A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Date: 2005 Jan 30, 14:54 +1100
From: Kieran KellySent: Sunday, January 30, 2005 2:03 PMSubject: Re Compass Adjustment - A Cautionary tale
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.