You’re coming into a harbor and your electronics aren’t working (believe me, it happens). You need to figure out how far away you are from making a landfall. Here is some great advice from Skipper Tips about how to figure this out on your own: In a pitch black night, you squint through the binoculars to try to pick up Libby Island lighthouse off the rugged coastline of Maine. The nautical GPS shows you dead on track and the light should be visible from 18 miles (note the abbreviation 18M). Right now, you estimate you are just about 18 nautical…