Maybe something on magnetic variation too Lyle, it is amazing just how often this subject crops up, and how confusing it appears to new and experienced navigators alike.
Oh Please....for the love of god. Mind you, chances are if I manage to nick Ls book back off of my colleague all will be understood.
I get it in parts, but I have so many grey areas (partly that if you have to work out the current GMA from the info printed on the map, what happens with the printable service from OS online where this info is not shown, and more to the point, if the relationship between grid and mag changes on various parts of the map sheet, let alone with time, what it the point of the sites that give the current variation?)....Or have I got GMA and Declination totally middle up and should I go and use the compass lanyard for something more constructive.....?
Its one of these things that once understood clearly, you get it. Then the challenge is getting it across to others.
Anyhow...happy xmas and new year folks, I will naff off and read....just off out onto the forest with 2 smelly spaniels and a new Sunto....see you next summer....probably