Thread: Sonar Quiz #45

I asked because that image of the beam shapes made it look like 800khz stops well short of the vertical center line. Wasn't sure if I should do 2d and SI combo instead of the triple view when using that frequency. I like the DI view as well as 2d, even though it isn't as clear as my dedicated DI I still find myself much better able to figure out fish sizes and structure shapes.

except for true di,the di you would be seeing is from your si,and if si did not see it di could not see it

Originally Posted by OrangeAgent

I asked because that image of the beam shapes made it look like 800khz stops well short of the vertical center line. Wasn't sure if I should do 2d and SI combo instead of the triple view when using that frequency. I like the DI view as well as 2d, even though it isn't as clear as my dedicated DI I still find myself much better able to figure out fish sizes and structure shapes.

The 800kHz has definitive side lobes that continue past vertical under the boat (as seen in the diagram) ...



There are several factors of Sonar frequency that come into play when deciding which frequency to use ...

*800kHz will be more detailed with less range (as depicted below - the outer edges of the 800kHz are getting darker quicker) ...

*455kHz will be less detail with more range (as depicted below - the outer edges of the 455kHz are brighter but the entire SI is less detailed) ...



Rickie

That is great info, I have seen that screen shot floating around the net but never with a good explanation to go with it. I was thinking that the 800kHz was just a narrower beam so you lost some of the upper part of the water column at the edge of the range but had more detail of the bottom.

So if I am going under a bridge with a span between the pilings of say 80 ft, if I use 800khz and a 50ft range I will still see the tops of the pilings but with super detail? I will have to take a sd card with me next time I go out I have been scanning these monster schools of shad and fish under some bridges I fish often.