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From: Brian_Sullivan@Carleton.CA (Brian Sullivan)
Subject: Re: looking for fluxgate
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Date: Tue, 4 Apr 1995 17:44:44 GMT
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In article <3lrohp$dvr@polytechnique.polytechnique.fr> jnguyen@olympe.polytechnique.fr (Julien Nguyen) writes:
>From: jnguyen@olympe.polytechnique.fr (Julien Nguyen)
>Subject: looking for fluxgate
>Date: 4 Apr 1995 15:27:53 GMT

>* WARNING * 

>this mail is not from me but from a friend who cannot post. don't send anything
>to the adress above please

Why not if the friend has access to news, they should have access to mail ????

>------------------------------------------beginning of
>message----------------------------------------------
>        I'm a  french student in  electronics engineering  and i'm working on a
>new automatic pilot for
>transoceanic sailboat.
>        I have a big problem with it because most of recent ones use a fluxgate
>compass
>and i don't know anything about such a system.

I believe this is how it works:

    Take an iron donut
    Put two coils around it, one at 12 and the other at 3 Oclock
    Send a plus from 12, and see how long it takes to read it at 3
   Depending on the relationship between 12 and mag north times will vary

This thing doesn't really know where north is so much as now if you are off 
track. You set your course, measure the time and try to keep it the same.

>        That would be kind to send me anything concerning this mechanism 
>and if you have any books references
>for bibliography, i'm very interested on.
>        
>                        Thank you very much for your kindness.

>                                Jerome JOANNY

>email address : joanny@enserb.u-bordeaux.fr
Spent 8 weeks sailing on the east coast of USA last fall. On one boat that 
used the fluxgate and one that used a GPS link.

The fluxgate sucked. On some tacks ( Beam reach or running) things were fine. 
But point it into the wind, get a bit of roll and it kept loosing track of 
where it was. The system we had refused to hold a cousre 35-60 off the wind.
Set it and in time it would settle in at 62-65 off.

I will admit this was one of the cheaper units. But talked to a few others who
had more expensive, and only those with the GPS link were happy.
