What navigation line maintains a constant true direction?

• A. Straight line
• B. Rhumb line
• C. Great circle
• D. Curved line

Answer: (B)

The correct choice is the rhumb line because it is defined as a path on the Earth's surface that crosses all meridians at the same angle. This consistent angle results in a true direction that remains constant, making it easier for navigators to follow when using traditional navigation techniques. Rhumb lines are particularly advantageous for chart work as they simplify course plotting and steering over longer distances.

Unlike great circles, which represent the shortest distance between two points on the surface of a sphere but do not maintain a constant heading, rhumb lines provide a straightforward navigational route despite not being the shortest distance between two points. Straight lines and curved lines are more general terms that do not specifically indicate the navigation characteristic of maintaining a constant true direction.