NavList:

Lagan's book has more than a few errors and plenty of fanciful pseudo-history, at least in the first edition. There's still some good stuff in there, but you should double-check everything. I remember that his plan was to describe tools and systems that modern navigators could benefit from that were based, sometimes very loosely, on historical prototypes. That left a lot of leeway for making thing up and getting things wrong...

I seem to recall that he claimed that the sunrise/sunset azimuth was always in the range of due East/West +/- 23.5°. That's true at the equator and not a bad estimate in other parts of the tropics, but it's certainly wrong at greater latitudes. And that's the sort of advice that could lead to some poor navigation in the modern world. It's also the sort of mistake that may well have been fixed in a second edition.

Viking "polar sticks"?? Really? Ask yourself: where is the evidence? Is there one in the museum of leprechauns and gnomes perhaps?? And as David Pike has pointed out, this requires a very long stick and a stable platform for the latitudes in question. Sure, it's true that something like this could have existed, but that's not history. And something like this could have existed in the hands of any navigators anywhere on the globe at any point in the past 50,000 years. It's possible. But is it true?

Frank Reed