How do you measure a distance that is longer that the span of your dividers?

Assume that you are sailing from point A to point B.

The true course is 110°, and you want to know how many nautical miles it is from A to B. However, the distance to be measured is greater than the divider’s span.

Use the dividers and span a distance of 10 miles on the latitude scale which is closest to point A and B. Walk the dividers along the course as many times as needed until you get close to point B, and mark the last point as point X. In our case we need to walk the dividers three times. That makes 3 times 10 miles, equalling 30 miles. Now measure the distance from point X to point B and apply this span on the latitude scale which is closest to point B.

On the scale you find that in this case the distance is 4 minutes or 4 nautical miles. So the distance from A to B is 34 nautical miles; 30 miles plus 4 miles.