouts.

 

[Greg QS]

I reiterate my previous question which is - what electronic compass is providing heading data to the autopilot?
t.

This is what I am talking about. Maybe my lingo is off. Each of your overlays are are going to pull from different data sources. If the screen orientations for each data source are not the same , you will get the conflict when the screens are overlayed.

A chart in auto piolet is a screen with an overlay. The side data bars are also overlays in my terminology. You have an orientation conflict between overlays

 

[Hippocampus]

Do you have multiple MFDs? If you do take out the micro SDs and switch them to another unit. Then use that one as the master.
May not help if the problem is in the AP and you’ve made sure there’s nothing near the compass. But will if the problem is in the MFD.
We had radar and AIS not line up with reality while in bumpy seas and switched masters. Knew it from the old school magnetic compass. Was out of sight of land so chart not helpful. Switching master worked. It was pre 2000 backbones and RM not Simrad. So just a thought.
With current boat replaced everything from RM to Simrad. So far so good except still find it hard to get it to autoroute (never follow autoroute any way). Have had to do the slow turns twice in two years. Both times after wife put metal near it. Best I can figure it remains screwed up even after metal is moved. Doesn’t make sense. Think TT is right satellite is better than flux gate

 

[twistedtree]

Maybe an opportunity to switch to a sat compass. It’s around a $600 premium over a magnetic compass, and I think superior in every way. Plus you get a much better GPS as well.

Ironically, sat compasses have historically been big boat gadgets, mostly because of cost. But in many ways they are more needed in smaller boats where it is difficult if not impossible to find a location for a mag compass that is free of interference.

With sat compasses now in the $1000-$1200 range, they are the same cost as buying a decent mushroom GPS plus a mag compass.

 

[diver dave]

Here is a product with orders of magnitude improvements in heading and more

Who needs to know their heading 2 and a half places beyond decimal?
.

 

[ofer]

Maybe an opportunity to switch to a sat compass. It’s around a $600 premium over a magnetic compass, and I think superior in every way. Plus you get a much better GPS as well.

Ironically, sat compasses have historically been big boat gadgets, mostly because of cost. But in many ways they are more needed in smaller boats where it is difficult if not impossible to find a location for a mag compass that is free of interference.

With sat compasses now in the $1000-$1200 range, they are the same cost as buying a decent mushroom GPS plus a mag compass.

Peter, I had same problem as you with my Furuno setup. could not get any calibration to work. wasn't sure if its some metal on the boat although i tried several locations or Alaska location, gave up and got the SX20 sat compass. totally stoked. it also gives you a bunch of other data like pitch and roll, air Temp, pressure etc.

 

[twistedtree]

Here is a product with orders of magnitude improvements in heading and more

Who needs to know their heading 2 and a half places beyond decimal?
. View attachment 142044

Nice. Does it have a price tag?

 

[diver dave]

Nice. Does it have a price tag?

No idea. But likely a lot cheaper than a late ‘80’s Sperry gyrocompass that i have seen on a yacht.

 

[mvweebles]

Great suggestions from many here. On Saturday, I'll spend some quality time recalibrating. There is a mystery issue involving my rudder that is too lengthy to describe via phone text. I had the rudder modified to a Schilling (sp?) rudder to enhance close quarter maneuvering and I wonder if it may be slightly asymmetric now. But all was good for a few hours of running. Went south when I bumped-up the RPMs - perhaps not a coincidence. Suffice to say there may be dual diagnosis here.

I was concerned about placement of Navicp PR-9 fluxgate compass from the beginning but frankly, finding a clean location on a 36 foot boat is difficult. Yet it worked fine for a while (single digit hours....)

I am intrigued by concept of sat compass mostly because it gets mounted outside of the bilge area. Found this Simrad GPS based compass for around $1k. Would appreciate other specific recommendations.

https://www.navico-commercial.com/simradcommercial/gps/hs60-gps-compass/

Thanks to the many who responded with substantive input. Very much appreciated.

Peter

 

[ksanders]

I have a different system, but had similar problems.

My magnetic compas on the dash showed one heading.
Two different Furuno screens showed different headings, not agreeing with each other.
My Simrad autopilot showed yet another heading.

Upon investigation I found that the compass settings were all over the board.
I changed them all to magnetic with zero offset and they all agree pretty closely.

