I don't know if this would be any help to you, and I don't know for sure
that they still do it, but Ritchie used to sell several different compass
cards for their Globemaster compasses, weighted according to the latitude
you'd be using the compass in. I can't lay my hands on my Ritchie catalog
right now, but I recall that there was a diagram that divided the
hemispheres into a number of bands and recommended a specific card for each
of the bands. Seems to me that a card was good for a center band and one
band on each side of it without too much dip.

For a hemisperical compass (i.e., with a flat cutoff on the bottom rather
than a true spherical shape), a northern-hemisphere compass will actually
hang up on the bottom of the compass when you get far to the south, because
of the extreme amount of dip. Powerboat compasses tend to be hemisperical.
Most sailing compasses, too, I believe. Ritchie's Globemaster is an
exception.

Tom Dacon

"Evan Gatehouse" wrote in message
...
Anybody have any experience using a Northern Hemisphere compass as far
south
as say New Zealand? I *know* you're supposed to have a s. hemisphere
compass in an ideal world, but I'm wondering how much the card deflects
i.e.
is it still useable, even if tilted.