• Ash

Nav puzzle 12 and a challenge

Okay, so this week most of us in the UK can get outside our house and explore a little bit, so along with a puzzle there is a challenge at the end of this too.


So, last week we looked at how transit lines can line up two physical objects.


This week we're going to do the same thing, but using a bearing on our compass.


Imagine you're sailing up the very beautiful Cardigan bay.

You know you are sailing along a certain line, like this

The dolphins are playing around on the bow, and sun is sparkling on the sea... [DREAMS]


You can spot the end of the point of the south side of the river entrance, and you keep sailing along your path until your compass bearing to that point is 090°.

This then gives you a position line along your route.


So for the puzzle this week, we'll define our path by using roads. See if you can locate these two points?


  1. If you start at SJ 0220 3263 and head North, what is your grid reference when the summit cairn at SJ 0780 3459 bears 093°?

  2. If you drive West along the A4212 starting at SH 9270 3625, what is your grid reference when the summit cairn at SH 8208 4152 bears 334°?


You can see that there is a difficulty in being super accurate, but it can give you a very good rough and ready location along a known point.


For this weeks challenge, get outside responsibly and safely (whoopie) with a map and compass. Plan a walk, run or cycle along a reasonably straight road or track and identify a landmark at roughly right angles to your direction of travel that you can find on a map. Set a bearing on your compass to that landmark you identified, at a point of the track where you can work out your own grid reference. Now with your compass set, travel along the track, checking the bearing against the point you identified, until the compass direction points at that identified landmark. You should now be able to see that you are at your chosen grid reference along the track. If you have a phone with an OS GB grid reference app (Like the free OS Locate ) or a GPS that shows grid references you can test yourself to see how accurate your compass work is!

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