About single target ranges

The range of a single target measures its distance from the center of the transducer face. The beam-axis distance is a related concept which measures the distance of a single target from the transducer face along the beam axis.

Beam-axis distance is visible only on the 2D projections graphs and ensures that a straight line in physical space (as a fish may swim) appears as a straight line on the projections displayed on this graph. It is orthogonal to both the minor-axis and major-axis distance (which measure distance along the minor and major axis of the transducer respectively).

The difference is illustrated below.

Note: Beam-axis distance cannot be exported, and is not used in the calculation of range related analysis variables.

See also

About depth, range and altitude
About single target depths

About analysis variables