ST4000 location of compass?

[andyorr]

Just installed above. Fluxgate compass has to as close as poss to pitch and roll centre of boat. Put mine at cabin sole level just aft of keel - in cupboard under sink. Deviation is 15 degrees. In same cupboard is water pump. Could this cause the deviation. I can only move it further outboard. Will this solve problem?
Thoughts, suggestions welcome.

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[MainlySteam]

I suspect it may be the pump, but not the compass's location with respect to the boat's motion. My Raymarine fluxgate compass sensor is up the mast about 5 m above the waterline and it works no problem at all even in very turbulent conditions (the boat is steel).

I cannot think of any good reason why the sensor cannot be mounted off the centreline of the boat, conventional steering compasses regularly are, but it is the practice to have it on the centreline and that is what I would try to do.

Have you tried checking the mounting location for deviation using a handheld compass?

John

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[AndrewJ]

It would appear as if the flux (magnetic field) from the pump motor (assuming it's an electric pump) is interferring with the
magnetic lines of force to the compass. I notice on mine when I turn on an electric motor nearby, the compass goes a bit awry.


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[sjohn_gibson]

Cor! you just brought back memories of the trials and tribulations that I went through to find a suitable location for my fluxgate compass transducer a couple of years ago.

In the end I had to uncleated the cable and try various positions around the boat using duck tape to hold it in position while I swung the boat. I did eventually win.

DC electric motors have a large pemenant/electro magnet in them and will have an influence on the compass trasducer. It sounds as though you will either have to move the pump or play silly beggars as I did.

Yours
John

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[quaelgeist2]

Pump and other electrical equipment is a problem.
Mounting the flux a bit away from roll/pitch center is not !

Example: Moody - Forecabin bulkhead, main cabin side, about waterline level.

Take a hand bearing compass (same effects, though less sensitive), walk through the cabin and find best place, with power switches on/off for neighbouring equipment.

chris

NB Don't mount it where you intend to store your beeer next season - cans can influence the flux if brought closer than 50cm...


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[Paul_H]

At least you lot know where your flux head is located! Owned this boat a year now and havent found mine yet - but then Ive not looked that hard. Found a sticky label to identify the fluxhead location -loose in the handbook. Found the computer buried in a locker but the fluxhead wire disapears behind a bulkhead never to be seen again.

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[MapisM]

Did you try the compensation already?
I experienced two cases of very strong deviations brought to an accuracy within 1 (one!) degree at any position, after some well done compensation circles.
That was with Furuno and KVH models, but I guess Raymarine should be no exception.
Just bear in mind that the compensation is useless if the magnetic fields are variable.
Maybe the pump could create different fields when turned on - not sure about that.

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[jfkal]

The fluxgate is internally gimballed. Mine is located away from all electrics in the starboard locker. Works fine there. Keep anything ferrous or magnetic as far away as possible.

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[Dave_Knowles]

I have recently had a lot to do with Raymarine over my compass and some interesting this was said. Firstly they set the compass up at their place by turning it slowly by hand on the bench and they said that once set up by them |I did not really need to reset it again on the boat. Also I was told that if I did set it up on the boat and got a high reading it was probably due to turning the boat to quickly so try again until I got the figure down. Generally the impression I got from what they said was that the fluxgate was design to take a certain amount of electrical things around it. As they said it is very difficult to find a position on a motor boat that is clear of electrical items espcially with the had that contains the compass and this had been taken into the design. I found that the wiring was important and eventually wired it via a fuse directly to the battery becuase the every time I switched on the windscreen wipers the current surge effected the autopilot.

As a parting thought and one I put to Raymarine was the best way to see if it works is to see if it holds a course, the compass even if the course read out is incorrect should still hold the course set when you press the auto button. If it does then just go into the setup and correct the reading to your boat compass.

I have spent hours moving the head going round in circles and now find that by putting it back in the original place and leaving the settings they did at Raymarine it works fine.

<hr width=100% size=1>Take care.

Dave

Dave Knowles
Southampton - UK

http://www.MyCleopatra.co.uk

 

[Andrew_B]

My fluxgate compass is mounted off centre in a cockpit locker an works fine UNTIL - my Air X marine starts producing more than 10 amps when it rapidly starts to increase the course shown on the display and send the boat around in circles.
It wouldnt be too bad but when the Air X is making 10 amps its usually pretty windy and not the time to be veering off course.
The compass is arond 3ft from the batteries which in my case obviously isnt far enough.

Andrew

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[Dave_Knowles]

Have you tried wiring it directly to the battery via a fuse. It worked for me.

<hr width=100% size=1>Take care.

Dave

Dave Knowles
Southampton - UK

http://www.MyCleopatra.co.uk