Autopilot fluxgate compass setup

[Badger]

Setting up my new ST4000 Tiller pilot , you are required to set up the fluxgate compass by giving it a magnetic heading (from a reliable source).Given that it is going to be taking inputs from the GPS to steer to waypoints should I use the magnetic heading reading from the GPS or the reading from the ships bulkhead compass.There is about a 4 degree variance betwwen these two right now and the ship's compass hasn't been swung yet. Thanks for any advice.

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[snowleopard]

the heading from the gps is your ground track, not the direction the boat is pointing. migh be better to use a transit and get the bearing from the chart.

or you could tie up alongside and sight across the boat with a hand-bearing compass from a distance.

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[peterb]

If you tie up somewhere then beware of local magnetic anomalies. Particularly noticeable near steel piles. If you're in a marina with steel piles then try taking a series of hand bearing-compass readings of a distant object while walking round the pontoons; it's easy to get a 30 deg error.

Best bet probably is to use the hand bearing-compass, but from a spot that's well away from any disturbing iron.

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[Badger]

ReMAg heading versus COG

I have something on the GPS called COG, course over the ground but this is a reading called MAG Heading.Isn't this the ships heading adjusted just like from the ships steering compass ?

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[claymore]

Re: ReMAg heading versus COG

If you just keep adding or taking away 5 degrees you'll find that you can ignore everything else. the other way to do is is to get a good visual fix on what you are heading for then push the buttons on your autopilot so that the desired object of destination (DOD) is on line with your forestay (OLWYF) and then just let it get on with it. I don't really think it pays to meddle with fluxgate compasses, particularly when offset from the centreline of the boat (CLOB)
Hope this helps

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Claymore
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[Badger]

Homer Simpson moment -DOHHH

Actually I just realised that the HDG MTG on the Multi is coming from the fluxgate compass via Seatalk and the HDG in the Autopilot control head is also coming from the fluxgare compass.So why the 4 degrees difference.., that's right I've got one setup for magentic and the other for true DOHHHHHH !

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[claymore]

Re: Homer Simpson moment -DOHHH

If you are in some way saying that my post helped you solve a problem, then I think it only fair that you say so and give me tha recognition and acknowledgement which I truly deserve.
I did in fact give you some slightly erroneous information in that I refered to the Centre Line of the Boat (CLOB)
In fact, as I'm sure you must realise - I was in fact referring to the Centre Line of the Ship (CLOTS)


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Claymore
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[Badger]

The infamous TLA

I am impressed that you have taken the IT Industry concept of the TLA and extended it for maritime use. However it was RTSL that solved the problem for me.They also told me to RTFM next time.

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[craigbalsillie]

Re: The infamous TLA

The RN thrives on TLA's and could teach IT techies at IBM a thing or 6 down the UPO over a cup of NATO standard,,,

and the RN have been at it longer than the IT lot...

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[Badger]

Re: The infamous TLA

OK, I've sailed with enough ex-military to know that NATO standard is milk and 2 sugars but what's the old UPO ???

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[craigbalsillie]

Re: The infamous TLA

Unit Personnel Office.. where you go to claim back your C28..
and the maco and a whole load of others that i've forgotten, thankfully


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