 

[oguidry]

I replaced my Precision 9 with an HS60 and it solved all my problems.

It is my understanding that the HS60 is no longer available and replaced with the more expensive and sophisticated HS75.

If you do go with an HS60 be aware that initially it can only be manipulated with a compatible CAN bus to USB converter and software available from the manufacturer Hemisphere GNSS has to be used to configure HS60.

It is my understanding that Hemisphere GNSS is the company that manufactured the Si-Tex and Simrad compasses and you may want to review their website.

I suggest you peruse The Hull Truth about the different compasses, particularly the posts by Abbor.

As a result of the difficulty in changing the heading, I was extremely careful to ensure that the receiver was aligned with the centerline of the boat. The receiver has sights like a rifle on the top to assist in alignment.

 

[mvweebles]

I replaced my Precision 9 with an HS60 and it solved all my problems.

It is my understanding that the HS60 is no longer available and replaced with the more expensive and sophisticated HS75.

If you do go with an HS60 be aware that initially it can only be manipulated with a compatible CAN bus to USB converter and software available from the manufacturer Hemisphere GNSS has to be used to configure HS60.

It is my understanding that Hemisphere GNSS is the company that manufactured the Si-Tex and Simrad compasses and you may want to review their website.

I suggest you peruse The Hull Truth about the different compasses, particularly the posts by Abbor.

As a result of the difficulty in changing the heading, I was extremely careful to ensure that the receiver was aligned with the centerline of the boat. The receiver has sights like a rifle on the top to assist in alignment.

Yet another high-quality response. Thanks. The HS60 is indeed discontinued and was $1k. The HS75 is also discontinued and was $2.5K. "Abbor" on THT recommended the Sitex H200 as it's identical to the HS75 ---- and $1152 (plus cable) from Hodges Marine, though will try the re-calibration stuff and checking setup menus for variances in settings.
(HODGES SITEX V200 HERE).

According to Abbor, the only difference is the install offset cannot be adjusted from the MFD but has to be done via some sort of software that is typically used by a Simrad installation tech. However, I am installing on centerline of my hard-top so should be okay.

A lot of money to make something work that should have worked in the first place. Grrr...... (I know, no crocodile tears from this crowd. We've all been there).

Peter

 

[Jc180]

I'm on a 10-hour run from Baja (MX) to San Diego. First longish run of systems. My Simrad MFD has developed a 25-degree difference between steering heading and course to waypoint. Screenshot attached tells the story (course to waypoint is correct compass reading, steering heading is incorrect). First couple hours system worked fine. I have checked the compass and nothing changed, and power-cycled the system. At some point I'll try heading in different directions to see if that makes a difference.

Any sage advice or suggestions where I can find a solution?

Peter View attachment 142007

Think key statement is that worked fine for first couple of hours. Agree with others that most likely seeing legitimate difference between course over ground (COG) and magnetic heading due to current.

I’m an Atlantic Ocean guy, don’t know Pacific area you’re in. But routinely experience similar COG and magnetic heading deltas in Gulf Stream. In fact, intentionally steer to an off course magnetic heading to get desired COG.

 

[Jc180]

Oh should add, I’ve got the Simrad autopilot system. Have had issues with metallic objects placed too close to rate compass causing deviation. But never sporadic or sudden change as you describe.

 

[Jc180]

Out of curiosity, checked California Current and the Southern California Eddy. Looks like you went through the eddy and were set by the current.

 

[twistedtree]

Yet another high-quality response. Thanks. The HS60 is indeed discontinued and was $1k. The HS75 is also discontinued and was $2.5K. "Abbor" on THT recommended the Sitex H200 as it's identical to the HS75 ---- and $1152 (plus cable) from Hodges Marine, though will try the re-calibration stuff and checking setup menus for variances in settings.
(HODGES SITEX V200 HERE).

According to Abbor, the only difference is the install offset cannot be adjusted from the MFD but has to be done via some sort of software that is typically used by a Simrad installation tech. However, I am installing on centerline of my hard-top so should be okay.

A lot of money to make something work that should have worked in the first place. Grrr...... (I know, no crocodile tears from this crowd. We've all been there).

Peter

Or just get the Furuno device and be done with it.