Making a Quadrant Calculator

[Gustav Schiebert]

Some of you might remember the KTBs I made. Well part of keeping a real war diary is plotting a 4-figure KM grid - AM5217 rather than AM52 which is marked on the game. Usually I look at the map, get a ruler out, and work out where I am on the screen to get my position.

I could do this by measuring the entire grid and dividing it into 9x9 squares. So, if the grid is 9cm long along the x axis, and my sub is, say, 1.5cm along, I know it's in the second column of squares. Do it for the y axis and you have your position. Make sense? No? Okay...

• Here you can see, I've measured the size of a grid square at a specified zoom level.
  
• Then I've cut that shape out of an index card.
  
• The whole thing gets put through a laminator.
  
• Then a 9x9 grid is drawn on, and the numbers filled in.
  
• Be aware that there are different sized grids in different areas of the map! I did this twice.

So I can read off my current position (pretty accurately, but not perfectly) as BF5818!