### Finding 6 digit grid ref Letterboxes - How to calculate

Posted:

**Fri Jan 13, 2012 5:50 am**Just wanted to ask how to go about finding 6 digit grid ref Letterboxes and how to calculate.

I learned once that in Memory Map I can draw lines from given points that are mentioned in the clue and see how all three lines cross at a specific point where the box is. Also read that I have to add or subtract °degrees.

But somehow using the many 6 digit grid refs I have I never end up with all three lines nearly near each other ... Anyone know how to calculate using Memory Map. Also after plotting on the map, also how to use the Silva 54 compass or any compass then once I am in the area of the box. I seem to always walk in one direction noticing that I am near the second point to target, but then the third point to target does not match at all.

Also does anyone of you have the old Word docs, where many many given obstacles, known places, poles etc. are listed, there are Word documents around that are older than 2000 and have this information I believe from the 90ties.

I learned once that in Memory Map I can draw lines from given points that are mentioned in the clue and see how all three lines cross at a specific point where the box is. Also read that I have to add or subtract °degrees.

But somehow using the many 6 digit grid refs I have I never end up with all three lines nearly near each other ... Anyone know how to calculate using Memory Map. Also after plotting on the map, also how to use the Silva 54 compass or any compass then once I am in the area of the box. I seem to always walk in one direction noticing that I am near the second point to target, but then the third point to target does not match at all.

Also does anyone of you have the old Word docs, where many many given obstacles, known places, poles etc. are listed, there are Word documents around that are older than 2000 and have this information I believe from the 90ties.