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    Re: Re Compass Adjustment - A Cautionary tale
    From: Glendon
    Date: 2005 Jan 31, 00:30 +1100

    ----- Original Message -----
    From: "George Huxtable" 
    Sent: Sunday, January 30, 2005 10:48 PM
    Subject: Re: Re Compass Adjustment - A Cautionary tale
    >. Unfortunately, this
    > renders the compass more susceptible to the sideways accelerations of a
    > vessel in a seaway. Also, the geometry was altered so that the card could
    > tilt further before it fouled anything. In that way it was possible to
    > a compass that would work anywhere in the world, but it's a matter of
    > compromise.
    > Presumably, a compass that's designed to operate in a restricted zone of
    > magnetic latitudes would be a better performer, in terms of motion
    > stability, than a "global" compass.
    George, I don't understand what you are saying here, and wouldn't mind a
    reference or source  to help develop what you are saying. My imperfect
    understanding at the moment is that the only difference between a zoned and
    a global needle is the bearing that the needle/card rides on. As I
    understand it, a global needle is based upon a more intricate and expensive
    bearing. A bearing that allows the needle to swing freely, despite the force
    of magnetic dip upon it. Properly built, it is unclear to me that a global
    needle will function any different to a zoned needle.
    Your comments on compass adjustment support my growing belief.....that
    ship's compass adjustment is to neutralize the magnetic effect of the ship,
    and that adjustment for magnetic dip is a separate issue, to be addressed by
    weights , etc.. However, I would love to hear from a professional compass
    adjuster on this issue.
    Lee Martin

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