Cone angle
Also called beam angle, sonar cone
How wide the sonar beam spreads as it travels down. Wide covers more water with less detail, narrow sees a sharper slice.
The transducer does not look straight down a line, it looks down a cone. A 20 degree cone in twenty feet of water covers a circle about seven feet across on the bottom. A 60 degree cone in the same depth covers over twenty feet.
Wider is better for searching, since more water passes through the beam, and worse for precision, since everything within that circle is stacked into one column on the screen. A fish showing at fifteen feet could be directly below you or well off to the side.
Frequency and cone angle are linked. Lower frequencies give wider cones and more depth penetration; higher frequencies give narrow cones and more detail. A dual-frequency transducer lets you switch between the two without changing hardware.
The cone also grows with depth, so the same unit feels precise in eight feet of water and vague in sixty. Marks at the edge of a wide cone in deep water can be a long way from directly below you.
In shallow water use the narrow, high-frequency cone. A wide cone in eight feet of water is mostly showing you the bottom nearby, not below.
Related terms
Where this comes up
The guides that use cone angle and show it on real gear.
Cone angle is one of 206 terms in the glossary.
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