What are some tools to navigate distances by boat?

BoatBookings.com has an online tool that allows users to navigate distances by boat using Google Maps. Dividers and nautical charts are analog tools used for measuring distances on open water.

To use dividers, place one point on the boat's starting point and the other at its final destination on the nautical chart. Keeping the dividers open to maintain the distance between the two points, move them over to the latitude scale on the nautical chart. Each minute on the chart is equal to one nautical mile on the water. To measure distances greater than the span of the dividers, draw a line to use as a guide and then walk the fully opened dividers to the final destination.