NavList:

Hi Stephen,

I looked and saw that the magnetic north pole is somewhere around 86N, 138E.

There are two main issues with magnetic compasses in high latitudes.  One is the angular difference between the magnetic north pole and the true north pole.  In aviation, this difference, measured in degrees, east or west of the "agonic" line is called "variation".   This "agonic" line is an imaginary line on earth, running roughly north and south, where if one was standing, the magnetic north pole and the true north pole would "line up", and there would be no variation. That is to say, variation on this line is 0 deg. If you were located east or west of this line, you would have to apply a correction to a true direction to arrive at a magnetic heading to fly. And so, whether it would be "easier", I would only offer that if you were on this "agonic" line, you would not have to apply any correction to variation, and that depends on exactly where you were in the Canadian north.  Looks like the agonic line nowadays runs down through the Great Lakes and over through the Southeastern states.  Oh yeah, it's not a straight line, either.

The other issue with magnetic compasses in high latitudes is what they call "dip".  On any magnet, of which the earth is one, the magnetic lines of force dip down at the poles, also causing compass errors.

There are no internal mechanisms in the astrocompass. No clocks or anything like that. Manual set-up every time. Take a look at the picture of the inside cover of Pub TP 784 that I posted.  I think if you click on it, it'll enlarge and you can read it.  It'll tell how to set it up.  Of course, you would need an Air Almanac or a Nautical Almanac, an accurate timepiece, and a close idea of your lat and long. It must be reset as time advances, because the earth turns at the rate of 15 nm every minute.There's also two links to the internet that show a pilot setting one up in day and at night. Take a look at those.  The Air Almanac is not printed anymore, but is available as a free download here: https://aa.usno.navy.mil/publications/aira 

My original post had a link and a phone no. for Transport Canada. I looked and Pub 748 is still available.  However, you have to call on the phone to order it. I don't have a current price. I've never seen an available download for one.

Also, I looked on eBay and there are several Mk II astrocompasses for sale in various conditions. I think that they're considered a military collectible, or something.  Maybe you can find a decent one. I have some wartime reprinted how-to-use pamphlets that I could perhaps copy for you, as well.

Regards,