can someone please explain why, according to the author of a history of the WW2 Artic Convoys, a giro compass would prove as unuseable for navigation in very high latitudes as a magnetic compass, due to its tendancy to,' point to a distant star'.
Not completely sure but as soi disant panel member for electronics department I'll have a go. Actually somebody siad they were a pilot before, was it Mrs S? I'm sure a pilot person would know. Meantime......
A giro compass doesn't naturally point north, it simply points in one fixed direction no matter how much you turn the boat or plane. To use it as a compass you have to set it first to point north and from then on it will continue to point north. (er until it needs resetting again). But to set it in the first place you need a compass that works, that is reliably pointing north. I think in the old days they used magnetic slave compasses, nowadays the electronic jobs use fluxgate, but the point is you need to be close enough to the planet earth to set it pointing north in the first plce, after that you can climb to the outer atmosphere and into space and stuff. Best to get proper training for that first, at least coastal skip I would think.
The type of compass used on big ships is designed to be north-seeking, and should align itself with the Earth's axis. But if you are near the N pole, then the giro will be pointing nearly vertically, and thus gives little help in defining horizontal directions.
This is correct - the magnetic lines of flux near the poles are near vertical as seen from ground. So it'd be pretty useless for finding the pole, so you'd just have to look for the flag. Or hang about and wait for something like a Pole (say, a Norwegian) and follow them.
Also, Mrs S is PPL (lapsed a bit) and knows what a compass is, but they don't ask more than that in the exams. Everyone thinks airplane pilots are ace at physics, but actually they know how to press the buttons and say "foxtrot one-eight-zero charlie tango mary barbecue"