What does the term "chart scale" refer to in navigation?

The term "chart scale" in navigation refers to the ratio between a distance on a chart and the corresponding distance on the ground. This measure is crucial for navigators as it helps to accurately interpret distances and sizes when navigating using nautical charts. For example, if a chart has a scale of 1:50,000, this means that one unit of measurement on the chart (e.g., an inch or a centimeter) represents 50,000 of the same units in reality. Understanding the chart scale allows navigators to compute actual distances based on their measurements, ensuring safe and efficient navigation.

Other options cover different concepts related to navigation. Communication of location pertains to methods of transmitting a ship's position, while measuring a ship's speed through water involves concepts unrelated to the chart's scale. Plotting navigational data on a map is an essential skill but distinct from what chart scale specifically denotes.