NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Kieran Kelly
Date: 2005 Jan 30, 14:03 +1100
I recently visited Whistler in British Columbia to experience backcountry
skiing. With me I took a Silva “Ranger” Baseplate compass that has served me
well for about 15 years and had proved rugged and reliable in some of the most
remote parts of Australia. I would, and have, staked my life on it.
To my horror as we were about to leave Whistler on our skiing trip I
pulled out the compass to orient myself and the map and found it would not
work. The magnetised end of the needle pointed downwards and would not swing.
To get the needle to swing I had to hold the compass at about 45d to the
vertical and then the needle would move freely but it was hard to determine an accurate
bearing and impossible to use the compass sighting mechanism.
Obviously the compass was reflecting the fact that Whistler at approx 48
dd North is a lot closer to the north pole than Sydney at 33dd 48m South and a
compass that swings plumb and level in Sydney wont swing plumb and level in Whistler.
This means that when the compass was manufactured in Japan the Silva company made
a presumption that it would always be used in the Southern Hemisphere and was
never intended to be an “all purpose” instrument. I presume that compasses made
for the Canadian and North American markets are similarly adjusted and will not
work in the southern hemisphere.
The compass works fine now that I have returned home.
I have a couple of questions:
- Is
there any way you can tell from looking at a compass what its effective
area of operation is ie are there any codes on compasses?
- If my
compass works at mid latitudes in the southern hemisphere would it also
work at extreme southern latitudes eg Antarctica
- Is
there any way a compass which works fine in the S hemisphere can be adjusted
so that it works fine up north
- Is
the usual practice if you live down here in the south and wanted to ski,
say Alaska or Northern Canada that you would have to buy a compass from a retailer
at the place where you were undertaking the journey. That compass of course
would then be useless when you returned home.
Kieran Kelly
Sydney
Australia
