In navigation, what is a "cross bearing"?

A "cross bearing" refers to the practice of taking bearings on two or more identifiable landmarks or objects from a vessel's position to determine an accurate location. By measuring the angles (bearings) to these known points, a navigator can triangulate their position on a chart by finding where the lines of bearing intersect. This method is particularly useful in scenarios where GPS may not be reliable, as it allows for a quick assessment of one’s position using visual references.

The other options do not accurately define a cross bearing. The first option’s description pertains more to techniques used in poor visibility rather than to the specific method of using bearings. The third option describes a technique related to GPS triangulation, which is a different navigation approach altogether. The fourth option addresses distance rather than angular relationships, which are central to the concept of cross bearings. Thus, the choice that best encapsulates the definition of "cross bearing" is indeed the measurement of angles between two objects to determine position.