Fishing Boat Accessories: Fish Finders

Fishfinders, also called fishing sonars or echo sounders, display a representation of what is under the water--the bottom, vegetation, structures, and fish. Systems come in single and double frequency models, but single frequency is adequate for most lakes and shallow coastal fishing.

Fishfinders use a submerged transducer, mounted on the transom, inside the hull, or on the trolling motor, to send and receive underwater high-frequency sound waves. A cable connects the transducer to the fishfinder. The unit’s specialized software figures out the distance to detected objects, and a graphic display uses shades of gray, symbols, or bright colors to represent structures, the bottom, different temperature layers, schools of fish, and even individuals. 

 

Fishfinders present their results on liquid crystal display (LCD) screen. LCD displays are measured in pixels - the little square blocks on the screen that make up the image. More pixels provide better resolution and a clearer picture. There are three main types of fishfinder displays:

 

Good fishfinders locate thermoclines, layers or abrupt changes in water temperature, and can help you catch fish. The contact between radically different temperatures causes some of the sonar signal to reflect back, creating a line across the LCD screen that indicates the thermocline, and potentially, fish.

 

Newer fish finders offer split and full screen zoom, real time imaging, adjustable backgrounds, and a choice of color palettes to highlight bottom structure or a particular fish species. An optional fuel kit enables you to track and display fuel data on screen.

 

Read our list of fish finder brands and manufacturers.