Page 2 of 2 FirstFirst 12
Results 11 to 13 of 13
  1. #11
    Join Date
    Sep 2004
    Posts
    4,180

    Default Re: Compass in southern hemisphere (Auckland)

    Magnetic dip in Auckland is quite a bit greater than 60 degrees (comparatively large for its latitude due to its relative proximity to the South magnetic pole when compared to geographic latitude) - so about the same as in the northern part of Bay of Biscay and quite a bit more than the Med. with which it shares, roughly, the opposite latitude.

    What I think most people think is that the card inclines to the extent of the dip or think that the error introduced by dip is important. The earth's magnetic field is very weak so the vertical component of that to the earth's surface is even weaker, even when dip is large. Compasses are normally pivoted with their centre of gravity below the pivot centre so that the pendulum effect largely offsets dip in so far as the tilt of the card is concerned.

    As far as I know any reputable compass uncorrected for dip will work anywhere (except to the extent of getting dizzy close to the poles) - at least I have not heard of any that don't and have never heard of it being a problem. Dip in Scotland is around a comparatively high 70 degrees, so quite high, and I wonder if anyone has had problems with a reputable uncorrected for dip compass there.

    The error from magnetic dip is only apparant in turns and during acceleration so is not of concern in a sailboat. But is in aircraft, for example, and for fast commercial MoBo's, 40 knotsish, have usually specified dip correction - hence my comment before about sea trialing for commissioning boats with Northern dip corrected compasses in the Southern hemisphere.

    John
    <span style="color:blue">www.sailroom.co.uk</span>

  2. #12
    Join Date
    Oct 2006
    Posts
    5

    Default Re: Compass in southern hemisphere (Auckland)

    The compass will work fine so long as he stands on his head.
    Captain Cook first discovered this phenomenon back in 1769 before he had special inverted compasses installed which he flipped over as he crossed the equator (like an egg timer).

    How close can this boy hold a compass course anyway?

    Man with watch always know time, man with 2 watches is never sure.

    follow my advice? ... I wouldn't so why would you?

  3. #13
    Join Date
    Nov 2004
    Location
    18A, Linear North
    Posts
    1,740

    Default Re: Compass in southern hemisphere (Auckland)

    [ QUOTE ]
    Dip in Scotland is around a comparatively high 70 degrees, so quite high, and I wonder if anyone has had problems with a reputable uncorrected for dip compass there.


    [/ QUOTE ]

    The b@stards seem to be able to find their way south easy enough. [img]/forums/images/graemlins/wink.gif[/img]
    Rum, it's not just for breakfast anymore.

Page 2 of 2 FirstFirst 12

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Find Boats For Sale

to
to