Thread: Question about fish on graph

It is extremely helpful to have two fish finders on a boat.Even if the second one is a cheap one. It is invaluable to see how two different sonars interpret a target. You can buy a cheap dedicated di unit. When you really want to just set up on top of something and get an accurate picture and compare the two units it can really help .

Originally Posted by OrangeAgent

Down imaging transducers have a beam that is aimed straight down. The cutaway above shows how the beam producing elements in an SI transducer are aimed out to the sides (for reasons which should be obvious). The down imaging screen on an SI unit is a computer generated image of a blend of the left and right sonar returns that are directly under the boat. Since the strongest returns come from the center of the imaging beam, the down imaging returns on an SI unit often leave something to be desired versus the down imaging returns from a DI unit. I still find that I prefer to include the DI returns in the triple view rather than just 2d and SI, you still get a much better idea of the size of fish and the shape of brush and such. I have been thinking about trying contour mode for my SI when not viewing SI only since I don't really need a big chunk of my display showing me the water column when I am already seeing it in 2d and DI.

Rickie