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-   -   Fluxgate compass and the st4000 Wheel "HELP" (http://www.sailnet.com/forums/electronics/99342-fluxgate-compass-st4000-wheel-help.html)

ltgoshen 05-09-2013 10:34 PM

Fluxgate compass and the st4000 Wheel "HELP"
 
O.K easy question?
How do I make my ST4000 and my boat compass read in the same direction?
I know, and have read how to swing them both for deviation. But the ST4000 control head when i hit auto keeps the wheel on target but it reads off? Is there a way to set it close? Thanks.


http://i148.photobucket.com/albums/s...IMG_2637-1.jpg

knuterikt 05-10-2013 03:39 AM

Re: Fluxgate compass and the st4000 Wheel "HELP"
 
Quote:

Originally Posted by ltgoshen (Post 1027971)
O.K easy question?
How do I make my ST4000 and my boat compass read in the same direction?
I know, and have read how to swing them both for deviation. But the ST4000 control head when i hit auto keeps the wheel on target but it reads off? Is there a way to set it close? Thanks.


http://i148.photobucket.com/albums/s...IMG_2637-1.jpg

I'm guessing that by "boat compass" you mean a standard magnetic compass.

The fluxgate compass is also a magnetic compass - it has some electronic circuits that measure the magnetic filed that surrounds it.

All magnetic types of compasses is designed to "read" the magnetic field of the earth to give a direction relative to the magnetic north.

The problem is that on a boat we have several other magnetic sources that disturbs the magnetic field the compass "see".
Depending on the placement of the sensor the disturbances will change.

I don't know where your fluxgate sensor is located but it's probably not in the same place as your "boat compass", so these two compasses "experience" different magnetic fields (noise/disturbance).

Which compass that is correct is impossible to know without doing proper compass deviation checks (for every 10th degree around the circle).

I don't think you can override the courses shown by the control head, but I think you can do a manual correction on the fluxgate instead of "swinging" it.

You will never get these two compasses to show exact same course on all headings.

ltgoshen 05-10-2013 07:00 AM

Re: Fluxgate compass and the st4000 Wheel "HELP"
 
I asked the wrong question.
Can I dile in the fluxgate compass usint the control head for the st4000?
Or what is the the 3 circle procedure for this process? It is the first time I have tried to use the auto helm st4000. When I put it on auto it holds the course just fine its just reading like 209 degrees when the boat is tied up at the dock at like meg 340 degrees?
Can I do a large dile in then swing the the boat for deveation?>

knuterikt 05-10-2013 08:37 AM

Re: Fluxgate compass and the st4000 Wheel "HELP"
 
Quote:

Originally Posted by ltgoshen (Post 1028065)
I asked the wrong question.
Can I dile in the fluxgate compass usint the control head for the st4000?
Or what is the the 3 circle procedure for this process? It is the first time I have tried to use the auto helm st4000. When I put it on auto it holds the course just fine its just reading like 209 degrees when the boat is tied up at the dock at like meg 340 degrees?
Can I do a large dile in then swing the the boat for deveation?>

Have you tried to follow the procedure for swinging the fluxgate?

A difference of 131 degrees is much...
What is the correct heading when you are tied up at the dock?

If it is the fluxgate that is off, you must check for any magnetic sources close to the heading sensor, lumps of iron (engine, fire extinguisher ++) , electrical components.

Worst case the heading sensor must be re-positioned.

It cold also be the magnetic compass that are off..

capecodda 05-10-2013 09:41 AM

Re: Fluxgate compass and the st4000 Wheel "HELP"
 
The setup process I am sure is available someplace on line if you google the manual for your autopilot.

That said, my guess along with the other advice you are getting is that if the fluxgate is reading that far off (I'm assuming your binnacle compass is reading good here), it is likely that is is close to something magnetic. If it worked well before, you may have moved a magnetic object close to the fluxgate sensor in the boat. Not that I've ever done that :)

Other possibilities, all of which have happened to me on different boats different years.

- I've had a builder place the fluxgate sensor too close to a deck wash pump, which has magnets in it of course.

- I've had a fluxgate fail. Some of them have a gimbal in them to keep the sensor level, and I've had that break internally to the fluxgate sensor.

Good luck.

Faster 05-10-2013 11:37 AM

Re: Fluxgate compass and the st4000 Wheel "HELP"
 
Pretty sure you can add a correcting 'offset' to your fluxgate readings. IIRC it's the last part of the commissioning process in the manual.

ltgoshen 05-10-2013 01:11 PM

Re: Fluxgate compass and the st4000 Wheel "HELP"
 
Well, First off i'm not sure it was ever working well or properly. When I got the boat all the insturments were in a box. They looked new. Bur the transducers were allready installed. The Fluxguate in mounter just above the back rest of the first settee bench seat on the starboard side. Thats like 4.5 feet from the engine nothing close there to create a field? The other thing I have never realy looked at the accuricy of the helm compass? I will start there this afterneoon. then I will swing the fluxguate an Saturday. If all else fails I will add a correcting 'offset' to your fluxgate as per the instructions.
check my hook up and clean. Anything more?

capecodda 05-11-2013 07:45 AM

Re: Fluxgate compass and the st4000 Wheel "HELP"
 
When you say behind a settee, is it mounted on a bulkhead (wall that is port/starboard) or behind the settee so it's facing sideways? Sounds like this stuff was partially installed and never tested.

ltgoshen 05-11-2013 09:44 AM

Re: Fluxgate compass and the st4000 Wheel "HELP"
 
Quote:

Originally Posted by capecodda (Post 1028606)
When you say behind a settee, is it mounted on a bulkhead (wall that is port/starboard) or behind the settee so it's facing sideways? Sounds like this stuff was partially installed and never tested.

Here is a photo before all the work was done on the boat.
Here's the thing, I went back to the boat yesterday to check some things after doing some reading on the manual. My boat is docked in her slip pointing north for the most part. both the the Auto-helm and the steering binnical show around 108 degrees. Actual the Auto-helm was 112-115 and the binnical was 108. "Well that's south?? What the hell does that mean?





http://i148.photobucket.com/albums/s...ps67adb009.jpg

capecodda 05-12-2013 06:40 AM

Re: Fluxgate compass and the st4000 Wheel "HELP"
 
Your fluxgate looks like it's mounted fine. Pointing the right way, etc.

Now you got me stumped, you say you should be reading around zero degrees magnetic, and you are reading in the low 100's of degrees both binnacle and fluxgate. If one was wrong, I'd have some advice.

Are you docked next to a huge magnet?


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