Measure distance on maps with pen marks on your compass string

If you are a regular user of 1:24,000 scale maps (7.5 minute, the USGS standard) here’s an easy way to measure distance.  At this scale, 2.6 map inches equal one mile in the real world.  If you make marks with a permanent pen on your compass string exactly 2.6 inches apart, you’ll be able to simply lay the string on your map, count marks, and instantly calculate mileage between points on your map.  The compass string also works great to measure distance of curving lines, such as trails, climbing routes or waterways.

A few notes . . .

• Use a sheet of paper under your compass string so the pen won’t mark up your table.
• Making a mark of 2.6 inches on the paper makes it easier to transfer the measurement to your string.
• If you use a map other than 1;24,000 scale, your marks will not equal 1 mile.
• The distance from the last mark to the starting mark will probably not be exactly 2.6 inches.  Use this segment for the knot when you girth hitch the lanyard back onto your to your compass.  This way it can’t be used to measure, as it’s “inside” the hitch.

In the image below, the little “V” marks indicate a pen scale mark on the string.