The mile used for measurement on most navigable waters is which unit?

• A. Statute Mile
• B. Meter
• C. Nautical Mile
• D. Kilometer

Answer: (C)

Distances at sea are measured in nautical miles because navigation relies on the Earth's latitude/longitude grid. One nautical mile corresponds to one minute of latitude, so chart measurements line up neatly with degrees, minutes, and seconds. This makes calculating travel time and distance intuitive: speed is often given in knots (nautical miles per hour), so distance equals speed times time when both are in nautical miles and hours. The nautical mile is defined as exactly 1,852 meters. Land miles or metric units don’t align with the navigational grid effectively, which is why the nautical mile is the standard unit for most navigable waters.