Hobo - yes, 1 nm = 1minute of arc along ( up and down ) the Longitude. I think technically that is supposed to be made at the Equator - but who's counting ?
Except that the difference had to be considered if using a Mercator chart in high latitudes, as the scale expanded towards the Pole.
As we now seem to measure distance in decimals of a minute via iPad GPS, I don't recall if we bothered about any distance less than one mile, which might seem a huge error now, but the scale of the charts we used meant that the thickness of ones' pencil line was almost a mile, anyway, and as our allowed "track error" was 10 nm ( IIRC ) we had a 20 nm "road" at our disposal, so corrections less than 1 nm were irrelevant. You description of Astro plotting is correct.
Will PM ref: the beer, I see that Amazon are considering Drone delivery now !
finncapt - Canada .... Once passed North of Goose Bay Westbound, not having had a fix for some time, en route Detroit I think. After about another hour of no fix capability finally admitted to the Captain that I was "temporarily unsure of my position". Using my presumed best guess he reckoned we were in range of the DEW Line, that line of radar Defence Early Warning stations stationed across Northern Canada in those days, and called for assistance - they couldn't see us !
Eventually a Canadian pilot asked where we thought we were, and having been told asked if I could see a 'spot height' on my chart of 1560 ft. ? ( or whatever it was ) Yes. Well it isn't a spot height, it's a misprint, it's a local broadcast station, try your ADF. Using that I eventually proved that in fact we were only about 40 miles off track - which after a long time without a fix wasn't as bad as it might sound now, it's the uncertainty that gets you wound up.
The mighty US of A Defence Early Warning system never did see us !
Happy Days.